Numerical Simulation Of Micro-jet Array Impingement Cooling

With the rapid development of modern micro-electronic technology and Micro-Electro-Mechanical System (MEMS), the power of their unit components is much higher while the volume is much smaller, so the problems of high heat flux management has to be solved as soon as possible. The conventional design methods and manufacturing technology cannot to meet today's demands. As a new cooling method, micro-jet array impingement cooling is being paid more attention. Jet impingement cooling is the best enhanced heat transfer method with very thin boundary layers of velocity and temperature. So it is importment to investigate the micro-jet array impingement cooling. The numerical simulation and optimized design to Leland's MJA cooling experiment device are investigated in the paper, and so is the application of MJA in turbine blade.RNGk-εturbulence model applied to the jet impinging flow, computing process and numerical method are analyzed in detail in the paper. Compared with the results of Leland's experiment, the numerical simulation proves that micro-jet array impingement cooling is much efficient in heat transfer, and at the same time, the similar "Hot Patch Phenomenon" is found in numerical simulation, and the target face temperature presents "low-high-low" from the center in radial. The jet impinging characters under the inlet tube are remarkable, and the local heat transfer coefficient is the highest in this place, while the jet vertical flow in the adjacent holes is very small, because of the low pressure area caused by the high speed horizontal flow in the plenum region and the re-circulation flow in the impingement region, and the "Hot Patch Phenomenon" is formed. The jet impinging velocity in the holes adjacent to the exit is higher, and the heat transfer effect is enhanced. But the jet in this place deflects because of the increasing cross-flow, and the jet impinging effect is weakened in a certain extent.The optimization design to MJA experiment device is investigated to find the best matching parameters case of geometry configuration. It shows that the heat transfer coefficient increases with the jet-hole diameter decreasing to the best diameter 0.200mm, the ratio of the jet-to-jet spacing to jet diameter decreasing, and the ratio of the impinging spacing to jet diameter decreasing. Increasing the inlet acreage can enhance heat transfer to the best case of 9mm diameter. The computing results of the convergent jet and the slot jet show that compared to circle jet, it cannot enhance heat transfer.The numerical simulation of the jet array impingement cooling applied to the turbine blade is also investigated in the paper. The result shows the jet array impingement cooling heat transfer capability enhances 3-5 times to the direct convection heat transfer. The best jet array collocation is smaller jet diameter and equidistant jet.