Abstract
The swirl flow in gas turbine combustor plays a major role in flame stabilisation and performance of engine. Since the swirl flow is very complex and boundary sensitive phenomena, it is difficult to interpret it properly. High shear injector is being used now a days in modern gas turbine combustor to generate the swirl flow and achieve better fuel atomisation in the combustion chamber. High shear injector accommodates a series of swirlers (primary and secondary) with a diverging flare at the exit and fuel nozzle mounted at the centre of the swirler.
In the present study it is tried to understand the influence of the flare angle on the non-reactive flow behaviour of the swirling spray flow-field generated through counter-rotating high shear injector. To perceive the influence of flare angle on the flow topology of the spray flow-field generated by a high shear injector, seven different flare half angles (β): 40°, 45°, 50°, 55°, 60°, 65° and 70° respectively were selected as a geometrical parameter to conduct the experiments. High-Speed Particle Image Velocimetry (HSPIV) technique was employed to perceive the topological structure of the spray flow field, mean and instantaneous behaviour of the velocity fields respectively. For all the cases mass flow of air and liquid (water) were kept constant. It was observed that with change in flare angle the size of the CTRZ, mean velocity and turbulent behaviour were also changing. Here the size of CTRZ is represented in terms of nondimensional radial width (W/Df) and height (H/Df) of the recirculation zone. The experiment was conducted without flare, initially and then subsequently with flares. It was found that both the radial width and the height of the recirculation zone were smallest for without flare case. With increase in flare angle the radial width and height of the CTRZ increases initially up to 60° flare angle and afterward decreased. The experiments made clear that flare angle has strong effect on the spray flow-field.
