Abstract:

The Euler-Euler two-fluid model combined with kinetic theory of granular flow was used to simulate the gas-solids dense phase fluidized bed at different superficial velocities.The experiments were carried out to compare the profile of pressure and pressure fluctuation power spectrum with the CFD simulated results, and the simulation method was validated.Statistical analysis and spectral analysis were used to investigate the granular temperature time series.It was shown that as superficial velocity increased, average and standard deviation of granular temperature time series increased, while flatness factor almost remained constant.By integrating acoustic energy theory into granular temperature and referring to acoustic energy profile with bed height,the average, standard deviation and flatness factor of granular temperature time series were used to determine the stagnant zone of particle motion.Furthermore, granular temperature spectrum was introduced and divided into energy-containing scale, inertial scale and dissipation scale based on the cascade theory of fluctuation energy.In the inertial scale, granular temperature spectrum deviated from Kolmogorov -5/3 law and tended to obey Levy-Kolmogorov law.In the application scope of Levy-Kolmogorov law, the decay index of inertial scale in the stagnant zone achieved a maximum, according to which the identification of stagnant zone by the decay index of granular temperature spectrum was proposed.