The turbulent flow-field characteristics in a 180° curved duct with rectangular cross-section were investigated.The profiles of tangential velocity and pressure were measured by using five-hole probe and simulated by FLUENT 6.2.The results showed that centrifugal force was generated as the fluid rotated,which contributed to the change of tangential velocity and pressure.Tangential velocity increased and pressure decreased in the section between 0° and 60° when the fluid rotation began,while tangential velocity decreased and pressure increased in the section between 60° and 180° near the inner wall.On the contrary,the tangential velocity decreased and pressure increased in the section between 0° and 60°,but tangential velocity increased and pressure decreased in the section between 60° and 180° near the outer wall.This investigation indicated that turbulent flow-field characteristics in the 180° curved duct could be understood by combined experiment measurement and numerical simulation.
The characteristics of pressure fluctuation in a standpipe at negative pressure gradient were investigated based on measurement in the gas-solid two-phase circulating fluidized bed(CFB).When the solid particles flowed downward from low pressure part to high pressure part in the standpipe, the particles compressed the gas entrained by them, which resulted in the instability of gas-solid two-phase flow.This instability was shown as pressure fluctuation, undulating particle velocity and uneven concentration.The range of pressure fluctuation was related to the negative pressure gradient in the standpipe.
