Effects of Jet to Wall Spacings on Heat Transfer Characteristics And Flow Fields of Turbulently Impinging Nozzled Jets on Hot Silicon

Abstract

The heat transfer distributions of axisymmetric confined turbulent jets impinging on a high power density silicon issued from dual primary circular nozzles and accelerated under tapered nozzles has been extensively investigated in this research to discretize the flow field characteristics under submerged conditions. Sixteen RANS CFD simulations with processed chilled water as impingement fluid by varying Reynolds number 8000 ≤ Re ≤ 20000 (based on the main inlet nozzle jet diameter and bulk velocity) and the nozzle jet orifice plate to the die standoff distance 4 ≤ z/d ≤ 16 (up to sixteen nozzle jet diameters distance) is researched along with four distinct LES cases at a Reynolds of 20000. The nozzle plate has 20 tapered nozzles used to distribute and accelerate the flow under the dual circular nozzles where the flow is initially issued from. The CFD RANS simulations for dual circular primary nozzles are compared to the CFD cases of the single primary nozzle cases published previously. An overall heat transfer coefficient to the order of 179,000 W/m2°K has been observed on the surface of the silicon when the flow is issued from a single primary nozzle and an overall heat transfer coefficient to the order of 333,000 W/m2°K has been observed when the jets are issued from dual primary nozzles for identical jet-to-wall distance. Large Eddy Simulations are used to predict the flow-field turbulent characteristics of dual circular jets impinging directly on the silicon wall for four significant cases with varying (0.5 ≤ z/d ≤ 2) distances at a Reynolds (Re) of 20,000 issued from main nozzle and the results are compared to the four LES cases of single nozzle direct impingement that is published previously. Results from these simulations reveal intricate features of flow field distributions including primary and secondary vortices, entrainment effects on the bare die hot silicon and guides the design of the impingement setup in terms of nozzle configuration, maximum power and power density dissipation criteria that can be met for a given nozzle configuration and impingement setup for hotspot mitigation.