Aerodynamics Study of a Linearly-Arranged 5-Swirler Array

Abstract

In this experimental work, a series of tests have been conducted to further study the aerodynamics of linearly-arranged 5-swirler arrays, using Laser Doppler Velocimetry (LDV). Two major parameters have been investigated for the 5-swirler arrays in this work, including the inter-swirler spacing, and the end wall distance. An additional effect of dome recession was studied for a single swirler in order to provide some insight into the results for the 5-swirler arrays. The 5-swirler arrays with an inter-swirler spacing of 1.75D, 2D, 2.5D, and 2.75D were studied, where D is the diameter of swirler exit. For the inter-swirler spacing of 1.75D or 2D, the center swirler is shown to have a weak, large center toroidal recirculation zone (CTRZ). The swirlers next to the center swirlers have strong, compact CTRZs whereas the outer swirlers have weak, large CTRZs. Thus, starting from the center swirler, the CTRZs exhibit a large – small – large pattern in either direction. For the swirler spacing of 2.5D or 2.75D, the trend is reversed, with a strong CTRZ for the center swirler and a small – large – small CTRZ pattern. The end wall distances of 0.75D, 1D, 1.25D, and 2D cases were studied. The end wall distances are seen to affect the strength of each CTRZ and the corner swirling flow pattern, though the bulk flow structure did not change significantly. The dome recession shows a clear impact on the expansion of swirling flow generated by a single swirler. As the dome recession distance increases, the expansion angle of the swirling jet reduces significantly for the unconfined cases. A phenomenological description is discussed to understand the reason for the periodically alternating CTRZ pattern observed in the experimental results of the 5-swirler arrays.

Experimental and Numerical Investigation of Flow, Combustion and Emission Characteristics of Novel Multi-Swirl LDI burners.

“…The performance of the multi-swirl LDI combustor depends on numerous design factors, such as the quantity and dimensions of injector elements, the type of air swirler (radial or axial), the design of the swirler (number of swirl vanes, swirler angle, and direction) and the type of fuel nozzle. Experiments and simulations were carried out to compare the effect of these variables on combustor performance in terms of flame stability, NOx, and CO emissions [26][27][28][29][30]. The effect of spacing between the swirlers on the flow field is studied by Kao et al [26] for a linear array of five nozzles.…”

“…Experiments and simulations were carried out to compare the effect of these variables on combustor performance in terms of flame stability, NOx, and CO emissions [26][27][28][29][30]. The effect of spacing between the swirlers on the flow field is studied by Kao et al [26] for a linear array of five nozzles. The study discovered that the size of the central recirculation zone varied from small to large along the swirler array.…”

Comparison of Flame Describing Functions Measured in Single and Multiple Injector Configurations

“…These effects may be enhanced if the injectors are fitted with an outlet cup [16,17]. neighboring flames [18][19][20]. If the flames are in close proximity and expanding sideways, strong interactions can take place between the reactive layers, with significant variations in the instantaneous heat release rate [15,[21][22][23].…”

A 3D Coupled Approach for the Thermal Design of Aero-Engine Combustor Liners

“…Measured and predicted flow field on the median plane Such phenomenon, yet not confirmed by the PIV measurements, was investigated experimentally by Kao et al[92], who studied a linearlyarranged 5-swirler array at non-reactive conditions. The authors investigated the impact of inter-swirler spacing, lateral walls distance and dome recession on the flow field, pointing out their effect in switching the swirling flow behaviour to a wall-attached configuration, generating air entrainment from the adjacent injector (seeFig.…”

“…Classical flow pattern of an array of swirles (top) and dome-attached swirling flow (bottom)[92] in fact that instability related to the presence of the PVC is drastically suppressed by heat release in reacting flows[93]) may results infeasible with standard RANS approach.The aim of this work is to investigate the heat transfer augmentation on combustion liners under the effect of a realistic gas side flow field.The considered geometry consists of the three-sector planar rig developed in the context of the EU project LEMCOTEC[60]. This test case can be considered of particular interest, being characterized by a strong interaction between adjacent injectors, due to the absence of any lateralconfinement of the swirled flow, and coolant injection through a slot embedded in the combustor dome.…”