超声速欠膨胀冲击射流数值模拟

Numerical Simulation of Under-expanded Supersonic Impinging Jet

超声速欠膨胀冲击射流有着重要的实际应用价值,如S/TOVL飞行器、火箭发射、除尘等。其流场结构复杂,包含间断激波、反射激波、马赫盘、滞止泡以及冲击平面传热不同于亚声速冲击射流的特点。为了分析超声速欠膨胀冲击射流流场和传热,采用有限体积法,结合k-l湍流模型以及二阶精度的TVD格式进行数值模拟:对比实验和k-ε湍流模型的努赛尔数,得出k-l湍流模型在传热问题中更具优势;对比阴影图和计算密度云图以及对比冲击平面压力系数的实验值和计算值,验证了k-l湍流模型模拟超声速欠膨胀冲击射流流场的合理性;采用k-l湍流模型研究3种冲击高度(3D,6D,10D),3种压比(2.0,3.4,4.4),3种喷管总温(493 K,591 K,580 K)下,冲击平面温度分布。数值研究结果对分析超声速欠膨胀冲击平面的烧蚀有一定的指导意义。

Under-expanded supersonic impinging jets are widely used in many engineering fields,such as S/TOVL aircraft,the rocket launch,and the removal of dust,et al.Supersonic impinging jet also has complicated structures,reflected shock,mash disk,stagnation bubble,and the local heat transfer on an impinged surface has a different characteristic than a subsonic impinging jet.In order to analyze the flow-field and heat transfer of under-expanded supersonic impinging jet,it is that used a finite volume approach combined with k-l turbulence model and second-order TVD scheme.The main investigation:Compared to the nusselt number of experimental value and k-εturbulence model,which showed that k-l turbulence model had an advantage in heat transfer problems.Compared to the shadowgraph and density contour,the pressure coefficient of calculated value and experimental value,which verified and validated the k-l turbulence model.The k-l turbulence model was then used to investigate the distribution of temperature on three impingement plane heights(3D,5D,7D,l0D),three nozzle pressure ratios(2.0,3.4,4.4)and three nozzle total temperatures(493 K,591 K,580 K).An understanding of these flow characteristics is essential since they contribute directly to the study of ground erosion.