Mild Ignition Research Articles

Water Microdroplets-Initiated Methane Oxidation.

The special redox reactivity of water microdroplets causes "mild ignition" of methane gas to form methane oxygenates. The C(sp3)-H bond of methane can be activated by the hydroxyl radical (OH·) or the hydrogen radical (H·) across the air-water interface (AWI) of microdroplets to generate the methyl radical (CH3·). Once CH3· is formed, it undergoes free-radical reactions with O2 in the air, excessive OH· and H· across the AWI, and H2O2 present at the AWI and generated CH3· itself to produce methanol and other species. Production of the methanol and other oxygenates was confirmed by gas chromatography, mass spectrometry, and 1H- and 13C-nuclear magnetic resonance. Formic acid, acetic acid, ethanol, carbon dioxide, and methyl peroxide were also detected as methane oxidation byproducts. This water microdroplet-initiated oxidation process can be further enhanced under ultrasonication to yield 2.66 ± 0.77 mM methanol conversion from the methane gas in a single spray run for 30 min, with a selectivity of 19.2% compared with all other oxygenated species.

Experimental Investigation on Aluminum-Based Water Ramjet for Propelling High-Speed Underwater Vehicles

Major challenges in developing and realizing a novel aluminum–water reaction-based water ramjet propulsion system for high-speed underwater vehicles and demonstration of a water-breathing jet propulsion test facility are investigated. Two stages of combustion, propellant grain combustion and subsequent water combustion, with primary combustion products are adopted. High-pressure-molded propellant grains up to 45% of micro–nano () aluminum were prepared and combusted in the primary chamber, which exhibits mild ignition delay, and a residue of 4–6% was retained. Once water is injected into the secondary chamber, the net thrust generation is increased more than twice from the exhaust jet and improves the specific impulse by 40%. The lean fuel conditions in the secondary chamber lead to reduction in combustion propensity, which causes drop in efficiency. The ultrafine iron-oxide-catalyzed micro–nano blended propellants marginally improved the propulsive performance than the uncatalyzed compositions. The efficiency of the catalyzed propellants was enhanced up to 38.6%. Aluminum agglomeration in primary combustion considerably occurred; apparently, only a fraction of aluminum particles or agglomerates are completely burnt within the secondary chamber, and the remaining aluminum particles are either partially burnt or go unreacted.

Ignition behaviors of primary reference fuels in a rapid compression machine under vortex-existing/minimized conditions

Knock is one of the main obstacles to improving the thermal efficiency of spark-ignition internal combustion engines. Although knock has been widely studied and accepted as a result of end-gas auto-ignition, the fundamentals regarding auto-ignition behaviors are still not fully revealed. In this study, the ignition behaviors of primary reference fuels were investigated in an optical rapid compression machine equipped with a quartz combustion chamber allowing for visualizing the combustion process from the lateral view. By combining both the lateral view and the top view photography, ignition behaviors under vortex-existing conditions with a creviced piston and vortex-minimized conditions with a flat piston were comprehensively analyzed to reveal the impact of the vortex on the ignition behaviors of PRF fuels. The influence of fuel reactivity was also investigated. The results showed that mild ignition was prevalent under large Da* numbers. The occurrence of mild ignition was closely related to the ignition delay time of the mixture, and the critical ignition delay time was not fixed but decreased with increasing initial temperature. The propensity of mild ignition could be boosted under vortex-existing conditions due to the increasing hotspot formation probability. Vortices were demonstrated to be capable of mitigating knock intensity via 1) the buffer effect of surrounding burned regions on the shock waves generated from surrounded unburnt pockets; 2) a larger burned mass fraction at the instant of the final ignition under vortex-existing conditions. The results also showed that strong ignition was more likely to occur under vortex-minimized conditions. Besides, higher fuel reactivity also could increase the probability of strong ignition occurrence. Compared with the creviced piston, the use of the flat piston could shift the ignition regime towards regions with higher Ret and lower Dat in the Dat-Ret diagram, where the strong ignition is less pronounced.

