Fundamental Studies of the Thermoacoustic Effect: Interactions of Acoustic Waves with Viscous Fluids

Farouk0853959这是一项声学驱动的粘性流动的实验和数值研究，在谐振器中嵌入了一层紧密间隔的薄板(堆叠)或紧密排列的平纹金属筛网(再生器)。对于此类装置中可压缩、粘性和导电流体中声激流动的非线性和随时间变化的行为，将开发精确和高保真的计算模型。这些模型将通过将在我们实验室进行的实验进行验证。应对声功率输入对系统的影响进行优化研究。将进行专门设计的实验，以测量谐振器中随时间变化的压力、温度和速度场(有和没有嵌入堆栈)，由具有不同强度和频率的声波的压缩驱动器驱动。这些测量将提供关于压力场和速度场的基本数据。流动可视化研究将确定稳定流动的可能形成及其作为声功率输入函数的行为。谐振器形状对谐振器中压力幅度的影响将被确定为压缩驱动器的操作参数的函数。数值求解可压缩流场的Navier-Stokes方程，得到这些典型问题的速度场、压力场和温度场。这项研究将提高目前在分析各种具有技术重要性的声学驱动问题方面的复杂程度，特别是与热声制冷机设计改进有关的问题。提案中涉及的问题的跨学科性质将引起广大科学家和工程师的兴趣。PI在计算声学和实验方法领域拥有丰富的过去经验。PI和他的学生将与来自政府实验室(华盛顿州NRL和科罗拉多州博尔德的NIST)和行业(CFIC Inc.，特洛伊，纽约州)的顶尖科学家合作。研究生和本科生的培训都纳入了该计划，并将努力从代表性不足的群体中招收研究生。所开发的软件可作为设计商业规模装置和优化操作条件以达到预期目标的工具。

Farouk0853959This is an experimental and numerical study of acoustically-driven viscous flows in resonators embedded with either a layer of closely-spaced thin plates (a stack) or with close-packed plain-weave metal screens (a regenerator). Accurate and high-fidelity computational models will be developed for nonlinear and time-dependent behavior of acoustically-excited flows in compressible, viscous and conductive fluids in such devices. The models will be validated with experiments to be carried out in our laboratories. Optimization studies of the effects of acoustic power input to the systems shall be conducted. Specially designed experiments will be conducted for measuring the time-dependent pressure, temperature and velocity fields in the resonators (with and without embedded stacks), driven by compression drivers with acoustic waves of varying intensities and frequencies. The measurements will provide fundamental data on the pressure, and velocity fields. Flow visualization studies will determine the possible formation of steady streaming flows and their behavior as a function of acoustic power input. The effects of the resonator shapes on the pressure amplitude in the resonators will be determined as functions of the operating parameters of the compression driver. The Navier-Stokes equations for a compressible flowfield will be solved numerically to obtain the velocity, pressure and temperature fields in these representative problems. This research will enhance the current level of sophistication in analyzing a wide variety of acoustically-driven problems of technological importance, specifically related to the design improvement of thermoacoustic refrigerators. The interdisciplinary nature of the problems addressed in the proposal will interest a broad section of scientists and engineers. The PI has significant past experience in the areas of computational acoustics and experimental methods. The PI and his students will collaborate with leading scientists from government laboratories (NRL, Washington, DC and NIST, Boulder, CO) and industry (CFIC Inc., Troy, NY). The training of both graduate and undergraduate students is integrated into the program and efforts will be made to recruit graduate students from the underrepresented groups. The software developed can be used as a tool for designing commercial scale devices and optimizing the operating conditions to desired goals.