Spray Dispersion in a Counter-Swirling Double Annular Airflow at Gas Turbine Conditions

Kurzfassung

The dispersion of a Jet A-1 kerosene spray generated by plain-jet-in-crossflow injection into the inner annulus of a counter-swirling double-annular airflow was investigated experimentally. Tests were conducted at 6 bar and 12 bar ambient air pressure at 750 K air temperature and at the corresponding cold test conditions in terms of air density, with an additional excursion to very high air density (9.3 bar at 290 K). The total air velocity was 114 m/s and the fuel flow through the 0.457 mm diameter plain jet nozzle was selected so that the fuel-to-air momentum flux ratio q (=(rliq×uliq2)/(rair×uair2)) was q = 4.6 . The airflow was characterized by Laser-Doppler-Anemometry (LDA) and the spray dispersion was investigated by Phase-Doppler-Anemometry (PDA). It was found that the very small droplets generated at high pressure have such a great ability to follow the streamlines of the airflow that they remain trapped in the inner annulus, preventing the formation of a homogenous fuel-air mixture in the annular flow.