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During the actual operation of the power plant, the steam turbine will appear to operate under low load conditions. This paper proposes a novel water spray arrangement for the exhaust channel. Spraying ports are evenly arranged on the cone wall so that the direction of water spraying is opposite to that of the exhaust steam flow (reverse spraying). The feasibility of the nozzle was verified by simulation calculations of existing wind tunnel experiments. The results show that evaporation increases with decreasing load. And the evaporation volume is greater in the reverse spraying than in the down spraying (the direction of water spraying is the same as the direction of steam flow), with a maximum difference of 0.42 kg/s. The deterioration of the aerodynamic performance in the exhaust passage after water spraying can be attributed to the combined effect of the evaporation of water droplets and droplet interference with the flow field. The maximum reduction of 8.17% in the static pressure recovery coefficient in the reverse spray mode increased the total pressure drop by 377.4 Pa. After the water spraying, the temperature dropped significantly compared to before the water spraying. In reverse spraying, the vortex scale in the exhaust passage becomes larger, the return vortex flow increases, the volume absorption ability is stronger, the water droplets and steam contact time is long, good temperature reduction is achieved, and the temperature of the leaf root high-temperature zone is reduced. The maximum difference in temperature drop between the two spraying methods is 56.87 K. The results of this paper provide a reference for the cooling of the exhaust passage when the turbine is operated under low flow conditions for a long time. [ABSTRACT FROM AUTHOR]

This study delved into the efficacy of enhanced oil production (EOP) within perforated horizontal wellbores across diverse flow profiles. The authors implemented five distinct configurations, encompassing uniform radial air injection (profile 1) and variable radial air injection (profiles 2–5), with a particular emphasis on the concomitant production of liquid and air phases. Additionally, the study examined the frictional behavior along the perforated wellbore. Liquid production was demonstrably amplified throughout the bubble, plug, and slug flow regimes; however, a decline was observed in the stratified, stratified transition, and stratified wave flow regimes. Notably, the liquid product exhibited a direct correlation with both the mixture flow rate and its associated Reynolds number, signifying an increase with holdup and a decrease with void fraction. Conversely, air production displayed a positive association with a higher air flow rate. Overall, profiles 2 and 4 yielded the most favorable production during the bubble, plug, slug, and stratified flow regimes. In contrast, profile 3 emerged as the optimal configuration for the stratified transition and stratified wave flow regimes. The friction factor remained relatively constant with profile 1, experienced a reduction in profile 2, and exhibited an escalation in profile 3. Additionally, it increased in the middle of profile 4 and decreased at the center of the perforated section in profile 5. The friction factor behavior of profile 1 remained stable and smooth due to the invariant air flow rate throughout the perforated section. Conversely, some fluctuation was observed in profile 2 due to the inherent variability of the radial air injection along the perforated section. Importantly, the experimental and numerical results demonstrated satisfactory agreement across all flow patterns, with some minor discrepancies noted in the static pressure drop behavior during the bubble, dispersed bubble, and slug flow regimes. [ABSTRACT FROM AUTHOR]

• Contact vibration model between a rigid punch and a half-space with hysteretic damping considering couple stress is studied. • The size effect has a pronounced impact on the peak effect of the dynamic contact stiffness and reciprocal receptance. • The real parts of the reciprocal receptance and dynamic contact stiffness are sensitive to the internal friction. This paper investigates the contact vibration between a rigid spherical indenter and a half-space with hysteretic damping within the framework of the couple stress theory. Firstly, the static contact pressure is determined by using the integral least square approach. Subsequently, the dynamic contact pressure is obtained through the perturbation technology, and the dynamic contact displacement is obtained by employing the Hankel transform. Finally, the receptance is obtained and the dynamic contact stiffness is deduced by adopting approximate dynamic displacement boundary conditions under the assumption of a sufficiently small oscillation force. Parametric studies are presented to clarify the effects of the characteristic material length, Poisson's ratio, shear modulus, and internal friction on the reciprocal receptance and dynamic contact stiffness. The results obtained reveal that the size effect has a pronounced effect on the peak values of the dynamic contact stiffness and reciprocal receptance. Furthermore, the present work provides a useful theoretical framework for applying contact resonance microscopy techniques to micro-structured materials. [ABSTRACT FROM AUTHOR]

Collapsibility significantly impacts the bearing capacity of pile foundations in loess areas. To improve the load-bearing capacity of piles, the pile-base postgrouting technique is widely used worldwide. However, there are still several related issues to be solved: the impact of loess collapsibility on the bearing capacity; the effectiveness of the pile-base postgrouting technique in enhancing the bearing capacity; and the diffusion pattern of the grout during the grouting process. To investigate these issues, this experiment utilizes a visual static pressure device combined with numerical simulation. According to the experiment, the maximum axial force and neutral point appeared to shift downward after grouting, resulting in a 17.5% increase in the bearing capacity of the pile foundation. Additionally, an increase in grouting pressure leads to a rise in both the number of shear cracks and the diffusion radius. As the permeability of the grout improves, the number of shear cracks and diffusion radii tend to stabilize after an initial increase. These discoveries enable a thorough analysis of the changes in side friction and base resistance of postgrouted piles in collapsible loess. Furthermore, they provide valuable references and guidance for the implementation of the pile-base postgrouting technique in loess areas. [ABSTRACT FROM AUTHOR]

We describe a method to run simulations of ground or excited state dynamics under extremely high pressures. The method is based on the introduction of a fictitious ideal gas that exerts the required pressure on a molecular sample and is therefore called XP‐GAS (eXtreme Pressure by Gas Atoms in a Sphere). The algorithm is most suitable for approximately spherical clusters of molecules described by quantum chemistry methods, Molecular Mechanics or mixed QM/MM approaches. We compare the results obtained by the algorithm here presented and by the XP‐PCM approach, based on a continuum description of the environment. As a test case, we study the conformational dynamics of 1,3‐butadiene either as an isolated molecule (“naked” butadiene) or embedded in a cluster of argon atoms, under pressures up to 15 GPa. Overall, our results show that the XP‐GAS QM/MM simulation method is in good agreement with the XP‐PCM QM/Continuum model (Cammi model) in describing the effect of the pressure on static properties as the equilibrium geometry of butadiene in the ground state. Furthermore, the comparison of XP‐GAS simulations with naked butadiene and butadiene in argon shows the importance, for XP‐GAS and related methods, of a realistic representation of the medium in modelling pressure effects. [ABSTRACT FROM AUTHOR]

