基于流体网络法的喷管冷却气流量分配计算方法

Calculation method of cooling air distribution in nozzle based on fluid network analysis method

流体网络法对喷管气膜冷却问题具有独特的优势,但难以反映出入流对冷却气流道静压变化的影响。针对此引入了可反映出入流导致静压变化的管道元件,并基于孔口速度落后角对静压变化量进行了建模。验证算例表明,这一改进使沿程静压变化趋势与实际吻合较好,使冷却气流量分配计算误差降低到0.5%以下。将改进后的流体网络法与主流通道的计算流体力学模拟耦合用于分析喷管冷却气流量分配,与全计算流体力学模拟相比结果差异小于1.2%,且大幅降低计算量;在某型喷管设计中的应用表明,可以有效反映冷却结构改变对冷却气流量分配的影响。

The fluid network analysis method has its unique advantages in nozzle film cooling problems,but it cannot predict the influence of inlet/outlet flow on the static pressure change along cooling air channel. In order to solve this problem,a type of element that can describe the static pressure change caused by inlet/outlet flow was introduced,and the variation of static pressure was quantified based on the lag angle of velocity at hole entrance. Results on verification examples showed that the improved method can correctly capture the static pressure trend along the cooling air channel and reduced the calculation error of cooling air distribution to less than 0. 5%.The improved fluid network analysis method was coupled with computational fluid dynamics sim-ulation of mainstream,and used to analyze cooling air distribution in nozzle. Compared with computational fluid dynamics simulation for whole system, the method had very low computation cost,meanwhile the difference between two methods was less than 1. 2%. The application in the design of a nozzle showed that the method reflected the influence of cooling structure changes on cooling air distribution effectively.