On the function of ribs as secondary flow inducer -application to cooling of gas turbine blade trailing edge-

摘要

An Experimental study was conducted to examine the effect of rib-induced flow on the heat transfer characteristics in a rectangular passage. The ratio of the long and short side walls (aspect ratio) of the passage cross-section was 2:1. Obliqueribs were attached to two opposing long side walls with the two short side walls (top and bottom walls) being left smooth. In this study oblique ribs were intended to function as a secondary flow inducer as well as a conventionalflow-separation-reattachment device to improve the heat transfer of the bottom wall (one of the short side walls). The results revealed, contrary to the common knowledge, that, in order to enhance the heat transfer of the bottom wall, the oblique ribsshould be arranged so that the flow along the ribs hits the top wall instead of the bottom wall. Flow visualization test was performed to understand the heat transfer mechanisms. It was confirmed that the heat transfer enhancement at the bottom wall wasattributed to the rib-induced secondary flow where the flow along the ribs hit the top wall, turned back and carried colder and higher-momentum air at the passage core toward the bottom wall.