In this Letter, we present the generation of terawatt-scale few-cycle short-wave infrared (SWIR) lasers using nonlinear compression in a large-core gas-filled hollow core fiber. Through the experimental verification, we investigate the energy scaling properties and nonlinear pulse propagation in the argon-filled hollow core fiber. At static pressure, the system delivers pulses with 5.55 mJ/9.04 fs at a central wavelength of 1.45 μm, resulting in a peak power of about 0.5 TW. Subsequently, based on the chirped input pulses and pressure gradient, the system delivers terawatt-scale two-cycle SWIR pulses with 9.52 mJ/10.65 fs, resulting in a record peak power of about 0.7 TW. This study marks a crucial advancement in the field of SWIR ultra-intense, ultrashort pulse nonlinear interaction platforms. This high-energy, few-cycle SWIR source has significant applications in high-intensity THz radiation, x-ray generation, and other fields of strong-field physics. [ABSTRACT FROM AUTHOR]

A circular non-touch mode capacitive pressure sensor can operate in both transverse and normal uniform loading modes, but the elastic behavior of its movable electrode plate is different under the two different loading modes, making its input–output analytical relationships between pressure and capacitance different. This suggests that when such a sensor operates, respectively, in transverse and normal uniform loading modes, the theory of its numerical design and calibration is different, in other words, the theory for the transverse uniform loading mode (available in the literature) cannot be used as the theory for the normal uniform loading mode (not yet available in the literature). In this paper, a circular non-touch mode capacitive pressure sensor operating in normal uniform loading mode is considered. The elastic behavior of the movable electrode plate of the sensor under normal uniform loading is analytically solved with the improved governing equations, and the improved analytical solution obtained can be used to mathematically describe the movable electrode plate with larger elastic deflections, in comparison with the existing two analytical solutions in the literature. This provides a larger technical space for developing the circular non-touch mode capacitive pressure sensors used for measuring the static gas pressure (belonging to normal uniform loading). [ABSTRACT FROM AUTHOR]

Background/Objectives: Studies have reported that patients suffering from ankylosing spondylitis (AS) have decreased postural stability in comparison to healthy subjects. Our study aims to compare static plantar pressure and stabilometry parameters in AS patients who performed an 8-week exercise program (spine motion and flexibility exercises; stretching of hamstring, erector spine, and shoulder muscles; control abdominal and diaphragm breathing exercises and chest expansion exercises), in three different testing conditions (eyes open, eyes closed, and head retroflexed). Methods: Plantar pressure (the loading of the first and fifth metatarsal heads (MT1, MT5) and calcaneus) and stabilometry (CoP path length, 90% confidence ellipse area, and maximum CoP speed) were recorded in 28 AS patients (age 56.64 ± 10.3 years; body mass index 29.4 ± 4.9 kg/m2) at the beginning of rehabilitation and after 8 weeks. At first evaluation, there were significant differences (p < 0.05) for the foot loading sites (MT1, MT5, and calcaneus), both for the right and left feet, when comparing eyes open with the other two testing situations. Results: After rehabilitation, significant differences were recorded between eyes-open and head-retroflexed conditions for MT1 (p = 0.03 for right; p = 0.004 for left) and calcaneus (p = 0.014 for right; p = 0.011 for left). A significantly higher CoP path length was registered in both initial and final assessments when tested with eyes closed. The maximum CoP speed had increased values at both evaluations when tested with head retroflexed. Conclusions: The CoP path length decreased after the physical exercise program, with a better postural stability after rehabilitation. [ABSTRACT FROM AUTHOR]

Fertigation technology plays a crucial role in the fertilizer utilization efficiency and sustainable development of modern agriculture. Among them, the piston-type fertilizer injection pump serves as the vital equipment for the uniform fertilizer injection in the large-scale irrigation systems. In this study, the numerical investigation and experimental validation were presented on the internal flow and external performance of the piston-type fertilizer injection pump during reciprocating motion. A three-dimensional numerical simulation model for the transient flow in the piston fertilizer injection pump was established based on the dynamic mesh and the RNG k-ε turbulence model. The gap between the dynamic mesh boundary and the static boundary was treated by thegap model with zero mass flux into the gap grid. The motion of the valve core in the flow field was analyzed by the six degrees of freedom (6DOF) solver. The external properties of the piston injection pump under different conditions were investigated, and the internal flow field characteristics of the pump under nominal condition were analyzed. The reliability of the numerical simulation model was verified by comparing the predicted flow rate with the experimental and theoretical data. It was found that the maximum relative error between the predicted and the experimental time-averaged flow rates was 3.58% for different strokes. The instantaneous flow rates were obtained from the numerical simulations and theoretical calculations. A high degree of consistency was demonstrated in both magnitude and trend, with the maximum relative error of 3.17%. The high velocity zone was concentrated in the flow channel of the outlet check valve, with the maximum velocity of 7.74 m/s, during the discharge phase of the pump. While a significantly increased pressure observed in the pump chamber with the maximum relative static pressure of 69.1 kPa. In the suction stage of the pump, the high flow velocity area was mainly concentrated in the inlet check valve channel. The maximum flow velocity of 8.05 m/s was found to increase the vacuum degree within the pump, resulting in the minimum relative static pressure of -79.8 kPa. In contrast to the discharge stage, the liquid in the suction process entered the pump cavity through the inlet valve, and then impinged on the wall of the pump chamber, indicating the complex mixing and turbulent structure within the pump cavity. There was a lag behavior at the initial stages of both the discharge and suction during the reciprocating motion of the piston. The formation of backflow was attributed to the delayed closure of the inlet and outlet valve core. A sudden change in the instantaneous flow rate of the fertilizer injection pump was also observed. The time of the sudden change was consistent with the time of valve core closure. The amplitude of the flow rate variations in the inlet and outlet valves at the sudden change point were equivalent. The timeaveraged flow rate of the fertigation piston pump showed a positive linear correlation with the ratio of piston stroke (k) and reciprocating frequency (f). The volume coefficient of the fertilizer injection pump decreased with the decrease of the piston stroke, but there was no significant change with the reciprocating frequency of the piston. Meanwhile, the measured volume coefficient of the variable frequency regulation differed by only 2.65% from the rated operating condition at the low flow rate (k=20% and f=10 Hz). In contrast, the volume coefficient of the variable stroke regulation differed by as much as 13.94%. Therefore, the frequency modulation control can be expected to more accurately regulate the flow rate of the piston injection pump. It is an optimal strategy for regulating the fertilizer injection in fertigation systems. The findings can provide a strong reference to optimize the fertigation piston injection pump. [ABSTRACT FROM AUTHOR]

Blending a specific proportion of hydrogen into a natural gas (NG) pipeline network is an effective strategy for achieving long-distance, large-scale, and cost-effective hydrogen transport. Static mixers played a crucial role in this process. In this study, a coaxial shear static mixer with ring-shaped structures instead of turbulence elements is proposed. The mixer exhibited favorable mixing performance and low pressure loss. The flow characteristics of NG and hydrogen within the mixer were investigated with computational fluid dynamics (CFD) methods. The effects of the number of cavities, hydrogen pipe diameter, hydrogen blending ratio and pressure on the mixer performances were investigated, taking into account both mixing uniformity and pressure loss. When the number of cavities in the coaxial shear mixer increases to 48, the mixing uniformity reaches 95.43% (SMX is 95%), and the pressure loss is 67.02 Pa (SMX is 500 Pa). • High mixing uniformity and low pressure loss in the new coaxial shear mixer. • Effects of structural and operating parameters on mixer performance analyzed. • Coaxial shear mixer performs better than SMX mixer. [ABSTRACT FROM AUTHOR]

