Heat Transfer Enhancement Study For Optimizing The Geometric Parameters Of Turbulator In A Rectangular Channel With Inverse Problem

The inverse heat transfer problem is mainly concerned with the heat conduction in the early stage,while the research pays attention to the heat transfer enhancement with inverse convection transfer problem.Compared with the inverse heat conduction problem,the inverse convection transfer problem is more complex,which mainly shows the nonlinear and complexity of the flow.Moreover the solution of the problem with ill-posed is more difficult.The inverse problem of geometric parameter of turbulator could be solved by the following steps: firstly,an initial value of the physical quantity is given by which the corresponding temperature field could be attained;secondly,structure the function with the calculated temperature and the measured temperature;finally,analysis of the function,if the error is within the allowable range,the result can be as the final result,if outside the allowable range,the given value should be corrected and repeats the process until the results fulfil the requirements.The research mainly studies the inverse problem of optimization shape and positon of the turbulator in rectangular channel,by use of the conjugate gradient method(CGM)with the sensitivity equation and the adjoint equation,the problem can be solved,then connecting the user defined function(UDF)with the Fluent software by using C programming language to complete the numerical simulation.As for the inversion of the optimization shape,the research has studied the semicircle turbulator,the pentagonal turbulator,the hexagonal turbulator and the triangle turbulator.The results show that the Nusselt number of flow filed after optimization increase by7.1%~41.4% than the turbulator before optimization,while the friction factor ?decrease by 2.2%~38.1%,and the comprehensive heat transfer effect of the optimized turbulator is better than the turbulator before optimization.The position distance of the turbulations with two rectangular elements and three rectangular elements is also optimized.The optimized distance is 101 mm with the two elements,while the optimized distance of three elements is 80.5mm.The research also reflects that the heat transfer effect of the optimized turbulator is better than the turbulator before optimization with the Nusselt number of flow filed after optimization increase by5.2%~6.1% than the turbulator before optimization,while the friction factor ?decrease by 4.9%~5.5%.