Research On The Flow Field Characteristics And Flow Control Of S-shaped Inlet

Modern high-performance fightersoften stressstealth capacity in tactical requirements,howeverthe most common used turbine enginescan easily be captured by detectdevicesbecause of the existence of periodic motion. S-shaped inlet has been widely used as theycan shield the turbine bladeseffectively and improve theirstealth capacity greatly.However, the boundary layer separation and secondly flow vorticesin the S-inlet willdecrease total pressure recovery and increase pressure distortion. The performance of theengine is greatly affected.PIV, seven-hole probe and pressure measurementwere used to study the inner flowfield characteristics of S-shaped inlet in this paper. The flow characteristics in S-inletwere grasped, separation region and the starting point of separation were defined.A method of flow control, installing vortex generators (VG), was considered toimprove the flow in S-inlet, the influence of location and height on the performance wasinvestigated. A new method, VG with feedback system, was proposed to enhance theeffectiveness and efficiency of control based on the results. This system is able toregulate the height of VG independently according to the inlet velocity, so that VG isalways in the optimal control parameters.Another active flow control method, synthetic jetwas also applied to S-inlet. Inorder to improve the flow field in S-inlet, a high speed synthetic jet actuator system wasdesigned. its exit velocity can up to100/s. Two kinds of export shape,3-bevel-gapsexport and eight-shaped export were investigated. The results proved that the pressurerecovery and pressure distortion can be greatly controlled by synthetic jet. At the streamvelocity V=160m/s, total pressure recovery coefficient was increased by1.4%,staticpressure distortion coefficient was decreased by28.7%, dynamic pressure distortioncoefficient was decreased by17.2%, by the control of eight-shaped synthetic jet.