翼型体广谱声的频域预报方法

Broadband noise prediction of an airfoil or hydrofoil based on a frequency-domain formulation

本文提出了一种广谱声预报的频域方法 ,并通过与试验数据的比较证明了方法的有效性 ,尽管文中以平板翼为例 ,进行了实例计算 ,但方法本身适用于任意形体在介质中以亚音速作惯性运动时的广谱声预报。相对于时域方法而言 ,由于省去了将频域数据转化为时域数据的中间过程 ,因此该方法较时域方法 (CasperandFarassat,2 0 0 2 )更为有效。本文的关键在于具有平均流效果的格林函数的成功应用 。

A frequency domain Green function formulation of the acoustical analogy is proposed for predicting airfoil or hydrofoil broadband noise radiation when the unsteady blade loading is known. The formulation is validated by comparing its numerical predictions with measured noise data from a single airfoil in a wind tunnel. Although the formulation is used to compute the noise radiated by a flat plate airfoil immersed in a uniform mean flow, however, the formulation described here can apply to arbitrary airfoil or hydrofoil geometry moving with constant speed. The proposed frequency domain formulation is computationally more efficient than the time domain method (Casper and Farassat, 2002) since there is no need to transfer frequency domain data into time domain. The methodology will be subsequently extended to allow broadband noise predictions from a turbofan or marine propeller in forward motion.