Effect of water and air injection on reduction of bend scour

Abstract

In the proposed method, air and water were injected into the 180° bend flow from both sides of a perforated tube to overcome curvature-induced secondary flows by creating a non-rigid barrier. The experimental results showed that the secondary flows were deviated from the outer bend causing a reduction in the maximum scour depth along the bend. The navigable width may also be increased by shifting the maximum scour depth from the outer wall to the centerline. On the other hand, the maximum scour depth was reduced by decreasing the distance between the perforated tube and the outer wall. For example, the maximum scour depth in the water and air injection main experiments at 130° section of the bend and two tube distances of 2.5 cm and 5 cm decreased by 88%, 91%, 63%, and 45%, respectively. With the increase in the Froude numbers, the maximum scour depth has increased.