Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Large-Eddy Simulation of Reacting Flow in a Turbine Stage

Yalu Zhu, Feng Liu, William A. Sirignano

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.

Large-Eddy Simulation of Reacting Flow in a Turbine Stage

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.

Paper Structure

This paper contains 12 sections, 22 equations, 18 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Numerical Methods
  3. Governing Equations
  4. Numerical Solver
  5. Computational Cases and Grid
  6. Boundary and Initial Conditions
  7. Results and Discussions
  8. Nonreacting Flow
  9. Reacting Flow
  10. Aerodynamic Performance
  11. Thermodynamic Performance
  12. Conclusions

Figures (18)

  • Figure 1: Sketch of fuel-injection structure at turbine inlet.
  • Figure 2: Computational grids over the hub and blade surfaces. Every other grid point is shown.
  • Figure 3: Sketch of fuel-injector configurations at turbine inlet.
  • Figure 4: Instantaneous vortex structures identified by the $\mathbf{\lambda_2}$ criterion and colored by temperature in the hub half of turbine stage in nonreacting cases.
  • Figure 5: Spanwise variations of flow parameters in nonreacting cases. Red: case 0N; blue: case 4N. Solid lines: LES; dash-dot lines: RANS.
  • ...and 13 more figures