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An electronic pressure control unit, coupled with a small built-in compressed air chamber, is applied to a field-portable gas chromatograph to precisely adjust the column head pressure with an accuracy of

Objective: Effective mechanical circulatory support (MCS) relies on cardiac function measures to guide titration. Left ventricular end diastolic pressure (LVEDP) is a useful measure that is indirectly estimated using pulmonary artery catheters (PACs). PACs require additional intervention and provide intermittent and unreliable estimations. MCS device signals can estimate LVEDP but are prone to inter-device variability and require rigorous specialized characterization. We present a scalable and implementable approach to calculate LVEDP continuously using device signals. Methods: LVEDP was calculated from MCS device measured aortic pressure and motor current, which approximates the pressure head between the aorta and left ventricle. This motor current-pressure head relationship is device-specific but approximated using existing flow calibration and assumed physiologic relationships. Performance was evaluated with comparison from direct measurement of LVEDP in a series of acute animal models. Results: LVEDP measures ( n = 178,279) from 18 animals had good correlation ( r = 0.84) and calibration (Bland-Altman limits of agreement −7.77 to 7.63 mmHg; mean bias −0.07 ± 0.02 mmHg). The total mean error prediction interval was −3.42 to 3.32 mmHg and RMS error was 3.85 mmHg. Conclusion: LVEDP can be continuously calculated using device signals without specialized characterization. Calculated LVEDP values improved upon PAC estimations and were found using a scalable and manufacturer-accessible method. Significance: This method improves upon existing LVEDP measures without the need for rigorous characterization, external calibration, or additional intervention; this allows widescale deployment of continuous LVEDP measurement for patients on MCS and demonstrates key considerations necessary to translate research-grade technologies.

To investigate liquid seepage process in a coal granular-type porous medium, a new sampling device was designed to obtain coal samples with required porosity. Meanwhile, an approach combining ultra-deep-field microscopy with advanced digital image processing technologies was proposed to rebuild granular-type porous medium models. The liquid seepage process was simulated with CFD, and the effects of head pressure, liquid viscosity, and pore size were studied. The results show that only liquids with head pressures above a critical value can penetrate into coal stacks and the hydraulic conductivity and permeability are positively correlated to the driving head pressure. Liquid viscosity enhances flow deformation, causing more eddy current energy dissipation; the turbulent eddy dissipation caused by acetone, methanol, and ethanol was 700, 1200, and 4700 m2/s3, respectively. Larger pores can strengthen the additional pressure at the front end of the flow, reducing the flow resistance and thus increasing the fluid kinetic energy and seepage velocity.

With the incidence of end-stage heart failure steadily increasing, the need for a practical total artificial heart (TAH) has never been greater. Continuous flow TAHs (CFTAH) are being developed using rotary blood pumps (RBPs), leveraging their small size, mechanical simplicity, and excellent durability. To completely replace the heart with currently available RBPs, two are required; one for providing pulmonary flow and one for providing systemic flow. To prevent hazardous states, it is essential to maintain balance between the pulmonary and systemic circulation at a wide variety of physiologic states. In this study, we investigated factors determining a CFTAH's inherent ability to balance systemic and pulmonary flow passively, without active management of pump rotational speed. Four different RBPs (ReliantHeart HA5, Thoratec HMII, HeartWare HVAD, and Ventracor VentrAssist) were used in various combinations to construct CFTAHs. Each CFTAH's ability to autonomously maintain pressures and flows within defined ranges was evaluated in a hybrid mock loop as systemic and pulmonary vascular resistance (PVR) were changed. The resistance box, a method to quantify the range of vascular resistances that can be safely supported by a CFTAH, was used to compare different CFTAH configurations in an efficient and predictive way. To reduce the need for future in vitro tests and to aid in their analysis, a novel analytical evaluation to predict the resistance box of various CFTAH configurations was also performed. None of the investigated CFTAH configurations fully satisfied the predefined benchmarks for inherent flow balancing, with the VentrAssist (left) and HeartAssist 5 (right) offering the best combination. The extent to which each CFTAH was able to autonomously maintain balance was determined by the pressure sensitivity of each RPB: the sensitivity of outflow to changes in the pressure head. The analytical model showed that by matching left and right pressure sensitivity the inherent balancing performance can be improved. These findings may ultimately lead to a reduced need for manual speed changes or active control systems.

Water distribution network design is going through many developments. Today, simulation software programs are essentially being used to design the whole network of water distribution systems to reduce the overall cost while meeting the water demand at adequate terminal pressure and maintaining CPHEEO standard water quality. In this study, we have used WaterCAD software to design and to analyze the proposed water distribution network of Bhogpur gram panchayat of Panskura 2 block of Purba Medinipur District in West Bengal. The analytic study is based on a surface water-based pipeline water delivery scheme, executed by the Public Health Engineering Department, Government of West Bengal at Purba Medinipur district of West Bengal. The outputs of the above-noted study are also verified theoretically. It was computed and ensured that the minimum pressure head available in the water distribution network is 8.82 m and the maximum flow velocity of 0.9 m/s. The study exercised in this paper is enthralled to support both academicians with industry-versed hydraulics engineer.

The effects of compression deformation of gas diffusion layer (GDL) on the performance of a proton exchange membrane fuel cell (PEMFC) with serpentine flow field were numerically investigated by coupling two-dimensional GDL mechanical deformation model based on Finite Element Analysis and three-dimensional two-phase PEMFC model with incorporating the deformation impacts. Emphasis is located on exploring the influences of assembly pressure on the non-uniform geometric deformation and distributions of transport properties in the GDL, flow behaviors and local distributions of oxygen and current density, cell polarization curves and net power densities of the PEMFC. It was indicated that the non-uniform deformation of GDL results in inhomogeneous distributions of porosity and permeability in the GDL due to the presence of rib-channel pattern, and the transport properties in the under-rib region are greatly reduced with increasing the assembly pressure, consequently weakening the gas flow and oxygen transport in the under-rib region and increasing the non-uniformity of local current density distribution. As for the overall cell performance, however, attributed to the tradeoff between the adverse impacts of GDL compression on mass transport loss and positive effects on reducing ohmic loss, the overall cell performance is firstly increased and then decreased with increasing assembly pressure from 0 MPa to 5.0 MPa, and the maximum cell performance can be achieved at the assembly pressure of about 1.0 MPa for all cases studied. As compared with the case for zero assembly pressure, the maximum net power density of the cell can be improved by about 7.7%, 9.9%, 10.5% and 10.7% for the cathode stoichiometry ratios of 2.0, 3.0, 4.0 and 5.0@iref = 1 A·cm−2, respectively. Practically, it is suggested that the assembly pressure is controlled in an appropriate range of 0.5 MPa–1.5 MPa such that the cell net power can be boosted and pressure head requirement for the pump can be maintained in a appropriate level.

