Archives—October 2010

Erosion Reduction By Air Entrainment Downstream Of A Stilling Basin

The CE Seminar this week, Thursday October 21, 4:00PM in Dow 642, will be presented by:

Ted M. Champagne

He will discuss:

Erosion Reduction By Air Entrainment Downstream Of A Stilling Basin

Abstract: Bed scouring at stilling basins downstream of gated spillways has been identified as posing a serious risk to the spillway’s structural stability. Although this type of scour has been studied in the past, it continues to represent a real threat to water control structures and requires additional attention. A 1/30 scale Froudian model of one such structure operated by the South Florida Water Management District was constructed at Michigan Technological University to further study this problem. Gates restricting flow were positioned at the spillway crest and at the end of the flume where the model was built to control the tailwater level. Provisions were made for injecting air into the water as it exited the stilling basing near the endsill. Positioned downstream of the stilling basin was a scour chamber filled with uniformly graded sand representing the channel bed. The “distance check” feature of an Acoustic Doppler Velocimeter was utilized during the experiments to determine when scour equilibrium was established for a particular case. The channel bed contour profile was measured after the scour hole reached equilibrium. Bed scour was studied under various scenarios where numerous water and air flow schemes were considered. These experiments show that utilizing air entrainment can result in scour reduction by up to 58%.