Simultaneous side-wall-schlieren and -emission imaging of autoignition phenomena in conventional and constrained-reaction-volume shock-tube experiments

Simultaneous schlieren and emission imaging through the side wall of a round shock tube is reported for application to experimental autoignition studies. A round, optically accessible shock tube featuring windows designed as aberration-corrected cylindrical lenses provides a large side-wall field of view compatible with both emission and schlieren imaging. Autoignition experiments are reported for non-dilute propane–oxygen–argon mixtures (ϕ=1 C3H8 in 21% O2, 79% Ar) at temperatures (T5) spanning the range 1,203–1,438 K and pressures near 1 atm. Experiments are performed using both conventional and constrained-reaction-volume (CRV) filling, allowing for the most detailed comparison to date of ignition dynamics between these two types of experiments. When T5 exceeds 1,290 K, strong ignition is observed to initiate in the immediate proximity of the end wall regardless of the filling strategy. In lower-T5 experiments, mild ignition is observed to initiate spontaneously at remote locations, which often exceeding the imaging FOV in conventional experiments but are constrained within about 5 cm of the end wall in CRV experiments. Measured ignition delay times (IDTs) are compared to predictions from three kinetic mechanisms. IDTs simulated using the San Diego and USC Mech II mechanisms are of the same magnitude as the measurements but exhibit a lower activation energy; the propane submechanism from NUIG 1.1, meanwhile, systematically over predicts observed IDTs by roughly a factor of two. Comparisons are also made between the experimental measurements and predictions from a recently introduced 1-D axial-temperature-gradient model describing remote ignition in shock tubes. Considering the effect of a supposed dT5/dz=150 K/m gradient, the 1-D model functionally predicts the remote ignition observed in T5< 1,290 K experiments and suggests the use of CRV filling may significantly reduce the error introduced into IDT measurements by remote ignition at low-T5 conditions.

Flame front dynamics, shape and structure on acceleration and deflagration-to-detonation transition

Developing a new generation of rocket engines based on detonation principles needs methods which ensure stability of operation including the onset of detonation wave after mild ignition. This aspect is crucial for ensuring safety of such engines. In the present paper the transition processes associated with flame acceleration and the onset of a detonation mode are under investigation. High-speed flame front photography has been performed during the deflagration of a premixed gas mixture in a long smooth tube. The evolution of flame front structure and shape has been determined, starting from the moment of deflagration initiation and ending with the occurrence of a local explosion leading to the formation of a detonation wave. Four characteristic flame propagation stages have been identified: the initial flame acceleration stage, followed by the apparent velocity deceleration stage, followed by the nearly constant propagation velocity stage, and finally the second acceleration stage, during which detonation is formed. The changes in process dynamics with a change in the initial pressure have been demonstrated. The behavior of flame front at the early stage of acceleration has been identified. The experimental findings are compared with the theoretical models available in the literature. At the initial stage of the accelerated propagation of flame extended along the channel walls — until deceleration — the velocity of the leading tip of the front is effectively described by the exponential relationship proposed by C. Clanet and G. Searby (1996). The most interesting and poorly studied, in the authors' opinion, stage of the deflagration-to-detonation transition process, the intensive repeated acceleration stage, during which flame shape changes abruptly, has been described in detail. The laminar burning velocity of the stoichiometric acetylene–oxygen mixture diluted with either nitrogen or argon at a reduced initial pressure (8–21 kPa) has been identified.

LES of HCCI combustion of iso-octane/air in a flat-piston rapid compression machine

Homogeneous Charge Compression Ignition (HCCI) engines promise better efficiency and cleaner emissions than conventional piston engines, but can be challenging to control. Rapid compression machines (RCM) provide a simplified configuration for investigating HCCI combustion behavior, which is necessary for effective control of engine ignition timing and peak pressures. In this study, we assess the utility of large eddy simulations (LES) for predicting HCCI combustion in a 3-D configuration. To this end, LES with finite-rate chemistry employing a 99-species iso-octane/air mechanism of two RCM operating conditions are performed. The RCM configuration under consideration was designed by Strozzi et al. (Combust. Flame, 2019) with a flat piston to introduce large amounts of thermal stratification representative of realistic HCCI engine conditions, through the generation of corner vortices. It is shown that the simulation provides reasonable agreement with temperature fluctuations (7% difference), as well as ignition delay in the short ignition case (1 ms difference), while the long ignition case (35 ms difference) highlights more substantial deficiencies that are still within the expected uncertainty from the employed chemical mechanism. Flame propagation modes predicted by LES agree with experimental observations: spontaneous ignition is seen in the short ignition case, while deflagration is more prominent in the long ignition case. Analysis of global and local quantities classify the short ignition case in a mixed ignition regime, and the long ignition case in the mild ignition regime. These results demonstrate the utility of FRC-LES for investigations of multimode combustion regimes of HCCI combustion in a 3-D configuration.

