Numerical simulations of inlet jets flow of propellants in the main combustion chamber equipped in a liquid rocket engine have been conducted by compressible CFD technics employing a van der Waals-type equation of state (EOS) and chemical reaction models. Various simulations have been already conducted both for combustion and non-combustion state in the chamber; however, the accuracy of EOS for the mixture of propellant employing a classical mixing rule (CMR), particularly for the sound speed, has not been understood well. Therefore, we have validated the applicability of Soave–Redlich–Kwong (SRK) EOS as one of the van der Waals-type EOSs coupled with the CMR for the sound speed using molecular dynamics (MD) simulations against an imaginary model of oxygen-hydrogen mixture system. We found that SRK EOS coupled with a well-employed CMR can reproduce the sound speed in the MD simulations within a relative error of several percent and that the CMR hardly increases the deviation of the SRK EOS in the single component. The present results suggest that the SRK EOS with the CMR cannot be the main factor to cause critical errors in the CFD based on RANS, which will give reliability to current CFD simulations for internal flows in a combustion chamber of a liquid rocket engine.

Due to the isotropy and high thermal conductivity of metal foam, a novel idea of isothermal chamber filled with graded copper foam (GCF) is developed to improve the isothermal characteristic of isothermal chamber. Firstly, an analytical effective thermal conductivity (ETC) prediction model of metal foam is proposed, with relative root-mean-square error (RRMSE) is 6.90%, which has higher ETC prediction accuracy than the semi-empirical models in the literatures. Secondly, the conventional porous random fiber bundle is replaced by the copper foam as the filler material to improve the isothermal characteristic, and this more accurate ETC prediction model of metal foam is used in the numerical simulation of the discharge process to determine the isothermal characteristic of isothermal chamber filled with homogeneous copper foam (HCF). Experiments are conducted to verify the results of simulation. Thirdly, the graded filling method is adopted to form an isothermal chamber filled with GCF, which enhance the heat transfer efficiency and further improve the isothermal characteristic. The results show that, compared with the conventional isothermal chamber filled with homogeneous porous random fiber bundle, the isothermal characteristic of the isothermal chamber filled with GCF is improved by 32.7%.

Recent studies of catalysis have highlighted the importance of heat-driven reaction enhancement, suggesting the need for improved understanding of heat transfer in the vicinity of catalyst particles in the reaction process. Specifically, it is essential and necessary to understand the heat of reaction transferred to catalyst particles and surrounding gas molecules in the vicinity of the catalyst surface. In the present study, we developed a method to estimate the ratio of the heat of reaction transferred to the catalyst particle and the gas molecules in the framework of ReaxFF. A molecular dynamics (MD) simulation using the ReaxFF reactive force field is applied to the case of carbon monoxide oxidation on the surface of a platinum nanoparticle. To estimate the amount of thermal energy transferred to the catalyst particle and the gas molecules during the reaction, we propose a calculation method using the interfacial thermal conductance (ITC) between the gas molecules and the solid surface. The thermal energy transferred in the vicinity of the particle was calculated from the results of MD simulation, and the heat conduction from the gas molecules to the catalyst and the substrate was calculated using the ITC. This study found that the heat of reaction transferred to the catalyst particle was of the same order as that transferred to the gas molecules in the catalytic reaction process investigated.

In this study, a new method of producing silicon crystal substrates is proposed as an alternative to conventional methods. The proposed method is characterised by the continuous production of plates from molten materials by surface tension and a reduction in the plate thickness by the compression effect of electromagnetic pressure. Low-melting point alloys were used in the experiments instead of silicon. In previous studies, the inefficient application of electromagnetic pressure to the molten metal and a reduction in the width of the produced substrate have been issues. Therefore, this study improved the coil shape used to apply electromagnetic pressure and to reduce the Laplace pressure acting on the liquid surface at the side edges of the molten metal, which is considered the cause of the plate width reduction. By reducing the number of coil turns, electromagnetic pressure was effectively applied to the molten metal part, the magnetic field frequency was increased and heat generation was reduced. The increased frequency was expected to enable the effective application of larger electromagnetic pressure. In addition, there was an increase in the local thickness at the side edges of substrates by installing grooves in the exit stage of the crucible, which reduced the Laplace pressure and facilitated the production of substrates with the prescribed width. Substrate production experiments were conducted with a reshaped coil and a crucible with grooves in the exit stage section, and substrates with thicknesses of less than 100 μm in several locations were successfully produced.

We experimentally investigated the influences of a small obstacle on the sidewall upon a detonation cellular structure using the smoked-foil technique for a stoichiometric hydrogen–oxygen mixture diluted with argon at pressures ranging from 15 to 60 kPa. The obstacles were of four types: forward-facing steps and slopes and backward-facing steps and slopes. The step height was varied and set to 1, 2, or 5 mm, but the slope height was fixed at 5 mm. The forward-facing slope angle was set to 40° or 75°, and the backward-facing slope angle was set to 20° or 40°. Under all conditions, for the forward-facing steps and slopes, the detonation cellular structure was negligibly affected, except for the region around the tip of the step and slope. However, for the backward-facing step, the detonation re-activation phenomenon occurred downstream of the obstacle. In addition, the enlarged cellular pattern due to the rarefaction wave and the trajectory of the re-activated strong transverse wave were observed downstream of the obstacle. Furthermore, a finer cellular pattern was observed downstream of the re-activation phenomenon. The distance between the backward-facing step and the re-activation position z_ra was fitted well by a power-law relation of the step height |h| and the cell width of the steadily propagating detonation λ_CJ as z_ra/λ_CJ = 2.7(|h|/λ_CJ)^0.80. When the obstacle was the backward-facing slope, the smoked-foil records could be classified into two types based on whether the signatures of the detonation re-activation phenomena were clearly observed or not. Finally, when the finer cellular pattern was observed, the behavior of the cell-width enlargement subsequent to the re-activation phenomenon was similar in all cases, and the characteristic length required for the finer cellular pattern to relax to the steady-state pattern was approximately 10 times z_ra.