Reducing underwater radiated noise of a SUBOFF model propelled by a pump-jet without tip clearance: Numerical simulation
Reducing underwater radiated noise of a SUBOFF model propelled by a pump-jet without tip clearance: Numerical simulation
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DOI：
10.1016/j.oceaneng.2021.110277
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发表时间：
2022-01
影响因子：
5
通讯作者：
Xiuchang Huang;S. Shi;Zhiwei Su;Wanghao Tang;H. Hua
中科院分区：
文献类型：
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作者：
Xiuchang Huang;S. Shi;Zhiwei Su;Wanghao Tang;H. Hua
提出了一种无叶尖间隙的泵喷推进缩比SUBOFF模型。本文报道了在非定常激励下，SUBOFF后泵射流的水动力性能、模态特性和声振响应，并与叶顶间隙为2mm的泵射流进行了比较。流体动力学的计算流体动力学（CFD）和振动声响应预测耦合有限元法（有限元法）和直接边界元法（边界元法）。通过定常水动力实验验证了无叶顶间隙泵射流的CFD模型。给出了SUBOFF后新型泵射流的脉动压力、脉动压力标准差和频谱。结果表明，该方法能有效地抑制单叶片上的脉动压力和转子上的脉动力，并使转子和管道上的监测点在叶片通过频率及其倍数处的幅值大大衰减。由于转子叶片增加了围带，围带与通道之间由于流体动力润滑而呈现出刚度，转子叶片悬臂状态的改变，使转子与通道产生了新的耦合变形模态，轴纵振模态的模态频率增加。提出了转子通过导管对船体激振和导管通过轴系对船体激振的新的传力路径，在对转子或导管施加激振力时，传递部分振动能量。消除叶尖间隙后，声辐射功率级得到了很大的抑制。特别是在特征结构模态处，由于交替结构模态远离激振力的特征频率和抑制转子和管道上的脉动压力的组合效应。
A pump-jet without tip clearance is proposed to propel a scaled SUBOFF model. The hydrodynamic performance of the pump-jet behind the SUBOFF, modal characteristics and vibro-acoustic responses of the SUBOFF – pump-jet under unsteady excitations are reported and compared with those by the pump-jet with a 2 mm tip clearance. The hydrodynamics are obtained by CFD (Computational Fluid Dynamics) and vibro-acoustic responses are predicted by coupled FEM (Finite Element Method) and direct BEM (Boundary Element Method). The CFD model of the pump-jet without tip clearance is validated by experimental results in a cavitation tunnel through steady hydrodynamics. Fluctuation pressure, standard deviation of fluctuation pressure and spectra of the new pump-jet behind SUBOFF are demonstrated. It is shown that fluctuation pressure on a single blade and fluctuation force of the rotor are suppressed remarkably, as well the amplitudes at BPF (blade passing frequency) and its multiples is greatly attenuated for the monitoring points on the rotor and duct. Since a shroud is added for rotor blades and stiffness is presented between the shroud and the duct due to hydrodynamic lubrication, a new mode of coupled rotor and duct deformation is borne and modal frequency at longitudinal mode of shaft is increased due to change of the cantilever supporing state of rotor blades. New force transmission paths for the rotor via the duct to excite the hull, and that for the duct via the shafting to excite the hull are presented, which will transmit part of vibration energy when applying excitation forces on the rotor or duct. The sound radiation power level is greatly suppressed after eliminating the tip clearance. Especially at the characteristic structural modes due to combined effect of alternating the structural modes to be far away from the characteristic frequencies of excitation forces and suppressing fluctuation pressures on the rotor and duct.