The surge in the global demand for plant-based proteins has catapulted pulse protein into the spotlight. To ensure economic viability and sustainable production, it is crucial to utilize pulse starch, a by-product of plant protein fractionation. Despite the increasing interest in pulse starches, there is a notable gap in knowledge regarding their modifications and applications compared to cereal and tuber starches. Non-thermal techniques such as electron beam radiation, static high pressure, microfluidization, and cold plasma are emerging as innovative methods for starch modification. These techniques offer significant advantages, including enhanced safety, environmental sustainability, and the development of unique functional properties unattainable through conventional methods. However, challenges such as equipment availability, high costs, and energy consumption hinder their widespread adoption. In light of the growing emphasis on "clean and green labelling" and effective "waste management" in food production, evaluating non-thermal techniques for pulse starch modification is critical. This review aims to thoroughly assess these non-thermal techniques and their combinations, offering valuable insights for researchers and the food industry. By maximizing the potential of pulse starches in innovative food applications, it provides a comprehensive guide for effective non-thermal methods that add value and align with sustainable practices. [ABSTRACT FROM AUTHOR]

As an advanced flow-drive technology, micro-electrohydrodynamic (EHD) conduction pumping has become a new prospect in many micro-scale industrial applications, including lab-on-chip devices and microfluidic cooling systems. Under micro-scale conditions, the effect of the electric double layer (EDL) has to be considered. Zeta potential is an adjustable and measurable experimental value and has been proposed to estimate the strength of EDL in simulations. In this work, the effect of zeta potential on the performance of micro-EHD conduction pumping has been numerically investigated. A method to estimate the surface charge density without the Debye–Hückel approximation was introduced. A two-dimensional flush electrode configuration with a typical size of 50 μm was considered. The coupled series of governing equations was implemented in the finite-volume framework of OpenFOAM® and solved based on the PIMPLE algorithm. The results show that zeta potential can enhance the asymmetry of the electric field and change the distribution of the Coulomb force. For the construction considered in this work, negative zeta potential can reduce the size and strength of the vortex in the flow field and improve the pump's net flow rate and static pressure. In contrast, positive zeta potential has the opposite effect. Maximum performance enhancement up to 94.8%–115.1% has been observed for different electrode length ratios within the parameters studied in this paper. The results guide the zeta potential optimization of micro-EHD conduction pumping. By matching the pairs of solid and liquid materials, researchers can adjust zeta potential to an optimal value, thereby improving the pump performance. [ABSTRACT FROM AUTHOR]

The non-cavitating tip vortex in the near field of an elliptical hydrofoil is studied utilizing tomographic particle image velocimetry. Both the instantaneous and time-averaged flow fields are analyzed to elucidate the flow characteristics of the near-field tip vortex. The tip vortex is mainly formed on the suction side of hydrofoil and exhibits a tube-like shape. The turbulence intensity is at a relatively high level around the hydrofoil tip due to the roll-up process of the separated shear layers from the pressure side. With increasing angle of attack, the initiating position of the tip vortex moves upstream along the hydrofoil outline. In the near field, the axial flow within the tip vortex manifests a jet-like profile at higher angles of attack (α ≥ 10 °), and the majority of the vorticity is contained within the vortex core. A special position is identified during the streamwise evolution of the tip vortex, where the vortex circulation reaches its local maximum for the first time and the tip vortex cavitation is more prone to incept. In the vicinity of this crucial position, the pressure–velocity relation is derived along the vortex centerline by combining the three-dimensional measured velocity fields with the governing equations. It is revealed that the mean static pressure is directly related to the local mean axial velocity, adhering to the form of Bernoulli's equation. Conversely, corresponding pressure fluctuation depends on both the mean and fluctuating parts of the local axial velocity. [ABSTRACT FROM AUTHOR]

Research into the flow mechanisms and heat transfer characteristics of two-dimensional supersonic cooling films has been extensive, yet studies on supersonic conical cooling films remain scarce. This study examined the flow characteristics and mechanisms of supersonic conical cooling film under varying ratios of static pressure (RSPs) using nanoparticle planar laser scattering and particle image velocimetry techniques. The mainstream Mach number was M a ∞ = 3.8 , and the supersonic conical cooling film was tangentially injected through a precisely calibrated annular nozzle of M a j = 2.8. Analysis of the instantaneous flow structure characteristics along and normal to the flow direction segmented the flow downstream of the slot into three distinct zones: the potential core region, the large-scale coherent structure region, and the turbulent boundary layer region. The reattachment location was assessed both qualitatively and quantitatively based on time-averaged and statistical velocity field data. The results indicated that the reattachment location extended with higher RSP. Moreover, the reattachment point of the supersonic conical cooling film was further forward than that of a two-dimensional supersonic cooling film. It was found that the supersonic conical cooling film was more significantly affected by the compression effect of the conical stream tube compared to the impact of RSP. [ABSTRACT FROM AUTHOR]

An unsteady simulation with a full-annular computed domain was conducted to explore the flow unsteadiness near the tip region and the mechanism of rotating instability (RI) in the transonic rotor. The numerical static pressure signals were monitored at the tip region. RI was identified by a frequency hump in the spectrum of the static pressure signal in a small mass flow coefficient with a narrow range of 0.9510–0.9174. The cross-power spectrum of two static pressure signals obtained in adjacent passages showed that the circumferential propagation speed of RI decreased with the decrease in the mass flow coefficient. The relative circumferential propagation speed of RI of the prominent mode order was −0.65 to −0.61 times the rotor speed. Details of the flow field near the tip showed that a new vortex structure was induced by the interaction of the tip leakage vortex and the shock wave, which was called as tip secondary vortex (TSV). The TSV was the key parameter to the formation of RI. The impact of the TSV on the pressure side surface generated a low-pressure area and changed the tip load of the adjacent blade. RI is result of the propagation of the interaction between the TSV and the tip load. [ABSTRACT FROM AUTHOR]

