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In this paper, we develop two discontinuous Galerkin (DG) finite element methods to solve the linear poroelasticity in the total pressure formulation, where displacement, fluid pressure, and total pressure are unknowns. The fully-discrete standard DG and conforming DG methods are presented based on the discontinuous approximations in space and the implicit Euler discretization in time. Compared to the standard DG method with penalty terms, the conforming DG method removes all stabilizers and maintains conforming finite element formulation by utilizing weak operators defined over discontinuous functions. The two methods provide locally conservative solutions and achieve locking-free properties in poroelasticity. We also derive the well-posedness and optimal a priori error estimates, which show that our methods satisfy parameter-robustness with respect to the infinitely large Lamé constant and the null-constrained specific storage coefficient. Several numerical experiments are performed to verify these theoretical results, even in heterogeneous porous media. [ABSTRACT FROM AUTHOR]

In this study, polymer membrane for CO2 separation was produced by blending polyvinyl alcohol and sodium polyacrylate. Tests were conducted on the produced membranes to evaluate their CO2 and He separation performance under various conditions. The optimal amount of cesium carbonate to be added to the prepared membrane in terms of separation performance was determined. It was found that the highest performance was obtained at 85°C. Effects of other process conditions such as total pressure, CO2 partial pressure, and humidity on membrane performance were also investigated. In particular, CO2 permeance of around 3.0E–10 (m3(STP)/m2 s Pa)) and selectivity of nearly 500 were observed for the separation of CO2 and helium at the CO2 partial pressure of Ptotal of 0.1 MPa. Through the above examinations, the present study was not only produced a high-performance separation membrane, but also found test conditions under which this membrane exhibited higher separation performance. [ABSTRACT FROM AUTHOR]

• Throughout cattle manure composting, average airflow resistance decreased by 40.1%. • All research parameters had the greatest variation at the thermophilic phase. • With the aerobic reaction, the total pressure ought to be adjusted to a lower level. • Ranks affecting airflow resistance were bulk density, particle size, specific gravity. Composting is widely adopted in livestock waste management, and the ventilation system control is essential for composting efficiency. For ventilation system, the airflow resistance is a major factor influencing the ventilation intensity and oxygen supply capacity. This study explored the variation law of airflow resistance, bulk density, specific gravity, particle size and total pressure throughout composting with cattle manure. The airflow resistance was calculated with Ergun equation, and contribution coefficients of different components were analyzed with principal component analysis (PCA). Results showed that the viscous airflow resistance was dominant throughout cattle manure composting. The average airflow resistance was 0.146 Pa/m, and resistance of pile at lower layer was higher than that at the upper layer by 18.1 %. For contribution coefficient affecting airflow resistance, the ranks were bulk density, average particle size and specific gravity. During composting process, the average airflow resistance decreased by 40.1 % and the total pressure reduced by 3.47 %. All parameters had the greatest variation at thermophilic phase, which accounted for more than 60 % of the total variation amplitude. Meanwhile, less than 10 % of the total pressure was used to overcome the airflow resistance. Therefore, reducing bulk density of pile should be considered preferentially to decrease the airflow resistance. During cattle manure composting process, the total pressure of ventilation system ought to be adjusted with the aerobic reaction to a lower level, especially at thermophilic phase with the most rapid descent rate. This study can provide support for reducing the energy consumption required for ventilation of composting. [ABSTRACT FROM AUTHOR]

In this research, to investigate the impact of the guide vanes on the flow analysis in the axial pump, unsteady numerical turbulence field simulations with and without guide vanes are simulated using the model of standard κ–ε turbulence with the technique of sliding mesh (SM). The numerical results are firstly validated and compared with experimental outcomes. Different detailed information data regarding flow analysis, for instance, static, dynamic, total pressures, turbulent kinetic energy, shear stress, and velocity magnitude are qualitatively analysed. Then pressure at varying regions in the pump is qualitatively investigated under different operating conditions. The results have shown that the flow field and performance of the pump are highly affected by adding the guide vane to the axial impeller. The impeller with guide vane can lead to enhance the pump performance. Moreover, results show that the pressure, kinetic energy, shear stress, and velocity are increased by adding a guide vane to the axial impeller. This study will provide good information and guidance to enhance and improve the axial flow pump design operation. [ABSTRACT FROM AUTHOR]

In order to clarify the effect of total pressure on the corrosion behavior of steel in the CO2/H2S/O2 system, the high temperature and high pressure reaction vessel, scanning electron microscope and its accompanying energy spectrometer, X-ray diffractometer, 3D optical profiler, and other instruments were employed to research the effect of the different total pressur on the corrosion behavior of L360NS steel in CO2/H2S/O2 system. Results showed that when the total pressure changed within the range of 0.2~1.5 MPa, the uniform corrosion rate of L360NS steel increased with the increase of total pressure. The reason might be that the increase in total pressure led to an increase in gas content in the solution, which accelerated the corrosion reaction kinetics and exacerbated corrosion. Moreover, the bottom of the corrosion product film was a mixture of wedge-shaped and granular products, while the surface was granular. The product composition was FeCO3, Fe2O3, FeS, and FeS2. Besides, with increasing the total pressure, the number of corrosion pits increased in the form of vertical and horizontal extension, and the local corrosion degree became deeper, which was due to the uneven protection of the substrate by corrosion products such as FeCO3, Fe sulfides, and Fe2O3 oxides.

