Effect of Nozzle Port Shape of Fuel Injector of Micro Gas Turbine Engine Combustor on Mixture Gas Formation for Combustion

Abstract

The objective of this study was to optimize the design of the injection nozzle hole of the fuel injector of a model MGT engine. To achieve a higher combustion efficiency of the mixed gas in the combustion chamber, first, well-mixed homogeneous gas should be formed to accelerate the flame propagation in the chamber to reach a higher combustion temperature and pressure. In this study, four different shapes of the nozzle hole of the fuel injector were designed, and the mixed gas formation characteristics in the chamber were numerically analyzed. Three parameters—the penetration, diffusivity, and amount of fuel injected—were analyzed and compared to find the optimum shape of the nozzle hole with the highest combustion efficiency in the chamber. CFD analysis was conducted using a general-purpose CFD (Computational Fluid Dynamics) code-named PHOENICS (ver. 2020). Based on the analysis results, it was found that the penetration length (lp), diffusion angle (θ), and volume flow rate (Q˙f) of the injected fuel of Model 3 had the best injection characteristics for the well-mixed gas formation condition in the combustion chamber. Especially, the volume flow rate of the injected fuel of Model 3, which directly affects the output power of the engine, increased by more than 5%. This result is useful and informative for making a sample combustor for a combustion performance test of the model gas turbine engine.