Effect of Wall Confinement on the Reflection of Diffracted Shock Wave

擴張圓管直徑對繞射震波影響之研究

許耀中(Yao-Chung Hsu) ； 趙怡欽(Yei-Chin Chao) ； 鍾光民(Kung-Ming Chung)

《中國機械工程學刊》 39卷5期 (2018/10) Pp. 487-490

摘要

The effect of wall confinement on propagation of a diffracted shock wave in an expansion tube is investigated. The pressure distribution shows a plateau of high pressure, following by a pressure drop. An increase in the expansion ratio results in a decrease in the amplitude of peak wall pressure. The concept of piston work is also adopted in this study. The maxima of peak wall pressure in an expansion tube can be correlated with the equivalent piston work of an incident wave and the expansion ratio.

關鍵字

wall confinement ； expansion ratio ； diffracted shock

並列摘要

本研究以定性與定量的方式來探討在擴張圓管直徑大小對於繞射震波於壁面上反射與傳遞之影響。由數值模擬的結果發現，入射震波活塞功與壁面反射震波所產生的壓力峰值呈現線性關係。此外在擴張圓管下游約0.5倍直徑處，顯示一高壓區，在1倍直徑處，壓力峰值則快速下降。此高壓區亦會隨著直徑的增加而逐漸消失。最高壓力峰值與管徑呈線性反比的關係，利用線性回歸來找出可以同時滿足活塞功以及擴張比的關係。