Length to Diameter Ratio and Row Number Effects in Short Pin Fin Heat Transfer

Recently, several experiments concerning heat transfer from short pin fins have been conducted with the results indicating lower heat transfer from short pin fins than from longer pin fins found in tube banks and other similar configurations. Assessments of the effect of the number of pin rows and row geometry have also been made. It was felt that there was a need to determine the relative contribution of pin length to diameter ratio and pin row geometry on the heat transfer. Array-averaged heat transfer coefficients on pin and endwall surfaces were measured for two configurations of staggered arrays of short pin fins (length to diameter ratio of 4). One configuration contained eight streamwise rows of pins, while the other contained only four rows. Results showed that both the eight-row and the four-row configurations for an L_p/D of 4 exhibit higher heat transfer than in similar tests on shorter pin fins (L_p/D of 1/2 and 2). It was also found that for this L_p/D ratio the array-averaged heat transfer was slightly higher with eight rows of staggered pins than with only four rows.