Influences of micro pin-fin on jet array impingement heat transfer: Effects of jet to target distance, micro pin-fin shapes, height, and Reynolds Number

摘要

In the current research of impingement on pin-fin wall, researchers mainly pay attention to macro pin-fin due to the limitation of manufacture. With the development of additive manufacturing, it is possible to manufacture the micro pin-fin. Hence, impingement on micro pin-fin wall becomes a new cooling technique that has attracted the researchers' attention. With experimental methodology , the investigation utilizes different jet to target distance, micro pin-fin shapes, height and Reynolds number for impingement cooling augmentation to illustrate the effects on jet array impingement heat transfer. The area-averaged target surface heat transfer coefficient distributions are measured with lumped capacitance method. The impingement hole diameter(D) is 4 millimeter, with streamwise and spanwise jet-to-jet spacing 4D. Considered are effects of jet to target plate distance(Z/D:0.75,3), micro pin-fin shapes(rectangle, pentahedron), and pin-fin height(h/D:0.05,0.2,0.4). In total, ten different test surfaces are considered(smooth surface included). Tests are performed at impingement jet Reynolds numbers from 2000 to 10000 for configuration of Z/D=0.75, from 5000-20000 for configuration of Z/D=3. The experimental results illustrate that there are significant heat transfer augmentation(30%-120% more than baseline flow condition) with micro pin-fin on impingement target surface, and discharge coefficient is almost the same.