破裂涡流中非定常现象与频率特性实验研究

通过流动显示、表面动态压力测量及热线测量等实验手段,对三角翼破裂涡流中的多种频率成分进行了分析。频谱分析确定了破裂点脉动和螺旋波的频率特征。实验结果表明,螺旋波主频随着弦向位置的增大先是迅速而后平缓减小。前缘涡破裂点振动具有准周期性,在不同的弦向位置上主频大小几乎没有改变,在靠近破裂点的位置有较大的振动能量。实验分析还表明,在破裂涡的流动状态下,虽然没有形成完全分离流,三角翼绕流流场中已经存在涡脱落的现象。

Study on Unsteady Flow Phenomena and Frequency Characteristics in Breakdown Vortex Flow

Based on flow visualization, dynamic pressure and hot wire measurements, the unsteady phenomena and frequency characteristics in flow over delta wings have been investigated. Spectrum analysis reveals the frequency characteristics of vortex breakdown point oscillation and spiral wave. Experimental results show that the dominant frequency of spiral wave decreases rapidly and then slowly with the increase of the chord-wise position. Oscillation of the vortex breakdown position behaves as the quasi-periodicity in which the frequency keeps almost constant along chord-wise position. It is found that the oscillation energy attains local maximum near the breakdown point. Besides, the test results also show that when the leading vortex breakdown point does not arrive at the top of the tested wing the vortex shedding does exit in the flow over the delta wing.