Determination of flow characteristics of weirs and bubble penetration depth in the downstream receiving pool

ABSTRACT Master Thesis DETERMINATION OF FLOW CHARACTERISTICS OF WEIRS AND BUBBLE PENETRATION DEPTH IN THE DOWNSTREAM RECEIVING POOL Fatma Zehra UNSAL Fırat University Graduate School of Natural and Applied Sciences Department of Civil Engineering 2005, Page :56 This study presents the results of a laboratory study on the flow characteristics of sharp-crested weirs, broad-crested weirs, and labyrinth weirs. The variation of the maximum bubble penetration depth and the over fall jet expansion for different weir types and shapes was investigated in relation to discharge, and drop height. Moreover, flow characteristics of over fall jet in an open channel system were studied. In this study, it is observed that the over fall jet expansion, bubble penetration depth and jet trajectory for different weir types and shapes are very different from each other. The results show that over fall jet expansion at the labyrinth weirs is significantly more than the trapezoidal sharp- crested weir, the rectangular sharp-crested weirs. It is demonstrated that the labyrinth weirs have the lowest values of bubble penetration depth among the weirs tested. Furthermore, it was demonstrated that the rectangular and the trapezoidal were observed to have the highest bubble penetration depth among all weirs. Hence, dimensionless equations were obtained for predicting the maximum penetration depth of bubbles of free over fall nappe, for trajectory of free over fall nappe, for jet expansion of free over fall nappe, and the length of the bubble zone of free over fall nappe. Key Words: Weir, Penetration depth, Jet expansion, Air entrainment, Aeration, Nappe, Jet trajectory, Bubble, Downstream receiving pool