The paper presents an experimental study of a novel self-rectifying twin-rotor air turbine to equip an oscillating water column wave energy converter. The turbine is based on a pair of conventional radial inflow rotors mounted on a common shaft, complemented by the corresponding inlet guide vane rows, by a curved-duct manifold arranged circumferentially in a periodic manner and by an axially-moving cylindrical valve. The valve ensures that the air flows alternately through one or the other of the two parts of the twin-rotor turbine, depending on the sign of the pressure head. Due to its symmetry, only one half of the twin-rotor turbine was constructed and tested in a relatively large-scale unidirectional flow at the blow-down test rig of Instituto Superior Tecnico. Results are presented in dimensionless form for efficiency, power output, pressure head and flow rate. A comparison with self-rectifying turbines commonly used in wave energy converters is shown. Additionally, an approach of turbine efficiency in random waves was made using the stochastic model.

In this paper, an experimental study has been performed to investigate the performance of varying diameter of orifice that made from acrylic plastic on the flow characteristics. A colour water has been used as a working fluid to flow through a PVC pipe system. The orifice has a sharp-edged with 30° angle and the pipe system has thirty tapping points across the orifice for the pressure measurement. The experiments have been carried out for different beta ratio and Reynolds number. The results clearly demonstrated that the beta ratio has a positive effects on the discharge coefficient particularly at the laminar flow regime whereas it has inversely effects on pressure head losses. Therefore, geometric parameters are required to be properly designed in order to achieve the desired objective. It has been also found that the orifice discharge coefficient reduces with increasing in Reynolds number for all values of beta ratio especially at the turbulent flow regime and hence adequate must be taken while designing such orifice. The results obtained in the present study have been compared with that predicted from an empirical correlations and they show a good agreement between them. Finally, a statistical analysis has been carried out in order to determine a fitting correlation for the discharge coefficient based on the present experimental data.

A rapid and convince component characteristics extrapolation method and starting control law design method were presented in the paper. The component characteristics extrapolation method based on the relationship between flow coefficient and adiabatic pressure head coefficient in low speed region was researched, and the starting process control law of some two-spool turbofan was designed using the Virtual Power Extraction Method (VPEM). The starting characteristics was researched in both steady-state and dynamic-state models, the starting process simulation result was quick and safe, and the validity of the extrapolation method and VPEM were proved.

Measurement of pressure is an important activity in the laboratory and industry since it is one of the most important variables that affects most processes. Many other properties of systems are affected by the operating pressure. For example, in an IC engine cylinder, the pressure varies continuously with time and determines the power output of the engine. Chemical reactions are affected by the operating pressure. In thermal power plants, the operating pressure of the boiler, for example, needs to be closely monitored during operation.

Additive manufacturing (AM) is an effective tool for accelerating knowledge gain in development processes, as it enables the production of complex prototypes at low cost and with short lead times. In the development of mechanical circulatory support, the use of cheap polymer-based AM techniques for prototype manufacturing allows more design variations to be tested, promoting a better understanding of the respective system and its optimization parameters. Here, we compare four commonly used AM processes for polymers with respect to manufacturing accuracy, surface roughness, and shape fidelity in an aqueous environment. Impeller replicas of the CentriMag blood pump were manufactured with each process and integrated into original pump housings. The assemblies were tested for hydraulic properties and hemolysis in reference to the commercially available pump. Computational fluid dynamic simulations were carried out to support the transfer of the results to other applications. In hydraulic testing, the deviation in pressure head and motor current of all additively manufactured replicas from the reference pump remained below 2% over the entire operating range of the pump. In contrast, significant deviations of up to 620% were observed in hemolysis testing. Only the replicas produced by stereolithography showed a nonsignificant deviation from the reference pump, which we attribute to the low surface roughness of parts manufactured thereby. The results suggest that there is a flow-dependent threshold of roughness above which a surface strongly contributes to cell lysis by promoting a hydraulically rough boundary flow.

A method is proposed for calculating main aerodynamic characteristics of the main rotor of the Mi-26 helicopter: a lift, a reactive moment, a required power of the propulsion system, a speed of the inductive air flow, a throttle response coefficient, a speed of the horizontal flight. This method based on the pressure propeller theory. The parameters of the Mi-26 helicopter and the propeller of the experimental setup calculated according to the pressure theory of the main rotor are experimentally confirmed. The percentage of the discrepancy between the statistical data on the aerodynamic characteristics of the Mi-26 helicopter rotor calculated with the pressure theory does not exceed 1.5%.