Air handling units (AHUs) with long distance flexible film air ducts are commonly adopted in modern large-scale greenhouses for temperature controlling. To study the performance of this type of AHU, theoretical analysis and numerical simulation methods were used to discover its air supply characteristics, and a full-scale experiment was carried out to verify the correctness of the calculation model. The calculation showed that the static pressure of different cross-sections in the thin film air duct sharply decreased to 0 at the small-hole opening, where the airflow velocity increased significantly. However, this influence only exists locally and had little effect on the pressure and gas velocity fields inside the wind duct. The velocity and velocity distribution of the gas flowing out from different openings on the same section of the wind duct are basically the same. Taking the wind speed of 2.45 m/s at the inlet end of the wind duct as an example, the maximum velocity of the airflow at the opening position of the wind duct wall at 60.06 m is 5.64 m/s, located at the center of the opening and flowing outward perpendicular to the opening plane. The velocity distribution is that the center has the highest velocity, and the closer to the edge of the hole, the lower the velocity. The volum of the airflow flowing out through the openings on the wall of the wind duct along the length direction shows that the air supply remains basically constant under different inlet wind speed conditions, and the uniformity coefficient is greater than 0.92. This indicates that this type of AHU can evenly distribute airflow along the length direction, and can evenly distribute heat or cold in the large space of the greenhouse, thus providing a guarantee for maintaining a uniform temperature field in modern large greenhouses. [ABSTRACT FROM AUTHOR]

Alteration in the normal mechanical forces of breathing can contribute to changes in contractility and remodeling characteristic of airway diseases, but the mechanisms that mediate these effects in airway cells are still under investigation. Airway smooth muscle (ASM) cells contribute to both contractility and extracellular matrix (ECM) remodeling. In this study, we explored ASM mechanisms activated by mechanical stretch, focusing on mechanosensitive piezo channels and the key Ca2+ regulatory protein stromal interaction molecule 1 (STIM1). Expression of Ca2+ regulatory proteins, including STIM1, Orai1, and caveolin-1, mechanosensitive ion channels Piezo-1 and Piezo-2, and NLRP3 inflammasomes were upregulated by 10% static stretch superimposed on 5% cyclic stretch. These effects were blunted by STIM1 siRNA. Histamine-induced [Ca2+]i responses and inflammasome activation were similarly blunted by STIM1 knockdown. These data show that the effects of mechanical stretch in human ASM cells are mediated through STIM1, which activates multiple pathways, including Piezo channels and the inflammasome, leading to potential downstream changes in contractility and ECM remodeling. NEW & NOTEWORTHY: Mechanical forces on the airway can contribute to altered contractility and remodeling in airway diseases, but the mechanisms are not clearly understood. Using human airway smooth muscle cells exposed to cyclic forces with static stretch to mimic breathing and static pressure, we found that the effects of stretch are mediated through STIM1, resulting in the activation of multiple pathways, including Piezo channels and the inflammasome, with potential downstream influences on contractility and remodeling. [ABSTRACT FROM AUTHOR]

Nowadays, high aerodynamic load has made blade separation an issue for compact axial compressors under high-altitude low-Reynolds-number conditions. In this study, herringbone grooves inspired by bird feathers were applied to suppress the suction side separation and reduce loss. To study the effect of bio-inspired herringbone grooves on the aerodynamic performance of compressor cascades, a high subsonic compressor cascade was taken as the research object. Under the conditions of different Reynolds numbers, the effects of herringbone grooves of different depths on the flow separation were numerically studied. The research results show that at a high-Reynolds-number condition (Re = 5.6 × 105), the sawtooth-shaped wake induced by herringbone grooves increases the turbulent mixing loss near the suction surface, and the blade performance deteriorates. At a low-Reynolds-number condition (Re = 1.3 × 105), the span-wise secondary flow and micro-vortex structure induced by the herringbone grooves effectively suppress the laminar separation on the suction surface of the blade, and there is an optimal depth for the herringbone grooves that reduces the profile loss by 8.33% and increases the static pressure ratio by 0.55%. The selection principle of the optimal groove depth with the Re is discussed based on the research results under six low-Reynolds-number conditions. [ABSTRACT FROM AUTHOR]

In this paper, with the application of a MARS 60 high-pressure rheometer, experimental tests are conducted on Shengli crude oil to test its gel point, viscosity and thixotropy under different static pressures. Consequently, the effect of static pressure on the rheological parameters of waxy crude oil is revealed. It is proven that with the increase in the static pressure, the gel point of Shengli crude oil increases linearly, and the viscosity also gradually increases. The power law equation is employed to describe the relationship between the apparent viscosity and shear rate of Shengli crude oil under different static pressures. With the increase in the static pressure, the consistency coefficient (K) increases linearly, and the rheological index (n) decreases linearly. The relationship between the viscosity of Shengli crude oil and the static pressure and shear rate can be obtained. The Cross thixotropic model is used to describe the thixotropic curve of Shengli crude oil under different static pressures. With the increase in the static pressure, the thixotropic coefficient of consistency (ΔK) and the structure fracture constant (b) increase linearly. This is because a high pressure results in high structure strength and strong non-Newton rheological behavior in gelled crude oil and also causes remarkable structure fracture in crude oil. The results in this paper can provide an important theoretical basis for crude oil production and transportation. [ABSTRACT FROM AUTHOR]

This article studies the influence of structural parameters of the optimization model for the gas–liquid mixing device of a fire truck (compressed air foam lift fire truck, model JP21/G2, made in China) on the liquid phase volume fraction, static pressure, velocity streamline, and the influence of smaller flow rates on the mixing effect. By using the computational fluid dynamics (CFD) software FLUENT 2021 R2, numerical simulations were conducted on the fluid domain model of the gas–liquid mixing device of the JP21/G2 fire truck. The changes in the mixing effect time dimension, liquid phase volume fraction, static pressure, and velocity streamline inside the gas–liquid mixing device were obtained. The optimal mixer structure combination in practical applications was inferred through orthogonal experiments, and the influence of flow rate on the optimal pipe diameter and shortest mixing distance was obtained through variable flow rate simulation experiments. The numerical simulation results show that the presence of bent pipes in the JP21/G2 real vehicle model hinders the gas–liquid mixing process. A straight pipe section of at least 8 m was added after the bent pipe to ensure the mixing effect. The optimal parameter combination for orthogonal experiments had an accurate value of 50°-50°-220 mm. Under the same pipe diameter, using a larger flow rate can achieve better mixing effects. [ABSTRACT FROM AUTHOR]

Uniform air distribution is the basic condition for the stable operation of circulating fluidized beds and closely related to the hole layout of nozzles and the air outlet conditions. In this paper, CAD modeling software is used to establish different opening types for nozzles and the corresponding gasifier models, and Fluent simulation software for numerical simulations (k-ε model) is introduced to the hydrodynamic behavior of the upper opening, the side opening and the combined opening types of nozzles, as well as the corresponding single-nozzle fluidized bed gasifiers. The flow field distribution under the above opening modes is obtained, including the velocity distribution, static pressure distribution, and total pressure distribution, and the influence of the boundary conditions, including the inlet gas velocity and outlet pressure, on the flow field distribution inside the nozzle and in the single-nozzle fluidized bed gasifier is also investigated. The simulation results show that the suitable optimal operating conditions for the coal gasifier can be achieved with an inlet velocity of 30 m/s and an outlet pressure of 25 kPaG. Under the above conditions, the local fluidization dead zone at the elbow and top of the nozzle is narrower, the uniformity of the wind velocity can be improved, the pressure drop of the inner core tube of the nozzle is gentle, and the pressure distribution tends to be stable. Theoretically, the anti-slag performance of the nozzle is improved, which will enhance the stability and reliability of the operation of the gasification unit. [ABSTRACT FROM AUTHOR]

