底部排气圆柱体模型尾部流场的数值模拟

Numerical Simulation of Base Flow Field Over a Cylindrical Model With Base Bleed

为研究底部冷排气的圆柱体模型的底部压力和尾部流场特性,采用有限体积法编程求解二维轴对称NavierStokes方程,对来流马赫数为2.47的底部排气圆柱体模型尾部流场进行数值模拟,并与实验进行对比。模型底部压力和尾部轴向速度场随排气参数的变化规律和实验吻合。分析了底排尾部流场中大、小回流区随排气参数的变化情况,以及底排气体出喷口后的流动规律。结果表明:在小排气参数时,底排气体出喷口后立即转向进入剪切层,底压迅速增加;随着排气参数增大,在喷口和底部拐角之间出现小的环状回流区,并不断增大,使底压增长率减小。研究结果可为进一步提高底排增压减阻效率提供参考。

To study the characteristics of base flows for a cylindrical model with cold base bleed,two-dimensional axisymmetric Navier-Stokes equations were solved by using a finite volume scheme.Base flow-field of the model with mass bleed in a freestream of Mach 2.47 was simulated.The regularities of base pressure and axial velocity field varying with bleed parameters accord with experimental data.The size of primary recirculation and secondary recirculation near the base annulus was observed,and the flow law of base bleed gases outside the nozzle was investigated.The results show that at low bleed rates,base bleed gases turn around immediately after ej ecting from the nozzle,and then flow into the shear layer rapidly,and the base pressures increase.With the increase of bleed rates,the small annular circum fluence-area appears between nozzle and base corner,and the area keeps increasing,and the rise rate of base pressure decreases. The results offer reference for further improving the pressurization and dragreduction efficiency of base bleed.