Abstract

This paper reports a numerical investigation of heat transfer and flow characteristics in a two-dimensional u-tube over semicircular turbulators. Repeated semicircular turbulators (ribs) are used inside a cooling passage to promote turbulence and enhance convective heat transfer in gas turbine blades to create higher thrust-to-weight ratios. The u-tube has a 180° bend while the turbulators are distributed on both walls in a staggered arrangement where the ratio h/d is 0.1 and the spacing ratio S/d is 1. Four Reynolds numbers, 40,000, 60,000, 80,000 and 95,000 are considered. The predicted velocity and heat transfer in the u-tube concur with measurement data from the relevant literature. High velocity regions occur near the lower wall in the downstream duct while the heat transfer is increased in the downstream duct. Furthermore, the greater the Reynolds number beyond a certain value (moderate Reynolds numbers), the smaller the increment in Nusselt number.

Key words: Blade cooling, CFD, turbulators, gas turbine.