Antierosion in a 90° bend by particle impaction

Ribbed bend protection, a new method to protect duct bends against erosion in gas-solid flows, was studied theoretically. In this method, ribs are evenly welded on the outer wall of the inside bend at 20degrees-80degrees, and the material of the bend is medium carbon steel. An experimental system is set up to perform 3-D numerical work simultaneously. Experimental and numerical results agree well and confirm that the method is simple and efficient for erosion protection. Numerical simulation is used to study the axial gas-flow characteristics along the bend and the secondary flow at the cross section. Detailed analyses involving the impact of velocity and the incidence angle of particle-metal (particle-rib or particle-duct) impact show the mechanism of the antierosion effect. As a result, both experimental and theoretical predications demonstrate that the average erosion rate of ribbed bends is only one-third of the bare bend under test conditions, and that rectangular ribs possess greater antierosion ability than square ribs do. Besides, the predictions suggest that the erosion of the wall is more serious than that of the ribs on a ribbed bend, while the wear distribution pattern remains unchanged after adding ribs at the bend.