Summary Extensive R&D activity provided reliable basis for testing a reservoir-specific surfactant-polymer mixture as EOR flooding pilot performed in the largest multi-layered (stacked) hydrocarbon occurrence at the Algyo field. The target formation was a sandstone reservoir with 70 mD permeability on average bearing low viscosity oil (0.64 cP at 98 °C and 190 bar). The injected SP solution contained a specific surfactant blend developed by MOL and his Hungarian university partners, and a mobility controlling agent was a commercial copolymer of acrylamide and ATBS. For the preparation of the SP solution, after additional filtration, formation water was used at the site. During the pilot period, altogether 1/3 pore volume of SP solution was injected into the reservoir. The surfactant/polymer solution was injected into two injection wells starting from April 2016 and was intended to finish in 2019, after 45 months of continuous injection period. The injection was started with 100 m3/day/well flow rate of chemical mixture, containing 15,000 ppm surfactant and 1,000 ppm polymer driven into the reservoir using injection well head pressure of 0 bar. Most important parameters and effects of the pilot were continuously recorded and evaluating the reservoir response as a function of the injected volume including both injection and production wells (seven oil wells were operating around the two injection wells). It should be noted that due to the high heterogeneity of the reservoir, a fine tuning of the injection plan supported the technology through the whole frame of the pilot. The successful upscaling of the surfactant manufacturing and the easily available raw materials provided a problem-free supply of surfactant with standard quality. Various laboratory measurements were performed to control the polymer and surfactant concentration as well as the rheological and interfacial properties of injected SP solution. In addition one of the main advantage of the EOR method was that the produced emulsion could be easily broken into bulk fluids. This paper summarizes the workflow and results of the pilot performed in the past four years. The results of this pilot provided reliable information and adequate basis to start a new project of similar field-scale chemical EOR technology for other blocks, hoping that it will further increase the recovery factor in the Algyo-2 reservoir and yielding substantial incremental oil production in matured, depleted fields in the coming years.

The sectorization of Water Distribution Networks (WDN) is characterized by permanent and periodic valve closures to control the volumes distributed and help to manage water losses. These valve maneuvers are characterized by wave propagations of varying severity. These transient phenomena are considered as a major problem in the under-load networks operation. These maneuvers can lead to bursting and breakage of the pipes because of water hammer. In this research work, we are interested in evaluating the impact of valve operations on the occurrence of transient regimes in a Discrete Hydraulic Sector (DHS) of the water distribution network of the city of Casablanca. The required hydraulic model for a real distribution network was established using the Bentley HAMMER. Several simulations with various transient severities of valve closures were performed and simulated in the field. Three examples have been considered: a pipe with and without a connection, a mesh network and a pipe with opening fire hydrant. The simulations thus carried out show that the sudden opening and closing, in the case of the valve of large diameter and pipe with a high wave propagation velocity, the transient phenomenon results in a significant induced pressure head which could lead to (i) significant transient severities in the pipelines, (ii) probable occurrence of leaks (iii) distribution break. The findings of this research work and the proposed approach would promote for the utility managers a new process to follow of partitioning a WDN without mechanical stress on the pipe components during the operation of sectorization.

This article reports the interaction between groundwater and surface water sources based on diurnal head fluctuations. The model uses the well-known Fick’s second law to numerically estimate the pressure head variations in heterogeneous aquifers. The developed numerical model can examine the effects of both stream level sudden diurnal and gradual variations on the pressure heads in a confined heterogeneous aquifer. Calculations of pressure heads as a result of the interaction indicated that independent of the sequence of diffusion coefficient in the two similar confined aquifers, variations in pressure head will be the same at considerable amount of distances from the interaction region, unless when the total effective diffusion lengths are different. In the investigated cases, through time, the significant difference in the pressure heads between the gradual and sudden increase in stream water levels vanished, and the pressure head variations between the two cases became negligible.

Spatiotemporal variations of the pore-water pressure and water table response to small amounts of water exchange were measured in a sand column. In the dewatering experiment, the pressure head variation can be divided into three stages: the initial pressure head declining phase when water table is above the sand surface, a sudden drop in accordance with the capillary fringe when water level passes through the sand surface, and a slow declining phase with respect to the specific yield of the sand. As for the watering experiment of the shallow groundwater with different initial truncation factors (TF), the addition of a minute amount of water results in a rapid rise of the pressure head initially, then a gradually increase to its equilibrium. When the upper extent of the fully saturated capillary fringe coincides with the sand surface (TF ≤ 1), a thin film of water addition produces nearly instantaneous increase in pore-water pressure, corresponding to a rapid rise of groundwater table to the sand surface. Pressure head increment increases linearly with the TF value and reaches its maximum when TF value approaches unity. Considering the vertical distribution of the pressure head, its gradient becomes larger right after the water addition, then decreases to its initial value of hydrostatic condition in the end. In the case of TF > 1, there is an unsaturated layer above the groundwater table, the pressure head increases after the water addition, whose magnitude however decreases as the increase of TF value. Nevertheless, the final position of the groundwater table is still below the sand surface, and the gradient of the pressure head vertical distribution dose not vary significantly throughout the entire process. In consideration of hydrostatic pressure assumption, temporal variation of the water table was also quantitatively obtained based on the measured instantaneous pore-water pressure data, which is consistent with time-varying process of the pressure head during both the dewatering and watering experiments.

Blockage effects are currently not accounted for in cavitation analyses of tidal turbine rotors. At higher blockage ratios, rotors are more heavily loaded and have potentially stronger suction peaks, so cavitation inception is more likely. In this paper, blade resolved computations are used to carry out a cavitation analysis over a range of blockage ratios and tip-speed-ratios. Our analysis suggests that increasing the blockage ratio from 0.01 to 0.197 reduces the minimum static pressure head in the fluid by approximately 0.5 m. To mitigate this reduction, either the submersion depth of the rotor can be increased or the maximum permissible tip speed ratio reduced. However, reducing the maximum permissible tip speed ratio is shown to severely restrict the rotor thrust and power. Spanwise flow effects are shown to reduce the strength of the suction peak on the outboard blade sections, reducing the likelihood of cavitation inception. Blade element based methods are shown to inadequately account for spanwise flow effects and thus are overly-conservative. Hence, rotors designed with these methods could potentially be operated at higher tip-speed-ratios or reduced submersion depths.

