EFFECT OF REYNOLDS NUMBER, HOLE PATTERNS AND HOLE INCLINATION ON COOLING PERFORMANCE OF AN IMPINGING JET ARRAY, PART Ⅰ: CONVECTIVE HEAT TRANSFER RESULTS AND OPTIMIZATION

摘要

This study comprehensively illustrates the effect of Reynolds number, hole spacing, jet-to-target distance and hole inclination on the convective heat transfer performance of an impinging jet array. Highly resolved heat transfer coefficient distributions on the target plate are obtained utilizing transient liquid crystal over a range of Reynolds numbers varying between 5,000 and 25,000. Effect of streamwise and spanwise jet-to-jet spacing (X/D, Y/D: 4-8) and jet-to-target plate distance (Z/D: 0.75-3) are employed composing a test matrix of 36 different geometries. Additionally, the effect of hole inclination (0: 0°-40°) on the heat transfer coefficient is investigated. Optical hole spacing arrangements and impingement distance are pointed out to maximize the area-averaged Nusselt number and minimize the amount of cooling air. Also included is a new correlation, based on that of Florschuetz et al., to predict row-averaged Nusselt number. The new correlation is capable to cover low Z/D-0.75 and presents better prediction of row-averaged Nusselt number, which proves to be an effective impingement design tool.