Shock Wave Mach Number Research Articles

Reversible photoluminescence shift in imidazolium l-tartrate crystal triggered by acoustic shock waves

Abstract Imidazolium l-tartrate crystal has been grown by employing the slow evaporation technique using de-ionized water as the solvent. An impact study on the exposure of shock pulses on the surface of the material has been carried out and the influence of shock waves on its photo luminance has been investigated. In the present work, in order to carry out the experiment, a shock wave of Mach number 1.5 has been utilized which has been generated by a semi-automated Reddy Tube. Imidazolium tartrate crystal is made into a fine powder and split into four identical parts to be used for further characterization. A series of shock waves such as 25, 50, and 75 are impacted on the respective samples while keeping one of the samples as the control. The powder X-ray diffraction analysis reveals that the observed increase in peak intensity and peak shifting is due to the increase in the number of shock pulses from 25 to 75. FTIR is performed to analyze the presence of functional groups in the material before and after shock exposure. Photoluminescence measurements are also carried out for the pre- and post-shocked samples to determine the nature of optical emission with respect to various shock pulse counts. The above experimental analyzes confirm that the title sample undergoes a reversible photoluminescence shift induced by shock waves.

Hypersonic inlet flow field reconstruction dominated by shock wave and boundary layer based on small sample physics-informed neural networks

High Mach number inlets face complex challenges such as shock wave/boundary layer interference, adversely impacting the aerodynamic characteristics and stable operating boundaries. Traditional computational fluid dynamics (CFD) simulations for performance and flow field analysis are slow, and data-driven deep learning technologies struggle with predicting flow fields in complex aerodynamic phenomena like shock wave/boundary layer interactions, boundary layer separation, and Mach disks. This study introduces a rapid, robust method for reconstructing hypersonic viscous inlet flow fields using inlet geometry design parameters. This method is called shock wave and boundary layer dominated two-dimensional multiphysical field reconstruction model based on multi-scale sensory field fusion residual physical information neural network (PIMSRF_ResNet), ensuring high-precision training data. Using the optimal Pareto solution set from multi-objective optimization with a small sample intelligence method, 150 sets of multi-physics fields under Ma10 conditions with varying geometric design parameters are calculated. Compared to traditional pure data-driven models, PIMSRF_ResNet's structural similarity in the test set reaches 0.9773, with a peak signal-to-noise ratio close to 30 dB and a correlation coefficient exceeding 98%. These experimental results demonstrated that the proposed method is a promising tool for real-time prediction of complex internal flow fields dominated by high Mach number shock waves and boundary layers.

Study on the Interface Instability of a Shock Wave–Sub-Millimeter Liquid Droplet Interface and a Numerical Investigation of Its Breakup

This study investigated the influence of instability on the interaction between sub-millimeter liquid droplets and shock waves. Experiments were conducted using 0.42 mm diameter droplets with varying shock wave Mach numbers. The investigation quantified the effects of Weber numbers and initial diameters on the development of Rayleigh–Taylor and Kelvin–Helmholtz instabilities at the shock wave–sub-millimeter liquid droplet interface. Three-dimensional numerical simulations were performed to investigate the deformation and breakup behaviors of sub-millimeter liquid droplets under the impact of a shock wave with a Mach number of 2.12. The post-shock gas flow environment in this condition was in a supersonic state. The simulations utilized the volume-of-fluid method to model the gas–liquid interface, employed unsteady Reynolds-averaged Navier–Stokes methods to simulate turbulence, and incorporated grid gradient adaptive technology to enhance computational efficiency. The results revealed that by increasing the Weber number or decreasing the initial diameter, both the growth rate and the wavenumber extremum of the Rayleigh–Taylor and Kelvin–Helmholtz instability waves increased. The variation in the K–H instability’s growth rate extremum increasing Weber number surpassed that of the R–T’s instability. This indicated that both the R–T and K–H waves on sub-millimeter liquid droplets tended to exhibit increased growth rates and reduced scales. Moreover, as the Weber number increased, the K–H instability became dominant in the aerodynamic fragmentation. The numerical simulations showed good qualitative agreement with the experimental data, affirming the viability of numerical methods for addressing such challenges. The evolution of the sub-millimeter liquid droplets was marked by two primary stages, flattening and shear stripping, signifying that the K–H instability-driven SIE mechanism governed the aerodynamic breakup in the supersonic post-shock airflow.

