Multi-Swirler Aerodynamics: Comparison of Different Configurations

The non-reacting fluid flow fields generated by multi-swirler arrays with two different port configurations were investigated experimentally. These two cases include a co-swirling array, where all swirlers act in the same direction, and a counter-swirling array, where all swirlers alternate between clockwise and counter-clockwise rotations. Each configuration consists of a three by three arrangement of swirlers, which use analogous geometries to generate the swirling flows, i.e. eight discrete jets. For each array, the mean and turbulence velocities were measured at approximately 25,000 discrete spatial locations by a two-component LDV system. Furthermore, the third velocity component was derived based on the symmetric geometry of the arrays. In both cases, the coalescence distance, distance for eight discrete jet streams to form uniform swirling flows, is very short; and each swirler within the arrangement possesses a central recirculation zone. These nine zones have varying strengths depending on the individual swirler location, and some rotate with the swirler direction. In comparison, the co-swirler configuration provides a large unified rotational flow in the same direction as the individual swirlers, while a counter-rotating flow pattern is formed by the other case. Lastly, interactions between the unified flow with that of each swirler in the array are discussed and further comparisons are made between the two cases.