Large-Eddy Simulation of Reacting Flow in a Turbine Stage

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.