Influence of different guide vanes on structural of flow field and axial pump performance under unsteady flow is carried out using numerical method. A three-dimensional axial flow pump model is numerically simulated using computational fluid dynamics (CFD) method with four number of impeller blades and 3, 4, 5 and 6 guide vanes depend on the SIMPLE code, standard turbulence k-ε model as well as sliding mesh method (SMM). The static, dynamic, total pressures, shear stress, velocity magnitude and turbulent kinetic energy are the important features which affecting instability operation in the pump. By monitoring above parameters and setting different measurement pressure points, the average pressures in the pump are discussed and the effect of guide vanes on the average pressure is analyzed. The results demonstrate that the numerical calculations can provide good accurately prediction for the characteristics of internal flow in the pump. The numerical results are closed to experimental results the minimum errors of pressure differences can reach 2.5% and the maximum errors 6.5%. The guide vanes have more effect on the flow field and pressure variations especially at outlet region in the axial pump. As compared with the using various guide vanes, the pressure increases as number of vanes increase that can lead the performance of pump also increases. Pressure differences in the pump at variety mass flow for vane 6 is higher than other vanes 3, 4 and 5 by 14.13, 11.35 and 3.85% for flow of 5 L/min. Further, the dynamic pressure differences for design flow between different vanes 6, 5, 4 and 3 are about by 2.87, 7.26 and 8.51% respectively.

Experimental and numerical studies have been made of the hydrodynamics of isothermal flows in a small-scale cyclone chamber (D = 0.21 m) with two-stage differently directed injection of tangentially blown air (with a cocurrent and countercurrent swirl). It has been established that the character of vortex flow with a countercurrent swire differs significantly from the structure of flow with a cocurrent swirl. The character of velocity and pressure distribution in the chamber′s volume has been revealed for the flows in question. Dimensionless dependences have been obtained for calculating the tangential velocity and pressure in the chamber. It has been shown that results of numerical modeling of vortex flows with the k–ω (SST) turbulence models for the concurrent and countercurrent air swirl are in satisfactory agreement with experimental data. [ABSTRACT FROM AUTHOR]

As the first continuous supersonic wind tunnel in China, Mach number and total pressure are the most important flow field parameters of the wind tunnel, how to precise control and rapid and stable adjustment of total pressure and Mach number is the key in the design and construction of the wind tunnel control system. By analyzing the principle of parameter control of the wind tunnel flow field and the coupling relationship of each adjustment methods, the construction of continuous supersonic wind tunnel control system is constructed, and the solution measure of each key technical problem is given. The total pressure is precisely controlled by the segmented variable parameter fuzzy PI control algorithm, and then the wind tunnel operation control process design is carried out. Finally the wind tunnel blowing test is verified. The result shows that the accuracy of total pressure accuracy is better than 0.05%, the Mach number accuracy is better than 0.167 3, all the flow field parameter is greatly better than the design index, which proves that the design idea proposed in this paper is effective and can provide reference for the design and debugging of continuous supersonic wind tunnels.

In this paper, the kerosene/air rotating detonation engines(RDE) are numerically investigated, and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE including the initiation, instabilities, and propulsive performance. A hybrid MPI + OpenMP parallel computing model is applied and it is proved to be able to obtain a more effective parallel performance on high performance computing(HPC) systems. A series of cases with the total pressure of 1 MPa, 1.5 MPa, 2 MPa, and the equivalence ratio of 0.9, 1, 1.4 are simulated. On one hand, the total pressure shows a significant impact on the instabilities of rotating detonation waves. The instability phenomenon is observed in cases with low total pressure (1 MPa) and weakened with the increase of the total pressure. The total pressure has a small impact on the detonation wave velocity and the specific impulse. On the other hand, the equivalence ratio shows a negligible influence on the instabilities, while it affects the ignition process and accounts for the detonation velocity deficit. It is more difficult to initiate rotating detonation waves directly in the lean fuel operation condition. Little difference was observed in the thrust with different equivalence ratios of 0.9, 1, and 1.4. The highest specific impulse was obtained in the lean fuel cases, which is around 2700 s. The findings could provide insights into the understanding of the operation characteristics of kerosene/air RDE.

Composite polymer membranes were prepared using carbonate, polyvinyl alcohol, an acrylic acid polymer partial sodium salt cross‐linked product, and sodium polyacrylate. In this study, the factors for further improving the separation performance of these membranes for the CO2/He mixed gas were investigated. It was confirmed that the prepared membranes did not provide stable separation under pressure unless they had a thickness of 2.0 μm. Moreover, they could not function as high‐performance separation membranes without a carbonate additive; the optimal carbonate concentration range was determined by considering the effect of the total pressure. As a result, this work produced a high‐performance, CO2 selective permeable membrane with selectivities of more than 500 and 150 at 0.1 and 0.7 MPa, respectively, for the separation of a CO2/He (80/20) gas mixture at 85°C. [ABSTRACT FROM AUTHOR]

Mitigation of pressure pulsations in the exhaust of a pulse detonation combustor is crucial for operation with a downstream turbine. For this purpose, a device termed the shock divider is designed and investigated. The intention of the divider is to split the leading shock wave into two weaker waves that propagate along separated ducts with different cross sections, allowing the shock waves to travel with different velocities along different paths. The separated shock waves redistribute the energy of the incident shock wave. The shock dynamics inside the divider are investigated using numerical simulations. A second-order dimensional split finite volume MUSCL-scheme is used to solve the compressible Euler equations. Furthermore, low-cost simulations are performed using geometrical shock dynamics to predict the shock wave propagation inside the divider. The numerical simulations are compared to high-speed schlieren images and time-resolved total pressure recording. For the latter, a high-frequency pressure probe is placed at the divider outlet, which is shown to resolve the transient total pressure during the shock passage. Moreover, the separation of the shock waves is investigated and found to grow as the divider duct width ratio increases. The numerical and experimental results allow for a better understanding of the dynamic evolution of the flow inside the divider and inform its capability to reduce the pressure pulsations at the exhaust of the pulse detonation combustor. [ABSTRACT FROM AUTHOR]

