绕翼型加速流动的数值模拟—加速度的影响

NUMERICAL SIMULATION OF ACCELERATED FLOW PAST AN AIRFOIL : INFLUENCE OF ACCELERATION

对绕30°攻角NACA 0015翼型的不可压缩加速流动进行了二维数值模拟,采用有限体积法计算了水道中4种不同加速度下绕翼型的非定常流动,最终稳定的流速都为100 mm／s,对应雷诺数为8000。给出了详细的瞬态流动结构、升力系数以及流动的演化过程,重点分析了加速度对流动结构的影响。计算结果表明启动过程和完成启动后的绕翼型流动结构复杂,其流动分离现象也明显区别于稳态过程自生和自维持的分离流动,具有明显的瞬态效应,并且启动加速度大小对流动结构和发展、漩涡强度等都有直接影响。

Accelerated flow past a NACA 0015 airfoil at an angle of attack of 30° during start period was studied computationally. The finite volume method was used to simulate two-dimensional unsteady incompressible viscous flow. Four different uniform accelerations were used to study the transient flow; the final uniform velocity was 100 mm/s for both cases, and the Reynolds number was about 8000. The structure and development of transient flow and lift coefficient were presented, and the effect of acceleration on flow structure was evaluated. The results of computations show that the structure of unsteady flow is complex during both the acceleration phase and the constant velocity post-acceleration phase. The separated flow structure during start period differs from that of steady state. The separated flow and vortical structure and intensity are dependent upon the magnitude of the acceleration.