STABILITY OF THE CO- AND COUNTER-ROTATING SWIRLERS IN A LIQUID-FUELED CAN COMBUSTOR

This study experimentally investigates the effects of swirler channel orientation on combustion instability. For this purpose, the performance of the co- and counter-rotating radial-radial swirlers is assessed in terms of pressure fluctuations in a liquid-fueled can combustor operated with kerosene fuel. High-frequency pressure transducers are used to obtain pressure fluctuations in the combustor in non-reacting and reacting flow conditions. First, non-reacting experiments are conducted to observe the performance of the swirlers at mass flow rates of 10.5, 12, 14, and 15 g/s. Non-reacting experiments show that Precessing Vortex Core occurs at a Strouhal number of 1.9 and dominates the flow field for both swirlers. In the reacting conditions, the effect of the mass flow rate (10.5, 12, 14, and 15 g/s) at a constant fuel flow rate (0.7 g/s) and the impact of the fuel flow rate (0.7, 0.8, 0.9, and 1.0 g/ s) at a constant mass flow rate (15 g/s) are investigated. The peak frequency decreases in the reacting conditions compared to non-reacting cases. In the constant fuel flow rate case, the Precessing Vortex Core is observed in the co-rotating swirler for all air flow rates, but it disappears in the counter-rotating swirler at higher mass flow rates. At the constant mass flow rate cases, combustion instability occurs in the co-rotating swirler, while the counter-rotating swirler operates without any sign of instability. In all reacting cases, the peak frequency amplitude is remarkably higher in the co-rotating swirler.