It is known that using paired laterals, in which two distribution pipes extend in opposite directions from a common manifold, contribute to increasing water use efficiency (WUE). Recently, an analytical procedure to optimally design paired drip laterals on uniform slopes was proposed. More recently, this design procedure was simplified by deriving simple explicit relationships, as a function of 16 calibration constants, with relative errors that were less than 2%. In this paper, further simple design relationships are derived that require only 3 calibration constants, thus more readily obtainable results are produced and the influence of the flow rate and diameter exponents of resistance equation are made more evident. Simple monomial relationships were also extended for the cases in which the lateral is laid on flat fields, on upward fields, and also considering layouts in which the manifold is located at the boundary, instead of inside, of the irrigation unit. For the five considered layouts, evaluations of the effects of design choices in terms of energy saving and comparisons between optimal lateral lengths, are carried out. Finally, simple linear relationships linking lateral pressure head tolerance (δ), coefficient of variation of pressure heads (CV) and emission uniformity coefficient of Keller and Karmeli (EU) are presented. Results showed that for any design solutions associated with the considered layouts and for δ < 0.1, the proposed procedure allows optimal design of the lateral, optimizing WUE, assuring low values of pressure head variability (CV < 6.1%) and high values of emission uniformity coefficient (EU > 95%).

The HeartWare HVAD is a radial rotary blood pump with a combination of passive magnetic and hydrodynamic bearings to levitate the impeller. The axial gap size between impeller and housing in this bearing and its sensitivity to speed, flow, and pressure difference is difficult to assess. Shear stresses are exceptionally high in this tiny gap making it important for blood damage and related adverse events. Therefore, the aim of this study was to measure the axial gap clearance in the HVAD at different operating conditions employing radiography. To quantify the gap size in the HVAD, the pump was positioned 30 mm in front of the X-ray source employing a microfocus X-ray tube with an acceleration voltage up to 300 kV. Beams were detected on a flat panel detector (Perkin Elmer XRD 1611-CP3). The pump was connected to a tubing circuit with a throttle to adjust flow (0, 5, 10 L/min) and a water glycerol mixture to set the desired viscosity (1, 4, 8 mPas). Rotational speed was varied between 1800 and 3600 rpm. In this study, for clinically relevant conditions at 5 L/min and 2700 rpm, the axial gap was 22 µm. The gap size increased with rotational speeds dependent on the viscosity (2.8, 6.9, and 9.4 µm/1000 rpm for 1, 4, and 8 mPas, respectively), but was independent from the volume flow and the pressure head at constant speeds. In summary, using X-ray radiographic imaging small gaps in a rotary blood pump during operation can be measured in a nondestructive contact-free way. The axial hydrodynamic bearing gap in the HVAD pump was determined to be in the range of about three times the diameter of a red blood cell. Its dependence on operating volume flow and generated pressure head across the pump is not pronounced.

Perforated pipes are widely used in applications such as drainage, irrigation and ventilation. The variation in the pressure head, h, in a perforated pipe follows a certain pattern. By analyzing h variation patterns at the tail ends of perforated pipes on flat slope, and the characteristic coefficient of the perforated pipe was proposed. According to the value of characteristic coefficient of the perforated pipe, perforated pipes are classified into three types, namely, short, medium and long pipes. In addition, a method for determining the type of perforated pipe based on its characteristic coefficient and length-to-diameter ratio is provided. Furthermore, on the condition of long perforated pipe, based on the locations of the maximum and minimum h values, the slope at which the perforated pipe is laid and the head loss ratio along the length of the perforated pipe, h curves are classified into five types. The experimental results demonstrate that the experimental data exhibit a variation pattern consistent with that of the calculation results, indicating that the classification of pressure head curves is, to a certain degree, reasonable and applicable.

We developed a high gas pressure calibration system that uses a liquid-lubricated (LL) pressure balance as a standard for pressures up to 100 MPa. The LL pressure balance can generate gas or hydraulic pressure by changing the pressure medium. We first evaluate characteristics of the LL piston–cylinder (PC), such as its effective area and fall rate. The effective area of the LL PC is evaluated through comparison with a hydraulic pressure balance. When the LL PC uses a gas, the fall rate is affected by gas dissolution into liquid in the LL PC reservoir. The results of calibrating a pressure gauge under the developed system are consistent with those by an existing hydraulic pressure calibration system.

The control rod hydraulic driving system (CRHDS) is a new type of built-in control rod drive technology. In the CRHDS the pulse flow from the pump into the hydraulic cylinder of the control rod hydraulic drive mechanism (CRHDM) is regulated by the integrated valve to perform the step motion of the reactor control rod. Transient flow occurs in the CRHDS during control rod step motion process which is studied by experiments. The time-history curves of flow rate, pressure and inner cylinder displacement were analyzed, and the results show that the water hammer pressure peak during the step-up motion is high, while there are no obvious pressure fluctuations in the corresponding step-down motion. In the step-up process, the pressure fluctuation amplitude increases with the increase of CRHDS driving pressure. The step-up time and the pressure increasing time before step-up decreases with the driving pressure. The step-up pressure increases with the driving pressure. In the step-down process, the step-down time, the step-down pressure and the pressure decreasing time before step-down do not change with the increase of the driving pressure. The experimental results lay the base for the working principle and vibration reduction analysis of the CRHDS and it’s also helpful for improvement of the working performance of the key facilities and instruments of the CRHDS loop.

Counterrotating axial fans (CRF) are being adopted in air ventilation to meet the demand for a higher pressure head and swirl-free discharge. This experimental and numerical study is aimed ...

SIRR-MOD is a DSS integrating two numerical modules: (1) A agro-hydrological model (named FLOWS-HAGES) for simulating flow of water and solutes in heterogeneous agri-environmental systems; (2) A model for simulating the hydraulics of the irrigation network (named COPAM). FLOW-HAGES provides a daily list of hydrants opening based on water or crop criteria. Then, an optimal sequence of hydrants may be established by passing the volumes to be delivered to a model (COPAM) for simulating the hydraulics of the irrigation network, in order to guarantee that the discharges flowing inside the distribution pipes network are delivered under optimal pressure head distribution. In this paper, we only illustrated the potential of FLOWS-HAGES model in simulating the daily evolution of: soil water contents and pressure heads in the soil profile; water uptake; stress periods for each crop; return fluxes to the groundwater under pressurized irrigation systems and climatic conditions at district level. This methodology has been applied to establish irrigation scheduling over the irrigation season for sector 6 of the Irrigation District 10 in the “Sinistra Ofanto” irrigation system. Irrigation water volumes calculated by FLOWS-HAGES model were compared to the volumes delivered by farmers, showing irrigation simulated by the model more frequent than those supplied by the farmers and with lower irrigation volumes.

