Heat transfer and pressure drop in two-pass rib-roughened square channels with bleed from sharp bend

Abstract

Abstract This experimental study investigates the heat transfer, pressure drop and thermal performance factor for the two-pass rib-roughened channel with and without bleed from its sharp bend. Detailed distributions of Nusselt number ( Nu ) and dimensionless wall temperature ( η w ) over the rib floor with coolant extractions from three different locations on the outer wall of the sharp bend at 0%, 10%, 20%, 30% of the total airflow rate are comparatively analyzed with 5000 Re Nu and pressure drop coefficients ( f ) for the entire two-pass ribbed channel with and without bleed are generated with thermal performance factors ( η ) compared. The bleed from the outer wall of the sharp bend provides considerable heat transfer enhancements (HTE) over the turning section with substantial reductions in pressure drops; while undermines both Nu and η w performances in the outlet-leg from the no-bleed conditions. Thermal performance factors for the bleed channel at each Re and bleed condition tested are improved from the no-bleed references. Empirical Nu and f correlations are derived for the present two-pass rib-roughened square channel with and without bleed.