城垛形喷口圆湍射流拟序结构的流动显示

用流动显示的方法研究了城垛形喷口对圆湍射流拟序结构的影响。实验中喷口流动Reynolds数为5000,Strouhal数为0.50。实验结果表明:城垛形喷口能够影响圆湍射流中大涡结构的产生和演化,进而控制湍射流。无动态激励时,该喷口对射流中拟序结构的影响与垛口数目和垛口高度有关。有动态激励时,城垛形喷口和声波扰动一起,在促进大涡结构的产生和演化方面,总是相互加强的。因此,城垛形喷口是控制圆湍射流拟序结构的一个有效途径。

Visualization of coherent structures in notched nozzle jet flow

The effect of notched nozzles on the coherent structures in turbulent round jets was investigated experimentally using flow visualization. The jet Reynolds number based on nozzle diameter and velocity was 5 000, and the Strouhal number based on the nozzle diameter was 0.50. The experimental results showed that the notched nozzles significantly affected the evolution of the coherent structures in the round jet. With unforced oscillations, the notched nozzles did not always promote the evolution of coherent structures, depending on the height and width of the notch. The coherent structures always occurred in the notched nozzles with forced oscillations. Therefore, the notched nozzles can effectively control coherent structures in turbulent round jets.