Heat/Mass Transfer in a Rotating Two-Pass Channel with Transverse Ribs

Abstract

Naphthalene sublimation experiments have been conducted to study the local heat/mass transfer distributions on the rib-roughened leading and trailing walls of a rotating, two-pass, square channel, that models internal turbine blade cooling passages. The height of the transverse ribs was equal to one-tenth the spacing between the ribs, which was the same as the hydraulic diameter of the test channel. The Reynolds number and rotation number ranged up to 1 3 10 4 and 0.24, respectively. The results showed that, for radial outward e ow in the e rst pass, there was very little spanwise variation of the local heat/ mass transfer between consecutive ribs on the trailing wall. When the rotation number was high, however, there was signie cant spanwise variation on the leading wall, with high heat/mass transfer in the middle of the wall and very low heat/mass transfer near the two side walls. For radial inward e ow in the second pass, the sharp turn reduced the difference between the heat/mass transfer on the leading wall and that on the trailing wall. The sharp turn also caused spanwise asymmetric variation of the local heat/mass transfer between consecutive ribs in the second pass immediately downstream of the turn. Relative to the heat/mass transfer in a corresponding stationary channel, the overall heat/mass transfer in a rotating channel with rib-roughened walls was not affected by the Coriolis force as much as that in a rotating channel with smooth walls.