基于DDES耦合FW-H方法的吊舱推进器水动力噪声特性

Analysis of hydrodynamic noise of podded propulsor based on DDES coupling FW-H method

为研究吊舱推进器非定常流场和诱发的声场结构,采用DDES耦合FW-H方法,对其开展了高精度非定常数值计算.结果表明:由于吊柱诱发的强烈动静干涉作用,使螺旋桨至吊柱区域内的压力脉动幅值上升;吊舱推进器的涡量分布较为复杂,由于吊舱体的扰流作用,除螺旋桨本身产生的主、副涡外,还出现干涉尾涡结构,且主涡区向上偏移.通过计算盘面上各个声接收点处的谐波频率标准差发现,声场在浆盘面上无明显声指向性.通过设置空间曲面内的声接收点阵列,获得了吊舱推进器的声场空间分布特性.发现轴频和叶频始终是其主要频率;在螺旋桨桨盘面附近的声压脉动无明显指向性,但在空间曲面上,轴频和叶频的分布特征明显,存在有明显形状的高低值区;在吊舱推进器后方,声压逐渐衰减,但叶频处能量衰减趋势小于轴频处.

To study the structure of the unsteady flow field and acoustic field of the podded propulsor,the DDES(delayed detached eddy simulation)method coupled with FW-H(Ffowcs Williams-Hawings)equation was used to carry out high-precision transient numerical simulations.The results show that the amplitude of the pressure pulsation in the area from propeller to the strut is increased,due to the rotor and stator interference induced by the strut.The vortex distribution of the podded propulsor is complicated.Due to the turbulence effect of the cabin,in addition to the vortex generated by the propeller itself,the structure of the interference wake vortex is also appeared,and the main region of vortex is upward offset.By calculating the standard deviations of harmonic frequencies at various sound receivers on the disk surface,it is found that the sound field has no obvious sound directionality on the disk surface.The spatial distribution characteristics of the acoustic field of the podded propulsor are obtained by setting the spatial acoustic receiver arrays.It can be found that shaft frequency and blade passage frequency are always the main frequencies.There is no obvious directivity of the sound pressure pulsation near the propeller disk,but on the space surface,the distribution characteristics of shaft frequency and blade passage frequency are obvious,where there are high and low value areas with distinct shapes.Behind the podded propulsor,the sound pressure gradually attenuates,but the energy attenuation trend of the blade passage frequency is smaller than that of the shaft frequency.