A computational investigation of New MEXICO test cases operating under axial flow conditions is reported. Three wind speed cases (10, 15, 24 m/s) corresponding to three different tip speed ratios (10, 6.67, 4.17) when the turbine operates at 425.1 rpm were considered. ANSYS CFX 2021R1 was employed to perform simulations using Single Reference Frame (SRF) and Multiple Reference Frame (MRF) approaches. The flow field is computed by solving unsteady Reynolds Averaged Navier-Stokes (uRANS) equations coupled with SST k - ω turbulence model and Gamma-Theta transition model. Validation involved comparing CFD-predicted integral quantities, static pressure distributions, and loads with corresponding experimental values demonstrating reasonably good agreement at all three wind speeds. Overall, SRF exhibited slightly better wake predictions (hypothetical), while MRF predictions were closer to measurements for integral quantities, static pressure and loads. This study demonstrates the utility of uRANS-based 3D CFD computations in wind turbine aerodynamics studies. [ABSTRACT FROM AUTHOR]

Additive manufacturing technologies increasingly revolutionize current production techniques for object manufacturing. Particularly, fused deposition modeling (FDM) strongly impacts production processes by enabling the cost‐effective and efficient creation of structures with complex designs and innovative geometries. The use of conductive filaments in FDM printing is paving the way for the advancement of entirely printed sensors and circuits, although this domain is still in its early stages. In this article, the design and production of bilayer deformable pressure sensors fabricated using conductive thermoplastic polyurethane are investigated. The potential to vary the mechanical and electrical characteristics of FDM‐printed components by adjusting printing parameters is explored. The influence of different levels of material infill (20%, 50%, and 100%) and different contact geometries between layers (domes, pyramids, and cylinders) is studied. Electromechanical tests are carried out to characterize the sensor, applying pressures up to 22 kPa. The 3D‐printed pressure sensors demonstrate tunable mechanical and electrical sensitivities at different infill values, with the highest value of −6.3 kPa−1 achieved by using a pyramid layer at 100% infill. Sensor outputs registered during cyclic tests show reproducible responses with a wide range of sensitivity, paving the way for applicability in recording both static and periodic pressure changes. [ABSTRACT FROM AUTHOR]

This study deals with base pressure management in a duct for various values of the Mach number (M), namely, Mach number corresponding to sonic and four supersonic conditions. In addition to the Mach number, the nozzle pressure ratio (NPR), the area ratio, the rib dimension, and the duct length are influential parameters. The following specific values are examined at M = 1, 1.36, 1.64, and 2, and NPRs between 1.5 and 10. The base pressure is determined by positioning ribs of varying heights at predetermined intervals throughout the length of the square duct. When the level of expansion is varied, it is seen that the base pressure initially drops for overexpanded flows and increases for under-expanded flows. When ribs are present, the flow field in the duct and pressure inside the duct fluctuate as the base pressure rises. Under-expanded flows can achieve a base pressure value that is suitably high without experiencing excessive changes in the duct flow in terms of static pressure if a rib height around 10% of the duct height close to the nozzle exit is considered. Rectangular rib passive control does not negatively affect the duct's flow field. [ABSTRACT FROM AUTHOR]

Pumps play a crucial role in various applications, and this study employs the CFD method to simulate the internal flow of an axial pump. Utilizing a three-dimensional model with real clearances, our investigation focuses on the pump's internal flow and pressure pulsation under diverse operating conditions. Specifically, we operated an axial pump at varying blade angles (30°, 45°, 60°, and 75°) to determine transient flow fields, aiming to identify both qualitative and quantitative characteristics. In line with current research practices, we present a comparison between numerical calculations and experimental results, revealing reasonable agreement. The simulation results highlight the influence of flow rate and plane blade angle on key parameters such as static pressure, dynamic pressure, total pressure, velocity magnitude fluctuations, and shear stress. Notably, pressure increases near or at the blade tip, and hydraulic flow becomes more evident under different blade angles and conditions. The highest pressure and velocity are observed on the blade with a 45-degree plane angle. These findings provide valuable insights for enhancing the hydraulic performance of axial pumps. To ascertain the model's accuracy and reliability, our research establishes a side-by-side comparison between numerical predictions and experimental data, demonstrating a satisfactory level of agreement. The CFD simulations yield critical insights into the pump's performance, emphasizing the profound sensitivity of parameters to variations in flow rate and blade angle, crucial for understanding and optimizing the pump's behavior. [ABSTRACT FROM AUTHOR]

Asphalt concrete impervious facings, widely adopted as the impervious structures for rockfill dams and upper reservoirs in pumped storage power stations, typically have a multilayer structure with a thin sealing layer, a thick impervious layer, and a thick leveling bonding layer. The properties of the interfaces between these layers are crucial for the overall performance of the facings. This paper develops a model to investigate the complex interface damage behavior of the facing under static water pressure and gravity. The model considers two damage origins: one is the interface adhesion–decohesion damage, which is described by the cohesive zone model (CZM) combined with the Weibull-type random interface strength distribution, and the other is the bulk damage of each layer, described by Mazars' model. Primarily, a comparison between numerical simulation and indoor direct shear tests validates the reliability of the CZM for the asphalt concrete layer interface. Then, the damage distribution of the two interfaces is simulated, and the characteristics of the interface stress are analyzed in detail. The interface shear stresses of the ogee sections, which have different curvatures, all show an interesting oscillation between the thin sealing layer and the impervious layer, and the interface damage at this interface exhibits high heterogeneity. Furthermore, tension stress exists in the local zones of the ogee section, and the damage in this section is significantly greater than in other parts of the facings. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to evaluate three types of textures designed to enhance the tribological performance of static and dynamic pressure thrust bearings. Design/methodology/approach: To explore the effects of different types of textures on tribological performance, the Reynolds equation is modified using lubrication theory and computational fluid dynamics methods while considering the influence of cavitation and turbulence on the physical field. In addition, the tribological performance is optimized through an improved selection algorithm based on Pareto envelope (PESA). Findings: The results indicate that textured thrust bearings exhibit superior tribological performance compared to untextured ones. The circular texture outperforms other textures in terms of load-bearing and friction performance, with improvements of approximately 28.8% and 18.9%, respectively. In addition, the triangular texture exhibits the most significant temperature improvement, with a reduction of approximately 1.93%. Originality/value: The study proposes three types of textures and evaluates the friction performance of thrust bearings by modifying the Reynolds equation. In addition, the optimal texture design is determined using an improved selection algorithm based on PESA. [ABSTRACT FROM AUTHOR]

