Reconstruction of Multi-Dimensional Convective Heat TransferCoefficient Distributions Using an Inverse BEM-Based Problem Approach

摘要提案编号：CTS 9978558主要研究者：A.卡萨布和J. Kapat该奖项是为了支持一个理论和实验计划，以开发、实施和验证一个基于三维边界元法（BEM）的逆算法，用于使用瞬态或稳态表面温度测量值作为输入来准确检索三维传热系数分布。热系统和部件暴露于对流传热的设计和分析依赖于传热系数（h），通常通过实验确定。传统上，精确的表面温度测量已被用作输入到一维模型的半无限介质受到脉冲对流边界条件，以提取值的h。这种方法的缺点在传热界早已被认识到：（1）在许多实际应用中，热传递实际上是二维或三维的，（2）在实验室中难以实现脉冲边界条件，（3）已经进行了瞬态实验以评估对于H不变的稳态过程的H，因此该方法难以用于H作为时间的函数而变化的时间依赖性过程。所提出的方法只需要一个边界离散化，并包括一个新的正则化技术，以提供鲁棒性的输入误差，并尽量减少由于这三个影响的错误。请拨资源的一部分将用于建立基准实验，以验证本文提出的方法。在实验中，热致变色液晶（TLC）热成像技术将被用来获得表面温度分布在一个后向台阶模型的各种纵横比。一旦验证所提出的方法可以潜在地取代传统的瞬态方法，依赖于一维model.This补助金将影响本科教育在中央佛罗里达大学（UCF）的学生在顶点高级设计课程的实验方面的工作，以及研究生教育的研究生热传递课程，如热传导和中间传热引入逆方法。此外，成功完成本提案下的工作将导致在UCF能源系统实验室建立经过验证的TLC热成像实验设施，进一步发展热系统基础设施，并补充UCF现有的热交换器传热研究工作。

ABSTRACTProposal Number: CTS 9978558Principal Investigator: A. Kassab and J. KapatThis award is to support a theoretical and experimental program to develop, implement, and verify a 3-D Boundary Element Method (BEM)-based inverse algorithm for accurate retrieval of 3-D heat transfer coefficient distributions using either transient or steady state surface temperature measurements as input. The design and analysis of thermal systems and components exposed to convective heat transfer relies on heat transfer coefficients (h) which are usually determined from experiments. Traditionally, precise surface temperature measurements have been used as input to a one-dimensional model for a semi-infinite medium subjected to an impulsive convective boundary condition to extract the values of h. The shortcomings of this approach have long been recognized in the heat transfer community: (1) in many practical applications the heat transfer is actually two- or three-dimensional, (2) impulsive boundary conditions are difficult to achieve in the laboratory, (3) transient experiments have been performed to evaluate h for steady state processes for which h is invariant, and thus this method is difficult to use in a time-dependent process where h varies as a function of time. The proposed method requires only a boundary discretization and includes a new regularization technique to provide robustness to input errors and minimizes the errors due to these three effects. A portion of the requested resources will be used to set up a benchmark experiment to validate the method proposed herein. In the experiment, a Thermochromic Liquid Crystal (TLC) thermography technique will be used to obtain the surface temperature distribution over a backward facing step model of various aspect ratios. Once validated the proposed method can potentially replace conventional transient methods that rely on the one-dimensional model.This grant will impact undergraduate education at the University of Central Florida (UCF) by enlisting students in the capstone Senior Design course into experimental aspects of the work as well as graduate education by introducing inverse methods in graduate heat transfer courses, such as heat conduction and intermediate heat transfer. Additionally, successful completion of the work under this proposal will lead to establishment of proven experimental facilities in TLC thermography at the UCF Energy Systems Laboratory, further the development of the thermal systems infrastructure, and complement existing research efforts in turbomachinery heat transfer at UCF.