Investigation of Unsteady Flow Phenomena in First Vane Caused by Combustor Flow With Swirl

Simon Jacobi,Krishan Chana,Cosimo Mazzoni,Budimir Rosic

doi:10.1115/1.4035073

Simon Jacobi, Krishan Chana + Show 2 more

Open Access

https://doi.org/10.1115/1.4035073

Copy DOI

Abstract

The flow at the combustor turbine interface of power generation gas turbines with can combustors is characterized by high and nonuniform turbulence levels, lengthscales, and residual swirl. These complexities have a significant impact on the first vanes aerothermal performance and lead to challenges for an effective turbine design. To date, this design philosophy mostly assumed steady flow and thus largely disregards the intrinsic unsteadiness. This paper investigates the steady and unsteady effects of the combustor flow with swirl on the turbines first vanes. Experimental measurements are conducted on a high-speed linear cascade that comprises two can combustors and four nozzle guide vanes (NGVs). The experimental results are supported by a large eddy simulation (LES) performed with the inhouse computational fluid dynamics (CFD) flow solver TBLOCK. The study reveals the highly unsteady nature of the flow in the first vane and its effect on the heat transfer. A persistent flow structure of concentrated vorticity is observed. It wraps around the unshielded vane's leading edge (LE) at midspan and periodically oscillates in spanwise direction due to the interaction of the residual low-pressure swirl core and the vane's potential field. Moreover, the transient behavior of the horseshoe-vortex system due to large fluctuations in incidence is demonstrated.

Highlights

Lean-Premixed (LPM) combustors are broadly used in industry due to their superior emission characteristics compared to conventional rich-burn combustors
This paper investigated the influence of engine realistic combustor flow with swirl on the steady and unsteady aerothermal response of the high-pressure turbines nozzle guide vanes
Experimental measurements were performed on a high-speed linear cascade comprising of two can combustors and four nozzle guide vanes

Summary

Introduction

Lean-Premixed (LPM) combustors are broadly used in industry due to their superior emission characteristics compared to conventional rich-burn combustors. Stringent regulations are set for the goal of reducing NOx emissions due to their detrimental effects and LPM combustion promises to offer the highest potential for NOx reduction [1] This is achieved by LPM combustor’s architecture, in which different configurations of swirl injectors generate a lean mixture of fuel and air prior combustion. This results in lower temperatures and lower NOx emissions compared to conventional rich-burn combustors. Corner recirculation zones establish when the main flow exiting the swirl generators encounters the ambient fluid, leading to shear layers due to velocity gradients and to vortex structures

Objectives

Methods

Findings

Conclusion