Fuel Nozzle Aerodynamic Design Using CFD Analysis

Abstract

The aerodynamic design of airflow passages in fuel injection systems can be significantly enhanced by the use of CFD analysis. Attempts to improve the efficiency of the fuel nozzle design process by using CFD analyses have generally been unsuccessful in the past due to the difficulties of modeling swirling flow in complex geometries. Some of the issues that have been obstacles to successful and timely analysis of fuel nozzle aerodynamics include grid generation, turbulence models, and definition of boundary conditions. This study attempts to address these obstacles and demonstrate a CFD methodology capable of modeling swirling flow within the internal air passages of fuel nozzles. The CFD code CFD-ACE was used for the analyses. Results of nonreacting analyses and comparison with experimental data are presented for three different fuel nozzles. The three nozzles have distinctly different designs (including axial and radial inflow swirlers) and thus demonstrate the flexibility of the design methodology. Particular emphasis is given to techniques involved in predicting the effective flow area (ACd) of the nozzles. Good agreement between CFD predictions of the ACd (made prior to experiments) and the measured ACd was obtained. Comparisons between predicted and measured velocity profiles also showed good agreement.