Heat Transfer and Friction Factor in the Rib Roughened Blade Leading Edge Cooling Passage

Abstract

This paper presents the results of heat transfer and surface friction factor numerical simulation in the blade internal cooling passage with trip strip turbulators of different configurations and rib coverage. The passage cross section shape is the equilateral triangle with rounded apex simulating the leading edge area. The leading edge wedge angle is 30 degrees, inner radius to passage hydraulic diameter ratio is 0.30; channel hydraulic diameter is 10 mm. Such geometric parameters are typical to a leading edge cooling passage of an actual gas turbine blade or vane. Totally six basic rib configurations have been studied including the continuous transverse ribbing (normal to bulk flow direction), V-shaped ribbing, inverted V-shaped ribbing, broken transverse ribbing, broken V-shaped ribbing, as well as helical ribbing (angled to the bulk flow direction). Three cases of the passage partial ribbing for the widely used transverse and V-shaped rib configurations have been also analyzed, and the smooth cooling passage of the same configuration and cross section have been studied for the reference comparison as well. The ribs geometrical parameters for all configurations are the same: a square cross section, rib height to channel hydraulic diameter ratio (blockage ratio) is 0.10; rib pitch (rib-to-rib spacing) is 10, angle of attack for V-shaped, inverted V-shaped and helical ribs is 45°. All calculations were carried out at the constant Reynolds number of 100 000 using commercial software package ANSYS CFX 11.0. The results presented in this paper include the heat transfer, surface friction, vortex structure analysis and thermal hydraulic performance evaluation.