The motion of liquid filling a pipeline is impeded when the gas ahead of it cannot escape. Entrapped gas will lead to a significant pressure build-up in front of the liquid column, which slows down the column and eventually bounces it back. The pressure and temperature in the gas may become dangerously high, and for example, lead to fires and explosions caused by auto-ignition. This paper considers the case where the trapped gas can escape through a vent. One new element is that the pressure head of the liquid supply reservoir is fluctuating instead of staying constant. The obtained analytical and numerical solutions are utilized in parameter variation studies that give deeper insight in the system's behavior.

With reference to a classical wet tank equipped with a wastewater submersible pump, in this research, an advanced numerical model has been used in order to obtain the optimal pump scheduling of on/off operation and variable pump speed. Then, in order to evaluate the time decay of pump performances, the mechanical wear has been artificially simulated and the performance curves have been experimentally obtained for different rotational speeds. Finally, the benefits, as well as the feasibility, of pump scheduling have been evaluated for differing operating conditions. According to the results, the optimal pump scheduling achieves large energy savings up to 43%, for soft mechanical wear. If the mechanical wear is considered, the energy savings are large as well, between 35.60% and 26.70%, for medium and hard mechanical wear, respectively. On the other hand, the limitation of such a strategy has been highlighted: the feasibility of pump scheduling is limited by the elevation of the downstream tank. According to the results, energy savings can be achieved until the elevation of the downstream tank is 67% of the pressure head at the best efficiency point, whereas such percentage decreases to 50% for hard mechanical wear. Finally, the results show that plant efficiency is strongly affected by the mechanical wear: an accurate maintenance of the pumping system is therefore recommended in order to attenuate the time decay of pump performances.

Physically-based dynamic modelling of shallow landslide susceptibility rests on several assumptions and simplifications. However, the applicability of physically-based models is only rarely tested in the field at the appropriate scale. This paper presents results of a spray irrigation experiment conducted on a plot of 100 m2 on an Alpine slope susceptible to shallow landsliding. Infiltrating precipitation applied at a constant rate (27.5 mm/h for 5.3 h) was monitored by means of 2D time-lapse electrical resistivity tomography, combined with time-domain reflectometry sensors installed at various depths. In addition, regolith characteristics were assessed by dynamic cone penetration tests using a light-weight cone penetrometer. The spray irrigation experiment resulted in a vertically progressing wetting front to a depth of 80–100 cm. Below that, the unconsolidated material was already saturated by rainfall in the previous days. The observed mean resistivity reduction attributed to infiltrating water during irrigation was scaled to pressure head. Mean variations in pore pressure were reproduced by a linear diffusion model also used in physically-based dynamic landslide susceptibility modelling. Sensitive parameters (hydraulic conductivity and specific storage) were tested over selected value ranges and calibrated. Calibrated parameter values are within published and experimentally derived ranges. The results of the comparison of observations and model results suggest that the model is capable of reproducing mean changes of pore pressure at a suitable scale for physically-based modelling of shallow landslide susceptibility. However, small-scale variations in pore pressure that may facilitate the triggering of shallow landslides are not captured by the model.

The ability to conduct dynamic calibrations of pressure sensors at different average pressures is very important because the dynamic properties of pressure sensors also depend on the value of the average pressure during the pressure pulsations. The main limitation of periodic dynamic pressure generators is the difficulty in achieving sinusoidal pulsations at higher amplitudes and frequencies in a gaseous medium due to the nonlinearities that result from the physical gas dynamics. This paper presents a newly developed dynamic pressure generator based on a double-acting pneumatic actuator in which the piston is driven by an electrodynamic shaker. In order to minimize the static preload of the shaker, which is due to the pressure acting on the piston, and therefore to enable the generation of larger pressure pulsations at different average pressures with the same excitation force, the cylinder chambers above and below the piston are pressurized with the same initial static gas pressure. As the dynamic characteristics of the dynamic pressure generator are also defined by the properties of the piston and both the cylinder chambers, the actuator dimensions were optimized with the help of mathematical modeling. In order to demonstrate the capabilities and limitations of the developed dynamic pressure generator, both mathematical and experimental analyses were performed.

Purpose – The purpose of this paper is to clarify the effect of material hardening model and lump-pass method on the thermal-elastic-plastic (TEP) finite element (FE) simulation of residual stress induced by multi-pass welding of materials with cyclic plasticity. Design/methodology/approach – Nickel-base alloy and stainless steel, which are used in J-type weld for manufacturing the nuclear reactor pressure head, can easily harden during multi-pass welding. The J-weld welding experiment is carried out and the temperature cycle and residual stress are measured to validate the TEP simulation. Thermal-mechanical sequence coupling method is employed to get the welding residual stress. The lumped-pass model and pass-by-pass FE model are built and two materials hardening models, kinematic hardening model and mixed hardening model, are adopted during the simulations. The effects of material hardening models and lumped-pass method on the residual stress in J-weld are distinguished. Findings – Based on the kinematic hardening model, the stresses simulated with the lumped-pass FE model are almost consistent with those obtained by the pass-by-pass FE model; while with the mixed hardening material model, the lumped-pass method has great effect on the simulated stress. Practical implications – A computation with mixed isotropic-kinematic material seems not to be the appropriate solution when using the lumped-pass method to save the computation time. Originality/value – In the simulation of multi-pass welding residual stress involved in materials with cyclic plasticity, the material hardening model should be carefully considered. The kinematic hardening model with lump-pass FE model can be used to get better simulation results with less computation time. The results give a direction for welding residual stress simulation for the large structure such as the reactor pressure vessel.