Numerical simulation of shock wave propagation over a dense particle layer using the Baer–Nunziato model

The present study examines the possibility of numerical simulation of a strong shock wave propagating over the surface of a dense layer of particles poured onto an impermeable wall using the Baer–Nunziato two-phase flow model. The setting of the problem follows the full-scale experiment. The mathematical model is based on a two-dimensional system of Baer–Nunziato equations and takes into account intergranular stresses arising in the solid phase of particles. The computational algorithm is based on the Harten–Lax–van Leer–Contact method with a pressure relaxation procedure. The developed algorithm proved to be workable for two-phase problems with explicit interfacial boundaries and strong shock waves. These issues are typical of problems arising from the interaction of a shock wave with a bed or a layer of particles. A comparison with the simulations and full-scale experiments of other authors is carried out. A reasonable agreement with the experiment is obtained for the angles of the transmitted compaction wave and granular contact, including their dependency on the intensity of the propagating shock wave. The granular contact angle increases with the incident shock wave Mach number, while the transmitted compaction wave angle decreases. An explanation is given of the phenomenon of the decrease in thickness of the compacted region in the layer with the increase in intensity of the propagating shock wave. The main reason is that the maximal value of the particle volume fraction in the plug of compacted particles in the layer rises with the increase in shock wave intensity.

Impact Of Shock Waves on Structural and Optical Properties of Li2so4.H2o Doped L-Alanine Single Crystals for High Pressure and Temperature Applications

The current study discusses the impact of shock wave of Mach number 1.7 on structural, molecular and optical properties of Li2SO4.H2O doped L-Alanine single crystals. PXRD, Raman spectral results confirm that the test crystal does not undergo any crystallographic phase transitions and conformational transitions against the shock wave. Optical micrographs and UV-Visible analysis communicate the subtle morphological changes and optical properties which is not significantly changed by shock wave. The results of crystallographic studies provide the strong proof that the crystal has molecular stability and a stable crystallographic structure against the impact of applied shock waves and suitable for a wide range of uses in aerospace applications.

Deflagration and detonation induced by shock wave focusing at different Mach numbers

Shock wave focusing is an effective way to create a hot spot or a high-pressure and high-temperature region at a certain place, showing its unique usage in detonation initiation, which is beneficial for the development of detonation-based engines. The flame propagation behavior after the autoignition induced by shock wave focusing is crucial to the formation and self-sustaining of the detonation wave. In this study, wedge reflectors with two different angles (60° and 90°) and a planar reflector are employed, and the Mach number of incident shock waves ranging from 2.0 to 2.8 is utilized to trigger different flame propagation modes. Dynamic pressure transducers and the high-speed schlieren imaging system are both employed to investigate the shock-shock collision and ignition procedure. The results reveal a total of four flame propagation modes: deflagration, DDT (Deflagration-to-Detonation Transition), unsteady detonation, and direct detonation. The detonation wave formed in the DDT and unsteady detonation mode is only approximately 75%−85% of the Chapman-Jouguet (C-J) speed; meanwhile, the directly induced detonation wave speed is close to the C-J speed. Transverse waves, which are strong evidence for the existence of detonation waves, are discovered in experiments. The usage of wedge reflectors significantly reduces the initial pressure difference ratio needed for direct detonation ignition. We also provide a practical method for differentiating between detonation and deflagration modes, which involves contrasting the speed of the reflected shock wave with the speed of the theoretically nonreactive reflected shock wave. These findings should serve as a reference for the detonation initiation technique in advanced detonation propulsion engines.

Experimental investigation of breakup times of droplet under the action of shock wave

In this paper, the morphological characteristics and breakup time of droplet under the action of shock wave were investigated experimentally. Morphological characteristics of droplet were captured by high-speed photography. By varying the diameter of droplets and taking the influence of the shock wave Mach number into consideration, eight tests were performed in the experiments. The experimental results showed that under the action of the shock wave, the droplet underwent two different stages: the deformation stage and the atomization stage. In the deformation stage, the droplet evolved from spherical shape to pineal shape under the action of accompanying airflow induced by shock wave. In the atomization stage, the growth of unstable wave on the surface of the droplet caused by the Rayleigh–Taylor instability was the main reason for the droplet to be atomized. The effects of initial diameter and shock Mach number on atomization time were analysed. The decrease of initial diameter and the increase of shock Mach number reduced the droplet atomization time. The Mach number played a dominant role in the breakup process of the droplet.

