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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]

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]

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. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

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 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]

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]

Abstract: The phosphide telluride Ti2PTe2 can be synthesised from the elements or from oxides in a thermite type reaction. Both ways have been optimised by consideration of the thermodynamic behaviour of the compound. Hence, the investigation of phase equilibria in the ternary system Ti/P/Te and of the thermal decomposition of Ti2PTe2 was necessary. This investigation was performed by using different experimental approaches as total pressure measurements, thermal analysis and mass spectrometry. The results were supported and further analysed by thermodynamic modelling of the ternary system. It was shown that Ti2PTe2(s) decomposes to Ti2P(s) and Te2(g) in six consecutive steps. The growth of single crystals of Ti2PTe2 is thermodynamically described as a chemical vapour transport with TiCl4(g) acting as the transport agent. [Copyright &y& Elsevier]

Abstract: The pressure variation in a natural circulation loop has been investigated for both steady state and transient operating conditions. The loop exchanges heat with hot and cold external fluid streams through counterflow concentric tube heat exchangers. Considering spatial changes only in the direction of the loop length, closed form expressions have been obtained for pressure difference under steady state condition. An iterative scheme based on finite element method (FEM) has been formulated to solve the conservation equations in the transient state. The variation of dynamic pressure and its relationship with the variation of temperature field and circulation rate has been described. [Copyright &y& Elsevier]

Kerosene/air two-phase rotating detonation is numerically investigated to find out the limits of detonation stability as a function of total pressure and total temperature considering the operation conditions of the detonation engine. The Eulerian-Lagrangian two-phase governing system is used and the kerosene/air two-step reaction mechanism is applied to simulate the unsteady features, such as self-sustained propagation and quenching. The findings from the parametric study show that stable rotating detonation is achieved in a limited range of total pressure and the increasing total temperature contributes to detonation stability. The bifurcated wave structure is formed in the two-phase rotating detonation and the promotion of droplet evaporation tends to weaken this near-inlet complex wave feature. The reaction-dominated quenching and the evaporation-dominated quenching are two mechanisms for the breakdown of the detonation front, which is due to the interaction among fluid dynamics, droplet evaporation, and exothermic reaction. [ABSTRACT FROM AUTHOR]

• Experimental data and modeling for CO 2 , H 2 O and mixed gasification at high pressure. • Beech wood chars produced in drop-tube reactor at 1400 °C and 1600 °C at 200 ms. • Gasification in single-particle reactor with forced flow-through conditions. • Interpretation of results based on graphitization, ash dispersion and morphology. This paper presents experimental data and modeling approaches to describe the influence of CO 2 and H 2 O partial pressure as well as absolute pressure on the gasification kinetics of two different beech wood chars. The chars were produced at 1400 °C (P1400) and 1600 °C (P1600) at high-heating rates and short residence times in a drop-tube reactor. The gasification experiments were conducted in a single-particle reactor with forced flow-through conditions reducing diffusional effects to a minimum. The interpretation of the experimentally determined reaction rates during gasification with CO 2 , H 2 O and its mixture is based on the char properties (graphitization, ash dispersion and morphology) presented in a previous publication. During gasification with CO 2 , P1600 shows higher reactivity as compared to P1400 for all CO 2 partial pressures and temperatures applied. The higher reactivity of P1600 during CO 2 gasification may be explained by a CaO film on the char surface catalyzing the char-CO 2 gasification reaction. On the other hand, P1400 shows higher reactivity towards H 2 O which may be evoked by the lower graphitization degree and higher specific surface area. Reaction kinetic modeling for single atmosphere gasification was successfully carried out using a power law approach. The Langmuir-Hinshelwood model, however, only gave good results where a possible saturation of the char surface at high pressure was observed. Increasing the CO 2 partial pressure during gasification in mixed CO 2 /H 2 O atmospheres leads to higher reactivity for both chars. The reaction rate r mix can be expressed by addition of the single atmosphere reaction rates in the low pressure area suggesting a separate active site mechanism. Catalytic activity of CaO increases the P1600 reactivity distinctively for lower H 2 O and CO 2 partial pressures. For higher H 2 O and CO 2 partial pressures, P1600 reactivity stagnates due to lower specific surface area and higher graphitization degree. Here, a common active sites mechanism can be assumed. [ABSTRACT FROM AUTHOR]

Various oblique detonation waves (ODW) structures have been investigated with the application background of ramjet engine, but effects of forebody compression have attracted little attention before. Two forebody compression models, the ESS (equal-strength-shock) compression and the SI (shock-isentropic) compression, have been introduced to study their effects on the ODW structure and thermal performance. Numerical results demonstrate that the compression method influences the ODW structure obviously, including the initiation location and the OSW–ODW transition type. Compared with the ESS compression, the SI compression leads to the downstream movement of initiation location, and the transition prefers to be abrupt rather not smooth. On the thermal features, the total pressure recovery is used to analyse the difference as the key parameter on the potential of engine impulse. The ESS compression corresponds a low total pressure loss when considering only the combustion process, while the SI compression performs better when considering the inlet–combustion whole process. Analysis on total pressure recovery gives the average total pressure recovery with flight Ma, altitude, and wedge angle. It is pointed out the SI compression has two shortcomings, including a long initiation length and a low total pressure recovery of combustion process, which should be considered in the future application. [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. [ABSTRACT FROM AUTHOR]