| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 91 === This study presents the numerical simulation of conjugate heat transfer of confined impinging jet, based on the experiment results of Chin-Yuan Li and Suresh V. Garimella (2000). The numerical simulation of steady, two dimensional, turbulent flow and heat transfer is adopted to test the accuracy of the theoretical model. The turbulent-governing equation are resolved by Control-Volume based finite-different method with power-low scheme, and the well-known turbulence model and its associate wall function to describe the turbulent structure. The SIMPLE algorithm is adopted to solve the pressure-velocity coupling.
The parameters studied include orifice diameter d=3~6mm, turbulent flow Reynolds number Re=4000~23000, and orifice to heat-source spacing H/d=2~4, and the working medium is water. The geometry of the free surface was determined iteratively. Velocity vector contour and turbulence levels are presented to describe the flow field in the recirculation pattern in the confined outflow, the development of the jet after exiting the nozzle and the development of the flow along the impingement surface. It is found that in addition to jet Reynolds number (Re), and orifice to heated surface spacing (H/d) have significant influence on temperature distribution and Nusselt number (Nu).Quantitatively， predictions underestimate the surface heat transfer above the heated surface by more than 100﹪. This underprediction is believed to be due to the underprediction of turbulent kinetic energy in that region.
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