The correction method uses the static pressures measured near the tunnelwalls during model tests as boundary conditions. It is required that the flow near thewalls is subsonic and the freestream Mach number is less th...The correction method uses the static pressures measured near the tunnelwalls during model tests as boundary conditions. It is required that the flow near thewalls is subsonic and the freestream Mach number is less than 1. It is still valid whenthere are shock waves and supersonic pockets near the model as long as shock waves donot extend to walls, and the method is applicable to various ventilated wall or solid walltest sections. Corrections for three models tested abroad are in quite good agreementwith NASA's results, which are obtained by a nonhnear correction method. Thepresnet method has been apphed to B737 inodel tcsted in CARDC 1.2 m wind tunnel.The results show that this method is suitable for transonic wall interference correctionfor high aspect ratio airplane tests.展开更多
Microjets are used to control the internal flow to improve the performance of an ultra-compact serpentine inlet. A highly offset serpentine inlet with length-to-diameter ratio of 2.5 is designed and static tests are c...Microjets are used to control the internal flow to improve the performance of an ultra-compact serpentine inlet. A highly offset serpentine inlet with length-to-diameter ratio of 2.5 is designed and static tests are conducted to analyze the internal flow characteristics in terms of pressure recovery, distortion and flow separation. Flow separation is encountered in the second S-turn, and two strong counter-rotating vortices are formed at the aerodynamic interthce plane （AIP） face which occupy a quarter of the outlet area and result in severe pressure loss and distortion. A flow control model employing a row of microjets in the second turn is designed based on the internal flow characteristics and simplified CFD simulations. Flow control tests are conducted to verify the control effectiveness and understand the characteristics as a function of inlet throat Mach number, injection mass flow ratio, jet Mach number and momentum coefficient. At all test Mach numbers, microjet flow control （MFC） effectively improves the recovery and reduces the distortion intensity. Between inlet throat Mach number 0.2 and 0.5, the strong flow separation in the second S-turn is suppressed at an optimum jet flow ratio of less than 0.65%, resulting in a maximum improvement of 4% for pressure recovery coefficient and a maximum decrease of 75% for circumferential distortion intensity at cruise. However, in order to suppress the flow separation, the injection rate should retain in an effective range. When the injection rate is higher than this range, the flow is degraded and the distortion contour is changed from 90° circumferential distortion pattern to 180° circumferential distortion pattern. Detailed data analysis shows that this optimum flow ratio depends on inlet throat Mach number and the monlcntunl coefficient affects the control effectiveness in a dual stepping manner.展开更多
文摘The correction method uses the static pressures measured near the tunnelwalls during model tests as boundary conditions. It is required that the flow near thewalls is subsonic and the freestream Mach number is less than 1. It is still valid whenthere are shock waves and supersonic pockets near the model as long as shock waves donot extend to walls, and the method is applicable to various ventilated wall or solid walltest sections. Corrections for three models tested abroad are in quite good agreementwith NASA's results, which are obtained by a nonhnear correction method. Thepresnet method has been apphed to B737 inodel tcsted in CARDC 1.2 m wind tunnel.The results show that this method is suitable for transonic wall interference correctionfor high aspect ratio airplane tests.
基金co-supported by the Postdoctoral Foundation of China (Nos. 2013M542525, 2014T71019)
文摘Microjets are used to control the internal flow to improve the performance of an ultra-compact serpentine inlet. A highly offset serpentine inlet with length-to-diameter ratio of 2.5 is designed and static tests are conducted to analyze the internal flow characteristics in terms of pressure recovery, distortion and flow separation. Flow separation is encountered in the second S-turn, and two strong counter-rotating vortices are formed at the aerodynamic interthce plane （AIP） face which occupy a quarter of the outlet area and result in severe pressure loss and distortion. A flow control model employing a row of microjets in the second turn is designed based on the internal flow characteristics and simplified CFD simulations. Flow control tests are conducted to verify the control effectiveness and understand the characteristics as a function of inlet throat Mach number, injection mass flow ratio, jet Mach number and momentum coefficient. At all test Mach numbers, microjet flow control （MFC） effectively improves the recovery and reduces the distortion intensity. Between inlet throat Mach number 0.2 and 0.5, the strong flow separation in the second S-turn is suppressed at an optimum jet flow ratio of less than 0.65%, resulting in a maximum improvement of 4% for pressure recovery coefficient and a maximum decrease of 75% for circumferential distortion intensity at cruise. However, in order to suppress the flow separation, the injection rate should retain in an effective range. When the injection rate is higher than this range, the flow is degraded and the distortion contour is changed from 90° circumferential distortion pattern to 180° circumferential distortion pattern. Detailed data analysis shows that this optimum flow ratio depends on inlet throat Mach number and the monlcntunl coefficient affects the control effectiveness in a dual stepping manner.
