Comparative Study of Mixing Characteristics of Particle-Laden Shear and Swirl Coaxial Jets

The effect of velocity ratio and recess on the mixing characteristics of gas-particle swirl and shear coaxial injectors was investigated. The concentration and mixing efficiencies of the particles and gas were measured by planar nephelometry based on Mie scattering and acetone planar laser-induced fluorescence methods, respectively. The mixing mechanism and mixing efficiency of the shear and the swirl coaxial injectors were compared with and without recess. The results showed that the mixing efficiency of the former was higher than that of the latter in the case without a recess because the swirling momentum of the coaxial gas did not change the particle concentration half-width. The mixing efficiencies of both injectors in the case without a recess were sensitive to changes in the velocity ratio. However, in the case of injectors with a recess, the mixing efficiency of the swirl coaxial injector was higher than that of the shear coaxial injector because the internal interaction of two propellants led to an increase in the particle concentration half-width, and the mixing efficiency of the swirl coaxial injector was less sensitive to changes in the velocity ratio than that of the shear coaxial injector.