Research on effects of thrust reverser exhaust flows on aerodynamic characteristics of wing-mounted civil aircraft

In order to reduce the ground roll distance during landing or rejected takeoff, cascade-type thrust reversers are adopted by modern civil aircraft to turn part of fan duct flow forward to generate braking forces, which results in thrust reverser exhaust flows affecting the aerodynamic characteristics of the aircraft. Numerical simulation of the flow field around a wing-mount civil aircraft with engines operating in reversed mode shows that exhaust flows from the thrust reverser cascades block the incoming flow and create a low energy area in the flow field around the airframe behind them. As the aircraft slows down and exhaust flow is less suppressed by the incoming flow, this affected area around the aircraft expands causing the changes in aircraft aerodynamic characteristics more significant. It is observed in the wind tunnel test using TPS (Turbine Powered Simulation) techniques to simulate thrust reverser exhaust flows that aircraft drag coefficient and yaw moment coefficient produced by rudder deflection of zero angle of side-slip at 60kts (knots) are only 55% and 25% of that of 140kts respectively due to the intensified shielding effect of exhaust flows from both engines’ cascades at lower speeds and that spoiler effectiveness at typical engine power for thrust reverser application is only 35%~59% that of idling power over the aircraft speed range from 60kts to 140kts.