Deflagration-to-Detonation Transition in Stochiometric Propane–Hydrogen–Air Mixtures

Hydrocarbon–hydrogen blends are often considered as perspective environmentally friendly fuels for power plants, piston engines, heating appliances, home stoves, etc. However, the addition of hydrogen to a hydrocarbon fuel poses a potential risk of accidental explosion due to the high reactivity of hydrogen. In this manuscript, the detonability of stoichiometric C3H8–H2–air mixtures is studied experimentally in terms of the run-up time and distance of deflagration to detonation transition (DDT). The hydrogen volume fraction in the mixtures varied from 0 to 1. Three different configurations of detonation tubes were used to ensure the DDT in the mixtures of the various compositions. The measured dependences of the DDT run-up time and distance on the hydrogen volume fraction were found to be nonlinear and, in some cases, nonmonotonic with local maxima. Blended fuel detonability is shown to increase sharply only at a relatively large hydrogen volume fraction (above 70%), i.e., the addition of hydrogen to propane in amounts less than 70% vol. does not affect the detonability of the blended fuel significantly. The observed nonlinear/nonmonotonic dependences are shown to be the manifestation of the physicochemical properties of hydrogen-containing mixtures. An increase in the hydrogen volume fraction is accompanied by effects leading to both an increase and a decrease in mixture sensitivity to the DDT. Thus, on the one hand, the increase in the hydrogen volume fraction increases the mixture sensitivity to DDT due to an increase in the laminar flame velocity and a decrease in the self-ignition delay at isotherms above 1000 K and pressures relevant to DDT. On the other hand, the mixture sensitivity to DDT decreases due to the increase in the speed of sound in the hydrogen-containing mixture, thus leading to a decrease in the Mach number of the lead shock wave propagating ahead of the flame, and to a corresponding increase in the self-ignition delay. Moreover, for C3H8–H2–air mixtures at isotherms below 1000 K and pressures relevant to DDT, the self-ignition delay increases with hydrogen volume fraction.

Ignition and deflagration-to-detonation transition modes in ethylene/air mixtures behind a reflected shock

Dynamics of ethylene autoignition and deflagration-to-detonation transition (DDT) are first numerically investigated in a one-dimensional shock tube using a reduced chemistry including 10 species and 10 reactions. Different combustion modes are investigated through considering various premixed gas equivalence ratios (0.2 − 2.0) and incident shock wave Mach numbers (1.8–3.2). Four ignition and DDT modes are observed from the studied cases, i.e., no ignition, deflagration combustion, detonation after reflected shock, and deflagration behind the incident shock. For detonation development behind the reflected shock, three autoignition hot spots are formed. The first one occurs at the wall surface after the re-compression of the reflected shock and contact surface, which further develops to a reaction shock because of “the explosion in the explosion” regime. The other two are off the wall, respectively, caused by the reflected shock/rarefaction wave interaction and reaction induction in the compressed mixture. The last hot spot develops to a reaction wave and couples with the reflected shock after a DDT process, which eventually leads to detonation combustion. For deflagration development behind the reflected shock, the wave interactions, wall surface autoignition hot spot as well as its induction of reaction shock are qualitatively similar to the mode of detonation after incident shock reflection, before the reflected shock/rarefaction wave collision point. However, only one hot spot is induced after the collision, which also develops to a reaction wave but cannot catch up with the reflected shock. For deflagration behind the incident shock, deflagration combustion is induced by the incident shock compression whereas detonation occurs after the shock reflection. The chemical timescale increases after the reflected shock/contact surface collision, whereas decreases behind the incident and reflected shocks, as well as after the reflected shock/rarefaction wave interaction. Therefore, mixture reactivity behind the reflected shock is weakened by the contact surface, but is intensified by the rarefaction wave. The multi-dimensionality characteristics, including reflected shock/boundary layer interactions, reflected shock bifurcation, destabilization, and detonation, are further present in a two-dimensional configuration. Planar autoignition occurs because of reflected shock compression and detonation combustion is formed first in the central region due to the collision of the reflected shock wave/reflected compression wave. The left and right bifurcations of the separation region in the wall boundary layer are then sequentially ignited.

