高频不稳定燃烧的声学数值仿真

高频不稳定燃烧一直是液体火箭发动机研制过程中所要面临的重大难题之一.采用具有低色散低耗散特点的计算气动声学方法,对自燃推进剂变轨发动机(OME)的高频不稳定燃烧进行时域下的数值仿真.由Crocco的压力时滞模型对燃烧热释放和声波之间的耦合进行模拟,并对不同的时滞模型参数对稳定性结果的影响进行了分析,给出发动机的稳定性极限图,确定一阶切向及一阶径向振型为主的不稳定振型,与地面试车实验捕捉到的不稳定振型相一致.结果表明:采用计算气动声学方法对带有Crocco压力时滞模型的声波扰动方程进行时域下的数值求解,可以对发动机的高频不稳定燃烧进行成功地预测.

Acoustic numerical simulation of high frequency combustion instability

High frequency combustion instability is one of the major issues existed in design process of liquid rocket engine. A time domain numerical simulation was used to predict high frequency combustion instability of hypergolic propellant orbit maneuvering engine (OME) by computational aeroacoustics, which was less dispersive and dissipative. The coupling between unsteady heat release and acoustics was realized by Crocco's pressure time lag model. The effects of different parameters of pressure time lag model on stability were analyzed, and the stability map was obtained. The first order transverse mode and the first order radial mode were recognized as the most dominant instable modes, which were consisted with the instable modes recognized from experimental results of ground test. The results show that high frequency combustion instability can be successfully predicted, when acoustic perturbation equations with Crocco's pressure time lag model are solved in the time domain by computational aeroacoustics.