Finite Element Modeling and Simulation of the Effect of Water Injection on Gas Turbine Combustor NO x Emissions and Component Temperature Joseph M. Basile Master’s Thesis 11/14/2014 Professor S. Bose Professor E. Gutierrez-Miravete Professor N. Lemcoff Rensselaer Polytechnic Institute

2 Water Injection and NO x Nitrous Oxides (NO x ) are a byproduct of gas turbine engine operation, and are considered harmful pollutants Reducing NO x emissions is the subject of contemporary research Most research focuses on methods that achieve the greatest reduction in emissions with the least impact to performance Water injection is perhaps the most studied and most effect means of reducing NO x What other benefits can water injection have?

3 Water Injection High combustion temperature can wear or damage engine components Like air cooling and high temperature coatings, liquid water injection into the engine could protect components from heat related damage while simultaneously reducing NO x emissions NO x emissions are highest when the temperature is highest J85-GE-17A turbojet

4 Engine Modeling 3D model created from a description of a research engine from University of Padova, Italy Engine interior from compressor outlet to turbine inlet, including the combustion chamber, were modeled and simulated A 2D axisymmetric model was created for initial simulations Boundary conditions and lessons learned were used to create a 3D model of 1/12 of engine

5 2D Axisymmetric Model Airflow Region Airflow Inlet Combustion Chamber Combustion Region Fuel Injector Combustor Outlet Water Injection Inlet Water Evaporation Region Axis of Revolution

6 Boundary Conditions Simulation Number Backpressure (Pa) Air Flow (kg/s) Fuel Pressure (Pa) Fuel Flow Rate (kg/s) Water Pressure (Pa) Water Flow (kg/s) Target

7 Boundary Conditions

8 2D Axisymmetric Model Results

9 3D Engine Model Airflow Region Airflow Inlet Combustion Chamber Combustion Region Fuel Injector Combustor Outlet Water Injection Inlet Water Evaporation Region

10 3D Model Results

11 3D Model Results Average Combustor Exit Temperature – Without water injection: K – With water injection: K NO x Production – Without water injection: 3.015E-5 kg/s – With water injection: 4.564E-6 kg/s – 84.86% reduction in NO x emissions Inner wall surface temperature – Without water injection: K – With water injection: ~373 K – Wall temperature of around ~370 – 380 K was maintained along the inner wall due to the evaporation of water droplets

12 Questions?

13 Backup Slides

14 NO x Emissions

15 2D Axisymmetric Wall Temp

16 3D Wall Temp

17 Flow Simulations - Results Fluid Streamlines – Without Water Injection

18 Flow Simulations - Results Fluid Temperature – Without Water Injection

19 Flow Simulations - Results Surface Temperature – Without Water Injection

20 Flow Simulations - Results Fluid Streamlines – With Water Injection

21 Flow Simulations - Results Fluid Temperature – With Water Injection

22 Flow Simulations - Results Surface Temperature – With Water Injection