Problem of pitot tube blocking is persistent because even in the recent past there have been several accidents based on inaccurate information from air speed indicators. This problem was caused by a partial or complete blockage of the total pressure probes. Certain principles of blocking detection are well known. This article describes research into another principle of the gradual blocking detection of the pitot tube with drain holes. Pitot tubes with different blockage ratios were made and tested. A gradual blocking curve was described. The independence of velocity magnitude for the investigated airspeeds was found. This research shows that the drain hole design can be useful for a pitot tube blockage detection. The principle is based on another pitot tube with a larger drain hole area. Airspeed error due to gradual blocking grows faster on the other pitot tube. Gradual blocking of both pitot tubes results in a difference in indicated airspeeds, even at constant speed flight and before full blockage. This airspeed difference can warn a pilot and gives him or her a valuable time to use emergency procedures.

Problem of pitot tube blocking is persistent because even in the recent past there have been several accidents based on inaccurate information from air speed indicators. This problem was caused by a partial or complete blockage of the total pressure probes. Certain principles of blocking detection are well known. This article describes research into another principle of the gradual blocking detection of the pitot tube with drain holes. Pitot tubes with different blockage ratios were made and tested. A gradual blocking curve was described. The independence of velocity magnitude for the investigated airspeeds was found. This research shows that the drain hole design can be useful for a pitot tube blockage detection. The principle is based on another pitot tube with a larger drain hole area. Airspeed error due to gradual blocking grows faster on the other pitot tube. Gradual blocking of both pitot tubes results in a difference in indicated airspeeds, even at constant speed flight and before full blockage. This airspeed difference can warn a pilot and gives him or her a valuable time to use emergency procedures. [ABSTRACT FROM AUTHOR]

A Counter Rotating Turbine (CRT) is an axial flow turbine with a nozzle followed by two rotors that rotate in the opposite direction of each other. Axial gap is an important parameter that affects the performance of turbine stage. Current work contains computationally analyzing the flow physics and performance of CRT with the axial gaps of 15, 30, 50 and 70% of the mean axial chord. Turbine components nozzle and the two rotors are modeled for all the axial gaps of CRT. At nozzle inlet, total pressure is taken as boundary condition and at rotor 2 outlet, mass flow rate is specified. Total pressure, entropy and TKE contours plotted at the inlet and outlet of the blade rows are utilized to analyze the effect of axial gap. Mass flow average distributions of entropy, TKE and relative stagnation pressure loss drawn at rotor 1 and rotor 2 outlets estimate the changes in flow losses with respect to axial gap. The intermediate axial gap of x/a = 0.3 is found to be beneficial for CRT for most of the flow rates. Also, it is found that the smallest and the largest gap cases are showing comparable performance. Thus, results confirm the influence of axial gap on the flow behavior and performance of CRT.

Tree-ring chronologies of stem discs and core samples have been widely used to reconstruct the climatic conditions of tree growth. However, insufficient attention has been given to the fact that root and stem wood accumulate biogenic gases, whose distribution in annual rings can also be related to the climate-dependent features of tree growth. The study of chronologies of gas samples extracted under vacuum from the wood of tree-ring discs of the Siberian stone pine (Pinus sibirica Du Tour), Scots pine (Pinus sylvestris L.), Siberian larch (Larix sibirica Ledeb.) and Siberian spruce (Picea obovata Ledeb.) suggests that annual distributions of CO2 and H2O in the rings and pressure variation in extracted samples follow a cyclic pattern. It was found that the sample pressure and the content of CO2 and H2O in the annual rings in stems and roots of the Siberian stone pine and Scots pine from Tomsk (Russia) area are characterized by varied time cycles, including periods of about 4 and 11 years, the latter corresponding to the period of the solar activity cycle. The four-year cycle in the above chronologies is explained by the presence of similar cycles in temperature and precipitation chronologies, where cyclic variations of CO2 in the rings can be interpreted as a response of the plant to the change in the climatic conditions. The established cyclic variation of the pressure and CO2 content in tree rings in stems and roots indicates that CO2 release into the atmosphere should also follow a cyclic pattern. Therefore, to estimate correctly the release of CO2 by tree stems and large roots, long-term measurements are required

Shallow water models are commonly used to simulate dam-break flow; however, shallow water equations usually assume a hydrostatic pressure assumption that can limit model applications. Dam-break flow can also be solved by total pressure formulation with Navier–Stokes equations, that are computationally more expensive but can deal with a wider range of problems. We propose a multiphase flow code with second-order precision, called SuLi-LS. This code uses the Level Set methodology and can consider total pressure or hydrostatic pressure assumption in Navier–Stokes solution. To analyse the differences between hydrostatic and total pressure, we compared SuLi-LS results with experimental cases. The comparison shows that total pressure consideration provides accurate results for the dam-break flow problems, and it is a considerably better approach than considering hydrostatic pressure assumption. We found that hydrostatic pressure assumption can be valid for dam-break flows in which there is an underlying water bed. [ABSTRACT FROM AUTHOR]

