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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.