Experimental study on the influence of the Buoyancy number on heat transfer in a pin-fins channel under rotational conditions

Abstract

The trailing edge of turbine blades poses a significant challenge for research in internal cooling technology. In previously published studies on heat transfer coefficient (HTC), the limitations of experimental testing techniques have hindered the ability to scale up the rotational radius ratio in a similar manner, resulting in significantly lower Buoyancy number (Buo) values tested compared to the actual operating conditions of turbine blades, leading to biased HTC results.This article delves into experimental studies to explore the HTC of a pin-fin channel. The experimental testing encompassed a broad spectrum of conditions, including varying inlet Reynolds numbers ranging from 5000 to 70,000, rotation numbers (Ro) from 0 to 1.0, temperature ratio from 0.04 to 0.22, rotational radius ratio (r/D) from 20 to 52.33, and Buo from 0 to 2.55. For the same Buo, there is a significant difference in HTC, with the high Ro and low TR scenario demonstrating a distinct advantage in HTC compared to the low Ro and high TR condition. Furthermore, heat transfer enhancement was observed at approximately 30 % of the dimensionless positions. Therefore, to achieve more accurate HTC results, it is necessary to precisely match the values of Re, Ro, Buo, TR, and r/D.

Keywords

• Turbine blade
• Internal cooling
• Temperature ratio
• Rotational radius ratio
• Buoyancy number
• Pin-fins