A Counter Rotating Turbine (CRT) is an axial flow turbine with a nozzle followed by two rotors that rotate in the opposite direction of each other. Axial gap is an important parameter that affects the performance of turbine stage. Current work contains computationally analyzing the flow physics and performance of CRT with the axial gaps of 15, 30, 50 and 70% of the mean axial chord. Turbine components nozzle and the two rotors are modeled for all the axial gaps of CRT. At nozzle inlet, total pressure is taken as boundary condition and at rotor 2 outlet, mass flow rate is specified. Total pressure, entropy and TKE contours plotted at the inlet and outlet of the blade rows are utilized to analyze the effect of axial gap. Mass flow average distributions of entropy, TKE and relative stagnation press are loss drawn at rotor 1 and rotor 2 outlets estimate the changes in flow losses with respect to axial gap. The intermediate axial gap of x/a = 0.3 is found to be beneficial for CRT for most of the flow rates. Also, it is found that the smallest and the largest gap cases are showing comparable performance. Thus, results confirm the influence of axial gap on the flow behavior and performance of CRT. [ABSTRACT FROM AUTHOR]

The effects of bypass ratio on co-flowing subsonic and correctly expanded sonic jet decay have been studied experimentally. Co-flowing jets with lip thickness 1.0 Dp (where Dp is the diameter of primary nozzle and is equal to 10 mm) with bypass ratios of around 0.7, 1.4, and 6.4 at primary jet exit Mach numbers 0.6, 0.8, and 1.0 have been analyzed. A single free jet equivalent to primary nozzle of the co-flowing nozzle was considered for comparison. Primary jet centerline total pressure decay, spread, and static pressure variation were investigated. The results show that the mixing of the high bypass ratio co-flowing jet with lip thickness 1.0 Dp is superior to low bypass ratio co-flowing jet. Both lip thickness and bypass ratio have a strong influence on the co-flowing jet mixing. Bypass ratio 6.3 experiences a significantly higher mixing than bypass ratio 0.7 and 1.4. Selected jets were also investigated computationally. The computations capture the salient flow physics and reproduce well with the experiments. [ABSTRACT FROM AUTHOR]

Sulfur Mass‐Independent Fractionation (S‐MIF) may provide a clue to understanding Earth's early atmosphere. We examined total pressure dependence of the S‐MIF produced by SO2 photolysis. Isotopic self‐shielding is known to produce S‐MIF, which could be changed by both the partial pressure of SO2 (pSO2) and by the total pressure (pTotal). Our experimental results show that both Δ33S and Δ36S values are constant when total pressure is below 10 kPa at constant pSO2, whereas they decrease as total pressure increases. The result suggests that pressure broadening of the SO2 absorption line is responsible for the S‐MIF. The modeled high‐resolution isotopologue cross sections can reproduce our experimental results and its changes depending on both pSO2 and pTotal. Consequently, we conclude that the Archean Δ33S and Δ36S correlation can only be achieved when the total pressure of the Archean atmosphere was below 100 kPa, or it was produced in the upper atmosphere. Plain Language Summary: Sulfur Mass‐Independent Fractionation (S‐MIF) in Archean sedimentary rocks could be useful to constrain the chemical and physical states of Earth's early atmosphere. SO2 photolysis is known to produce large MIF. However, experimental results have yet to model the observed mechanisms of S‐MIF in SO2 photolysis. We examined the total pressure effect of S‐MIF by SO2 photolysis and succeeded in modeling the observed S‐MIF and its total pressure dependence. Comparing the results of this study with geological records, large Archean S‐MIF could only be achieved when total pressure is below 100 kPa, suggesting that the Archean atmosphere was not thicker than the modern atmosphere or that the S‐MIF‐yielding photolysis occurred mainly at a high altitude. Key Points: Total pressure effect of sulfur mass‐independent fractionation during SO2 photolysis was examinedThe observed total pressure dependence can be explained by self‐shielding with pressure broadening of the SO2 absorption lineBased on the results, the large Archean Δ36S/Δ33S fractionations can only be achieved when total pressure was lower than 100 kPa [ABSTRACT FROM AUTHOR]

In order to investigate the influence of steam ingestion on the aerodynamic stability of a two-stage low-speed axial-flow compressor, multiphase flow numerical simulation and experiment were carried out. The total pressure ratio and stall margin of the compressor was decreased under steam ingestion. When the compressor worked at 40% and 53% of the nominal speed, the stall margin decreased, respectively, by 1.5% and 6.3%. The ingested steam reduced the inlet Mach number and increased the thickness of the boundary layer on the suction surface of the blade. The low-speed region around the trailing edge of the blade was increased, and the flow separation region of the boundary layer on the suction surface of the blade was expanded; thus, the compressor was more likely to enter the stall state. The higher the rotational speed, the more significant the negative influence of steam ingestion on the compressor stall margin. The entropy and temperature of air were increased by steam. The heat transfer between steam and air was continuous in compressor passages. The entropy of the air in the later stage was higher than that in the first stage; consequently, the flow loss in the second stage was more serious. Under the combined action of steam ingestion and counter-rotating bulk swirl distortion, the compressor stability margin loss was more obvious. When the rotor speed was 40% and 53% of the nominal speed, the stall margin decreased by 6.3% and 12.64%, respectively.

This paper presents results obtained between 2010 and 2014 in the field of fan aerodynamics at the Department of Composite Technology at the VZLÚ aerospace research and experimental institute in Prague – Letnany. The need for rapid and accurate methods for the preliminary design of blade machinery led to the creation of a mathematical model based on the basic laws of turbomachine aerodynamics. The mathematical model, the derivation of which is briefly described below, has been encoded in a computer programme, which enables the theoretical characteristics of a fan of the designed geometry to be determined rapidly. The validity of the mathematical model is assessed continuously by measuring model fans in the measuring unit, which was developed and manufactured specifically for this purpose. The paper also presents a comparison between measured characteristics and characteristics determined by the mathematical model as the basis for a discussion on possible causes of measured deviations and calculation deviations.

