CAJ | 학술논문

通过二维射流混合层中相干时间尺度的测量,对声激励不稳定波增长过程及破碎点后的相干特性进行研究.实验结果表明,相干时间尺度在基波和第一亚谐波增长区较大,在破碎点后突然下降并在下游呈逐渐减小趋势.增加声激励强度可使不稳定波增长区的相干时间尺度增大,并对下游的流动结构有明显影响.
통과이유사류혼합층중상간시간척도적측량,대성격려불은정파증장과정급파쇄점후적상간특성진행연구.실험결과표명,상간시간척도재기파화제일아해파증장구교대,재파쇄점후돌연하강병재하유정축점감소추세.증가성격려강도가사불은정파증장구적상간시간척도증대,병대하유적류동결구유명현영향.
Experimental researches on coherent characteristics of sound generated by instab ility waves in the mixing layer of a planar jet under acoustic excitation are pr oceded through the measurement of the coherent time scale.It demonstrates that the coherent time scale keeps a high level in the growing stage of coherent stru ctures under the motivation of instability waves and then turning down abruptly at the breaking point where the large-scale eddies begin to shed downstream .It provides a criterion whether the instability wave or convective eddy becomes dom inant in the contour map of the fluctuating velocity amplitude distribution with their particular expression of Lighthill stress.