Abstract
Flow separation under crosswind conditions seriously jeopardizes the quality of the nacelle’s flow field. In this paper, microsecond pulsed surface dielectric barrier discharge (μSDBD) is used to suppress the flow separation and reduce the crosswind distortion of the nacelle. The flow structure induced by the μSDBD is first explored by a high-speed schlieren system. The pressure waves composed of a cylindrical wave surrounding the electrodes and a flat wave at the top of the cylindrical one can be perceived, which indicates the fast gas heating produced by the μSDBD. A set of wind tunnel tests are then conducted to verify the ability of μSDBD to suppress the nacelle flow separation and study the influence laws of pulse frequency, coverage area, and the actuator layout on the flow control effects. Results show that plasma actuation can not only improve the total pressure at the exit of the nacelle but also suppress the flow distortion caused by the crosswind. The best flow control effect can be achieved at the pulse frequency of 500 Hz, with the value of sectional distortion coefficient reduced by 57.76% compared with the baseline condition. The flow control effect with the plasma actuator covering 120° of the nacelle perimeter is better than that of 60° and 180° coverage, showing the highest flow control efficiency in the 120° condition. The μSDBD can improve mixing between the boundary layer and the main flow, enhancing the ability of the boundary layer to resist the adverse pressure gradient, which is beneficial to flow separation control.
Highlights
The large bypass ratio turbofan engines are widely used in civil airliners and military transport aircraft (Seddon et al 1999), due to their advantages such as large thrust, low fuel consumption, and low noise (Joly et al 2004)
The μSDBD can improve mixing between the boundary layer and the main flow, enhancing the ability of the boundary layer to resist the adverse pressure gradient, which is beneficial to flow separation control
3.1 Flow field characteristics induced by μSDBD under the static atmosphere
Summary
The large bypass ratio turbofan engines are widely used in civil airliners and military transport aircraft (Seddon et al 1999), due to their advantages such as large thrust, low fuel consumption, and low noise (Joly et al 2004). Control of the compressor tip leakage flow using SDBD plasma actuation was studied by numerical and experimental methods under the flow velocity of 43 m/s. The influence of the parameters including freestream velocity, engine suction speed, pulse frequency, and actuator layout and covering area, to the flow control is explored and the flow control mechanism is discussed. On this basis, an optimum plasma actuation method for nacelle flow separation control is obtained, which can help to improve the quality of the inlet flow field and broaden the flight envelope of the aircraft
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