Diffusers convert kinetic flow energy into a rise in static pressure. This pressure recovery is the primary aerodynamic design objective for exhaust gas diffusers in power-generating steam and gas turbines. The total pressure loss is an equally important diffuser design parameter. It is strongly linked to the pressure recovery and the residual kinetic energy of the diffuser outlet flow. A reduction benefits the overall thermodynamic cycle, which requires the adjacent components of a diffuser to be included in the design process. This paper focuses on the total pressure losses in the boundary layer of a highly loaded annular diffuser. Due to its large opening angle the diffuser is susceptible to flow separation under uniform inlet conditions, which is a major source for total pressure losses. However, the unsteady tip leakage vortices of the upstream rotor, which are a source of losses, stabilise the boundary layer and prevent separation. Experiments and unsteady numerical simulation conducted show that the total pressure loss reduction caused by the delayed boundary layer separation exceed the vortex-induced losses by far. This flow interaction between the rotor and diffuser consequently decreases the overall total pressure losses. The intensity of the tip leakage vortex is linked to three rotor design parameters, namely work coefficient, flow coefficient and reduced blade-passing frequency. Based on these parameters, we propose a semi-empiric correlation to predict and evaluate the change in total pressure losses with regards to design operating conditions.

In continuation of works on the determination of cyclic tree-stem CO2 efflux, vacuum-extracted gas samples of large woody roots of Siberian stone pine and Scots pine are studied. Laser photoacoustic gas analysis was used to obtain chronologies of CO2 and total pressure of gas components in root rings. Spectral and cross-spectral analyses reveal the cyclic character of variations in the chronologies. Such a behavior of the total pressure and CO2 content in large roots can testify to possible cyclic diffusion of CO2 from the roots into soil and then into the atmosphere, which can be considered as a new feature of autotroph respiration. An attempt is made to analyze results of some previous work on a similar subject based on cyclic CO2 efflux from large roots. [ABSTRACT FROM AUTHOR]

A plunging jet is an efficient device to entrain gas into liquid flow. In many practical occasions, the gas entrainment needs to be carefully controlled, and the interaction between the shear flow turbulence and entrained bubbles has to be better understood. This paper presents a physical study of vertical supported two-dimensional plunging jets using a relatively large-size facility. The air-water flow and turbulence properties were measured with an intrusive phase-detection probe and a total pressure sensor simultaneously. The inflow pre-aeration and turbulence level of the falling jet were carefully characterised, and the effects of jet impact velocity and jet length on air entrainment in plunging pool were investigated. The experimental results were systematically compared to relevant studies. A discussion was developed on the quantification of turbulence intensity in highly-aerated flow based on total pressure measurement. The flow turbulence properties were derived respectively from the interfacial phase-detection signals and total pressure signals. The results highlighted difference in terms of the turbulence intensities between interfacial motions and water-phase turbulence. The present work showed that the jet impact velocity, jet length, inflow disturbance and pre-entrainment of air had considerable effects on air entrainment capacity and subsurface air-water flow properties in plunging jets hence should be carefully characterised in relevant studies. [ABSTRACT FROM AUTHOR]

This study investigated the determination of hydrogen production by three H 2 -producing microorganisms ( Thermotoga maritima, Thermococcus kodakarensis KOD1 and Enterobacter cloacae) cultured in 116-mL serum bottles. A gas pressure manometer was used to measure total pressure in the serum-bottle headspace. It was demonstrated that total pressure is the sum of the saturation pressure of water, the pressure expansion of gases, and the partial pressures of H 2 ( P gH 2 ) and CO 2 ( P gCO 2 ). A linear relationship was established between the partial pressure of H 2 measured by gas chromatography and the sum of the partial pressures of H 2 and CO 2 measured by the manometer. When pH of culture medium was not controlled (pH decreased from 7 to 5), the P gH 2 / P gCO 2 ratio was close to stoichiometric H 2 /CO 2 yield ratio of the most plausible metabolic pathways of each strain. P gH 2 / P gCO 2 values were 1.7, 1.9 and 0.9 for T. maritima , T. kodakarensis and E. cloacae , respectively. In these experimental conditions, P gH 2 can be deduced from total pressure measured by manometer. [ABSTRACT FROM AUTHOR]

Dynamic loads on specimens in live-fire conditions as well as at different locations within and outside compressed-gas-driven shock tubes are determined by both static and total blast overpressure–time pressure pulses. The biomechanical loading on the specimen is determined by surface pressures that combine the effects of static, dynamic, and reflected pressures and specimen geometry. Surface pressure is both space and time dependent; it varies as a function of size, shape, and external contour of the specimens. In this work, we used two sets of specimens: (1) anthropometric dummy head and (2) a surrogate rodent headform instrumented with pressure sensors and subjected them to blast waves in the interior and at the exit of the shock tube. We demonstrate in this work that while inside the shock tube the biomechanical loading as determined by various pressure measures closely aligns with live-fire data and shock wave theory, significant deviations are found when tests are performed outside. [ABSTRACT FROM AUTHOR]

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, three-dimensional numerical simulations are carried out to study the influence of inlet total pressure (such as 1 MPa, 1.5 MPa and 2 MPa) on the two-phase rotating detonation wave behavior. The flow field characteristics, the formation mechanism and propagation parameters of two-phase rotating detonation wave are discussed in detail. The simulation results show that the inlet total pressure has a significant impact on the two-phase rotating detonation wave in the scope of our study. Specifically, it is found that n -decane droplets are not completely consumed around the detonation wave, the escaping droplets are still evaporated and deflagrated behind the detonation wave. The increasing total pressure contributes to droplets evaporation. In addition, the generation of hot spots is a crucial factor in the detonation formation process. The shock wave induction and pressure wave accumulation are two mechanisms for it. As the total pressure increases, chaotic instability is observed before the stable stage, including the quenching, re-ignition and re-orientation, which is responsible for the variation of the propagation mode and direction of the rotating detonation waves. Moreover, in our study, with the increasing of total pressure, the intensity and stability of the detonation waves both increase, while the variation of detonation velocity is not sensitive. Our results can provide useful guidance for the research of two-phase rotating detonation engines. [ABSTRACT FROM AUTHOR]

