Investigation of the supersonic flow characteristics in an Aerodynamic Window

• Main Authors: Kuan-Shiuh,Chen, 陳冠旭
• Other Authors: Fang-Ming,Yu
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/83324720521121290596

碩士 === 國立成功大學 === 航空太空工程學系 === 81 === The double pulsed laser holographic interferometry tech- nique has been used to investigate the flow structure of a free vortex type supersonic Aerodynamic Window.On comparing the flow visualization results of three Aerodynamic Windows with designed Mach number ratio of 1.6/2.65,1.6/3.0 and 1.6 /3.2,it was observed that all of them can produce a very uniform supersonic shear flow in the free vortex type shear flow generation section.However,with the air supply total pressure being comparatively low,on the high Mach number side of the window the static pressure being dropped to lower than the outside atmospheric pressure and thus the adverse pressure gradient effect being propogated upstream through the subsonic boundary layer causes the flow separa- tion on the wall of high Mach number side.The radius of curvature of the jet stream is being shift from its design condition due to the centrifugal force of the jet stream as well as the results of the flow separation.A diffuser was installed to overcome the change of the curvature of the jet stream.It was found that with a diffuser of same radius of curvature installed with its center of curvature at same position as the Aerodynamic Window. The jet stream from the Aerodynamic Window has the best curvature and the low pre- ssure side of the sheared jet stream has a very good acce- leration behavior.As the diffuser installed with position of the center of curvature moving upward,the curvature of the jet stream decreased and the flow separation point on the low pressure side wall inside the Aerodynamic Window moves upstream.For an Aerodynamic Window without diffuser,the flow structures was observed that the jet stream exiting from it is straight and no curvature.However,the flow separation point on the low pressure side wall of the Aerodynamic Window is at more downstream position comparing it of the Aerodynamic Window with a diffuser installed 3mm away from its original position.It shows that a proper choice