Vertical-lift tunnel-type gates are subjected to hydrostatic and hydrodynamics forces created as a result of operation conditions of a wide range of partial openings, discharges and heads. Among these forces is the uplift hydrodynamic force resulting from the effects of flow issuing below the gate bottom. The evaluation of this force requires the determination of bottom pressure coefficient (Kb) which is based mainly upon the measurements of the jet flow velocity across the vena contracta, the pressure head distribution along and across the bottom gate surface and pressure head of flow just downstream the gate shaft. In the present research, a random hydraulic model was created to identify the effect of twelve gate lips orientation on the behavior of flow and consequently on the bottom pressure coefficient. The main conclusion is that the values of bottom pressure coefficient (Kb) are inversely proportional to gate opening ratios (Y/Y0) and range from high values with small gate openings ratios and low values for (Y/Y0 > 30%). The study finds that the bottom pressure coefficient (Kb) and the fluctuations flow pattern below the gate surface are influenced mainly by the gate geometry.

The energy efficiency of pumping stations in irrigation networks was examined using a methodology to determine the optimum pumping station regulation. The methodology was developed in the MATLAB® environment using the EPANET® toolkit and developed using three on-demand irrigation networks located in the Castilla—La Mancha region of Spain. In each irrigation network, the energy efficiency and energy consumption were obtained for three cases: a fixed pumping head, a pumping head that guaranteed minimum pressure head required at the open hydrant and a pumping head that minimised the absorbed power at the pumping station. With the three networks average energy savings of 3%, 7% and 30% were obtained by using the optimum pressure head compared with the current management based on fixed pressure regulation. This methodology is intended to be useful in irrigable areas to improve the management of pumping systems where the use of fixed pressure regulation is extensive. It is important to measure electrical and hydraulic parameters of pumps which make it possible to determine the energy efficiency of a pumping station for each combination of discharge and pressure head as well as the pressure head which minimises the energy consumed for the pumping station to guarantee a specific pressure at open hydrants. These results were related to the fact that with fixed pressures, and mainly low and medium discharges, the energy efficiency of pumping systems can drop.

The research examines the influence of constructive features of a pressure hydraulic structure on the intensity of suffusion processes in the tailwater. The equations of non-vortex filtration fluid motion under a hydraulic structure in the form of a sheet pile wall are calculated by the finite element method using the Neumann and Dirichlet boundary conditions. The influence of immersion depth of the sheet pile on the erosion processes in the tailwater is investigated. The possibility of protecting the pressure head structure by creating an apron in the tailwater which prevents soil suffusion is analyzed. Calculations show that the greatest pressure gradients are observed at the sheet pile tip and at the outlet to the tailwater. From the point of view of the suffusion process, the zone at the lower end of the sheet pile is not dangerous; therefore, predictions about the suffusion intensity for a particular structure should be made on the basis of the output gradients at the tailwater border. Calculations show that the constructive features of a pressure hydraulic structure have a significant impact on the processes of suffusion and pile heave. The graphs are based on the calculation results; they clearly demonstrate that the filtration rate in the structure tailwater sharply decreases with an increase in the depth of driving the sheet pile, regardless of the soil type of the structure base. Besides, an additional protective effect is provided by a structure in the apron tailwater.

In case of a large or medium LOCA accident of marine nuclear power plant, the loop pressure drops rapidly. In case of power failure of the whole ship at this time, the active safety injection system will lose its function because the safety injection pump needs AC power, and the core is at risk of melting. A passive marine safety injection system based on high-pressure compressed gas is designed for the superposition of large and medium LOCA accidents and the whole ship's power failure accidents, including the safety injection subsystem of medium and low pressure and the safety injection subsystem of recirculation. The energy required for safety injection is provided by the potential energy of compressed gas, the pressure head is provided by the technology of gas-liquid booster pump, and the collection signals and valves are controlled by the technology of intelligent fluid control unit with small power consumption. The power supply used in the system is provided by DC 24 V battery. The mathematical and physical models of accumulator, gas storage tank, gas-liquid booster pump, reactor body and its pipeline are established for the designed passive safety injection system. The operation and safety characteristics of medium pressure safety injection, low pressure safety injection and recycling safety injection under LOCA accident conditions are simulated. The safety injection time and flow rate of three safety injection pressures are simulated by medium pressure safety injection, the safety injection time and peak temperature are simulated by low pressure safety injection, and the pressure and system temperature are simulated by recirculation safety injection. The simulation results show that the marine passive safety injection system designed under LOCA accident conditions can meet the requirements of core cooling.

Point-of-use biosand water filters are widely distributed in undeveloped or developing regions due to their water treatment success and low-cost design, but two gaps remain in the basic technology: (1) the filter body is oversized relative to its contaminant removal performance, and (2) the heavy design largely excludes difficult to reach locations in need of clean water solutions. Here, we model design modifications to the v.10 Centre for Affordable Water and Sanitation Technology biosand filter using a reduced filter height, increased biolayer area, and conserved reservoir volume. We compare the hydraulic characteristics (dynamic velocity and head pressure) and percent contaminant removal of bacteria Escherichia coli and virus MS2 of the modified designs to the traditional control design using a finite element approximation of Darcy&rsquo, s law with discrete time steps and a slow-sand filtration model. We demonstrate that a reduced-height design has a greater impact on contaminant removal compared to the traditional design (largely due to the increased residence time from the decreased flow rate inside the filter). For example, our 70% reduced-height filter design removed 99.5% and 73.93% of E. coli and MS2, respectively, where the traditional filter design removed 62.81% and 27.6%, respectively. Reduced-height designs should be pursued as a viable solution to improve filter performance while allowing for alternative construction techniques with greater end-user accessibility compared to the traditional design.

