Analysis of choked two-phase flows of gas and particle in a C-D nozzle

Abstract

Particle–gas two-phase flows show significantly different behaviors compared to single gas flow through a convergent–divergent nozzle. Non-equilibrium effects, thermal and velocity lag results to the inefficiency of nozzle performance. In the present studies, theoretical analysis and numerical simulations were carried out to investigate particle–gas flows in a C-D nozzle. Homogeneous equilibrium model that no lag in velocity and temperature occurs between particles and gas phase was used to derive mass flow rate and sound speed of multiphase flows. Two-phase flows are regarded as isentropic flows that isentropic relations can be used for homogeneous equilibrium model. Discrete phase model (DPM) where interaction with continuous phase and discrete random walk model were considered was used to calculate particle–gas flows. Particle mass loadings were varied to investigate their effects on choking phenomena of particle–gas flows. Mass flow rate and sound speed of mixture flows were theoretically calculated by homogeneous equilibrium model and compared with numerical results. Shock wave structure and particle number density were also obtained to be different at different particle mass loading and operating pressure conditions.

Keywords

• Multiphase flows
• Particle number density
• Shock wave
• Sound speed of mixture
• Flow choking