Aerodynamic design and experimental modelling of an innovative supersonic three-dimensional air-intake

Abstract

Aerodynamic design of an innovative supersonic three-dimensional air-intake including a starting device has been carried out. The intake concept is based on the use of an external compression ramp in the form of a caret waverider. In a design fl ow regime, this ramp generates a plane oblique shock wave lying on its swept leading-edges and a subsequent two-dimensional isentropic compression wave. The intake starting is provided with a device special fl aps of which in the throat are opened slightly in order to enlarge it and to form here both longitudinal and cross slots for air bleed and boundary-layer diversion. The same device can also serve for regulation of intake operating regimes depending on the fl ight velocity. The experimental model intake with a design Mach number М D = 2 has been developed and tested at fl ow Mach numbers 1·5, 1·75, and 2·0 in the T-313 supersonic wind tunnel based at ITAM. Flow patterns about the intake have been observed, and fl ow parameters characterising the intake performance have been measured. The experimental results obtained have confi rmed the workability of the starting/regulating device; the data on the effi ciency of the model intake have demonstrated its good characteristics in terms of the total pressure recovery. NOMENCLATUREa velocity of sound a * critical velocity of sound A  frontal area of air-intake A  area of free air-stream captured by intake A f area of air-stream captured by intake in fl ow directly in front of it A e cross-sectional area of intake entrance A sl total area of slots for air bleed and boundary-layer diversion in intake throat A th cross-sectional area of intake throat A thst cross-sectional area of throat providing intake starting M fl ow or fl ight Mach number (M = V/a) M  free-stream Mach number M D design Mach number M e fl ow Mach number at intake entrance M f fl ow Mach number in front of intake M th Mach number of uniform fl ow in intake throatׁm fl ow rate of air-stream measured in intake throat ׁm  fl ow rate of free air-stream captured by intake Δׁ m sl fl ow rate bled through slots p static pressure p  free-stream static pressurē p relative static pressure (¯p = p/p  ) p th mean static pressure measured in intake throat p 0 total pressure of fl ow p 0 free-stream total pressure p 0f total pressure of fl ow directly in front of intake p 0th mean-mass total pressure of fl ow in intake throat p' 0i total pressure measured by a pitot probe Re 1 unit Reynolds number (1/m) R u specifi c gas constant T 0 total temperature of free-stream fl ow T 0f total temperature of fl ow in front of intake T 0th total temperature of fl ow in intake throat V velocity of fl ow γ ratio of specifi c heats α angle-of-attack λ reduced velocity of fl ow (V/a * ) φ fl ow rate factor ( = A  /A 0 or  = A f /A 0 ) σ total pressure recovery factor(σ = p 0 /p 0 or σ = p 0 /p 0f ) SUFFIXES0 stagnation values of fl ow quantities  free-stream conditions f parameters related to fl ow in front of intake th parameters related to intake throat