Endwall Heat Transfer Measurements in a Staggered Pin Fin Array With an Adiabatic Pin

Abstract

Full surface endwall heat transfer distributions have been acquired in a staggered pin fin array with the use of an infrared camera. Values are presented at Reynolds numbers of 3000, 10,000 and 30,000 based on pin diameter and average velocity through adjacent pins. Average endwall Nusselt numbers agree closely with archival values at each Reynolds number. Locally averaged heat transfer levels show a substantial increase from the inlet through the first few rows and finally a nearly streamwise periodic condition in the second half of the eight row geometry. Increasing levels of heat transfer in the inlet region can be attributed to the leading edge vortex system, flow acceleration around pins, and the generation of turbulence. Distributions of turbulence intensity and turbulent scale are shown to help document the turbulent transport conditions through the array. Detailed endwall Nusselt number distributions are presented and compared at the three Reynolds numbers for the first four and last four rows. These detailed heat transfer distributions highlight the influence of the horseshoe vortex system in the entrance region and the wake generated turbulence throughout the pin fin array. Local velocity and turbulence distributions are presented together with local Stanton number and skin friction coefficient data to examine the aggressive nature of the turbulent mixing.

Extended Surface Heat Transfer Coefficients via Endwall Temperature Measurements

“…number cases that were run, compared to some of the previous work done by researchers. (Ames et al (2007), Metzger et al (1982), van Fossen(1982) From this figure, it becomes clear that the pin surface Nusselt numbers are higher than the endwall by 40% which is consistent with previous findings (Chyu(1999), VanFossen(1981, Al Dabagh and Andrews (1992)). It should be noted that pin average Nusselt number shown in the above figure is an average of the three pins' surface average Nusselt number that were obtained using the analytical methodology in the previous section.…”

“…Pin-fins could be of several different shapes but the most commonly preferred for experimental investigation are circular cylindrical ones due to the ease of manufacturing. (Ames et al, ( ,2007, Chyu et al (1999), VanFossen (1981), Metzger & Haley (1982), Lawson et al, (2011)).…”

“…In the 1990's, heat transfer characteristics of the pin surface were studied via a mass transfer analogy using a naphthalene sublimation technique (Goldstein et al, (1994), Chyu (1998Chyu ( ,1999, Sparrow (1984). In the late 90's and 2000's, non-intrusive techniques such as IR and TLC were used to acquire endwall and pin surface data (Camci et al 2005, Ames et al, (2007), Lawson et al (2011), Kirsch et al, (2013)).…”

Time Resolved Stereo-PIV Measurements of the Horseshoe Vortex System in a Low Aspect Ratio Pin-Fin Array

“…Examining the location of the primary HSV's spiral node, it is noted that the change in the X/D location is greatest from row 1 to row 3, while the change from row 3 to row 5 is minimal. For the downstream rows, the relatively invariant behavior of the time-average HSV is consistent with the evolution of a fullydeveloped state in the endwall heat transfer in an array found by other researchers 15,16 .…”

Detailed Numerical Study of Flow and Vortex Dynamics in Staggered Pin-Fin Arrays Within a Channel

“…There have been a wide range of studies on the time mean and instantaneous flow, and on the mechanisms that give rise to an increase in the end-wall heat transfer of a body end-wall junction. Ames et al [3] performed a detailed study of the end-wall heat transfer distributions in a staggered pin-fin array using an infrared camera at Reynolds numbers of 3000, 10000, 30000. Their detailed heat transfer distributions highlighted the influence of the horseshoe vortex system in the entrance region on the end-wall heat transfer and the wake generated turbulence throughout the pin-fin array.…”