非空泡螺旋桨低频线谱噪声时域预报方法

摘要

针对非空泡螺旋桨的低频线谱噪声特点和数值处理方法,用基于速度势的面元法和噪声时域预报方法进行了研究.用面元法对非均匀流场中的螺旋桨非定常压力分布进行计算,将计算得到的压力时域信号输入到噪声积分方程中,可以得到螺旋桨诱导的噪声声压,该方法直接将噪声源分布在真实的螺旋桨表面而非螺旋桨的拱弧面,对噪声源和观测点的距离没有作任何近似,并可以考虑桨毂对噪声声压的影响.计算结果表明,在非空泡条件下,桨叶厚度、桨毂负荷和桨毂厚度引起的噪声声压非常小,对螺旋桨低频线谱噪声总声级的贡献可以忽略不计,高阶叶频声压级比一阶声压级明显低,一阶叶频声压级在桨轴方向上最大,在桨盘面方向最小.%In order to study the characteristics and prediction method of low-order blade frequency noise of a non-cavitation propeller, the velocity potential-based surface panel method and the noise analysis method in a time do?main were adopted. The unsteady loading (dipole source) on the blade surface was calculated by a surface panel method. Then the time-dependent pressure data were used as the input for the Ffowcs Williams-Hawkings formula?tion to predict the acoustic pressure induced by the propeller. The integration of the noise source was performed o-ver the true blade surface rather than the arc blade surface. The distance between the noise source and observation point was not approximated and the effect of the propeller hub was considered. Through comparison and analysis of computation results, it was shown that the sound pressure level (SPL) caused by the blade thickness and hub is very small and can be ignored. The 2nd order higher order blade frequency SPL is obviously lower than the 1st or?der blade frequency SPL. The 1st order blade frequency SPL is the highest in the direction of the propeller axis and lowest in the direction of the propeller disc.