This study details experiments investigating a previously unrecognized surge instability on a cavitating propeller in a water tunnel. The surge instability is furst explored through visual observation of the cavitation on the propeller blades and in the tip vortices. Similarities between the instability and previously documented cavitation phenomena are noted. Measurements of the radiated pressure are then obtained, and the acoustic signature of the instability is identified. The magnitudes of the fluctuating pressures are very large, presumably capable of producing sever hull vibration on a ship.ududThe origins of the instability are explored through separate investigation of the cavitation dynamics and the response of the water tunnel to volumetric displacement in the working section. Experiments are conducted to quantify the dynamics of the propeller vacitation. Finally, a model is developed for the complete system, incorporating both the cavitation and facility dynamics. The model predicts active system dynamics (linked to the mass flow gain factor familiar in the context of pump dynamics) and therefore potentially unstable behavior for two distinct frequency ranges, one of which appears to be responsible for the instability.
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机译:这项研究详细介绍了一些实验,这些实验研究了之前未认识到的水洞中空化螺旋桨的喘振不稳定性。通过目视观察螺旋桨叶片和叶尖旋涡上的气蚀现象,可以最大程度地探索喘振不稳定性。注意到不稳定和先前记录的气蚀现象之间的相似性。然后获得辐射压力的测量值,并确定不稳定性的声学特征。脉动压力的幅度非常大,大概能够在船上产生严重的船体振动。 ud ud通过分别研究空化动力学和水洞对船体中容积位移的响应,探索了不稳定的根源。工作部分。进行实验以量化螺旋桨空位的动力学。最后,为整个系统开发了一个模型,其中包含了空化和设备动力学。该模型预测了主动系统动力学(与泵动力学中熟悉的质量流量增益因子相关),因此预测了两个不同频率范围的潜在不稳定行为,其中一个似乎是造成不稳定的原因。
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