约束空间内的空化射流演化与次生空化现象研究

Cavitating flow is a kind of two-phase jet, which is induced by high-speed submerged liquid under low local pressure and strong shear. Cavitating flow often appears at the throttle of high pressure drop and high flow rate in hydraulic systems (such as: throttle of hydraulic valve, damping mouth of plunger pump with flow plate), the cavitation cloud caused by phase change is its main characteristic. Bubbles move and collapse with the jet, which could induce the vibration, noise and other problems in fluid systems. Meanwhile micro-jets and pressure shocks induced by a large number of collapsing bubbles can lead to serious cavitation damage to surrounding walls. In practice, the cavitating flow often occurs in a restricted space. Under the constraint of adjacent boundaries, there is a complicated coupling relationship between the high-shear two-phase jet and the bubble’s collapse, which will cause secondary cavitation and so on. Even the harm caused by the secondary cavitation is greater than that of the first cavitation. The project focuses on three aspects: the coupling mechanism of cavitating flow in restricted space; the collapse of bubbles in restricted space; the mechanism of secondary cavitation induced by the collapse of bubble group. Based on in-depth understanding of the development of cavitating flow in restricted space, it will provide important theoretical and technical support for the application of cavitation and noise suppression in fluid systems and the utilization of cavitating flow.

空化射流是一种两相射流，是在淹没环境下由高速液体在局部低压和强剪切作用下诱发相变所产生的。空化射流多发生在流体系统中高压降、高流速的节流处（如：液压阀的节流口、柱塞泵配流盘的阻尼口），相变形成的云状空泡群是其主要标志。空泡群随射流运动并发生溃灭，会造成流体系统的振动、噪声等问题，而且大量空泡溃灭时形成的微射流和压力冲击，会对周围的固体壁面产生严重的气蚀破坏。实际中的空化射流往往发生在狭小的约束空间中，在邻近边界的约束作用下，高剪切两相射流与空泡群溃灭之间存在复杂的耦合关系，容易造成次生空化，其危害范围有时还大于一次空化影响。项目从三个方面开展研究：约束空间中空化射流的耦合作用机理；研究约束空间中空泡群的溃灭行为；研究空泡群溃灭诱发次生空化的机制。通过深入认识约束空间中空化射流发展规律，为空化射流现象的应用及流体系统中气蚀、噪声问题的抑制技术以及拓展空化射流的利用等提供重要的理论与技术

空化射流是一种两相射流，是在淹没环境下由高速液体在局部低压和强剪切作用下诱发相变所产生的。在液压阀的节流口、柱塞泵配流盘的阻尼口这种空化射流现象，会造成流体系统的振动、噪声等问题，而且大量空泡溃灭时形成的微射流和压力冲击，会对周围的固体壁面产生严重的气蚀破坏。项目完成了研究计划中的内容，取得的实际研究成果超出了预期。揭示了复杂约束条件下射流流场与空泡群发展的耦合作用规律，揭示了约束空间内空泡射流中空泡群溃灭行为模式和次生空化的发生机理，建立了约束空间内中空化射流演化的数值模型和次生空化预测模型，为抑制空化射流对流体系统的危害或拓宽空化射流应用范围提供了理论基础，同时在介电驱动的射流领域取得突破性进展。项目部分研究成果在国防和民用领域进行推广应用，取得了良好的社会与经济效应。在项目资助下以第一作者或者通讯作者在Nature Communications、Science Advances、Journal of Fluid Mechanics等期刊共发表SCI检索论文21篇，授权发明专利9项。项目研究成果获日内瓦发明金奖1项（“面向机器人的可定制的自愈型柔性泵”，2022），获中国机器人科学引领奖1项（“静音型柔性驱动与传动关键技术”，2022），获全国发明展览会发明创业奖项目奖金奖1项（“抗空蚀阀芯结构”，2021），获中国产学研合作创新成果奖一等奖1项(“高安全高性能场内作业车辆关键技术自主创新及产业化”，2021)，1篇论文获得IEEE Global Fluid Power Society PhD Symposium(IEEE GFPS) 最佳海报奖。

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