Experimental investigations of fuel preparation in a swirling airflow under realistic conditions without reaction in a combustor model with a point fuel source

Abstract

This paper presents quantitative experimental results of non-reacting spray analysis inside a model combustor at realistic jet engine conditions based on a point fuel source and with using kerosene Jet A-1 for the first time. Therefore, two test conditions with combustor pressures of 0.4 and 1.2 MPa, air preheat temperatures of 440 and 740 K and fuel preheating temperatures of 358 and 467 K were investigated. The basis for this investigation was a specially made combustor model in combination with a burner model similar to a fuel-staged lean burner. The focus was on the main stage with a single decentralised point fuel source. This fuel entry is a liquid jet in cross flow (LJICF) with the jet direction normal to the main air flow. The velocity of the air flow was measured by Laser Doppler Anemometry (LDA). Phase Doppler Anemometry (PDA) was used for the simultaneous measurements of fuel drop size and velocity. Sauter mean diameter (SMD) distributions and drop size dependent velocities were shown for the different axial distances inside the model combustor and were discussed with respect to the distributions and the ability of fuel droplets to follow the airflow. The consequent findings of the drop dispersion were verified by Stokes numbers. The drop diameters, and therefore the Stokes numbers, are heavily dependent on test conditions. With values of 8 < SMD < 20, the drop sizes were accordingly small. For validating the liquid fuel combustion codes, the dataset is completed by histograms of drop size and the determined Rosin-Rammler (RR) parameters.