A cold-gas test campaign has been conducted at the DLR's P6.2 test bench in Lampoldshausen, with the objective of investigating the linear aerospike nozzle flow in interaction with secondary injection thrust vector control (SITVC). In this campaign, the influence of nozzle truncation, injection position and injection pressure on the nozzle surface and base pressure is analysed using pressure probes and Schlieren flow-visualisation techniques. The effects of injection position and truncation on the nozzle surface pressure development are comparable for all geometric variations, resulting in a locally increased static pressure upstream and a locally decreased static pressure downstream of the injection. The magnitude and dimension of these high- and low-pressure regions are correlated with the injection pressure. However, the influence of injection position and truncation on the base pressure is not entirely predictable by the named parameters, indicating an interdependence between both geometric parameters. Finally, the required pressure ratio of injection to the primary flow to ensure sonic injection has been analysed on TUD's cold-gas test bench. This allows the respective injection position-dependent threshold to be identified. The analysis reveals that these experiments have been conducted under transsonic injection conditions. [ABSTRACT FROM AUTHOR]

To study the air‐suction separation mechanism of fresh tea leaves, this article adopts the coupling simulation method of discrete elements and computational fluid dynamics to conduct numerical simulation and experimental research on the movement of fresh tea leaves adsorbed by negative pressure air flow. In the gas–solid coupling model, three‐dimensional scanning technology is applied to establish a three‐dimensional model of fresh tea leaves with one bud and two leaves. Through the Fluent module in CFD, the negative pressure adsorption gas phase of the simulation process was established, bench tests were established, and parameters of the coupling model were optimized. Finally, the minimum error between the simulated value and the test value was 2.85% and the maximum error was 7.43%, indicating that the coupling model established had certain accuracy and could be theoretically analyzed according to the coupling model established. It is found that when the static pressure values of the adsorption surface are −120 Pa, −340 Pa, and −500 Pa respectively, the initial distance from the adsorption surface is 250–550 mm. It is found that fresh tea leaves with one bud and two leaves all fall to the pipe before adsorption, and then move to the adsorption surface. Under the same static pressure value of the adsorption surface, the initial falling distance of tea particles from the adsorption surface (250–550 mm) has a linear function relationship with the distance between the turning point and the adsorption surface. When the initial distance between falling tea particles and the adsorption surface is the same, the distance between the turning point and the adsorption surface is an exponential function when the initial position is 250–350 mm from the adsorption surface, and the distance between the turning point and the adsorption surface is a linear function when the initial position is 400–550 mm from the adsorption surface. [ABSTRACT FROM AUTHOR]

Abstract To explore the static pressure dynamic disaster mechanism of coal-and-gas outburst (CGO) fluid, the self-developed multi-field coupling large-scale physical simulation test system of coal mine dynamic disaster was used to carry out gas outburst and CGO physical simulation tests in straight, L-shaped and T-shaped roadways. The influence of roadway shape on the evolution of static pressure was explored, and the role of pulverized coal in the process of static pressure dynamic disaster was clarified. The results indicated that the static pressure showed a fluctuating downward trend during the outburst process. When gas outburst, the middle and front parts of the roadway in the straight section roadway were the most serious areas of static pressure disasters in the three shapes of roadways. The duration and range of high static pressure disaster in L-shaped roadway were larger than those in T-shaped and straight roadways in turn. When CGO, the most serious area of static pressure disaster in L-shaped and T-shaped roadways moved backward to the middle of the straight section roadway, and there was a rebound phenomenon in the process of static pressure fluctuation decline, which showed the pulse characteristics of CGO. During the outburst, the static pressure dynamic disaster hazard of L-shaped roadway was higher than that of T-shaped roadway, and the static pressure at the bifurcation structure decayed faster than that at the turning structure, which indicated that T-shaped roadway was more conducive to the release of static pressure in roadway, thus reduced the risk of static pressure disaster. When gas outburst, the static pressure attenuation of the fluid in the roadway before and after the turning and bifurcation structure was greater than that of CGO. The peak static pressure and impulse of the fluid during gas outburst were 2 times and 4–5 times that of CGO respectively. The presence of pulverized coal reduced the attenuation of static pressure and the hazard of dynamic disaster, prolonged the release time of energy, and led to the change of the maximum static pressure disaster area.

Ultrasonic rolling is an effective technique for enhancing surface integrity, and surface integrity is closely related to fatigue performance. The process parameters of ultrasonic rolling critically affect the improvement of surface integrity. This study proposes an optimization method for process parameters by combining machine learning (ML) with the NSGA-II. Five ML models were trained to establish relationships between process parameters and surface residual stress, hardness, and surface roughness by incorporating feature augmentation and physical information. The best-performing model was selected and integrated with NSGA-II for multi-objective optimization. Ultrasonic rolling tests based on a uniform design were performed, and a dataset was established. The objective was to maximize surface residual stress and hardness while minimizing surface roughness. For test specimens with an initial surface roughness of 0.54 µm, the optimized process parameters were a static pressure of 900 N, a spindle speed of 75 rpm, a feed rate of 0.19 mm/r, and rolling once. Using optimized parameters, the surface residual stress reached −920.60 MPa, surface hardness achieved 958.23 HV, surface roughness reduced to 0.32 µm, and contact fatigue life extended to 3.02 × 107 cycles, representing a 52.5% improvement compared to untreated specimens and an even more significant improvement over without parameter optimization. [ABSTRACT FROM AUTHOR]

The effects of back pressure on the transonic cascade operating state are crucial and can determine the structure of internal shock waves and secondary flows. In this paper, numerical methods validated by experiments were employed to investigate the evolution mechanisms of the inlet flow field, shock structure, secondary flow structure, and cascade performance under different back pressures. Analysis revealed that transonic cascade exhibited unique incidence characteristics in the inlet flow field under both subsonic and supersonic regimes, although these two regimes involved different physical mechanisms. The results revealed that the operating state of the transonic compressor cascade under the unique incidence condition was influenced by the outlet back pressure, and there existed a critical static pressure ratio. The critical static pressure ratio shifted from 1.61 for two-dimensional flow to 1.37 for three-dimensional (3D) flow at M1 = 1.1, due to the corner separation and the characteristics of 3D shocks. The 3D shock structure exhibited a non-uniform distribution along the spanwise direction due to the influence of back pressure and the separated boundary layer. The vortex structures analysis revealed that the secondary flow structure on the sidewalls of the transonic compressor cascade was primarily dominated by corner vortices, whose formation mechanism was related to the interaction between the shock wave and the sidewall boundary layer. Additionally, this interaction also led to the formation of detached shock and lip shock vortex structures. Finally, loss analysis indicated that the wake region of the transonic cascade primarily includes six types of loss, and the total loss of the cascade decreased with the rise in back pressure. [ABSTRACT FROM AUTHOR]

