Evaluation of pressure oscillations by a laboratory motor  

作　　者：Roohollah TAHERINEZHAD Gholamreza ZAREPOUR 

机构地区：[1]Department of Mechanical Engineering,University of Guilan,Rasht 51665-315,Iran

出　　处：《Chinese Journal of Aeronautics》2020年第3期805-825,共21页中国航空学报（英文版）

摘　　要：Aeroacoustic pressure oscillation is one of the important challenges in segmented solid rocket motors with high slenderness ratio.The reason for these oscillations can be searched in vortex shedding due to grain burning surfaces, holes and slots.In this paper, a novel sub-scaled motor was used for evaluation of aeroacoustic pressure oscillations.First, the related parameters to scale down using Buckingham's Pi-theorem were determined and then the sub-scaled motor was designed and manufactured.After this, Strouhal number in various grain forms and vortex shedding prediction criteria have been discussed.Then, one-dimensional linear and non-linear solution approaches have been presented.To understand the motor internal flow and vortex shedding formation, steady state computational fluid dynamic performed for seven regression steps and finally, two static tests have been performed.Results show that various definitions for Strouhal number are useful only for primarily glance on vortex shedding and pressure oscillations and so CFD solution and the test program are inevitable for a correct understanding of the ballistic operational condition of the motor.Experimental results demonstrated the existence of such oscillations with frequencies nearly equal to axial modes.It seems that non-linear parameters have small effects on aeroacoustic pressure oscillation and therefore the linear solution is acceptable to obtain approximate data.Of course,it should be emphasized that linear solution represents oscillations on overall motor action time,whereas the output of non-linear solution depends on thermochemistry properties of solid propellant and combustion products.Therefore, with a non-linear solution, oscillations maybe occur in some intervals of action time.FFT(Fast Fourier Transformation) results demonstrated that although both first and second acoustic modes have been excited, the position of longitudinal oscillation has an important role on which one is dominant.

关 键 词：AEROACOUSTIC Pressure oscillation Solid rocket motor Strouhal number Sub-scale Vortex shedding 

分 类 号：V435[航空宇航科学与技术—航空宇航推进理论与工程] TJ760.33[兵器科学与技术—武器系统与运用工程]