不同航速下喷水推进器压力脉动分析

为了了解喷水推进器内部压力脉动特性,以对旋轴流式喷水推进器为研究对象,基于计算流体动力学CFD方法,采用雷诺时均法并引入SST k-ω 湍流模型使方程封闭,对喷水推进器进行设计工况下的非定常数值模拟.经网格无关性检验后,计算得到的推进器功率与扬程的设计值基本一致.在喷水推进器进水流道与首级叶轮之间、两级叶轮间隙之间、次级叶轮与导叶间设置监测点,监测不同位置的压力脉动数据,得到各监测点的时域图和频域图,并对各监测点的压力脉动特性进行对比分析.以设计工况下的喷水推进器相同位置处压力脉动作为参照,对比分析了不同航速下推进器各监测点处脉动分布情况.结果表明:推进器首级叶轮对其进口处压力脉动作用较大,次级叶轮对两级叶轮间隙处脉动影响较大;在低航速下,导叶对次级叶轮出口处脉动影响较大;沿轴线方向,喷水推进器两级叶轮间隙处脉动的幅值最大,在高航速下,次级叶轮出口处脉动幅值增大且变化剧烈.

Analysis of pressure fluctuation of water jet propellerunder different ship speeds

In order to understand the internal pressure pulsation characteristics of the water jet propeller, the contra axial water jet propeller is taken as the object of study and based on the computational fluid dynamics(CFD)method with the SST k-ω turbulence model is used to close the equations.A mesh independence analysis shows that the calculated power and head are well consistent with the design data. In waterjet inlet and first impeller, two stage impeller clearance between the impeller and the diffuser and the secondary impeller set between the monitoring points, monitoring the pressure data in different positions. The time domain and frequency domain diagrams of each monitoring point are obtained, and the pressure fluctuation characteristics of each monitoring point are compared and analyzed. Under the design conditions, according to the pressure pulsation of the water jet propeller at the same design position, the pulsation distribution of the propeller at different speeds is compared and analyzed. The results show: The first impeller of the propeller mainly affects the pressure fluctuation at its inlet,and the secondary impeller mainly affects the pressure fluctuation at the two-stage impeller clearance; at low ship speed, the vane mainly affects the pressure pulsation at the secondary impeller exit; in the axial direction of the propeller,due to the two-stage impeller counter-rotation,the amplitude of the pressure pulsation changes the most. At high ship speeds, the pressure fluctuation between the secondary impeller and the vane changes drastically