螺旋桨水动力噪声数值计算方法研究

Research on computational method of hydrodynamic noise of propeller

为了确立水动力噪声量化计算规程,对基于FW-H方程的声类比计算方法进行系统性研究。采用螺旋桨水动力性能EFD及CFD标模DTMB 4 119螺旋桨为研究对象,基于大涡模拟方法系统探讨了声类比计算收敛性相关问题,包括声学计算时间的影响分析、单个叶片声压与叶片总声压的关系、声压与流动压力比较等。研究表明,声学计算时间的长短对频率谱的分布有影响,但平均声压级几乎不受影响,误差不到1%;单个叶片的SPL几乎相等但声压存在相位差,总体SPL相比单个叶片有所降低;螺旋桨远场声压一般低于流动压力,近场螺旋桨域内则例外,呈现不收敛趋势。由此可见,将流动与声传播解耦的声类比方法对于近场声压求解有一定局限性。

In order to establish the quantitative calculation procedure of hydrodynamic noise, the acoustic analogy calculation method based on FW-H equation was studied in detail. Adopting the standard model propeller of hydrodynamic performance in EFD and CFD, DTMB 4119, as the research object, based on the large eddy simulation method, the problems related to the convergence of the acoustic analogy calculation were systematically discussed, including the analysis of the impact of acoustic computation time on the sound field points, the relationship between the sound pressure of a single blade and the total sound pressure of the blades, the comparison between the sound pressure and the flow pressure, etc. It's shown that the acoustic computation time has an effect on the frequency spectrum, but the overall sound pressure level is almost unaffected, with an error of less than 1%. SPL of each blade is almost the same, but there is phase difference in sound pressure. The overall SPL is lower than that of single blade. The far-field sound pressure of propeller is generally lower than the flow pressure, except in the near-field propeller region, which shows a non convergence trend. It can be seen that the acoustic analogy method that decouples the flow and sound propagation has certain limitations for solving near-field sound pressure.