HEAT TRANSFER IN ROTATING, TRAILING EDGE, CONVERGING CHANNELS WITH FULL AND PARTIAL HEIGHT STRIP-FINS

A wide variety of pin-fins have been used to enhance heat transfer in internal cooling channels. However, due to their large blockage in the flow direction, they result in an undesirable high pressure drop. This experimental study aims to reduce pressure drop while increasing the heat transfer surface area by utilizing strip-fins in converging internal cooling channels. The channel is designed with a trapezoidal cross-section, converges in both transverse and longitudinal directions, and is also skewed β=120° with respect to the direction of rotation in order to model a trailing edge cooling channel. Only the leading and trailing surfaces of the channel are instrumented, and each surface is divided into eighteen isolated copper plates to measure the regionally averaged heat transfer coefficient. Utilizing pressure taps at the inlet and outlet of the channel, the pressure drop is obtained. Three staggered arrays of strip-fins are investigated: one full height configuration and two partial fin height arrangements (Sz=2mm and 1mm). In all cases, the strip fins are 2mm wide (W) and 10mm long (Lf ) in the flow direction. The fins are spaced such that Sy/Lf = 1 in the streamwise direction. However, due to the convergence, the spanwise spacing, Sx/W, was varied from 8 to 6.2 along the channel. The rotation number of the channel varied up to 0.21 by ranging the inlet Reynolds number from 10,000 to 40,000 and rotation speed from 0 to 300rpm. It is found that

Effect of Pin-fins On Jet Impingement Heat Transfer Over a Rotating Disk

Many engineering applications consist of rotating components which experience high heat load. For instance, applications like the gas turbine engine consist of rotating disks and the study of heat transfer over such rotating surfaces is of particular interest. In the case of gas turbines, the disk also needs to be protected from the ingress of hot turbine gases caused by the low pressure region created due to the radially outward pumping of fluid close to the rotating surface. Present experimental study investigates the effects of introducing pin-fins on heat transfer over surface of a rotating gas turbine disk. Experiments were conducted at rotational Reynolds numbers (ReR) of 5487 - 12803 and jet Reynolds numbers (Re) of 5000 - 18000, nozzle to target spacing (z/d = 2 - 6), impingement eccentricities (e = 0 -0.67), angles of impingement (0°-20°), and the pin fin height (Hf = 3.05mm - 19.05mm). Steady state temperature measurements were taken using thermocouples embedded in the disk, and area average Nusselt number (Nu) was calculated. The results have been compared with those for a smooth aluminum disk. Nu was significantly enhanced by the presence of pin-fins. The enhancement was higher for lower Re and the maximum enhancement was found to be 3.9 times that of a smooth disk for Re = 5000. Qualitative visualization of flow field has been performed for smooth and the pin-fin case using the commercial simulation package Ansys Fluent to further understand the flow features that result in the enhancement.