Application of numerical spray simulation to accompany experiments in the LPP premise duct at DLR

Kurzfassung

The presentation communicates some numerical results achieved during BRITE/EURAM Low-NOx III, which are based on experimental results obtained in Task 2.1.5 of Low-NOx II at the LPP premix duct at DLR. Experimental results are given here only for comparison purposes or where experimental and numerical results complement each other. The evaporation and mixing of kerosine emerging from a flat prefilming airbalst atomizer were studied in a straight rectangular duct at conditions relevant for lean premixed and prevaporized combustion. Computations werde based on the Lagrangian particle tracking technique using a standard single-component evaporation model for the multicomponent fuel Jet A-1, whose measured spray features obtained by Phase-Doppler-Anemometry were captured sufficiently well, with and without taking into account the spray feedback on the gas field. A degree of evaporation of ~95% was found after 100 mm for 9 bar air pressure, 750 K air temperature and 120 m/s air velocity. Parametric variations of pressure, air temperature and athe initial temperature of the spray were conducted. The latter turned out to have a strong influence on evaporation. The air pressure had mainly an indirect but strong effect through atomization quality. The strong increasse of evaporation with the air temperature is caused both by atomization and by the evaporation process itsself. It turned out that proper estimations or measurements of the initial spray conditions, especially the dropsize distribution and the spray initial temperature were important for the accuracy of the spray simulation. If proper spray initial conditions are provided, the chosen standard single component evaporation model gives sufficient agreement with the experiment and can be used as a design tool.