Fuel/Air Premixing Uniformity of Low Swirl Burner

Different methane/air premixing schemes are designed and the premixing uniformity of the low swirl burner is studied to provide a reference for the overall design of the burner. Comparisons are performed with experimental measurements for the aim to validating the numerical method. Then a numerical simulation of premixed gas at equivalent ratio of 0.7 was conducted to investigate the influence mechanism of the characteristics of fuel orifice and low swirl flow field on premixing process. Results show that jet aperture affects the initial distribution of fuel which largely determines the final mixing efficiency that can be achieved in a limited space. For the given structure, an optimal equivalent aperture b=0.01 and a corresponding average momentum flux ratio J= 75.59 can be found to optimize the mixing efficiency, where the spacial mixing deficiency at the burner outlet reaches 6.57%. The low swirl flow field is under the interaction of central direct-current flux and outer swirling flux, wherein the swirling effect plays a leading role during the fuel diffusion process. Under the prerequisite of flowing in a low swirl state, the premixing uniformity can be improved through enhanced swirling intensity by increasing the blockage ratio of the perforated plate or the geometric angle of the swirling vane. © 2021, Editorial Department of Journal of Propulsion Technology. All right reserved.