Experimental Investigation of Innovative Internal Trailing Edge Cooling Configurations with Pentagonal Arrangement and Elliptic Pin Fin

Abstract

This paper describes a heat transfer experimental study of four different internal trailing edge cooling configurations based on pin fin schemes. The aim of the study is the comparison between innovative configurations and standard ones. So, a circular pin fin configuration with an innovative pentagonal scheme is compared to a standard staggered scheme, while two elliptic pin fin configurations are compared to each other turning the ellipse from the streamwise to the spanwise direction. For each configuration, heat transfer and pressure loss measurements were made keeping the Mach number fixed at 0.3 and varying the Reynolds number from 9000 to 27000. In order to investigate the overall behavior of both endwall and pedestals, heat transfer measurements are performed using a combined transient technique. Over the endwall surface, the classic transient technique with thermochromic liquid crystals allows the measurement of a detailed heat transfer coefficient (HTC) map. Pin fins are made of high thermal conductivity material, and an inverse data reduction method based on a finite element code allows to evaluate the mean HTC of each pin fin. Results show that the pentagonal arrangement generates a nonuniform HTC distribution over the endwall surface, while, in terms of average values, it is equivalent to the staggered configuration. On the contrary, the HTC map of the two elliptic configurations is similar, but the spanwise arrangement generates higher heat transfer coefficients and pressure losses.

Experimental Investigation of Turning Flow Effects on Innovative Trailing Edge Cooling Configurations With Elliptic Pin Fins

“…By comparison of G2.1 with G2.2 for both axial and axial-radial configurations, the spanwise oriented pin fins always generate a higher HTC value over the whole investigated surfaces L1 and L2, due to higher turbulence level induced by their disposition. For the axial configuration, see Fig. 2, previous results [Facchini et al, 2008], by comparison with the axial-radial geometries, show lower values of HTC over L1 and L2 surfaces and the HTC distribution is uniform along the spanwise direction. On the contrary with the axial redirection of inlet radial flow, the HTC distribution is dependent on massflow rate percentage flowing through the tip section and is independent from pin disposition.…”

DES study of blade trailing edge cutback cooling performance with various lip thicknesses

“…[15], Tarchi et al [39] and Effendy et al [40], who studied similar subjects through the staggered arrays of pin-fin cooling. For example, the peak heat transfer occurred in the last row of the pin-fin located in a wedge duct, and the increase of the heat transfer coefficient is stronger within a contraction channel than that in a parallel duct.…”

Heat Transfer Measurements of Oblong Pins

“…The turbulence generated by the elliptical pins was greatly reduced in comparison to the cylindrical pins and, as such, the heat transfer performance from the array was also reduced. Tarchi et al [4] also studied elliptical pins, but oriented them with their major axis perpendicular to the flow. While these elliptical pins exhibited higher heat transfer than the array of cylindrical pins, they generated much higher pressure drop.…”

“…The addition of pin fins into a flow increases the heat transfer by adding area over which heat transfer can take place and by inducing vortical structures at the pin's base. Conventional pin fins are cylindrical in shape, though other shapes have been studied as well [1][2][3][4][5][6]. Generally, previous studies have examined the combined effects on heat transfer from both pin and endwall surfaces.…”