This paper proposes a methodology for leak detection and isolation (LDI) in pipelines based on data fusion from two approaches: a steady-state estimation and an Extended Kalman Filter (EKF). The proposed method considers only pressure head and flow rate measurements at the pipeline ends, which contain intrinsic sensor and process noise. The LDI system is tested in real-time by using an USB data acquisition device that is implemented in MATLAB environment. The effectiveness of the method is analyzed by considering: online detection, location as well as quantification of non-concurrent leaks at different positions. The leak estimation error average is less than 1% of the flow rate and less than 3% in the leakage position. Furthermore, the incorporation of a steady-state estimation shows that the solution of the LDI problem has improved significantly with respect to the one that only considers the EKF estimation. An experimental analysis was also performed on the effectiveness of the proposed approach for different sampling rates and for different leakage positions

The study was undertaken to determine the performance of submersible pump and mono-block centrifugal pump to develop characteristic curves of and its operating conditions. The results revealed that submersible pump the maximum all over pump set efficiency was found 54.98 % at working head 40.43 m, discharge equal to 24.10 lps, WHP 12.99 and input HP 23.63, it was operating point of pump. More than 50 % efficiency can be achieved with discharge capacity varied between 24.10 to 17.89 lps. While Mono-block pump testing was done for suction lifts 0.5 m, 0.7 m, 1.6 m and 2.5m, the maximum efficiency was found 75.10 % at 0.7 m suction lift and at 29.34 m head under same static lift minimum efficiency was found 47.94 .So, operating head may be adopted 17 m against this head maximum efficiency is 48 %, discharge 11.9 lps and 5.5 HP

The first-ever power interconnection between existing Floating Production Storage and Offloading (FPSO) units, including retrofit of existing power generation and integration of an overall Power Management System, has enable the implementation of subsea multiphase pumping to activate the existing production loops.Despite gas lift activation at riser base, the back pressure generated by pressure drop in the subsea network was limiting the liquid production of the high productivity wells. Providing a pressure boost in the production network using the subsea multiphase pumps enabled to lower the well head pressure, thus increasing production rates and ultimate recovery.The paper will present the miscellaneous technical challenges that have been faced during the project development from the early design stage down to commissioning, start up and operation of both FPSOs as an integrated asset while maintaining and enhancing the full oil and gas production.It will cover both surface and subsurface aspects with the design and implementation of power generation upgrade, electrical network modifications, overall power management system involving load sharing and load shedding as well as the interconnecting power cable (IPC) with specific dynamic sections and the power supply and integration of the subsea multiphase pumps with an offset up to 18 km.

Conventionally, a multi-stage flash evaporation (MSF) process is modelled with a large system of nonlinear ODEs accounting for the pressure head, salinity and brine temperature changes spatially and temporarily. This paper demonstrates that the ODE system can be represented with PDEs as a simpler system and controlled efficiently with boundary controls that maximize the distillate production rate of MSF process. In PDE representation a whole desalination plant that includes brine recirculation can be modelled and controlled simpler than in ODE representation.

As gradually wide applications of MHD fluid, transportation as well as control with pumps and valves is unavoidable, which induces MHD fluid hammer. The paper attempts to combine MHD effect and fluid hammer effect and to investigate the characteristics of laminar MHD fluid hammer. A non-dimensional fluid hammer model, based on Navier–Stocks equations, coupling with Lorentz force is numerically solved in a reservoir–pipe–valve system with uniform external magnetic field. The MHD effect is represented by the interaction number which associates with the conductivity of the MHD fluid as well as the external magnetic field and can be interpreted as the ratio of Lorentz force to Joukowsky force. The transient numerical results of pressure head, average velocity, wall shear stress, velocity profiles and shear stress profiles are provided. The additional MHD effect hinders fluid motion, weakens wave front and homogenizes velocity profiles, contributing to obvious attenuation of oscillation, strengthened line packing and weakened Richardson annular effect. Studying the characteristics of MHD laminar fluid hammer theoretically supplements the gap of knowledge of rapid-transient MHD flow and technically provides beneficial information for MHD pipeline system designers to better devise MHD systems.

The amount of asphaltene is usually the minimum portion of crude constituents; however, due to its negative impact on the well performance and the overall efficiency of oil reservoir management, a large number of mostly academic studies are directed toward understanding the asphaltene behavior and mitigation of its deposition in flow processes from reservoir to process facilities. Typically, a small number of these are actual case studies. Among them is the asphaltene deposition in Marrat oil well string. In this particular case, significant amount of valuable field data were gathered for a long period of time under controlled conditions. By carefully reviewing the presented data in the original paper, we concluded that re-analysis of the field observation results, for improved understanding of the asphaltene deposition process, is necessary. By recalling the concept of liquid loading in the gas wells, the reduction of flowing well head pressure is interpreted due to the left asphaltene solid micelles in the well string. Also, we judge that the process of asphaltene deposition in the production tubing is a ‘seating and carving’ dynamic process, and at a critical thickness, the amount of asphaltene ‘cutting’ increases which is responsible for further pressure drop in the well tubing. By performing fundamentally simple calculations, the amount of asphaltene ‘left’ in tubing and the amount of asphaltene ‘cutting’ are computed. Also the minimum oil flow rate to handle and remove the asphaltene micelles is estimated in the Marrat case. Finally, we propose certain recommendations for future data gathering and optimum handling operation of asphaltene precipitation and deposition in well string.

The linear friction welding (LFW) process is a very effective solid-state welding method. Friction process is very significant for temperature distributions on the surface between two contacting workpieces during LFW process. In this paper, a finite element method (FEM) model is implemented to analyze the temperature distributions in friction interface of GH4169 superalloy cylindrical specimens. The simulation studies were conducted using ABAQUS software. Temperature distributions during the simulation of one rotation of the pressure head on the specimen were simulated. Temperature distributions of specimens in the end of different rotations were also investigated. The validation experiments were conducted to validate the simulation results. The detailed microstructure investigations demonstrate that the temperature distributions obtained in the present model are correct. This friction model is able to simulate the friction process of the GH4169 superalloy, but further research about FEM models is still needed for more precise prediction of microstructure evolution in the friction process of this alloy. Keywords: Linear friction welding, Friction process, Finite element method, GH4169 superalloy, Temperature distributions

In this study, a novel prototype high-efficiency miniature pump that uses magnetic properties of a ferrofluid in both pumping and valving mechanisms is presented. The minichannel consisting of a cylindrical pumping chamber, a check valve, an inlet and an outlet, comprises six bonded layers of PMMA. A cylindrical permanent magnet that is placed inside the chamber and is externally actuated by a motorized off-center permanent magnet, functions as a revolving piston which sweeps the perimeter of the cylinder. Ferrofluid is used to cover the gaps between the magnetic piston and the channel walls, also serves as a separating plug between the inlet and the outlet of the chamber preventing recirculation of the pumped fluid inside the chamber. This novel revolving piston design eliminates the need for an inlet valve. Pressure head is maintained using one ball check valve at the outlet of the pump. Water has been successfully pumped at flow rates of up to 934 μL/min, backpressures of up to 994 Pa, and maximum achieved volumetric efficiency of 79 percent while working at 80, 52, and 9 rpm rates, respectively.

