Dynamics of cavitation bubbles in compressible two-phase fluid flow

该项目的主要目标是更好地了解靠近顺应壁的单个空化气泡坍塌造成的破坏机制。为此，可压缩两相流的方程(35)将与模拟固体的弹塑性行为的偏微分方程组耦合。为了模拟相变效应，并考虑气泡崩塌过程中形成的无法分辨的微小气泡，将现有的流动求解器扩展为对两相混合物的均匀描述。在实验部分，将考虑两个问题：(I)压力对气泡动力学的影响；(Ii)流固耦合作用。在第一部分中，我们将用已有的方法研究加热液体中的气泡和由声场驱动的气泡。此外，还应使用激光诱导荧光来显示液体中的温度变化。在第二部分中，提出了一种基于短激光脉冲干涉测量壁面随时间变化的压力载荷的新方法，并将其推广到以透明固体为边界的应力状态的可视化。它将与已建立的实验方法相结合，获得关于壁面附近气泡坍塌的全面实验数据，并将实验结果作为数据库，与数值计算进行比较。

The primary objective of the project is to provide a better understanding of the damaging mechanism caused by the collapse of a single cavitation bubble near to a compliant wall. For this purpose, the equations for compressible two-phase flows (35) will be coupled with a system of partial differential equations modeling elastic-plastic behavior of the solid. In order to model phase transition effects and to take into account tiny bubbles forming during the bubble collapse that can not be resolved, the existing flow solver will be extended by a homogeneous description for two-phase mixtures. The experience of the French partners concerning homogenized models such as (40) will be used for the selection as well as for the implementation of such an ansatz.In the experimental part two problems will be considered; (i) pressure effects on bubble dynamics, and (ii) fluid-structure interaction. In part (i), bubbles in a heated liquid and bubbles driven by a sound field will be investigated by established methods. Also, laserinduced fluorescence shall be employed to visualize temperature variations in the liquid. In part (ii) a novel method to measure the time-dependent pressure load on the wall based on interferometry with short laser pulses shall be developed and furthermore extended to visualize stress states in a transparent solid as the boundary. It will be combined with the established experimental methods to obtain comprehensive experimental data on the bubble collapse near a wall.The experimental results will be used as a data base for comparison with numerical calculations.