Heat transfer enhancement in a converging passage with discrete ribs

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Abstract

An experimental investigation has been carried out to measure detailed distributions of internal heat transfer coefficients in a model of a blade mid-chord convergent cooling passage. The test is performed with a staggered array of 45° discrete ribs, and also with a combination of the discrete ribs with grooves on two opposite walls of the passage for a range of engine representative Reynolds numbers from 1.0 x 104 to 5.0 × 104. The data is presented as contours of enhancement factors (defined as heat transfer coefficient divided by heat transfer coefficient in the absence of the discrete ribs). The data of stream-wise Nusselt number are correlated. The area-averaged enhancement factors of 3 to 4 and 2.5 to 3.2 are obtained, respectively, for both promoter configurations studied. The flow visualization has been performed. The complex flow patterns observed successfully provide a mechanismic explanation for the contours of enhancement factors. The friction factors are also measured in the passages with the discrete ribs and combination of the discrete ribs with grooves.

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