Measurement and simulation of the two-phase velocity correlation in sudden-expansion gas-particle flows

摘要

In this paper the present authors measured the gas-particle two-phase velocity correlation in sudden expansion gas-particle flows with a phase Doppler particle anemometer(PDPA) and simulated the system behavior by using both a Reynolds-averaged Navier-Stokes(RANS)model and a large-eddy simulation(LES). The results of the measurements yield the axial and radial time-averaged velocities as well as the fluctuation velocities of gas and three particle-size groups(30μm,50μm,and 95μm) and the gasparticle velocity correlation for 30μm and 50μm particles.From the measurements,theoretical analysis,and simulation,it is found that the two-phase velocity correlation of sudden-expansion flows,like that of jet flows,is less than the gas and particle Reynolds stresses. What distinguishes the two-phase velocity correlations of sudden-expansion flow from those of jet and channel flows is the absence of a clear relationship between the two-phase velocity correlation and particle size in sudden-expansion flows. The measurements,theoretical analysis,and numerical simulation all lead to the above-stated conclusions. Quantitatively,the results of the LES are better than those of the RANS model.