暫態量測於震波風洞之應用

• Main Author: 郭璟璘
• Other Authors: 邵耀華
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/47792110349466081852

碩士 === 國立臺灣大學 === 應用力學研究所 === 85 === In this study, heat-flux measurement system using co-axial thermocouples and thin film gauges was constructed. Instantaneous changes of flow properties behind the incident shock in a shock tube were used to detect the response characteristics of the temperature sensors. The response time of co-axial gauge at the stagnation point is about 10usec. Because the surface quality of sensors may change due to the severe environment in a shock tunnel, calibration of sensor on site is very important. The hypersonic aero-thermodynamic problems on a sharp cone-cylinder model in whick thermal gauges were installed to measure the heat flux on the model surface were studied. Tests were conducted in Mach 6.8 flow in a shock tunnel. 　　The free stream properties in the test section of the shock tunnel were measured with pitot probe and stagnation temperature probe. Experimental results showed good repeatability, and accurate control of initial condition can be achieved. Based on the Pitot pressure results, the useful test time is about 9.5 ms, and the free stream Mach number is less than theoretical isentropic value due to the growth of boundary layer thickness. The mass flux and momentum flux were calculated based on the pitot pressure and stagnation heat flux (p12 qsph) via Fay-Riddell relation. The results of heat flux measurements at the model surface show that the heat flux concentrates in the vicinity of the stagnation point which agrees well with the estimation using Eckert's reference temperature method. The measurement and calibration systems constructed have shown high performance on both accuracy and frequency response.