Rotor tip clearance has significant influences on both the performances and internal flow fields of compressors. To explore the relationship between these influences and compressor loading levels, four single-stage compressors, with loading levels ranging from 0.36 to 0.59, have been designed for experiments. Compressor characteristics and flow fields at blade row inlet and outlet planes were measured under two rotor tip clearance conditions: 1% and 2.2% blade height. Based on these experimental results, an analysis was conducted to examine the influence of loading levels on the sensitivity to rotor tip clearance. The experimental results indicate that increase in the loading level enhances the sensitivity of compressor stage characteristics to rotor tip clearance. At the design point, an increase of 1% in the rotor tip clearance causes reductions of 1.3% in the stage efficiency and 2.3% in the stage static pressure rise when the loading level is 0.36. However, when the loading level is 0.59, the reductions are 2.9% and 3.4% in stage efficiency and stage static pressure rise, respectively. Increasing the rotor tip clearance brings the static pressure rise at the rotor tip region closer to its limit, resulting in a rapid growth of local loss. This trend becomes increasingly pronounced with higher compressor loading level. [ABSTRACT FROM AUTHOR]

The generation of the suction force between a rigid cylindrical frame constricting a submerged cavitating jet and a solid surface is considered. The separation force needed to overcome the suction effect is experimentally determined in a specially developed setup. The dependences of the suction force on the frame diameter and the distance from the nozzle cavitator are obtained using numerical modeling. The volume fraction of the vapor phase inside the frame and the static pressure along the suction surface are calculated. The mechanism of the appearance of the effect and the criteria of its vanishing are explained on the basis of the data obtained. [ABSTRACT FROM AUTHOR]

The aim of this article is to study the degradation of a composite material under static pressure. The high pressure condition is similar to the one encountered inside hydrogen tanks. Damage modeling was used to evaluate the behavior of hydrogen tanks to high pressure. A practical approach, coupling a finite element method (FEM) simulation and machine learning (ML) algorithm, is suggested. The representative volume element (RVE) was used in association with a choice of a behavior law and a damage law as an input data. Algorithms for ML classification such as K‐nearest neighbors (k‐NN) and a special k‐NN with a dynamic time warping metric were used. The hierarchical clustering through dendrograms visualizations allowed to exhibit the impact of composite parameters in relation to fiber, matrix properties and fiber volume fraction on the strain degradation under external static pressure. Continuing this, the optimum RVE which shows a low degradation value will be exhibited. [ABSTRACT FROM AUTHOR]

A pulsed detonation chamber (PDC) equipped with Hartmann–Sprenger resonators has been designed and tested for both Hydrogen/air and Hydrogen/Oxygen mixtures. A full-factorial experimental campaign employing four factors with four levels each has been carried out for both mixtures. Instantaneous static pressure has been measured at two locations on the exhaust pipe of the PDC, and the signal has been processed to extract the average and maximum cycle pressures and the operating frequency of the spark plug. The PDC has been shown to be able to reach sustained detonation cycles over a length below 200 mm, measured from the spark plug to the first pressure sensor. The optimal regimes for both air and Oxygen operation have been determined, and the influence of the four factors on the responses is discussed. [ABSTRACT FROM AUTHOR]

Understanding violent sloshing is of practical concern to a wide range of applications as it may compromise safety in a number of engineering applications. The present study investigates violent sloshing in a 2D tank. In particular, the evolution and influence of an air pocket and the impact pressure on tank walls are numerically studied. Since the problem involves multi-phase flows, standard dam-break problem is used for validations. The liquid depth and amplitude of excitation are systematically varied to assess the impact pressures on walls and roof of the tank. Non-linear effects are captured qualitatively and the distribution of impact pressures on the tank walls is examined. The entrainment of an air pocket by a standing wave at the tank roof is delineated. The violent sloshing wave motion causes the formation of air pockets that arise for a range of forcing amplitudes and a variety of liquid depths. Gradual decay in the impact pressure due to the generation of these air pockets is significant on overall sloshing dynamics. The maximum peak pressure predicted on the tank roof is about 10 times the static pressure, which is also about twice the peak pressure obtained on the side wall. Furthermore, the distribution of average impact-pressure profiles on the tank walls and roof is presented for different loading conditions vis-á-vis global impact characteristics of sloshing wave motion. [ABSTRACT FROM AUTHOR]

To further optimize the static performance of static pressure gas radial bearings,a composite throttling type static pressure gas radial bearing with axial and circumferential pressure equalizing grooves was proposed based on the traditional small hole throttling.Fluent was used to compare and analyze the static characteristics of the bearings with traditional orifice throttling and different forms of composite throttling,and the influence of the cross-sectional shape of the equalizing groove and the gas supply pressure on the static characteristics of bearings was explored. The orthogonal experiments were used to explore the influence of the structural parameters of the restrictor on the bearing characteristics. The results show that the composite throttling static pressure gas bearing improves the static characteristics of the bearing to a certain extent,and the best effect is achieved when the pressure equalizing groove is arranged in a "mouth" shape and the cross-sectional shape is rectangular.An increase in gas supply pressure can also improve the static characteristics of bearings.The influence of the diameter of the orifice and the depth of the equalizing groove on the static characteristics of bearings is larger than that of the depth of the orifice and width of the equalizing groove. The increase in the diameter of the orifice and the depth of the equalizing groove results in a trend of first increasing and then decreasing in the bearing capacity and stiffness of bearings. [ABSTRACT FROM AUTHOR]

With the escalating severity of the global climate crisis and the strengthening global demand for carbon neutrality, hydrogen produced from renewable energy offers a pathway towards achieving carbon neutrality. To reduce the cost of eco-friendly hydrogen production, we need to increase the current density in proton exchange membrane water electrolysis for green hydrogen production, a promising technology. One problem arising from an increase in current density is that it leads to a significant generation of oxygen, resulting in mass transfer losses. However, there have been few studies on oxygen transport near the anode catalyst layer, with most studies only measuring current density. In this study, local static pressure and temperature were measured in real-time to elucidate the relationship between voltage and current. At 2.1 V (corrected voltage = 2.03 V), the static pressure amplitude is approximately −5 to 5 kPa. At 2.55 V (correction voltage = 2.41 V), it decreased by about 50 % to about −2.5 to 2.5 kPa, and the frequency became faster. With increasing voltage, the decrease in static pressure amplitude and the increase in frequency occur because oxygen rapidly increases in the catalyst layer, resulting in a reduction in residence time. At 1.65 V (corrected voltage = 1.63 V), there is little change in local static pressure, indicating the dominance of the liquid single phase. At 3.6 V (corrected voltage = 3.05 V), there is little change in local static pressure. This is due to the rapid detachment of oxygen bubbles, leading to the dominance of the gas single phase. This elucidates how oxygen bubbles are influenced by fluctuations in local static pressure, leading to the conclusion that efficient design patterns for future anode flow fields can be achieved. • The frequency and amplitude of local pressure fluctuate depending on the voltage. • Local current density distribution doesn't change depending on the voltage. • As The voltage increases, oxygen accumulation decreases. • The increase in polarization curve slope at low voltage is due to oxygen residence time. [ABSTRACT FROM AUTHOR]

