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

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.