The Three-dimensional Numerical Study Of Instability On Premixed Flame Interface Induced By Shock Waves

The interface separated two different densities gas,which is not merge with each other produces the curvature of initial perturbation because of flow instability or environment disturbed.The interaction between the shock waves and disturbed interface leads to baroclinic effect.The disturbance of the interface grows under the baroclinic effect lead to instability of the interface.The phenomenon is called Richtmyer-Meshkov(RM)instability is essentially a three dimensional instability process,which is very complex and accompany with the turbulent mixing phenomenon later.In addition,the RM instability(especially the reactive RM instability)is very common in nature and human life.The research object in the paper is the interaction process between the plane incident shock wave or reflected shock waves and interface which has initial disturbance.Nine order WENO high precision numerical simulation method is adopted to carry out the numerical simulation research of reactive RM instability and examine the flow field characteristics and evolution characteristics of flame interface instability in the different incident shock waves and different interface conditions.This paper innovation points are as follows:(1)The paper carries out the numerical simulation of the process between the incident shock wave or reflected shock waves and the single-mode and investigates the instability of the flame interface under the different incident shock waves.Firstly,the two-dimensional results and three-dimensional results of the interaction between the shock waves and sinusoidal flame interface are compared,which is found that the “spike-bubble” structure includes the vortex and rib structures in the three-dimensional simulation.These new structures are not observed in the two-dimensional simulation,therefore the two-dimensional simulation result is incomplete and the three-dimensional simulation of the process between the shock waves and flame interface is necessary.Secondly,the evolution rules of the flame interface forms,statistics and time scales are investigated,which are show that the vortex structures on the single-mode flame interface develop from spanwise structures to streamwise structures over time and the vortexes from large scale structures to small scale structures in space.The simulation results show that the spanwise vortex structures develop to streamwise vortex structures over time in the single-mode initial disturbed flame interface.Under different incident shock waves intensity,the mixed zone average vorticity,the average scalar dissipation rate and the average chemical reaction rate increase with the strength of the shock waves increase.The paper studies the vortex induce flow instability characteristic time scale,chemical reaction time scale and scalar dissipation rate characteristic time scale which is found that the effect on the interface development from large scale vortex is greatest.After the reflected shock wave,the effect from the chemical reaction increases.The small scale mixing has little impact on the flame interface.(2)This paper also carried out numerical simulation of the interaction process between plane incident shock wave and the reflected shock waves and the random multimode initial perturbation flame interface.Compared with the single mode initial perturbation flame interface,the random multimode initial perturbation interface structure is more chaos.The two-dimensional slices of multimode flame interface component figure shows that the multiple “spike-bubble” structures on the interface appear after the incident shock wave an d then the “spike-bubble” structures form a whole structure,after reflected shock waves.After the interaction between the multimode flame interface and shock wave,the large scale vortex structures are main vortex slice structures,which is different from the single mode flame interface.The statistic results of the multimode flame interface are studied,which is show that the average vorticity,the average scalar dissipation rate and average chemical reaction rate of single mode flame interface is larger than these of multimode flame interface,after the incident shock wave.But after the reflected shock waves,the three parameters of single mode flame interface are respectively same as these of multimode flame interface.It means that the average vorticity,the average scalar dissipation rate and average chemical reaction rate are not affected by initial interface morphology,after the reflected shock waves.(3)The mixing process which the flame interface instability induced by shock wave is studied by the way of spectrum analysis in the paper.First of all,we verified the effect of the numerical method and grid size to describe the turbulence mixing on the interface later.The simulation of compressible homogeneous isotropic turbulence confirms calculation format and the grid size has the capability of turbulent flow field simulation.On the basis,Fourier transform is adopted to analyse spectrum space develop of turbulent kinetic energy and enstrophy,pressure,density.The results show that when incident shock wave Ma is low,the kinetic energy spectrum slope of mixing zone is-5/3 after the reflected shock wave.When incident shock wave Ma is high,the kinetic energy spectrum slope of mixing zone is-3/2.It means that if incident shock wave Ma is low,the interface mixing zone transform to isotropic turbulence.If incident shock waves Ma is high,the interface mixing zone transform to turbulence model driven shock waves.In the process of the development of the flow field,the streamwise turbulent kinetic energy is dominant.The distribution of the turbulent kinetic energy is associated with incident shock wave intensity,initial interface perturbation shapes and wave numbers.The enstrophy spectrum,pressure spectrum and density spectrum in the interface mixing zone are analysed,which is found that after interaction between the shock wave and flame interface,the enstrophy energy spectrum slope is-1 in the low wave number part;the enstrophy energy spectrum slope is-3 in the high wave number part.If incident shock waves strength and initial interface perturbation shapes are different,energy spectrum slope development rule are the same.The pressure spectrum slopes and the density spectrum slope in interface mixing zone present unique change rules.