Theoretical Analysis And Experimental Study Of The Drag Coefficient In The Velocity Field Of The Free Falling Particle Stream

Countries in the world, especially in many developed countries, the cost of economic prosperity in the chemical industry, power plants, construction, food industry, agricultural products processing, transportation and other fields is producing a large number of scattering dust particles into the environment in the air, resulting in serious air pollution. Ambient air pollution posed a great threat on the health status of most of the world population. Particulate pollution which was the major sources of pollution in city contamination had attracted increasing majority of scientific researchers and environmental protection scholars at home.In natural environment, industrial production and transportation, particle of dust often present as the state of free falling or suspension. Therefore, researching on the interrelationship between free falling dust particles and ambient air under normal temperature conditions had become one of the most important topics in the field of exploring on the mechanism of dust particles and air pollution. Meanwhile, the frictional resistance coefficient between particle stream and surrounding fluid which is often obtained by experimentation is one of the most difficult parameter in research.In this paper, basing on coupling rule of gas-solid flow theory, the mathematical model of frictional resistance coefficient of single particle in free falling particle stream has been found. With existing experiment condition of free falling particle plume experiment table, the experimental installation which is used for technically exploring the frictional resistance coefficient of particle streams in free falling process was designed for dynamic experiments. Through theoretical analysis and experimental research, explore the resistance effect of particle stream which is caused by ambient fluid and the coupling relationship between parameters of environmental fluid and particle. Ultimately, the Frictional resistance between ambient air and particle plume in free falling process was described by physical parameters which were falling head of particle plume, mass flow rate, particle size, particle density, bulk density, section start geometry radius of particle plume and velocity of surrounding fluid. Furthermore, using a large number of experimental results fit the experience formula of frictional resistance coefficient between single particle and ambient air in free falling particle stream.