Energy analysis of a detonation combustor with a bladeless turbine, a propulsion unit for subsonic to hypersonic flight

This paper details an energy conversion unit for the combined power extraction and thrust increase from high subsonic to hypersonic flows. The energy transfer is achieved through a wavy hub surface that promotes shocks and expansion fans. First, a design procedure and the non-dimensional steady-state performance characteristics (the reduced torque, non-dimensional mass flow, and non-dimensional speed) are presented (including an exergetic analysis) at on– and off-design conditions through time-averaged Reynolds Averaged Navier Stokes simulations. A cycle analysis was performed on a Mach 3 vehicle to demonstrate the feasibility of this technology. Second, energy extraction is achieved from the highly unsteady exhaust of rotating detonation combustors without needing an additional intermediate diffuser or nozzle. The rotating boundary conditions were computed from a reactive unsteady simulation. The influence of three shock parameters (pressure ratio across the shock, shock wave Mach number, and the number of waves) is investigated through a sensitivity study to assess the robustness of the new device. Furthermore, depending on the sense of rotation of the bladeless turbine relative to the rotation of the incoming shock and the helix angle, we can define two different modes of operation in which power extraction was achieved, namely, the shock mode and reversed mode.

Mach and Reynolds number dependency of the unsteady shock-induced drag force on a sphere

Shock–particle interaction is an important phenomenon in a wide range of technological applications and natural phenomena, and the development of accurate models for this interaction is therefore of interest. This study investigates the transient forces during shock–particle interaction at particle Reynolds numbers between 100 and 1000, and incident shock wave Mach numbers between 1.22 and 2.51. This is achieved with the aid of particle-resolved large-eddy simulations. The simulation results show that shock–particle interaction differs qualitatively for subcritical and supercritical incident flow conditions. By decomposing the total force, the inviscid and viscous unsteady forces are estimated. The inviscid unsteady component is significantly larger than the viscous contribution, but the magnitude of the viscous component is comparable to steady-state drag. The predictions of current state of the art force models are compared to the computed particle forces. For subcritical flows, the models are quite successful in predicting the drag. For these conditions, the magnitudes of both the inviscid and viscous unsteady force models agree well with the simulation results, but the transient nature of the viscous unsteady force history is not well captured. For supercritical flows, the inviscid unsteady force model is not able to capture the force dynamics. This highlights the need for the development of unsteady force models for supercritical flow conditions.

The modeling of two-dimensional vortex flows in a cylindrical channel using parallel calculations on a supercomputer

Objectives . The study aimed to examine vortex structures formed during the interaction of incident and reflected shock waves in a cylindrical channel. The shock wave was described by the Hugoniot relations, which make it possible to determine the parameters of the gas behind the shock front by a given Mach number and the values of the gasdynamic parameters ahead of the pressure jump. The propagation of a strong shock wave (Mach number was 20) in argon was simulated. Methods . The methods of mathematical modeling were used. A parallel algorithm for solving two-dimensional equations of gas dynamics in cylindrical coordinates (r, z, t) was developed and a new version of the NUTCY_ps program created. The calculations were performed on an MVS-100K supercomputer. Results. Two methods of parallelization when solving a system of equations were considered. Using a specific task as an example, a comparison of the effectiveness of these methods was conducted. A parallel algorithm was developed and a program was upgraded for solving two-dimensional equations of gas dynamics in cylindrical coordinates (r, z are spatial coordinates, t is time). Numerical calculations were performed to simulate: 1) the shock wave incidence to and reflection from a metal screen; 2) the propagation of the shock wave through a hole in the screen; 3) the propagation of the shock wave through a cylindrical channel and its reflection from the bottom of the channel and interaction with the incident wave. The results obtained by the parallel supercomputer with different numbers of processors are presented. It is shown that using 16 processors, it is possible to reduce the computation time for getting a solution for the test problem by approximately 12 times. Conclusions . It is shown that the interaction of incident shock wave and the one reflected at an angle leads to the formation of regions with low and high gas densities, as well as vortex flows. The vortex interaction area (turbulence zone) gets a complex shape. The article discusses the possibility of carrying out full-scale experiments in shock tubes or using a laser shock tube. Such studies would make it possible to compare experimental data with the results of numerical simulation and, on their basis, to develop more advanced models of turbulent motions.

