Side force augmentation at high angle of attack from pneumatic vortex control

Abstract

An experiment has been undertaken to measure side and lift forces with various nozzle blowing locations on an elliptic fore body. In this study a jet of small momentum excites a corrective instability to produce an amplified side force at high angle of attack for a fighter forebody. This study has identified an optimized nozzle position around the circumference of the forebody and axial location using a slotted nozzle at various pressure ratio values. A forward sweep of the nozzle provided for the greatest augmentation of side force at angles of attack below 55 deg. A beveled nozzle has shown active control of side force beyond 55-deg angle of attack and has merit in extending the angle of attack range. The mass flow requirements to produce a side force are sensitive to the angle of the jet relative to the forebody axis. The required mass flow is compatible with available engine bleed air that could be dedicated to pneumatic control. Data for different forebody strake configurations shows a degradation in side force magnitude with pneumatic blowing.