Mild ignition and flame trajectory of horizontal transformer insulating oil spray by hot surface with different angles

In this study, a hot surface of 0°, 45° and 90° was used as the ignition source for mild ignition experiments of large-scale horizontal transformer insulating oil spray. Combined with the principle of spray impinging, it was found that during ignition, the angle of hot surface affects the heat transfer from hot surface to oil droplets and vapor, and the minimum ignition temperature and time to ignition increase with increasing angle. There exists an inverse exponential correlation of time to ignition and ignition temperature. After ignition, the deceleration effect caused by the hot surface dragging spray reduces the flame projection length and leads to different trajectories. The deceleration effect can be modelled using the effective initial velocity of spray derived from the reduced axial velocity at the hot surface location. The predicted flame trajectories considering the deceleration effect presents a good agreement with the experimental records.

Mild Ignition and Flame Trajectory of Horizontal Transformer Insulating Oil Spray by Hot Surface with Different Angles

Mild Ignition and Flame Trajectory of Horizontal Transformer Insulating Oil Spray by Hot Surface with Different Angles

Reflected shock-initiated ignition probed via simultaneous lateral and endwall high-speed imaging with a transparent, cylindrical test-section

A TRAnsparent cylindrical (TRAC) shock tube test section has been developed to explore the ignition structure behind reflected shockwaves via simultaneous lateral and endwall high-speed imaging using three fuel/oxidizer mixtures: 0.1% n-C7H16/1.10% O2/4.14% N2/94.66% Ar, 0.1% iC8H18/1.25% O2/4.69% N2/93.96% Ar, and 5% CH4/10% O2/85% CO2. During mild ignition, the first exothermic centers were located outside of the observable test section. It is shown that with increasing temperature the far-wall ignition events move closer to the endwall, until a strong ignition is achieved. The temperature gradients that promote mild ignition were quantified and were found to have a slight dependence on fuel with the RMS temperature gradients being 0.80% for n-heptane and 1.07% for isooctane. The impact of temperature gradients on metrics used to improve kinetic models, such as species time histories, is noteworthy. From this temperature gradient, an experimental correlation is provided to estimate the transition temperature from mild to strong ignition for a mixture. The effect of diagnostic location in non-homogeneous reactions is quantified in reference to ignition delay. The unique and insightful perspective on the ignition process under heavy shock bifurcation is also discussed.

Modes of mild ignition in shock tubes: Origins and classification

The paper analyses numerically the scenarios of ignition kernels formation in the shock tube in the intermediate temperature range. Three modes of mild ignition are distinguished among which are: ignition related to the shear heating in the developed boundary layer, ignition due to the shear heating in the recirculation zone behind the reflected shock and ignition in the central region of the tube due to the axial compression. All three modes define short ignition delays at low temperatures compared to the ideal shock-tube values. Moreover, it is shown that the gas-dynamic mechanisms responsible for additional local heating of the test mixture provide close rates of heating. As a result, all the data on ignition delays fall in a certain range defined by the mixture composition and pressure, independent on the particular mode of mild ignition.

Effects of High Fuel Loading and CO2 Dilution on Oxy-Methane Ignition Inside a Shock Tube at High Pressure

Abstract Ignition delay times were measured for methane/O2 mixtures in a high dilution environment of either CO2 or N2 using a shock tube facility. Experiments were performed between 1044 K and 1356 K at pressures near 16 ± 2 atm. Test mixtures had an equivalence ratio of 1.0 with 16.67% CH4, 33.33% O2, and 50% diluent. Ignition delay times were measured using OH* emission and pressure time-histories. Data were compared to the predictions of two literature kinetic mechanisms (ARAMCO MECH 2.0 and GRI Mech 3.0). Most experiments showed inhomogeneous (mild) ignition which was deduced from five time-of-arrival pressure transducers placed along the driven section of the shock tube. Further analysis included determination of blast wave velocities and locations away from the end wall of initial detonations. Blast velocities were 60–80% of CJ-Detonation calculations. A narrow high temperature region within the range was identified as showing homogenous (strong) ignition which showed generally good agreement with model predictions. Model comparisons with mild ignition cases should not be used to further refine kinetic mechanisms, though at these conditions, insight was gained into various ignition behavior. To the best of our knowledge, we present first shock tube data during ignition of high fuel loading CH4/O2 mixtures diluted with CO2 and N2.

