Flow characterization with and without combustion in a swirl type combustor

The aerodynamic effect of combustion in a swirl type combustor was studied. By a flow direction detector, the reverse flow region inside the recirculation zone was found. The velocity and the velocity fluctuation were measured by a Laser Doppler Velocimeter and were compared with results obtained without combustion. When the swirl number of the flow was higher than 0.5, the reverse flow zone was increased by the thermal expansion due to the combustion occurring in this zone. The axial velocity in this zone was also increased by combustion. On the contrary, when the swirl number was 0.23, the reverse flow zone was decreased by the combustion. The RMS and the large scale fluctuation of the velocity was increased by the combustion. Flow photographs taken for flow visualization by a Spark Tracing technique showed that the small turbulence in the flow was diminished by the combustion.