• The vertical water entry motion and load change law is explored, and the mechanism of the influence of gas expansion and contraction is revealed. • Compared with the water entry of surface closed object, the flared cavity will generate a cyclic alternating load due to the repeated expansion and contraction of the gas in the cavity. • As the air density in the cavity increases, the gas compresses and the pressure in the cavity increases; the air density in the cavity decreases, the gas expands and the pressure in the cavity decreases. The water entry of flared cavity is a strong nonlinear process of multi-phase and multi domain coupling. In the process of liquid flowing into or out of flared cavity, there will be an obvious gas expansion and contraction in the cavity, which will not only lead to the bubble wall fluctuation, but also lead to the cyclic fluctuation of flared cavity's motion and load characteristics. In this study, a series of water entry tests of flared cavity were carried out, the fluctuation phenomenon of flared cavity during water entry was found, and their physical mechanism were revealed. Meanwhile, a hydrodynamic model is established to take into account the effect of gas pressure expansion and contraction, and a method of predicting the total pressure of flared cavity is proposed. The results show that: 1) During the water entry of flared cavity, the speed and pressure time history have obvious fluctuations effects, and the larger the water entry speed is, the more obvious the fluctuation effect is. 2) As the air density in the cavity increases, the gas compresses and the pressure in the cavity increases as well; Correspondingly, the air density in the cavity decreases, the gas expands and the pressure in the cavity decreases at the same time. 3) Compared with the surface closed objects, the water entry of flared cavity is affected not only by the hydrostatic pressure and dynamic pressure but also by the air pressure. Based on this rule, a prediction model (PMSP) of flared cavity's total pressure is proposed. [ABSTRACT FROM AUTHOR]

The front part of the flow is very important and complex in the case of debris flow where there is an accumulation of large boulders. It is important to control or dampen the energy of the frontal part of a debris flow for the safety of the downstream area because the impact pressure of debris flow is much greater than that of clear fluid. The main objective of this study is to analyze the hydraulic characteristics of the proposed dam (i.e. closed-type dam with flap). The vertical pressure distribution of this type is compared with conventional dam types. In the experiments, the total pressure associated with major debris flows was recorded in real time by a system consisting of four dynamic pressure sensors installed on different types of dam. The results from experimental data clearly show that the dam with the flap has advantages of capturing the debris flow with large boulders and controls the total pressure by flow circulation due to presence of the flap structure compared to a closed-type dam without flap. Furthermore, the empirical coefficients of hydrodynamic and solid collision models were proposed and compared with available coefficients. [ABSTRACT FROM AUTHOR]

Zirconium carbide (ZrC) coatings were deposited on graphite substrates by chemical vapor deposition from the Zr-Br 2 -C 3 H 6 -H 2 -Ar system. The influence of total pressure on the growth of ZrC was investigated in the range of 5–60 kPa. As the total pressure increased, the deposition rate increased evidently, and the preferential orientation of ZrC coatings changed from the (200) plane to the (220) plane. The growth mechanism changed from a mass transport reaction to a surface reaction at the total pressure of 20–40 kPa. At the total pressure below 20 kPa, the deposition was dominated by crystal growth, so the coatings were composed of well-faceted pyramidal-shaped crystals growing along the <001> direction. At the total pressure above 60 kPa, the growth of ZrC coatings was controlled by the nucleation mechanism, so the coatings were cluster-like crystals rapidly growing along the <110> direction. In addition, low pressure was conducive to the formation of near-stoichiometric ZrC without free carbon. These variations of ZrC coatings can mainly be attributed to gas supersaturation and remarkably changed transport diffusion coefficients with increasing total pressure. [ABSTRACT FROM AUTHOR]

Experimental investigation of the radial distributions of tangential air velocity and total pressure in the vortex overbed zone of a fluidized bed of diameter 0.393 m has been carried out. The influence of the entrainment of particles from the bed in the exhaust trails of gas bubbles on the maximum values of tangential velocity and total pressure has been established. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present the stages of designing a water in-line ejector used for ballast tanks stripping operation. The design operation was performed using NX Siemens CAD and ANSYS 15 for computer fluid dynamic analysis CFD. This ejector’ design was based on descriptive drawings of component parts, all dimensions being chosen from a worldwide supplier of high quality marine products. Computer Fluid Dynamic analysis is based on the finite element method (FEM), meshing, boundary condition and loads. Finally, we reached important conclusions regarding velocities, pressure and temperature of the fluid.

The high power consumption of auxiliary equipment, particularly that of the primary air fan, in a coal-fired power plant provides ample scope for reducing power consumption. Therefore, a power-saving control strategy for the primary air fan is proposed that automatically calculates a primary air pressure offset value in real time, which, when combined with the existing primary air pressure setting, reduces the total pressure, and correspondingly decreases the power consumption of the primary air fan while maintaining the mill outlet temperature within the optimum range. The power-saving control strategy implements two models that are respectively applicable to normal conditions and mill outlet over-temperature conditions. Mechanistic modeling is implemented for the model applicable to normal conditions. The model evaluates the mill inlet hot air damper opening for determining the potential for reducing the power consumption, the mill inlet cold air damper opening is applied for adjust the mill outlet temperature, and the total pressure and corresponding power consumption are thereby reduced. The other model is controlled by a conventional proportional derivative controller, which employs the deviation of the mill outlet temperature as its input. The proposed power-saving control strategy is applied to a 1000 MW commercial power plant, and the power consumption of the primary fan is demonstrated to be reduced by as much as 465 kW for a 500 MW load, resulting in a power consumption reduction of 15%. [ABSTRACT FROM AUTHOR]

