SCALING OF THE 2-PHASE FLOW DOWNSTREAM OF A GAS-TURBINE COMBUSTOR SWIRL CUP .1. MEAN QUANTITIES

A production gas turbine combustor swirl cup and a 3 x -scale model (b oth featuring co-axial, counterswirling air streams) are characterized at atmospheric pressure. Such a study provides an opportunity to asse ss the effect of scale on the behavior of the continuous phase (gas in the presence of spray) and droplets by comparing the continuous phase velocity, droplet size, and droplet velocity at geometrically analogo us positions. Spatially resolved velocity measurements of the continuo us phase, droplet size, and droplet velocity were acquired downstream of the production and 3 x -scale swirl cups by using two-component pha se-Doppler interferometry in the absence of reaction. While the contin uous phase flow fields scale well at the exit of the swirl cup, the si milarity deviates at downstream locations due to (1) differences in en trainment, and (2) a flow asymmetry in the case of the production hard ware. The droplet velocities scale reasonably well with notable except ions. More significant differences are noted in droplet size, although the presence of the swirl cup assemblies substantially reduces the di fferences in size that are otherwise produced by the two atomizers whe n operated independent of the swirl cup.