Experimental Study on the Shock Oscillating in an Underexpanded Jet to Cavity Interaction Flow

• Main Authors: Wang, Chang-Nan, 王昌楠
• Other Authors: Fang-Min Yu
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/94226655554655524878

碩士 === 國立成功大學 === 航空太空工程學系 === 85 === Underexpansion jet to cavity flow induced pressure oscillation inside the cavity tube and the induced temperature increasing on the bottom of the tube has been investigated based on three parameters of nozzle pressure ratio, nozzle exit to cavity distance and the cavity tube length. Two major flow modes named as regurgitant mode and screeching mode were observed. The measured major frequency on the pressure oscillation inside cavity tube is very closed to the theoretical fundamental frequency of the flow system or its multiplier. Instead of a solid cavity tube end, as replacing it with a sponge-end or a open-end, it has been observed that the amplitude of the pressure oscillating reduced to a negligible level, however, the major frequency remains on the same characteristics. It is concluded that the major mechanism for the pressure oscillating inside cavity tube is owing to the pressure wave reflection between the solid end surface and the inlet surface of the cavity tube. On some regurgitant modes the amplitude of the pressure oscillation can be as high as 70 psia, with a frequency closed to the fundamental frequency. Due to the accumulation of the entropy on the cavity tube end on the pressure oscillation processes in regurgitant mode, an obviously temperature rising has been measured on the end of the cavity tube.