Impact of the Inlet Boundary Condition on High-Pressure Turbine Temperature Predictions

Project Description

Aviation gas turbine engines are an essential part of transportation and industry. In 2012, the world’s commercial aviation industry is forecasted to spend $207 billion dollars on fuel, or about 33% of their operating costs. This amounts to approximately 5 million barrels of oil per day, or about 6% of the world’s total oil usage. Aviation gas turbine engines are also responsible for 2% of the worlds’ CO2 production and 3% of the world’s harmful greenhouse gas emissions. As the commercial aviation industry grows by about 5% per year long term, and as oil prices continue to rise, the absolute values of these metrics are forecasted to continue to increase for the foreseeable future.
Desirable features for next generation aviation engines are combustion efficiency, compact combustor size, reduced emissions, and stable combustion. While the unsteady mixing process can be studied accurately by using direct numerical simulation (DNS), application of DNS to a full scale combustor at relevant conditions has not been yet demonstrated. Large-eddy simulations (LES), in which all scales larger than the grid resolution are numerically simulated have been successfully used over the past decade to solve for reacting systems.

The present study uses Large Eddy Simulations to predict exit temperature profile of the General Electric CFM56 combustor. The vida solver, developed by Cascade Technologies is used to advance the flow equations and particles, representing the liquid fuel injected into the system. Results show that reasonable agreement is obtained between the Cascade solver vida and measured profile data. Influence of grid resolution and boundary conditions on the flame characteristics and exit temperature profile are presented. In particular, fuel injection boundary condition effects on multi-cup exit temperature distribution are considered. Three different injection patterns are presented in order to understand how this parameter affects the temperature and the neighboring cup flowfield.