Heat Transfer Augmentation for Impingement of Steady Air Jet under Exponential Heat Flux Boundary Condition.

The cooling rate under impingement of air jet finds massive application in electronic packaging, material processing industries and cooling of gas turbine. The conventional cooling of heat sinks was till date carried out using a fan and pump. Recently, the momentous impingement of air has been found to produced 1.5 times the cooling rate, as compared with conventional method, under same pumping power. Previously, attractive amount of Research is carried out in observing the cooling rate for constant heat flux boundary condition, and less are available for constant wall temperature. The present research provides an in-depth numerical investigation for such jet impinged heat sinks, with a heat flux boundary condition. The exponential variation of heat flux magnitude with radial distance (Away from impingement point), is observed to be a generic alternate of constant wall temperature boundary condition. The numerical computation for heat transfer of such exponentially powered heat flux sink is carried out using FLUENT (ANSYS 2023R1). An orthogonal 2-D mesh computational domain with a compactible SST and K-Omega turbulence model is simulated for various inlet velocity and nozzletarget spacing. The impingement of jet and local cooling of target surface is defined using a well know non-dimensional Reynolds and Nusselt number, respectively. The exponential power for non-uniformly heated sinks can be readily selected (0.1-1) to replicate the present non-uniform heating or constant wall temperature boundary condition. Non-uniform heating has gained lots of attention of heat transfer researcher across the globe. The computation results extracted for various impinging Reynolds number and nozzle-target spacing, were closely best fitted using regression and validated with referred previous literature results. Tight dependency of slope parameter, over Reynolds number and z/d is observed in local cooling rate. These dependencies are judged based on the power of exponents. The semi - empirical correlations are defined separately for and stagnation, transition, and wall jet regions, separately. Such correlation can plan the design of cooling system, under non-uniform heating conditions. [ABSTRACT FROM AUTHOR]

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