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

使用基于逆 BEM 的问题方法重建多维对流换热系数分布

• 批准号: 9978558
• 负责人: Alain Kassab
• 金额: $ 11.06万
• 依托单位: The University of Central Florida Board of Trustees
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-15 至 2002-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9978558&HistoricalAwards=false
• 关键词: Reconstruction; Multi; Dimensional; Convective; Heat

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.

项目负责人：a . Kassab和J. kapat该奖项旨在支持一个理论和实验项目，开发、实现和验证基于三维边界元法（BEM）的逆算法，该算法使用瞬态或稳态表面温度测量作为输入，精确检索三维传热系数分布。对热系统和部件进行对流传热的设计和分析依赖于通常由实验确定的传热系数(h)。传统上，精确的表面温度测量已被用作半无限介质的一维模型的输入，并受到脉冲对流边界条件来提取h的值。这种方法的缺点早已在传热界被认识到：(1)在许多实际应用中，传热实际上是二维或三维的；(2)脉冲边界条件很难在实验室中实现；(3)对于h不变的稳态过程，已经进行了瞬态实验来评估h，因此这种方法很难用于h随时间变化的时间相关过程。该方法只需要边界离散化，并包含一种新的正则化技术，以提供对输入误差的鲁棒性，并将这三种影响引起的误差最小化。请求资源的一部分将用于建立基准实验来验证本文提出的方法。在实验中，将使用热致变色液晶（TLC）热成像技术来获得不同纵横比的后向台阶模型上的表面温度分布。一旦验证，所提出的方法有可能取代依赖一维模型的传统瞬态方法。这项资助将影响中佛罗里达大学（UCF）的本科教育，通过在高级设计课程的顶点课程中招募学生参与工作的实验方面，并通过在研究生传热课程中引入逆向方法，如热传导和中间传热，影响研究生教育。此外，该提案下的工作的成功完成将导致在UCF能源系统实验室建立TLC热成像实验设施，进一步发展热系统基础设施，并补充UCF在涡轮机械传热方面的现有研究工作。