Abstract
Nonreacting swirling flow behavior through a novel double swirl burner has been investigated in this paper using Detached Eddy Simulation (DES) calculations and experimental measurements. The effect of mixing both the swirling flow of the inner jet (primary air or inner swirler) and the swirling flow of the annular jet (secondary air or outer swirler) on the flow structure has been analyzed. Moreover, pressure losses and flow field characteristics have been investigated at different inlet air mass flow rates and combustor diameters. Due to the drawbacks of general pressure loss to predict the pressure drop through high turbulence swirl flow as well as the complex geometry, the time-averaged viscous dissipation field function is used to predict the pressure drop through the burner. This function is based on the relationship between viscous dissipation and pressure losses. DES flow fields are compared with high-speed particle image velocimetry measurements at different inlet air mass flow rates. It is found that there is good agreement between numerical and experimental results, and both the central toroidal recirculation zone and the corner recirculation zone are well captured. In the case of a single inner swirler, the general pressure drop is very high compared to single outer and double swirl generators, and 84% of the inlet air pass through the outer swirler and just 16% of the air pass through the inner swirler in the case of a double burner (partially premixed). The time-averaged viscous dissipation field function is very important to identify the locations that lead to pressure drop inside the burner, which induces to select the appropriate design for the best performance. In addition, it is concluded that the performance of the double swirl burner is more efficient compared with the other two single swirlers in terms of pressure losses and flow structure.
Highlights
Combustion stability is still a major interest in many industrial combustion applications such as boilers, furnaces, and gas turbines
To enrich our knowledge of the flow characteristics in a dual swirl burner, this paper aims to investigate the flow structure produced by a novel double swirl burner with respect to the inlet mass flow rate and influence of the combustor diameter
The simulation overestimates the peak of the measured mean velocity slightly, and there are some natural variances between the Particle Image Velocimetry (PIV) and Computational Fluid Dynamics (CFD) results
Summary
Combustion stability is still a major interest in many industrial combustion applications such as boilers, furnaces, and gas turbines. Swirl flows created by swirl burners have been used extensively in modern combustion applications for the stabilization of the flame. It could achieve high combustion efficiency and low emissions by enhancing the mixing performance between air and fuel.. Swirl burners and cyclone combustors in gas turbines and other combustion applications use powerful vortices and recirculation regions created by these flows to increase the momentum or collision velocity between tangential axial and flows, extending the residence time for mixing air and fuel. Previous studies show that the swirler can control flame size, shape, stability, and combustion efficiency
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