船舶无空泡螺旋桨非定常推力脉动及其诱导线谱噪声分析

Analysis of the unsteady thrust pulsation and noise line spectrum of ship propellers

对船舶无空泡螺旋桨非定常推力脉动及其诱导的线谱噪声进行了研究,主要目的在于螺旋桨非定常推力脉动理论预报方法的验证。基于速度势面元法计算得到非均匀流场中无空泡螺旋桨的推力脉动,在大型循环水槽中利用非定常动力仪测试得到全附体船后螺旋桨的脉动推力,以脉动推力作为声源项预报得远场线谱噪声。一阶叶频非定常推力系数理论计算值与试验值最大相差29.3%,由此引起的线谱噪声差别为3.0 dB。上述结果表明,面元法预报船后螺旋桨非定常推力脉动已达到较高精度,为船舶螺旋桨低频线谱噪声的预报提供了物理基础和重要参数。

Unsteady thrust pulsation and induced noise of ship propeller under non-cavitating conditions is investigated. The main purpose is to check the validity of theoretical prediction method of unsteady thrust pulsation of propeller. The thrust pulsation in non-uniform flow conditions of propeller is calculated with potential-based panel method, and corresponding quantity is obtained by measurement using unsteady propeller dynamometer after the complete hull model in large cavitation tunnel. And then the time-dependent thrust data are used as sound source to predict the far-field noise line spectrum. The maximal discrepancy of the calculated unsteady thrust coemcient of the first blade passage frequency （BPF） with the test results is 29.3%, and the variance of the first BPF noise line spectrum is 3.0 dB. The investigation reveals that the prediction precision of propeller＇s thrust pulsation with panel method have reached higher accuracy, and the researches provide the physical base and significant parameters for prediction of ship propellers＇ low frequency noise line spectrum.