Liquid Jet Atomization at Supercritical Pressure

新技术，如先进的燃气涡轮发动机和其他先进的发动机，涉及在更高的压力下喷射液体，其压力可以达到大气压的数百倍。在液体流破裂（雾化）过程中，需要新的预测能力来描述小液滴从表面破裂的大小、形状和位置。该项目寻求对物理机制的解释，以及对破碎过程和由此产生的喷雾的控制。研究生和本科生将进行该项目。专题发展将允许加强流体动力学主题的各种研究生课程和未来的第三版教科书。通过现有的UCI少数民族支持计划，首席研究员和他的研究生可以支持项目工作，并就感兴趣的主题进行公开演讲。该项目的目标是提供一个令人满意的超临界压力下液体流破裂的计算分析，并根据实际气体状态方程和相平衡定律确定重要的混合长度尺度。溶解在液体中的气体的数量和新的，实质上更高的临界压力将被确定，确定何时存在两个不同的相。液体和气体都是可压缩的，在高压下密度是可变的。分析将给出相关特征时间和尺度的预测（例如，扩散时间、频率、最不稳定波长和增长率）。感焓，作为压强和温度的函数；传输特性;表面张力;蒸发能也就确定了。三维Navier-Stokes解决方案，通过流体体积或水平集方法进行界面跟踪，然后是？涡度动力学分析将解释在破裂级联中出现的较小结构的序列。这种方法将描述和解释射流破裂是在两相还是超临界气体状态下的行为；在这两种情况下，较小的结构出现。原子化，在雷诺数和韦伯数的实际利益，将被分析和适当地视为过渡湍流。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

New technologies such as advanced gas-turbine engines and other advanced engines involve injection of liquids at higher pressures, which can reach levels that are hundreds of times greater than atmospheric pressure. There is a demand for new predictive capabilities to describe the sizes, shapes, and locations of small droplets breaking from the surface during the liquid-stream breakup (atomization) process. This project seeks an explanation of the physical mechanisms and to control of the breakup process and of the resulting spray. Graduate and undergraduate students will conduct the project. Topical development will allow strengthening of various graduate courses in the topic of fluid dynamics and a future third edition of a textbook. Through existing UCI minority support programs, the Principal Investigator and his graduate students can support project work and give public talks on topics of interest. The project goals are to provide a satisfactory computational analysis of the liquid stream breakup at a supercritical pressure and to determine the important mixing length scales with real-gas equations of state and phase-equilibrium laws. The amount of gases dissolving into the liquid and the new, substantially higher critical pressure will be determined, establishing when two distinct phases exist. Both liquids and gases will be compressible and have variable density at high pressures. The analysis will give predictions of relevant characteristic time and scales (e.g., diffusion times, frequencies, most unstable wavelengths, and growth rates). The sensible enthalpy, as a function of pressure and temperature; transport properties; surface tension; and energies of vaporization will be determined. Three-dimensional Navier-Stokes solutions, with interface tracking through volume-of-fluid or level-set methods, followed by ?2 vorticity-dynamics analysis will explain the sequence of smaller structures that appear in the breakup cascade. This approach will describe and explain the behavior whether the jet breakup is in a two-phase or supercritical gaseous state; in either case, the smaller structures appear. Atomization, at the Reynolds and Weber numbers of practical interest, will be analyzed and properly viewed as transitional turbulence.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.