An experimental and numerical investigation of the effects of the diaphragm pressure ratio and its position on a heated shock tube performance

AbstractThe main purpose of this work was to investigate the performance of heated shock tube (ST) with different pressure ratios and diaphragm positions numerically and experimentally. The numerical model was developed to simulate the fluid flow inside a shock tube test facility located at Qatar University. The shock tube was a cast‐iron hollow tube with 6 m length, 50 mm internal diameter and 10 mm thickness. ST driver and driven sections were filled with helium–argon mixture and air. The driven section was heated up to 150°C using coils. At the middle of the ST, the diaphragm was made of aluminium sheet (0.5 mm) layers. Five different pressure ratios were implemented during the experiment, and performance evaluation depended on the strength of the incident shock Mach number. The inviscid numerical model solver used transient two‐dimensional time‐accurate Navier–Stokes CFD. The model introduced a parametric study regarding three different diaphragm positions (1m, 2m and 3m) and five pressure ratios (6–10) for each position. In addition to yielding the incident and reflected wave Mach number, reflected wave temperature was also considered a shock tube performance indicator. The incident Mach numbers for the diaphragm middle position from the experiment were compared against those conducted from the model, and good matching was observed. The parametric study results showed that at high‐pressure ratios, diaphragm Positions 1 and 3 could generate a 7.4% increase in shock wave Mach number compared with the diaphragm position‐2 model. Moreover, the diaphragm position‐3 model tends to have a 2% increase in the temperature behind the reflected shock wave compared with the other two positions.

A computational study on shock induced deformation, fragmentation and vaporization of volatile liquid fuel droplets

This study investigates the fundamental mechanisms underlying the deformation, fragmentation, and vaporization of volatile liquid fuel droplets impacted by a normal shock wave using a high-fidelity, VOF-DIM (volume of fluid - diffuse interface method)-based framework. The theoretical and mathematical formulation of this multiphase, multi-fluid problem is based on a modified 5-equation Kapila formulation with pressure-relaxation, viscous, and surface tension effects. A thermal-mechanical-chemical equilibrium relaxation procedure is implemented to simulate vaporization. The framework is first validated against measurements of shock impact on a non-vaporizing water droplet; the computations agree well with the experimental data. Next, the vaporization model is validated against the d2 law, showing excellent agreement. This is followed by a systematic investigation of the atomization and vaporization physics of a n-dodecane droplet as it interacts with a shock wave traveling at a Mach number of 6.5. To compare and contrast the effect of vaporization on breakup physics, two numerical experiments were conducted with and without the vaporization model. It is found that when the vaporization model is not enabled, the gaseous and liquid phase dynamics are similar to that of non-vaporizing water droplet-shock wave interactions. However, when vaporization is enabled, aerothermal heating from the shock impact and high temperatures in the post-shock region provide sufficient heating for volatile liquid droplets to undergo phase change and the breakup behaviors are significantly different from the non-vaporizing counterpart. Furthermore, it is found that vaporization is a strong function of the shock strength – low Mach number shock waves lead to higher vaporization.

Redistribution of Energy during Interaction of a Shock Wave with a Temperature Layered Plasma Region at Hypersonic Speeds

The paper is devoted to the problem of the interaction between a shock wave and a thermally stratified energy source for the purpose of supersonic/hypersonic flow control realization. The effect of the thermally stratified energy source on a shock wave with the Mach number in the range of 6–12 is researched numerically based on the Navier-Stokes system of equations. Redistribution of specific internal energy and volume density of kinetic energy behind the wave front is investigated. Multiple manifestations of the Richtmyer-Meshkov instability has been obtained which has caused the blurring and disappearance of shock wave and contact discontinuity fronts in density fields. A study of the efficiency of using a stratified energy source instead of a homogeneous one with the same value of the full energy is carried out. The agreement with the available experimental data for the shock wave Mach number 6 has been obtained.

Two-phase Interactions between Propagating Shock Waves and Evaporating Water Droplets

One-dimensional numerical simulations based on hybrid Eulerian-Lagrangian method are performed to study the interactions between propagating shocks and dispersed evaporating water droplets. Two-way coupling for exchanges of mass, momentum, energy and vapour species is adopted for the dilute two-phase gas-droplet flows. Interphase interactions and droplet breakup dynamics are investigated with initial droplet diameters of 30, 50, 70 and 90 {\mu}m under an incident shock wave Mach number of 1.3. Novel two-phase flow phenomena are observed when droplet breakup occurs. First, droplets near the two-phase contact surface show obvious dispersed distribution because of the reflected pressure wave that propagates in the reverse direction of the leading shock. The reflected pressure wave grows stronger for larger droplets. Second, spatial oscillations of the gas phase pressure, droplet quantities (e.g., diameter and net force) and two-phase interactions (e.g., mass, momentum, and energy exchange), are observed in the post-shock region when droplet breakup occurs, which are caused by shock / droplet interactions. Third, the spatial distribution of droplets (i.e., number density, volume fraction) also shows strong oscillation in the post-shock region when droplet breakup occurs, which is caused by the oscillating force exerted on the droplets.

