Gas and Liquid Fuel Injection Into an Enclosed Swirling Flow

Abstract

A swirler with good premixed performance has been tested with direct central propane injection and with direct central kerosene and gas oil injection using the swirler air for atomisation. The results have been compared with non swirling flow systems at the same test conditions. Direct propane injection results in a major extension of the stability limits compared with the premixed situation, but with liquid fuel injection the stability limits are generally worse than for premixed fuel and air. It is argued that the cause of this is the action of the centrifugal forces on the liquid droplets in the swirl flow which results in vaporisation in the outer swirl flow and weaker mixtures in the core recirculation region than for propane injection. The gas composition results support this conclusion. Direct propane injection caused a deterioration in the combustion efficiency and a large increase in NOx. The poor stability limits with liquid fuels prevented a high combustion efficiency and low NOx situation from being achieved. A comparison of the performance with non swirling systems showed that all emissions were higher with swirl for propane but that the swirler may have some advantages for liquid fuels.