串列双圆柱同步测压实验结果的相关分析

Correlation Analysis for Experimental Result of Simultaneous Multi-pressure Measurement of Two Circular Cylinders in Tandem Arrangement

本文在雷诺数2×10^4下，同步测量了12个不同间距下串列双圆柱的表面压力分布，积分得到脉动升、阻力的时间历程，并对前、后柱之间的脉动升、阻力以及脉动升阻力和圆柱表面的脉动压力进行了相关分析。在本实验中，串列双圆柱流态切换的临界间距比在3．5～4．0之间，在临界间距前后，相关曲线的形态差别很明显。当串列双圆柱之间的距离小于临界间距时，前后柱之间的影响显著，造成脉动升／阻力和脉动压力之间的相关程度下降。串列双圆柱之间的距离大于临界距离时，前、后柱的脉动升力之间的相位差随间距线性增加。分离点的脉动压力和脉动升力之间以及背压和脉动阻力之间都有较好的相关性，可以用分离点的脉动压力和背压来分别表征脉动升力和脉动阻力。

The pressure distributions on the surfaces of two circular cylinders in tandem arrangement at Re = 2 × 10^4 were simultaneously measured at 12 different distances, and integrated to acquire the time series of fluctuating lifts and drags. The correlation of fluctuating lifts and drags between the upstream and downstream cylinders were analyzed, as well as the correlation between the fluctuating aerodynamic forces and the fuctuating pressure on the suface of cylinders. In this experiment, the critical space ratio where the flow pattern begin to shift is between 3.5-4.0. The shapes of correlation curves within the critical space differ from those beyond the critical space. Within the critical space, the correlation between fluctuating aerodynamic forces and fluctuating pressure decreases, due to the interferences of two cylinders. Beyond the critical space, the phase lag of fluctuating lift between upstream and downstream cylinders increases linearly as the distance increases. The distinct correlation between fluctuating pressure at separate point and fluctuating lift is confirmed, also that between base pressure and fluctuating drag. Therefore the fluctuating lift can be characterized by the fluctuating pressure at separate point, and the fluctuating drag by the fluctuating base pressure.