Propagation of a planar shock wave along a convex–concave ramp

The propagation of a normal shock wave along a coupled convex–concave surface of equal radii has been analysed experimentally and numerically in this study. The experimental and numerical studies were conducted using a similar geometry as of that used by Ram et al. (J. Fluid Mech., vol. 768, 2015, pp. 219–239) for studying the shock wave transition from regular reflection to Mach reflection. Many interesting flow features such as shock wave transitions over the ramp, characteristics of the induced flow behind the shock wave and the development of a stationary separation shock wave have been observed in the study. The numerical results are validated with experimental data. While the shock wave transitions over the ramp are found to depend mainly on the ramp geometry, the characteristics of the stationary shock wave and the flow separation in the concave region of the ramp surface have been found to vary with the shock wave Mach numbers.

A multiplicity of regimes of transonic flow in channels with branching

The flow in 2D channel with a flat plate located along the plane of symmetry of the channel at a certain distance from the inlet was numerically studied. Straight segments formed the channel walls. At the inlet and the outlet of the channel, a supersonic flow was set. The first and third parts of the channel diverged. The middle part converged. Solutions to the Euler equations were obtained using the Ansys CFX finite volume solver. Four solutions were found that differed in the position of the shock waves. The hysteresis in the shock wave position versus Mach number given at the inlet was found. In a certain range of the inlet Mach number, there were asymmetric solutions of the equations.

Effect of shock waves on enhancing the optical properties of Ammonium Pentaborate Hexahydrate single crystal molecular structure

Ammonium Pentaborate Hexahydrate (APBHH), a novel inorganic nonlinear optical single crystal was grown by slow evaporation solution growth method and the Properties of the grown crystals were investigated. The grown crystal was subjected to single crystal XRD and Powder X-ray diffraction analysis to confirm the crystal structure to the monoclinic system with centrosymmetric nature. The presence of various functional groups has been identified by using FT-IR spectral analysis ranging between 4000 and 500 cm−1. The percentage of optical absorbance was ascertained by recording the UV-Vis spectrum, crystals shows transparent in the entire visible region with a 5.56 eV optical bandgap. The dielectric constant and dielectric loss of APBHH crystal as a function of frequency and an AC resistivity, conductivity with impedance also were calculated at room temperature. Ammonium Pentaborate Hexahydrate (APBHH) crystal under pre and post shock loaded conditions. A shock wave of Mach number 1.7 was utilized for the present investigation which was generated by a table-top pressure driven shock tube. The optical properties of test material are investigated by UV-Visible spectrometer over the range between 200 and 800 nm. The observed result showed that the transparency of the crystal increase by applying Shock Waves.

Реализация кинетических механизмов горения метана на примере расширения функциональных возможностей физико-химических библиотек совместно с решателем reactingPimpleCentralFoam

The possibility of using reduced combustion mechanisms for hydrocarbon fuels in solvers developed and used at ISP RAS is investigated. These mechanisms contain smaller number of stages and substances appearing in them, but they allow obtaining results in a good agreement with experimental data in a much shorter calculation time. The comparison is made with the results obtained with using the Moscow Aviation Institute solvers. A modified mechanism of methane combustion is considered. It can be extended to describe the chemical reaction processes in other hydrocarbon-oxygen mixtures. The choice of methane is due to the prospects of this fuel at the present time. As the first test problem, a standard chemFoam is used. This solver was designed to demonstrate the occurrence of chemical reactions in a computational domain consists of one cell only. The ignition delay and the parameter values of the thermodynamic equilibrium state reached are taken as the comparison criteria. The second test problem is the flow modeling in a shock tube after the shock wave has been reflected from the wall. This problem is considered in a three-dimensional domain using the ISP RAS reactingPimpleCentralFoam solver. Results were compared with ones obtained by grid-characteristic and Godunov's methods in one-dimensional nonstationary calculations. The effects of viscosity, thermal conductivity and diffusion are not taken into account. The distributions of the flow parameters behind the reflected shock wave are obtained. Results are analyzed depending on the value of the falling shock wave Mach number. Estimates of the possible application of this reduced mechanism are given.