Diesel spray ignition behind a reflected shock wave

This study investigates single-event ignition of diesel fuel injected into air and into methane–air, the latter being applicable to compression ignition dual fuel engines. Diesel fuel was injected into the reflection-end of a 76 mm square-channel shock tube via a modern eight-orifice tip piezoelectric injector. Simultaneous schlieren and direct photography was used to characterize the ignition process and obtain a measure of the ignition delay time. Tests were carried out at a nominal reflected pressure of 10 bar and temperatures in the range of 880–1500 K. The test gas was composed of synthetic air, with argon replacing nitrogen. Diesel injection duration, e.g., 0.15 and 0.5 ms were tested, was found to have an effect on the ignition location and ignition delay time. A crossover in ignition delay time was observed at roughly 1100 K, which was attributed to evaporative cooling at higher temperature and fuel overmixing at lower temperatures. For the 0.15 ms diesel injection duration, ignition did not occur at temperatures below 1000 K due to overmixing. Premature ignition events caused by diaphragm metal particles were observed in the lower temperature range. When the premature ignition data was filtered out, the ignition delay time correlated well with an Arrhenius temperature dependency, except for temperatures below 1000 K where the ignition delay time became insensitive to temperature and showed significant data scatter. Experiments with diesel injection into methane–air resulted, in most cases, in mild ignition of the methane before diesel ignition. For temperatures above 1000–1100 K, detonation initiation of the methane–air occurred before diesel ignition.

Hot-spot induced mild ignition: Numerical simulation and scaling analysis

Mild ignition is a ‘non-ideal’ autoignition process observed at some conditions in rapid compression machine, shock tube and flow reactor experiments where flames and/or reaction fronts initiate due to non-uniformities within the test mixture. These flames/fronts can consume the entire mixture, or compression-heat the unburned gas, causing bulk ignition at times earlier than in homogeneous environments. This study numerically investigates mild ignition features using computational fluid dynamics techniques under a scenario where a small hot-spot is employed to initiate the process in a spherically-symmetric geometry. Only subsonic regimes are considered. The intent is to develop greater fundamental understandings of competing phenomena, and formulate a robust framework to quantify the perturbative behavior. Syngas blends (CO/H2 = 80/20) are employed as the fuel, mixed with air at lean fuel loadings of φ = 0.2 and 0.5, with the initial temperatures and pressures covering 900–1120 K, and 1.5–15 bar, respectively. Hot-spots ranging from 50 to 2,000 µm in diameter are utilized with temperatures elevated from the surroundings by 1 to 90%, i.e., Thot/T0 = 1.01–1.90. Scaling arguments are derived to analyze competing processes of: (a) quenching vs. ignition, (b) extinction vs. propagation, and (c) flame consumption/forced autoignition vs. homogeneous ignition. This work provides new insight into non-uniform autoignition phenomena, and discusses opportunities and challenges associated with mitigating it. In particular, scaling arguments indicate that experimental parameters could have potential to either suppress hot-spot initiated flame formation (e.g., via bath gases with high thermal diffusivity), or avert flame compression of the end gas (e.g., via lean/diluted mixtures, or bath gases with high heat capacity).

Low temperature autoignition of 5-membered ring naphthenes: Effects of substitution

The development and design of future internal combustion engines requires fundamental understanding and the capability to model the autoignition and pollutant formation behavior of petroleum-based and other fuels. Naphthenes are an important constituent of gasoline, and they can comprise larger portions of unconventionally-derived gasoline. There is a lack of data and validated models for 5-membered ring naphthenes. In this work, the autoignition characteristics of cyclopentane, and two of its substituted analogues, methylcyclopentane, and ethylcyclopentane are investigated using a twin-piston rapid compression machine. Each fuel is studied at engine-representative conditions: 20, 50 bar and 700–980 K, with mixtures containing stoichiometric fuel/oxygen ratios at various extents of dilution with inert gases.Negative temperature coefficient (NTC) behavior is observed for cyclopentane, though first-stage ignition and associated low temperature heat release behavior are only evident at temperatures below that for the transition to NTC. Pressure is found to have a larger impact on the reactivity than oxygen dilution, with both effects amplified in the NTC region. The cyclopentane experiments in this study are challenged by the sensitivity of this molecule to non-uniform, or mild ignition phenomena within the NTC region. The addition of saturated sidechains in methyl- and ethylcyclopentane significantly increases the reactivity of the molecules, especially at low temperature and NTC conditions. At the highest temperatures though, there is little difference between the three naphthenes. Typical two-stage ignition behavior is observed across a wide range of temperatures for these alkyl cyclopentanes with no mild ignition observed within the NTC region.A recently developed model for cyclopentane is extended to include reactions for methylcyclopentane, and this is used to simulate the new experiments. The simulation results indicate that low temperature reactivity of cyclopentane is dominated by HO2 elimination of the RO2 species producing cyclopentene, and this inhibits autoignition since it is a very stable molecule. When a methyl group is substituted on the ring, additional RO2 isomerization pathways are available, and these substantially increase the fuel reactivity. HO2 elimination is also important with methylcyclopentane, and this leads to significant production of cyclic olefins which can further react to produce diolefins. These findings are consistent with observations that have been made in other experimental apparatuses.

