大涵道比涡扇发动机TPS短舱低速气动特性分析

Numerical Study on Low Speed Aerodynamic Performance of Large Bypass Ratio Engine TPS Nacelle

关键词:  涡轮动力模拟器  进气道  短舱  阻力  数值模拟

Key words:  Turbine Powered Simulator  Inlet  Nacelle  Drag  Numerical simulation

摘要:

为了评估民机低速带动力试验时进排气效应的影响，选取大涵道比发动机涡轮动力模拟器(TPS)短舱和真实发动机短舱作为研究对象，采用数值模拟方法对其起飞、进近状态的低速气动特性进行对比分析。结果表明:由于TPS流量低于真实发动机需求，其唇口、外罩流场特征和真实发动机短舱有所不同，阻力特性也有差别；在进气道处于亚临界状态时，TPS短舱阻力系数比真实短舱大了约1.7个阻力单位，又由于唇口当地气流攻角更大，使得TPS短舱失速攻角相对降低了约1.0°；当进气道工作于超临界状态时，TPS短舱虽然也可以反映真实短舱的流动特性，但由于捕获流管收缩情况和气流驻点随攻角的变化，使得在0°～20°攻角时TPS短舱的阻力系数高于真实短舱，而在20°～30°攻角时其阻力系数略低，差量最大约为1.8个阻力单位。对于研究的大涵道比发动机，未经唇口及外罩修正的TPS短舱其低速气动特性基本可以反映真实进排气效应的影响，但在气动特性分析中可以考虑进一步修正进气效应的影响。

Abstract:

In order to study the propulsion effects on the aerodynamic performance of a civil aircraft by using a Turbine Powered Simulator (TPS) in the wind tunnel experiment，numerical simulations were performed and the aerodynamic characteristics were investigated on the TPS nacelle as well as on the nacelle of a real large bypass ratio engine at low speed conditions of takeoff and approach. The lip and cowl geometry of the TPS nacelle was kept the same as that of real engine. The results suggest that some flow-field features of the TPS nacelle are different from the field of engine nacelle in terms of flow capture characteristics，resulting in a slightly different drag coefficient. When the inlet is at subcritical condition，the drag coefficient of TPS is 1.7 counts higher than that of the real engine. In addition，the flow on the upper cowl of TPS nacelle would be easier to separate due to the lower mass flow ratio at high angle-of-attack (AOA) than the real nacelle，therefore，the stall AOA for TPS is about 1.0° smaller. When the inlet is at supercritical condition，due to the variation of stagnation locations and contractions of flow tube with AOA，the drag coefficient of TPS nacelle is higher than that of real engine at AOA about 0°～20°，while the state is reverse at AOA about 20°～30°. Although the differences of drag coefficients are up to 1.8 counts，the aerodynamics characteristics in general are similar between the two. It can be concluded that even TPS nacelle with the same lip and cowl geometry could capture most of the flow features around a real engine. Certain corrections to the drag coefficient of the TPS would nonetheless make the wind tunnel results more accurate.