关键词: 涡桨飞机, 螺旋桨噪声, FW-H声类比, 改进的延迟分离涡模拟（IDDES）, 降落构型

Abstract:

In this study， a hybrid method combining hybrid RANS/LES simulation on the fine Cartesian mesh and FW-H acoustic analogy is proposed for aero-acoustic prediction of two turboprop models （1/6 scaled） in the landing configuration： one is the powered model with twin propellers， and the other is the unpowered model without propeller. By comparing the near-field flow structure， data of pressure distribution and pulsation on the fuselage surface， distribution of Lamb vector divergence， and noise data at the far-field observation point， it is found that the surface pressure pulsation at the wing tip， flap side edge， wing-flap connector and fuselage-flap connection part are stronger than that at other areas in the unpowered model. In contrast， the surface pressure pulsation at the engine compartment， the wing leading edge and the flap are amplified significantly under the interference of propeller slipstream in the powered model. Far-field noise observation data show that the noise prediction method used in this paper can accurately capture not only the main frequency of propeller rotation noise， but also the 2， 3 and 4 times harmonic frequencies. The final results show that the rotation noise generated by the propellers is the main noise source with the highest amplitude. The overall sound pressure level of the powered model is 20 dB higher than that of the unpowered model. Therefore， it is suggested that the noise reduction design of this turboprop aircraft should focus on noise reduction of the propeller.

Key words: turboprop aircraft, propeller noise, FW-H acoustic analogy, Improved Delayed Detached Eddy Simulation (IDDES), landing model