Analysis of mild ignition in a shock tube using a highly resolved 3D-LES and high-order shock-capturing schemes

A highly resolved three-dimensional large-eddy simulation (LES) is presented for a shock tube containing a stoichiometric hydrogen–oxygen ( $$\hbox {H}_2$$ / $$\hbox {O}_2$$ ) mixture, and the results are compared against experimental results. A parametric study is conducted to test the effects of grid resolution, numerical scheme, and initial conditions before the 3D simulations are presented in detail. An approximate Riemann solver and a high-order interpolation scheme are used to solve the conservation equations of the viscous, compressible fluid and to account for turbulence behind the reflected shock. Chemical source terms are calculated by a finite-rate model. Simultaneous results of pseudo-Schlieren, temperature, pressure, and species are presented. The ignition delay time is predicted in agreement with the experiments by the three-dimensional simulations. The mechanism of mild ignition is analysed by Lagrangian tracer particles, tracking temperature histories of material particles. We observed strongly increased temperatures in the core region away from the end wall, explaining the very early occurrence of mild ignition in this case.

Identification of governing physical processes of irregular combustion through machine learning

This study is concerned with the data-driven analysis of predictive parameters associated with regime transition for ignition and detonation. To this end, we introduce machine learning as a technique to analyze the predictive capability of these parameters. Machine learning enables the critical evaluation of combustion regimes from disparate sources and allows for a generalized comparison of the parameters. The parameter set is composed of features that have been found to be effective in classifying ignition regimes and are supposed to have a universality in predicting the regularity of the ignition process. Three different configurations are examined: weak ignition shock tubes, mild ignition in rapid compression machines, and the regularity of cellular detonations. All configurations are demonstrated to show a strong sensitivity to the heat deposition time of the chemical reaction. Additionally, detonations are found to be primarily sensitive to the heat release and show that an increased chemical sensitivity has a regularizing effect when plotted against the heat release rate. The data are found to be well classified with only one or two parameters, indicating that a universal, governing parameter is plausible.

Temperature perturbations evolution as a possible mechanism of exothermal reaction kernels formation in shock tubes

The basic question raised in the paper concerns the origins of exothermal reaction kernels and the mechanisms of detonation onset behind the reflected shock wave in shock-tube experiments. Using the conventional experimental technique, it is obtained that in the certain diapason of conditions behind the reflected shocks a so-called “mild ignition” arises which is characterized by the detonation formation from the kernel distant from the end-wall. The results of 2-D and 3-D simulations of the flow evolution behind the incident and reflected shocks allow formulation of the following scenario of ignition kernels formation. Initial stage during and after the diaphragm rupture is characterized by a set of non-steady gasdynamical processes. As a result, the flow behind the incident shock occurs to be saturated with temperature perturbations. Further evolution of these perturbations provides generating of the shear stresses in the flow accompanied with intensification of velocity and temperature perturbations. After reflection the shock wave interacts with the formed kernels of higher temperature and more pronounced kernels arise on the background of reactivity profile determined by moving reflected shock. Exothermal reaction starts inside such kernels and propagates into the ambient medium as a spontaneous ignition wave with minimum initial speed equal to the reflected shock wave speed.

