[论文解读] Evaluation of a new cavitation erosion metric based on fluid-solid energy transfer in channel flow simulations

Gina M. Magnotti, Michele Battistoni+2 more|arXiv (Cornell University)|Oct 8, 2018

Cavitation Phenomena in Pumps参考文献 16被引用 6

一句话总结

本文提出了一种基于累积流固能量传递的新空化侵蚀度量方法，用于预测喷油器孔口的侵蚀潜力。通过在通道流模拟中采用欧拉混合模型，所提出的储能度量方法在准确捕捉材料侵蚀前的潜伏期方面优于最大局部压力，且经实验数据验证。

ABSTRACT

Although there have been extensive investigations characterizing cavitation phenomenon in fuel injectors, much is still unknown about the mechanisms driving cavitation-induced erosion, and how these complicated physics should be represented in a model. In lieu of computationally expensive fluid-structure interaction modeling, the Eulerian mixture modeling approach has been accepted as an efficient means of capturing cavitation phenomena. However, there remains a need to link the erosive potential of cloud collapse events with the subsequent material deformation and damage of neighboring surfaces. Even though several cavitation erosion indices have been proposed in the literature, no single metric has been identified as universally applicable across all injector-relevant conditions. The objective of this work is to identify parameters that characterize the erosive potential of cavitation cloud collapse mechanisms that are likely to occur within injector orifices. While a commonly employed cavitation erosion metric, namely the maximum local pressure, was found to provide indications of potential sites for pitting and material rupture from single impact events, no additional information could be determined regarding the material erosion process. To improve representation of the incubation period within the cavitation erosion process, a new metric was derived based on cumulative energy absorbed by the solid material from repeated hydrodynamic impacts. Through evaluation of predicted cavitation cloud collapse events in a channel geometry against available experimental data, the stored energy metric yielded insight into the erosive potential of recorded impact events. The stored energy metric provided a means to accurately predict the influence of flow conditions on the incubation period before material erosion. ...

研究动机与目标

• 解决在喷油器相关条件下缺乏通用适用的空化侵蚀度量方法的问题。
• 改进空化诱导侵蚀中潜伏阶段的建模，该阶段对于预测材料损伤起始至关重要。
• 开发一种计算效率更高的替代方法，以替代流固耦合模拟，捕捉侵蚀潜力。
• 通过基于能量的度量方法，将水动力冲击事件与材料变形及损伤联系起来。
• 通过实验数据验证新度量方法，评估其对侵蚀起始的预测能力。

提出的方法

• 采用欧拉混合模型模拟通道几何结构中的空化，避免昂贵的流固耦合模拟。
• 在每个时间步长计算空化云塌陷时传递至固体壁面的能量。
• 将多次冲击事件中的能量进行累积，定义累积储能度量。
• 以最大局部压力作为对比基准的侵蚀度量。
• 将储能度量与实验数据中关于侵蚀潜伏期的观测结果进行关联。
• 评估储能度量在不同流动条件下的预测性能。

实验结果

研究问题

• RQ1 累积能量传递度量是否能比最大局部压力更准确地预测空化侵蚀的潜伏期？
• RQ2 储能度量与喷油器类几何结构中侵蚀起始的实验观测结果相关性如何？
• RQ3 新度量在多大程度上能够捕捉流动条件对侵蚀潜力的影响？
• RQ4 储能度量是否提供了超越单次冲击压力的材料损伤机制的额外见解？
• RQ5 储能度量能否作为可靠且计算高效的全流固耦合模型替代方案？

主要发现

• 储能度量成功预测了流动条件对材料侵蚀前潜伏期的影响。
• 与仅指示潜在点蚀位置但无法揭示潜伏期的最高局部压力不同，储能度量捕捉到了侵蚀的渐进性特征。
• 与基于压力的指标相比，该度量在侵蚀起始的实验数据上表现出更优的相关性。
• 重复水动力冲击导致的累积能量吸收，比单一峰值压力更能提供侵蚀预测的有用信息。
• 储能度量能够识别因重复低强度冲击而具有高侵蚀潜力的区域。
• 该方法在保持侵蚀潜伏期预测精度的同时，提供了计算效率更高的流固耦合模拟替代方案。