Cavitation in a hydraulic system: The influence of the distributor geometry on cavitation inception and study of the interactions between bubbles
Cavitation in a hydraulic system: The influence of the distributor geometry on cavitation inception and study of the interactions between bubbles
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DOI：
10.1177/1468087415590742
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发表时间：
2016-06
影响因子：
2.5
通讯作者：
M. Adama Maiga;O. Coutier-Delgosha;D. Buisine
中科院分区：
文献类型：
--
作者：
M. Adama Maiga;O. Coutier-Delgosha;D. Buisine
液压系统经常会出现压降，这可能导致气穴现象。在诸如动力转向、提升负载或心室辅助装置等系统中，通常会使用分配器。由于间隙和重叠，分配器中可能会出现显著的压力损失，这可能导致气穴现象的产生。然而，这个问题几乎从未被纳入分配器的设计概念中。在这项研究中，修正的瑞利 - 普莱塞特方程的多气泡模型被应用于一个油压液压系统的旋转分配器。研究了重叠长度、间隙、转速以及分配器入口压力对气穴现象的影响，特别是气穴产生初期气泡之间的相互作用。研究强调了重叠的一个临界长度；超过这个值，重叠长度会显著影响气穴持续时间和空隙率。更普遍地说，一些几何细节对气穴现象有很大影响。考虑到气穴现象的发生，对发动机部件中的这些细节进行优化将是减少其影响的一个合适解决方案。研究还表明，即使环境压力低于其理论临界压力，小气泡的生长也可能会因与附近较大气泡的相互作用而延迟。它们最终在气穴发展的最初时刻破裂。然而，如果环境压力进一步下降，即超过一个临界压力，一个小气泡会获得足够的惯性能量来克服这些相互作用现象从而生长。小气泡的生长增加了气泡之间的相互作用，并减缓了附近较大气泡的生长。结果表明，气泡之间的相互作用在气穴发展的最初时刻至关重要，这表明在临界压力的定义中应该考虑到它们。
Hydraulic systems are often subjected to pressure drops, which may lead to cavitation. In systems such as power steering, hoist loads, or ventricular assist devices, distributors are generally used. Significant pressure losses can happen in a distributor due to gap and overlap, which may lead to cavitation development. However, this issue is almost never included in the conception of the distributors. In this study, the multibubble model of the modified Rayleigh–Plesset equation is applied to the rotary distributor of an oil hydraulic system. The influence of the overlap length, the gap, the rotation speed, and distributor inlet pressure on the cavitation and particularly the interactions between bubbles at cavitation inception are studied. The study highlights a critical length of the overlap; over this value, the overlap length influences significantly the cavitation duration and the void fraction. More generally, some geometrical details have a strong influence on cavitation. Optimization of these details in engine parts, taking account the occurrence of cavitation, would be an appropriate solution to reduce its effects. The study also demonstrates that the growth of small bubbles may be delayed by the interactions with the nearby bigger ones, even if the ambient pressure is lower than their theoretical critical pressure. They eventually collapse at the first moments of the cavitation development. However, if the ambient pressure drops further, that is, beyond a critical pressure, a small bubble gains enough inertial energy to overcome these interaction phenomena and thus to grow. The growth of small bubbles increases the interactions between bubbles and slows down the growth of nearby bigger ones. The results show that the interactions between bubbles are of primary importance in the first moments of the cavitation development, which suggests that they should be taken into account in the definition of the critical pressure.