Effects of CO-to-H2 ratio and diluents on ignition properties of syngas examined by weak flames in a micro flow reactor with a controlled temperature profile

Weak flame positions at various CO-to-H2 ratios in syngas combustion were investigated for stoichiometoric fuel (CO/H2) and oxidizer (O2/N2) mixtures at 1:7 O2:N2 using a micro flow reactor with a controlled temperature profile. In the case of low H2 mole fractions in fuel (0–10%), the experimental weak flame position significantly shifted to the lower temperature region with the increase of the H2 mole fraction in fuel, and this trend was well reproduced by the computations with all reaction mechanisms employed (GRI Mech. 3.0, San Diego Mechanism, Princeton C1 Model, AramcoMech 1.3). The reactivity of the syngas strongly depended on the variation of the CO-to-H2 ratio, in the case of higher H2 mole fractions in fuel (25–100%), on the other hand, the experimental weak flame position was almost insensitive to the CO-to-H2 ratio. This trend was well reproduced by the computations except GRI Mech. 3.0 among the above reaction mechanisms.Weak flame positions for three kinds of diluents (N2, CO2 and H2O) and their molar fractions in fuel were also investigated for stoichiometoric fuel (CO/H2/Diluent) and oxidizer (O2/N2) mixtures at 21:79 O2:N2 (equivalent to air). The diluent fraction in fuel varied up to 50% (mole fraction of 0.228 in a mixture). Only in H2O dilution among these three diluents, the experimental weak flame position shifted to the higher temperature region with the increase of the diluent fraction. The chemical inhibition of reactivity by the H2O dilution was observed in the present micro flow reactor. Rate of production and reaction-pathway analyses by San Diego Mechanism revealed that the higher H2O mole fraction enhanced R10: H+O2(+M)=HO2(+M) and R16: 2OH(+M)=H2O2(+M) because of higher third-body efficiency of H2O. The similar inhibition mechanism by an increase of pressure is extensively known in the mild ignition regime of the general H2–O2 explosion peninsula. An analogy between the inhibition mechanisms by the increases of pressure and H2O concentration was discussed. The chemical inhibition by H2O dilution was considered to be found due to the unique characteristic of the present micro flow reactor which allows to evaluate the reactivity of a given mixture in the thermally-equal condition independent of diluent thermal properties.

MILD combustion for hydrogen and syngas at elevated pressures

As gas recirculation constitutes a fundamental condition for the realization of MILD combustion, it is necessary to determine gas recirculation ratio before designing MILD combustor. MILD combustion model with gas recirculation was used in this simulation work to evaluate the effect of fuel type and pressure on threshold gas recirculation ratio of MILD mode. Ignition delay time is also an important design parameter for gas turbine combustor, this parameter is kinetically studied to analyze the effect of pressure on MILD mixture ignition. Threshold gas recirculation ratio of hydrogen MILD combustion changes slightly and is nearly equal to that of 10 MJ/Nm3 syngas in the pressure range of 1–19 atm, under the conditions of 298 K fresh reactant temperature and 1373 K exhaust gas temperature, indicating that MILD regime is fuel flexible. Ignition delay calculation results show that pressure has a negative effect on ignition delay time of 10 MJ/Nm3 syngas MILD mixture, because OH mole fraction in MILD mixture drops down as pressure increases, resulting in the delay of the oxidation process.

G0510305 反射衝撃波と境界層の干渉による流れの3次元挙動に関する数値解析([G051-03]流体工学部門一般セッション(3),流体工学部門)

At the reflected shock rear, a chemical reaction starts at a temperature and pressure constant static premixed gas conditions by filling reactive premixed gas in the shock tube, and reflects the shock wave in the pipe ends. Meyer and Oppenheim were classified into ignition two forms Mild Ignition and Strong Ignition, the start of the H2/O2 detonation due to the reflected shock wave. In order to ignite instantly in the tube cross-section of the entire near-wall reflection, Strong Ignition is a form ignition reaction theory. Mild Ignition is a firing mode hydrodynamic, under the influence of lambda shock wave generated by the mutual interference between the boundary layer and are reaching the ignition shock wave backward flow becomes multidimensional. Mark was revealed from the experiment due to the mutual interference between the boundary layer and the reflected shock, lambda shock wave to be formed in connection with this phenomenon. Thus, experiments by the reflected shock ignition is performed, there are cases in which ignition occurs is unexpected due to the interference of the reflected shock wave and boundary layer. In this study, we focus on the flow field due to the interference of the boundary layer and reflected shock, it is an object of the present invention to elucidate the flow three-dimensional.