A projection method for computing incompressible fluid flow is proposed. For the method, the rotation form Navier-Stokes equation (NSE), for which the velocity and the total pressure are employed, is discretized on the half-staggered, finite difference spatial grid. The total pressure couples the static pressure gradient and the convection of momentum in the continuous NSE while the half-staggered grid provides weak pressure-velocity coupling in discrete space. These two features interact synergistically for the discretized NSE to produce smooth pressure fields without additional numerical artifacts such as the momentum interpolation. The method preserves the kinetic energy at the inviscid limit condition. Numerical solutions of the decaying Taylor vortex, the inviscid Taylor vortex, the sudden expansion channel and the square-prism wake are presented. [ABSTRACT FROM AUTHOR]

When stagnation pressure rises in a natural or numerically simulated flow it is frequently a cause for concern, as one usually expects viscosity and turbulence to cause stagnation pressure to decrease. In fact, if stagnation pressure increases, one may suspect measurement or numerical errors. However, this need not be the case, as the laws of nature do not require that stagnation pressure continually decreases. In order to help clarify matters, the objective of this work is to understand the conditions under which stagnation pressure will rise in the unsteady/steady flows of compressible, viscous, calorically perfect, ideal gases. Furthermore, at a more practical level, the goal is to understand the conditions under which stagnation pressure will increase in flows simulated with the Reynolds averaged Navier–Stokes equations and eddy-viscosity turbulence models. In order to provide an improved understanding of increases in stagnation pressure for both these scenarios, transport equations are derived that govern its behavior in the unaveraged and Reynolds averaged settings. These equations are utilized to precisely determine the relationship between changes in stagnation pressure and zeroth, first, and second derivatives of fundamental flow quantities. Furthermore, these equations are utilized to demonstrate the relationship between changes in stagnation pressure and fundamental non-dimensional quantities that govern the conductivity, viscosity, and compressibility of the flow. In addition, based on an analysis of the Reynolds averaged equation (for eddy-viscosity turbulence models), it is shown that stagnation pressure is particularly likely to experience a spurious rise at the outer edges of shear layers that are undergoing convex curvature. Thereafter, numerical experiments are performed which confirm the primary aspects of the theoretical analysis. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present the stages of designing a water in-line ejector used for ballast tanks stripping operation. The design operation was performed using NX Siemens CAD and ANSYS 15 for computer fluid dynamic analysis CFD. This ejector' design was based on descriptive drawings of component parts, all dimensions being chosen from a worldwide supplier of high quality marine products. Computer Fluid Dynamic analysis is based on the finite element method (FEM), meshing, boundary condition and loads. Finally, we reached important conclusions regarding velocities, pressure and temperature of the fluid. [ABSTRACT FROM AUTHOR]

In this paper we advance the analysis of discretizations for a fluid-structure interaction model of the monolithic coupling between the free flow of a viscous Newtonian fluid and a deformable porous medium separated by an interface. A five-field mixed-primal finite element scheme is proposed solving for Stokes velocity-pressure and Biot displacement-total pressure-fluid pressure. Adequate inf-sup conditions are derived, and one of the distinctive features of the formulation is that its stability is established robustly in all material parameters. We propose robust preconditioners for this perturbed saddle-point problem using appropriately weighted operators in fractional Sobolev and metric spaces at the interface. The performance is corroborated by several test cases, including the application to interfacial flow in the brain. • Well-posedness of the coupled problem is proved treating the problem as a perturbed saddle-point system. • Operator preconditioning is utilized to derive mesh independent and parameter robust preconditioners. • Construction of the discrete preconditioners is detailed with focus on the non-standard fractional components. • Robustness of the preconditioners is demonstrated by numerical examples using (H 1)-non/conforming FE. • Feasibility of the preconditioners is illustrated in an application to interfacial flow in the brain. [ABSTRACT FROM AUTHOR]

As the injection total pressure increases, the flow field in the combustion chamber of rotating detonation engine (RDE) becomes complicated and the detonation wave becomes unstable. When the total pressure is high enough, the detonation oscillates periodically and alternates between strong and weak. Under the same injection conditions, no oscillation is observed in two-wave RDE, and the two detonation waves propagate stably in the combustion chamber. The choking ratio of the injection Laval nozzle along the head end is not influenced by the total pressure, the mode of propagation, or the number of detonation waves. And thus the mass flux of RDE can be estimated using the maximum mass flux of the injection Laval nozzle. The specific impulse and thrust of RDE show overall growth as total pressure increases. However, they oscillate with the unstable detonation wave in one-wave RDE at high total pressure. [ABSTRACT FROM PUBLISHER]

A numerical investigation of flows in a cyclone chamber has been carried out at the fraction of bottom blast φ =0-0.5, at the values of the dimensionless pinch diameter d/D =0.7 with different locations and configurations of nozzles for air intake. In the simulation of swirling flows, the well-known k-ε and k-ω turbulence models, as well as the laminar flow model, were used. A satisfactory agreement between the results of numerical simulation and experimental data at d/D =0.5-0.7 is obtained. For a chamber with a relative pinch diameter d/D =0.3 the calculated flow parameters differ substantially from experimental values. [ABSTRACT FROM AUTHOR]

