主动射流抑制云空化及流致噪声的研究

Effect of Active Water Injection on Suppressing Cloud Cavitation and Flow Induced Noise

云空化及其诱导噪声对螺旋桨、船下附体等海洋装备的水动力性能有不利的影响。针对NACA66水翼,提出了在吸力面上布设单排射流孔向流场中注入流体,以期改善流场。采用密度修正的k-ε湍流模型和ZGB空化模型对水翼的云空化非定常过程进行数值模拟,数值计算结果与试验观测吻合较好。研究结果表明:在相同的云空化条件下,主动射流有效地抑制了空化的发生、发展和脱落,并对水翼近场噪声的降低具有积极影响。与原始水翼相比,射流水翼云空化团的脱落频率降低了41.2%,在一个周期内的平均空泡体积减少了72.9%。采用主动射流后,低频段的噪声峰值得到大幅削弱,中、高频段的噪声普遍降低。监测点的总声压级平均降低了16.1 dB。这项研究对海洋装备领域抑制空化、降低流致噪声和改善水动力性能具有一定的参考意义。

Cloud cavitation and its induced noise have a bad impact on the hydrodynamic performance for ocean engineering equipment such as marine propellers and ship appendages.Taking a NACA 66-hydrofoil as the investigation object,a scheme of arranging a single row of jet holes on the suction surface and injecting fluid into the flow field is proposed in this paper.The density modified k-εturbulence model and ZGB cavitation model are used to simulate the unsteady characteristics of cloud cavitation flow.The numerical results are in good agreement with the experimental observations.It is shown that under the same cloud cavitation conditions,active jet flow can well suppress the occurrence,development and shed of cavitation,and has a positive effect on the reduction of noise in the near-field.Compared with the original hydrofoils,the frequency of cavitation shed is reduced by 41.2%,and average cavitation volume in one cycle is reduced by 72.9%.Peak value of noise in low-frequency band is greatly reduced,and noise in the middle and high frequency band is generally reduced.It is found that the overall sound pressure level is reduced by 16.09 dB on average.This study has certain reference significance for suppression of cavitation,reduction of fluid-induced noise and improvement of hydrodynamic performance for marine equipment.