The boiling point of liquid hydrogen is very low, at −253 °C under atmospheric pressure, which causes boil-off gas (BOG) to occur during storage and transport due to heat penetration. Because the BOG must be removed through processes such as re-liquefaction, venting to the atmosphere, or incineration, related studies are required to estimate the heat transfer of storage and transport devices and to improve insulation to reduce BOG generation. In this study, a vaporization analysis was performed on a vacuum-jacketed valve used in liquid hydrogen storage and transport devices to calculate the amount of BOG generation considering the flow characteristics at the vena contracta and the saturation temperature. At a pressure of 1 bar in the liquid hydrogen storage tank, the maximum fluid flow velocity and minimum static pressure occurred at the vena contracta, with values of 62.9 m/s and −0.4 bar, respectively, and the BOG generation rate was estimated as 0.132 m3/h, where the saturation temperature was minimized at 19.3 K. Furthermore, through case studies, when the pressure in the liquid hydrogen storage tank increased to 1.5 and 2 bar, the static pressure and saturation temperature decreased, and the BOG generation rate increased to 0.221 and 0.283 m3/h, respectively. [ABSTRACT FROM AUTHOR]

The chimney junction of solar chimney power plant was the main element coupled the solar collector to the chimney. It presents an important impact on the SCPP design, which is change the air-flow direction. The numerical code ANSYS Fluent was used in this study to investigate how the chimney Junction radius affected the local air-flow characteristics and the turbine site. Using test results from an experimental prototype constructed in Sfax, Tunisia, the numerical method was validated and verified. For four set-ups with various chimney connection radii, thermodynamic variables such as distributions of the total pressure, static temperature, static pressure, and magnitude velocity were examined. Also, the influence of these parameters on the air turbulence was analyzed through the transition zone. The results showed that the local air-flow characteristics and therefore, the SCPP efficiency were significantly impacted by changes in junction radius. Besides, the maximum velocity inside the chimney was varied and changes its location when the junction radius changed. These facts affect directly the overall turbine expenditure, which represented in terms of structure and power capacity. [ABSTRACT FROM AUTHOR]

The focus of this study is on the design and experimental validation of MRF self-sealing (also known as MRF seal) utilizing permanent magnets. The MRF seal has been built to readily replace traditional seal (lip-seal) for rotation shaft sealing. Following a review of studies on MRF seals, two configurations of MRF seal featuring an axial permanent magnet and two distinct pole head forms, rectangular and trapezoidal, are presented. The two MRF seals are then subjected to a magnetic analysis using the finite element method (ANSYS APDL). The Bingham plastic model of MRF and the assumption of linear velocity profile of MRF in the sealing gap are employed to construct mathematical models of crucial seal characteristics such as maximum static working pressure and frictional torque. The seals are optimized employing the optimization toolbox integrated in the ANSYS APDL to obtain the optimal geometric dimensions of the MRF seals. Finally, prototypes of the two MRF seals are fabricated and testing work is conducted to validate and compare them with the simulated results. [ABSTRACT FROM AUTHOR]

Respiratory diseases, including the cronic obstructive pulmonary disease (COPD) are among the leading causes of death worldwide. To date, there is no physical examination procedure that can quantify important parameters within a specific lesion area inside the lung. In this study, we propose a novel sensor probe system consisting of a basket forceps and 2 pressure sensors to simultaneously measure the expiratory airflow and the static pressure inside the pulmonary airway. A Pitot tube mechanism using 2 pressure sensors is introduced in the system for measuring both the physical quantities. Small fiber‐optic pressure sensors with 0.3 mm diameter were utilized, and both the airflow rate and the static pressure characteristics were evaluated for obtaining the calibration curves. Finally, the proposed sensor system was implemented to measure both the airflow and pressure in an artificial ventilator and an experimental animal. The measurement of expired airflow and static pressure inside the airway of a rat with the diameter of 1.8 mm were demonstrated. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to study the influence of cylindrical texture parameters on the lubrication performance of static and dynamic pressure thrust bearings (hereinafter referred to as thrust bearings) and to optimize their lubrication performance using multiobjective optimization. Design/methodology/approach: The influence of texture parameters on the lubrication performance of thrust bearings was studied based on the modified Reynolds equation. The objective functions are predicted through the BP neural network, and the texture parameters were optimized using the improved multiobjective ant lion algorithm (MOALA). Findings: Compared with smooth surface, the introduction of texture can improve the lubrication properties. Under the optimization of the improved algorithm, when the texture diameter, depth, spacing and number are approximately 0.2 mm, 0.5 mm, 5 mm and 34, respectively, the loading capacity is increased by around 27.7% and the temperature is reduced by around 1.55°C. Originality/value: This paper studies the effect of texture parameters on the lubrication properties of thrust bearings based on the modified Reynolds equation and performs multiobjective optimization through an improved MOALA. [ABSTRACT FROM AUTHOR]

The storm sewer geyser is a process where an air–water mixture violently erupts from a manhole. Despite the low hydrostatic pressure, violent eruptions can achieve a height of tens of meters above the ground. This current study experimentally investigates large-scale violent geysers using a large air pocket inserted from a pressurized air tank. The total length of the pipe system is approximately 88 m with a 0.1572 m diameter pipe. This large-scale experiment facilitates the investigation of spontaneous geyser eruptions. This study identifies the role of air–water volume ratio and coefficient of pressure (ratio of absolute initial static pressure to initial dynamic pressure) on the geyser intensity using eruption images and pressure plots. A total of 116 cases are tested, in which the volume ratio is parametrically increased from 0 to 1.1 under various operating conditions. A geyser score is defined to quantify the geyser eruption nature based on visual observations. The key findings are as follows: first, a sharp transition in geyser intensity is observed at the critical volume ratio of 0.5, and pre-transition and post-transition intensity exhibit a linear relationship with the volume ratio; and second, the critical volume ratio linearly varies with the coefficient of pressure. [ABSTRACT FROM AUTHOR]

It is difficult to assess the temperature and pressure resistance of the existing soluble bridge plug seal ring used in fracking for shale gas reservoirs, to go with its high plasticity and good solubility. To overcome this shortcoming, aluminium matrix composites with the addition of 0%, 0.5% and 1.0% of graphene were prepared by spark plasma sintering. Uniaxial static pressure test results show that the composite has the maximum compressive strength and compression ratio when the graphene content is 0.5%. Microporous copper coatings were prepared on graphene/1070 aluminium surface by electroless plating. The synergistic effect of the surface microporous copper coating and the internal graphene on the corrosion performance of 1070 aluminium alloy was analysed by the weight loss and electrochemical methods. The results showed that the surface microporous copper coatings could significantly improve the uniform corrosion rate and pitting depth of graphene/1070 aluminium. [ABSTRACT FROM AUTHOR]