Erosion of a Pipe Bend by Solid Particles Entrained in Water

The erosion process in a 90-deg pipe elbow is studied to determine the magnitude and location of the maximum wear point. A two-dimensional, theoretical model of the erosion process is set up to track the particle trajectories and then calculate the wear at impingement. Erosion tests on electroplated, 1-in. I.D. elbows are made using particle sizes which vary by over an order of magnitude, but the location of maximum wear for an elbow whose R/D value is 1.5 is almost unaffected. The average angle, φ, which locates the point of maximum erosion, is determined to be 85 deg, measured from the beginning of the curve. The average wear coefficient, K_e, is found to be 0.011. Another test using a more gradual bend curvature (R/D = 5.0, and a mitre bend tested as an approximation of an elbow with R/D value of 0.5, give similar results.) There are considerable discrepancies between computed and measured values of the position of maximum wear, because the model does not account for secondary flows. Finally, a simple technique is outlined to predict the erosion depth at the maximum wear point.