Optimal Chute-slope Adjustment for Avoiding Flip Bucket Abutment Erosion Due to a Flood Projectile Jet in Ogee Spillway

Abstract

Poor geometrical design of dam structures may lead to high-risk erosion problems. The unbalanced design of the spillway and flip bucket causes damage in different locations, especially impingement locations. Sustainable solutions should focus on modifying defective geometric dimensions that cause damage, rather than just repairing the damaged area. Numerical simulation of the modified profile is preferred to avoid expensive experimental field adjustments. A damaged existing dam in Africa was considered as a case study. Erosion in the rock steps that support the elevated flip bucket was observed during the ejection of the flood jet. The geometrical parameters of the spillway’s slope, flip bucket radius and lip angle were adjusted. Elongating the ejected water stream range away from the supporting area was accomplished. A numerical detached eddy simulation (DES) model was constructed for this desired objective. The high reliability of this model was early detected by the authors. The flow properties on two modified slopes of the chute were simulated numerically without any change in the original flip bucket properties. ANSYS FLUENT software was used in all simulation processes. The optimal modified slope model was determined. Within different operation stages, the performance of the new slope model was analyzed and compared with the optimal pre-determined parameters of the flip bucket’s modification. The optimal individual models of chute slope and flip bucket parameters were combined. The combination achieved a more reliable model for stabilizing the abutment. Jet velocity, trajectory length, total pressure and turbulent intensity results were recorded for the assessment stages.