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Mixing Enhancement of Liquid Jet using Curved Pylon in Supersonic Crossflow

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Mixing Enhancement of Liquid Jet using Curved Pylon in Supersonic Crossflow

Aerospace Engineering

Hypersonic air-breathing engines are constrained to do supersonic combustion because of the effects such as vibrational excitation, dissociation, and high total pressure loss when performing subsonic combustion. Supersonic combustion has its challenges due to the very low residence time and limited combustor length. The use of liquid fuel is an attractive option for supersonic combustion due to its high energy density. Liquid fuel can also be used as a coolant since hypersonic air-breathing vehicles produce high thermal loads. Additional challenges like atomization and evaporation are added along with mixing when liquid fuel is used, further complicating the supersonic combustion process. The pylon-aided injection can be a suitable option over other injection techniques because of its very low blockage area, better penetration for the same momentum flux ratio, and less total pressure loss than strut injectors. An experimental investigation has been carried out for the liquid injection behind a curved pylon at an angle of 60o in supersonic crossflow with Mach number 1.71. High-speed Schlieren and Mie scattering experiments were performed to evaluate the performance of curved pylon on the mixing of the liquid jet. Results show a better performance of curved pylon than the standard pylon. The penetration height of the liquid jet was 7.79% more for the curved pylon case as compared with the standard pylon case for the same momentum flux ratio. Further increase in the momentum flux ratio increased the penetration height to 15.53% more as compared with the standard pylon case. The spread area of the liquid jet was 17.42% more at x/dj = 25 and 25.97% more at x/dj= 40 for the curved pylon case than the standard pylon case for the same momentum flux ratio. The presence of counter-rotating vortices at the top of the liquid plume and in the near-wall region caused a higher spread area in curved pylon cases than in standard pylon cases.

 

Instantaneous Schlieren images ((a),(d)) , Mie scattering images((b),(e)), Penetration height((c)) , and Spread area((f)), and the schematic ((g)) of Standard pylon((a),(b)) and Curved pylon((d),(e)) cases

Ref: Anbarasan Sekar, Mayukhmali Chakraborty, and Aravind Vaidyanathan. "Mixing characteristics of liquid jet injected behind a curved pylon in supersonic flow." Experimental Thermal and Fluid Science 134 (2022): 110570. https://doi.org/10.1016/j.expthermflusci.2021.110570

 

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