涡桨飞机缩比模型机体噪声预测研究

Noise prediction research of a scaled turboprop aircraft

民用飞机机体噪声水平已成为衡量飞机性能的重要指标,受到了越来越多的关注。当前基于CFD数值模拟的机体噪声预测研究大多针对飞机单独部件开展,缺乏对全机高保真复杂构型的噪声预测。由于部件之间的干扰,针对部件的噪声预测在计算条件、噪声的产生及传播等方面均和实际构型之间存在很大的差异,因此采用高保真真实飞机模型才能对飞机机体噪声进行更准确的预测。采用精细化高分辨率网格与高精度混合RANS/LES方法,结合FW-H声类比方法,对涡桨飞机高保真1/6缩比模型在降落状态下的气动噪声进行了数值预测研究。采用改进的延迟分离涡模拟(IDDES)方法对近场声源区流动进行模拟,得到了涡桨飞机全机的近场声源特性。除了捕捉到襟翼侧缘和翼尖2个重要噪声源之外,还发现了由短舱尾迹和后缘襟翼之间的干扰引起的噪声源、襟翼内侧和机身之间的复杂流动引起的噪声源。远场噪声研究结果显示,在机身的纵向对称面内,噪声主要向前下方和后上方传播,偶极子特性十分明显。在垂直于来流的平面内,横向噪声较弱。

Aerodynamic noise level has become an important performance index of civil aircraft,and it is drawing more and more attention.Most airframe noise research based on CFD method is aimed at aircraft individual parts at present,while lack of noise prediction for the complex high fidelity full aircraft model.Due to the interaction between aircraft parts,noise prediction between single part and the actual configuration are very different in the aspect of calculation conditions,noise generation and propagation.Only by using more realistic model can the noise be accurately predicted.In this paper,high-resolution mesh and high-precision hybrid RANS/LES method,combined with the FW-H acoustic analogy method,are employed to predict the noise of a turboprop′s high-fidelity 1/6 scale model of landing configure.The improved delayed detached eddy simulation(IDDES)method was used to simulate the flow in the near-field sound source region,and the sound source characteristics of the whole turboprop are obtained.In addition to the two important noise sources-flap side edge and wing tip,numerical simulation also found other two important noise sources resulting from the interaction between parts-interaction between nacelle wake and flap,and the complex flow between flap inner side and fuselage.Results of far-field noise show that in the longitudinal symmetry plane of the fuselage,the noise mainly propagates to the lower front and over back direction,and the dipole characteristics are very obvious.In the plane perpendicular to the incoming flow,the noise in the transverse direction is weaker.