We consider a multiphysics model for the flow of Newtonian fluid coupled with Biot consolidation equations through an interface, and incorporating total pressure as an unknown in the poroelastic region. A new mixed-primal finite element scheme is proposed solving for the pairs fluid velocity–pressure and displacement–total poroelastic pressure using Stokes-stable elements, and where the formulation does not require Lagrange multipliers to set up the usual transmission conditions on the interface. The stability and well-posedness of the continuous and semi-discrete problems are analysed in detail. Our numerical study is framed in the context of applicative problems pertaining to heterogeneous geophysical flows and to eye poromechanics. For the latter, we investigate different interfacial flow regimes in Cartesian and axisymmetric coordinates that could eventually help describe early morphologic changes associated with glaucoma development in canine species. [ABSTRACT FROM AUTHOR]

Abstract: This study investigates the effect of total pressure (P0 ) and nozzle divergent length (Ld ) on the flow character and particle impact velocity in cold spraying. Computational fluid dynamic (CFD) approach is employed in the present work to achieve this objective. The simulated results indicate that P0 and Ld significantly influence the flow regime and particle acceleration. With gradually increasing P0 , the nozzle exit Mach number (Me ) firstly increases and then fluctuates after P0 exceeds a critical value, finally Me reaches the maximum value and maintains stable. Differing from Me , the particle impact velocity (Vp ) continually goes up with P0 due to the increasing gas density which can improve the drag force, but the growth rate levels out gradually. Besides, it is also found that Me shows a downward trend with increasing Ld . However, as for Vp , there exists an optimal Ld which can guarantee the particle achieving the maximum Vp . Moreover, for nozzles with larger expansion ratio, the optimal Ld is longer. This optimal length is considered as a consequence of the competition between the particle acceleration time and drag force on the particle surface. [Copyright &y& Elsevier]

Abstract: In this work we discuss the reliability of the coupling among three-dimensional (3D) and one-dimensional (1D) models that describe blood flowing into the circulatory tree. In particular, we study the physical consistency of the 1D model with respect to the 3D one. To this aim, we introduce a general criterion based on energy balance for the proper choice of coupling conditions between models. We also propose a way to include in the 1D model the effect of the external tissue surrounding the vessel and we discuss its importance whenever this effect is considered in the 3D model. Finally, we propose several numerical results in real human carotids, studying different configurations for the 1D model and highlighting the best one in view of the physical consistency. [Copyright &y& Elsevier]

An axial-type fan that operates at a relative total pressure of 671 Pa and a static pressure of 560 Pa with a flowrate of 416.6 m3/min is developed using an optimization technique based on the gradient method. Prior to the optimization of the fan blade, a three-dimensional axial-type fan blade is designed based on the free-vortex method along the radial direction. Twelve design variables are applied to the optimization of the rotor blade, and one design variable is selected for optimizing a stator which is located behind the rotor to support a fandriving motor. The total and static pressure are applied to the restriction condition with the operating flowrate on the design point, and the efficiency is chosen as the response variable to be maximized. Through these procedures, an initial axial-fan blade designed by the free vortex method is modified to increase the efficiency with a satisfactory operating condition. The optimized fan is tested and compared with the performance obtained with the same class fan to figure out the optimization effect. The test results show that the optimized fan not only satisfies the restriction conditions but also operates at the same efficiency even though the tip clearance of the optimized fan is greater than 30%. The experimental and numerical tests show that this optimization method can improve the efficiency and operating pressures on axial-type fans. [ABSTRACT FROM AUTHOR]

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A low mass flux steam jet in subcooled water was experimentally investigated. The transition of flow pattern from stable jet to condensation oscillation was observed at relatively high water temperature. The axial total pressures, the axial and radial temperature distributions were measured in the jet region. The results indicated that the pressure and temperature distributions were mainly influenced by the water temperature. The correlations corrected with water temperature were given to predict the dimensionless axial pressure peak distance and axial temperature distributions in the jet region, the results showed a good agreement between the predictions and experiments. Moreover, the self-similarity property of the radial temperature was obtained, which agreed well with Gauss distribution. In present work, all the dimensionless properties were mainly dependent on the water temperature but weakly on the nozzle size under a certain steam mass flux. [ABSTRACT FROM AUTHOR]

During yarn formation by ring spinning, fibres are bent into approximately helical shapes and torque or twist-liveliness is created. The yarn torque causes yarn instability, manifested as snarling or entanglements, and this instability must be controlled during manufacturing processes. Generally, the torque depends on yarn geometric factors such as the yarn twist, linear density and the fibre properties. A practical solution to the problem of twist-liveliness is the formation of a two-fold yarn. This twisting or plying process produces a yarn structure where the energy of the system is determined by purely geometrical constraints of the plied structure and consequently when an energy minimum is reached the plied yarn obtained from the process is torsionally balanced and torque-free. In the present paper, the stability of plied textile yarns will be evaluated using the Topological Conservation law (Fuller, F. B., 1971, Proc. Nat. Acad. Sci. USA, 68, 815-819.) developed to study the post-buckling behaviour of twisted rods by Van der Heijden et al. (Jut. J. Mech. Sci., 45, 161-196, 2003). The present work considers the equilibrium configuration of a series of multi-ply twisted yarns (2,4, and 6 strands) of finite length. Several structural and mechanical properties are highlighted: (i) the influence of structural properties (the number of strands, the strand linear density and strand twist) and the ratio of the torsional and bending stiffnesses of the strands on the balance point in multi-ply yarns. The topological invariant of the twisted yarn (link) is used to calculate the ply and strand properties (writhe) and compared with experimental results obtained at CSIRO. The inter-strand pressure between strands of a multi-ply yarn, a feature of interest for fibre interactions in yarn structures, is also calculated at the balance situation across a range of structural and mechanical conditions. [ABSTRACT FROM AUTHOR]