An analytical solution for the seepage field in water-filled karst tunnel is derived based on the inversion of complex function and groundwater hydraulics theory. The solution considers the distance between the tunnel and the cavern, the size of the cavern, and the properties of the lining structure, such as the permeability coefficient as well as the radius of the grouting ring. This paper also performed numerical simulations for two cases: the application of gravity and the absence of gravity. The numerical solution was obtained to verify the analytical solution, and a good agreement was found. Then, the effect of parameters is discussed in detail, including the distance between the tunnel and the cavern, the radius of the cavern, the grouting ring, and the initial support. The results show that when the radius of the cavern is constant, the pressure head and seepage flow decrease as the distance between the tunnel and the cavern increases. When the distance is constant, the pressure head and seepage flow increase with the increase of the radius of the cavern. In addition, the pressure head and the seepage flow decrease with the increase of the thickness of the grouting ring and decrease with the decrease of the permeability coefficient. As the thickness of the initial support increases, the pressure head gradually increases and the percolation decreases. Furthermore, due to the great influence of the grouting ring and initial support on the pressure head and seepage flow, the thickness and permeability coefficient of the grouting ring and initial support should be taken into account carefully during construction.

In this paper, according to the typical hypersonic vehicle,a study of flushair data sensing system using BP neural network algorithm were carried out. The independent research and development of CACFD software for solving the Euler equations, calculation of vehicle head pressure distribution as the neural network training input, the corresponding flow conditions, such as the static pressure, the Manumber, angle of attack and sideslip angle as the target samples to train the neural network, set up FADS algorithmbased onBP neural network and testing. Studies showed that the FADS algorithm based on neural network technique is robust and has good precision, strong real-time, is a very effective algorithm. Research results had showed that: in the sample number range, the precision of FADS is increasing with the the number of samplesincreasing; the average error of FADS algorithm decreases with increase of pressure measuring point of layout combinations; contains large cone angle position measurement points, points than only the small cone angle measuring point combination results average error .To remove vertex pressurepoint, had little effect on the precision of algorithm,the FADS algorithm generalization performance is very stable with 1% pressure measurement error

An obstruction meter widely used to measure flow rate of a fluid through a pipe line works on the principle of Bernoulli's equation, where the pressure difference between two sides of the obstruction is taken as a measure of flow rate. Thus the pipe line may suffer from a loss of static pressure and maximum flowing capacity cannot be utilized. In the present paper a novel technique of flow measurement is proposed in order to avoid this difficulty of obstruction meter. In this technique, no obstruction is used in the pipe line and the decrease in pipe line pressure head due to flow is taken as measure of flow. The effect of static pressure head in the pipe line is cancelled out by using to specially design identical bourdon gauges where the movement of the free tip of the bourdon tubes due to pressure is sensed by identical inductive pick up coils. One of the special gauges senses the static pressure at the source under no flow condition and the other pressure gauge senses the pipe line pressure at a given flow rate of the fluid. The free arm of aU-shaped ferromagnetic wire attached with the free tip of each bourdon tube acts as a moveable core inside and inductive pick up coil fixed with the base plate of the bourdon tube. Thus the self inductance of each pick up coil changes the change of pressure in the bourdon tube. Hence the difference between the inductances the two coils measures the change of pipe line pressure due to flow only. In the present paper a modified op-amps based differential inductance measuring circuits is designed whose output varies with the variation of flow rate. This circuit acts as proposed flow transducer. Its principle of operation is describe in the paper the performance of a prototype unit tested experiment mentally is reported in the paper in terms of static characteristics. The characteristics are found to follow the mathematical relation derived in the paper with very good repeatability.

This paper presents a method of on-site density measurement of pressure transmitting medium at high pressures. The density is estimated by precisely detecting head differential pressure using a monitoring pressure gauge. A flexible pressure tube which is durable for high pressures is used to change the vertical position of the monitoring pressure gauge. We measured the density of dioctyl sebacate, which is commonly used as hydraulic pressure transmitting oil for pressure calibrations. The estimated density was almost similar to the previously reported value at low pressures, but became smaller by approximately 1 % at 100 MPa. This method is applicable to other pressure transmitting medium, which are being used at calibration laboratories and industries without accurate density values at high pressures, and will help users to estimate head differential pressure more accurately.

The active liquid cooling system is urgently required for heat dissipation of high-power electronics. However, the key part of the system, micro-pump, is still challenged by the bearing failure problem caused by the mechanical friction. We designed a hydro-dynamically levitated centrifugal micro-pump, providing a 1.0 L/min flow rate and a 45 KPa pressure head at 20000 rpm with the size as small as 23mm×23mm×25mm. By utilizing radial and axial hydro-dynamically levitated bearings, the rotating units can be successfully levitated and realize no contact and no friction. The designed micro-pump has large power density, high rotating speed, long-life and high-reliability and we believe that it may have extensive application in active liquid cooling systems.

The working principle of a new kind of double-acting pneumatic-hydraulic pressure amplifier having two-step output pressure driven by the pneumatic cylinder with rodless piston is introduced. The output flux and the output pressure calculating formulae are also given out. Compared with the known single-acting pressure amplifier,the innovative pressure-amplifier is simple in structure and has much higher working efficiency. It can also output adaptive two-step liquid pressure, which is similar with the hydraulic differential connection, thus it is easy to realize move quickly in low pressure and move slowly at high pressure. This system also fits a trend of green manufacturing for using green air as transmission medium and with closed oil without leak to output pressure liquid.