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

这个小型企业创新研究（SBIR）二期项目将进一步开发、验证和演示概率密度函数（PDF）空化模型，用于空化流动的多维稳态和瞬态模拟。通过使用PDF方法，第一阶段已经显示了包括湍流压力波动对相变速率影响的可行性和效益。虽然这种效应如假设的那样提高了解的精度和数值稳定性，但还需要进一步的研究来解释额外的物理现象，如气泡动力学和不可冷凝气体的存在。第二阶段的工作将集中在a)利用Rayleigh-Plesset方程和分压概念开发相变速率的适当函数，以及b)提高迭代求解过程的鲁棒性和效率。每个修改将通过比较数值解决方案与选定的基准数据进行系统评估，涵盖广泛的问题和流动条件。最终的模型将应用于航空航天、海军/海洋和汽车工业的三类问题。开发的空化模型将使使用泵、螺旋桨、孔板、水翼、静压轴承和机械心脏瓣膜等生物医学设备的工程设备的改进设计成为可能。空化模型将可用于商业项目。＊＊＊

*** 9801239 Singhal This Small Business Innovation Research(SBIR)Phase II project will further develop, validate and demonstrate the Probability Density Function (PDF) cavitation model for multi-dimensional steady and transient simulations of cavitating flows. Phase I has shown the feasibility and benefits of including the effects of turbulent pressure fluctuations on phase change rate, by using a PDF approach. While this effect has, as postulated, improved both the accuracy and numerical stability of solutions, further study is needed to account for additional physical phenomena such as bubble dynamics and presence of non-condensable gases. The Phase II effort will focus on a) developing appropriate functions for phase change rates by making use of the Rayleigh-Plesset equation and partial pressure concepts, and b) improving robustness and efficiency of the iterative solution process. Each modification will be systematically assessed by comparing numerical solutions against selected benchmark data, covering wide range of problems and flow conditions. The final model will be applied to three classes of problems from aerospace, naval/marine, and automotive industry 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 cooercial programs. ***