Heat Transfer and Pressure Loss in Rectangular One Side Ribbed Channels With Different Aspect Ratios

Abstract

An investigation was conducted to assess the thermal performance of Wshaped, 2Wshaped and 4Wshaped ribs in a rectangular channel. The aspect ratios (W/H) were 2:1, 4:1, and 8:1. The ribs were located on one channel wall. The rib height (e) was kept constant with a rib heighttohydraulic diameter ratio (e/Dh) of 0.02, 0.03, and 0.06. The rib pitchtoheight ratio (P/e) was 10. The Reynolds numbers investigated (Re > 90 000) are typical for combustor liner cooling configurations of gas turbines. Local heat transfer coefficients using the transient thermochromic liquid crystal technique and overall pressure losses were measured. The rib configurations were investigated numerically to visualize the flow pattern in the channel and to support the understanding of the experimental data. The results show that the highest heat transfer enhancement is obtained by rib configurations with a rib sectiontochannel height ratio (Wr/H) of 1:1. Wshaped ribs achieve the highest heat transfer enhancement levels in channels with an aspect ratio of 2:1, 2Wshaped ribs in channels with an aspect ratio of 4:1 and 4Wshaped ribs in channels with an aspect ratio of 8:1. Furthermore, the pressure loss increases with increasing complexity of the rib geometry and blockage ratio.