Large-Eddy Simulation of Reacting Flow in a Turbine Stage

TL;DR

This study uses large-eddy simulation to analyze the effects of fuel injection and combustion on turbine stage performance, demonstrating potential for turbine-burner applications with improved efficiency and temperature management.

Contribution

It applies LES to simulate reacting flows in turbines, providing new insights into fuel injection effects and guiding turbine-burner design.

Findings

Fuel injection minimally affects total-pressure loss.

Reacting cases increase turbine work and efficiency.

High rotor blade temperatures are reduced with uniform fuel distribution.

Abstract

An in-house large-eddy simulation (LES) code is applied to compute the chemically reacting flow in a turbine stage to analyze the influence of fuel injection and combustion on its aerodynamic and thermodynamic performance. Two reacting cases--with four and sixteen fuel injectors at the inlet for each stator passage--are computed and compared against two nonreacting cases, one with four fuel injectors and the other without. The turbine-stage analyses indicate viability for the turbine-burner concept. Fuel injection and combustion have minimal influence on the total-pressure loss in the stage. The mass flow rates in the two reacting cases are reduced by 7% and 8% relative to the nonreacting cases, respectively. Compared with the baseline nonreacting case, the turbine-stage work per unit mass increases by 8.5% and 11.5% in the two reacting cases, while the residual work rises by 17.3% and 16.0%, respectively. The two reacting cases exhibit a 14.5% increase of overall work, with a thermal efficiency of 44% for the fuel injection, which is comparable to the overall thermal efficiency of modern gas-turbine engines. Local high temperature on the rotor blade is suppressed by using a more uniform spanwise distribution of fuel injectors. The work extraction process of a turbine-burner is theoretically analyzed from both thermodynamic and mechanical views, providing guidance for future turbine-burner design.