Experimental measurements of the flow field around a film-cooled blade leading edge using particle image velocimetry

José Omar Dávalos Ramírez,Juan Carlos García Castrejón,Arturo Paz Pérez,Francisco Carrillo Pereyra,Carlos Ponce Corral,Carlos Felipe Ramírez Espinoza

doi:10.1177/1687814018802904

Abstract

In this article, particle image velocimetry studies were conducted in a low-speed wind tunnel to investigate the effects of blowing ratio and blade span in terms of the characteristics of the flow field around a film-cooled blade leading edge. The measurements were performed at 20%, 40%, 60%, and 80% of blade span and blowing ratios of M = 0.5, M = 0.75, M = 1, M = 1.5, and M = 2. Velocity, turbulence intensity, and structure of vortices during the interaction between cooling flow and mainstream were analyzed in detail. The analysis shows a significant increase in mainstream velocity at low blowing ratios, M < 1. Peaks of turbulence were observed at low- and high-span locations. Aerodynamical losses are expected at higher blowing ratios due to the formation of secondary vortices near the outgoing jet. These vortices were a consequence of velocity gradients at this zone.

Highlights

One of the ways to improve the performance of gas turbines is to increase the temperature of mainstream flowing through turbine blades
Vortical structures were visualized by Song et al.[18] by means of particle image velocimetry (PIV), on a flat plate with the addition of a vortex generator located at one-dimensional (1D) downstream the film cooling hole varying injection angle and blowing ratios
The results showed that downstream the jet exit, mainstream accelerates drastically as blowing ratio decreases, M \ 1, and span increases

Summary

Introduction

One of the ways to improve the performance of gas turbines is to increase the temperature of mainstream flowing through turbine blades. Turbulence intensity, and structure of vortices during the interaction between cooling flow and mainstream were analyzed in detail. The effectiveness of the film cooling technique is influenced by characteristics of mainstream and cooling flows, such as the blowing ratio, the velocity ratio, the density ratio, the temperature ratio, and the free stream turbulence, among others.

Results

Conclusion