SBIR Phase I: Numerical Simulation of Cavitating Flows Using an Innovative Probability Density Function Model for Phase Change

这项SBIR项目将开发、验证和演示一个适用于空化流动的多维稳态和瞬变模拟的空化模型。缺乏对空化流动的预测能力是许多工程设备和生物医学设备发展的关键障碍。所提议的模型将采用蒸汽的传输方程，该方程充分考虑了蒸汽的产生/破坏以及速度和压力的湍流波动。相变率将取决于流体的热力学性质和流动特性，特别是湍流压力波动。压力波动将与流动的湍动能有关。将使用概率密度函数(PDF)方法从瞬时压力值计算局部时间平均相变率。在第一阶段的研究中，该模型将被纳入基于压力的有限体积CFD程序中，并应用于三个基准问题，例如孔口、文丘里和水翼。第二阶段的工作将包括几项修改(例如，气泡动力学和速度滑移)、广泛的验证和实际应用。开发的空化模型将使使用泵、螺旋桨、孔板、水翼和静压轴承以及机械心脏瓣膜等生物医学设备的工程设备的设计得到改进。空化模型将适用于各种(和代码。CFDRC将与其商业CFD代码CFD-ACE一起将其商业化。

This SBIR project will develop, validate and demonstrate a cavitation model suitable for multidimensional steady and transient simulations of cavitating flows. The lack of prediction capability for cavitating flows is a critical road block in the development of many engineering equipment and biomedical devices. The proposed model will employ a transport equation for vapor with full account of vapor generation/destruction and turbulent fluctuations in velocity and pressure. The phase change rates will depend upon thermodynamic properties of fluid, and the flow characteristics, particularly turbulent pressure fluctuations. The pressure fluctuations will be related to the turbulent kinetic energy of flow. A Probability Density Function (PDF) approach will be used to calculate the local time-mean phase change rates from instantaneous pressure values. In Phase I study, the model will be incorporated in a finite-volume, pressure-based, CFD code and applied to three benchmark problems e.g., orifice, venturi and hydrofoil. Phase II work will include several modifications (e.g., bubble dynamics and velocity slip), extensive validation and practical applications. The developed cavitation model will enable improved designs of engineering equipment using pumps, propellers, orifices, hydrofoils, and hydrostatic bearings and biomedical devices such as mechanical heart valves. The cavitation model will be useable with various (and codes. CFDRC will commercialize it in conjunction with its commercial CFD code, CFD-ACE.