Effect of inlet configurations on the aerodynamics of swirl combustors

The flowfield in a swirling combustor with a Confinement Ratio of 1.6 was simulated in water. Qualitative measurements were made from flow visualization in a horizontal water rig with the help of Pliolite beads and liquid dye. Velocity and turbulence measurements were made in a cold air flow rig. Mean velocity measurements were made using a five hole Pitot probe and turbulence measurements were obtained from a hot wire anemometer. All the flow visualization tests were made with Reynold's number between 10,000 and 47,500, and quantitative measurements in the cold air flow were made at a Reynold's number of 7.1x10⁵. The experiment was conducted for two configurations of the combustor system inlet- 1) Straight inlet and 2) S-inlet. Both configurations were tested with swirling and non-swirling flows. The straight inlet configuration with non-swirling flow produced a uniform corner recirculation near the wall of the combustion chamber. The S-inlet made the corner recirculation zones unequal. The introduction of swirling in the flow created a central recirculation zone in addition to the corner recirculation zone. It was found that the central recirculation zone was most prominent in the configuration with the S-inlet and swirling flow. An oscillating central core was seen in the straight inlet case. The average turbulence level was higher in the configuration with the s-inlet.