3D Numerical Study On Flow-induced Vibration Of A Rotating Detonation Combustor

Rotating detonation engines offer advantages in terms of high thermal efficiency and high specific impulse,showcasing their significant potential for propulsion systems.Despite their potential,this technology is still underdeveloped,with extensive research primarily focused on investigating the flow field and combustion processes inside the engine.However,the analysis of the combustor component structure has been comparatively overlooked.In this paper,a numerical study on the flow-induced vibration characteristics of a rotating detonation combustor is investigated,and certain results and conclusions have been obtained,which will promote the actual engineering and application of the rotating detonation engine.A threedimensional model of fluid-structure interaction was established to calculate the structural transient response of a rotating detonation combustor under the flow pressure loads.Moreover,the effects of the annular combustor radial thickness,the mass flow rate and equivalence ratio of the reactant,on the vibration behavior were considered.For the numerical study of the flow field,a hydrogen-air premixed model was used.Then the flow pressure on the coupled interface between the fluid and the structure was extracted as the dynamic load in the structural analysis.The modal analysis and transient structural simulation of the combustor component were carried out.The main work and conclusions are as follows:(1)The flow field in the combustor is numerically simulated and the single mode rotating detonation wave was obtained successfully.On the annular fluid-structure coupling interface,the high-pressure region is mainly concentrated on the wavefront of the shock wave and the triangle-like region after the wave,and the extreme value appears on the wavefront.Meanwhile,both the pressure peak and the detonation wave height fluctuate due to the interference of transverse waves.Under the excitation of the periodic shock wave,the forced vibration of the combustor component shows a strong correlation with the excitation pressure.The correlation between the vibration and pressure is caused by the dominant state of the rotating detonation wave among the vibration sources.The main frequency of the forced vibration is equal to the propagation frequency of the shock wave.In addition,with ignoring the effect of viscosity,there is an order of magnitude difference between the moment value around the rotation axis and other directions on the outlet surface.(2)The relationship between vibration intensity and radial thickness of annular combustor was studied.In the modal analysis,the first natural frequency of the structure increases with the increase of wall thickness,and the difference between the frequency of the excitation load and the natural frequency also increases accordingly.The results show that the vibration intensity is also reduced and the structure is less susceptible to excitation under the action of periodic shock waves.(3)The effects of changing the mass flow and equivalent ratio of reactant on combustor vibration in a certain range were discussed.The results indicate that both of them will further modify the vibration response frequency by influencing the propagation frequency of the detonation wave.On the one hand,the increase of the flow rate leads to an increase in the pressure intensity on the fluid-solid coupling interface,which further intensifies the intensity of the structural vibration.On the other hand,the equivalence ratio of the fuel affects the stability of detonation wave,with the detonation wave being most stable under the stoichiometric ratio condition.Consequently,the variation in structural vibration intensity is smaller under such equivalence ratio conditions.