Evaluating the Impact of the Decline of the Swirling Flow on Discharge Capacity in Two Cycle Crown Wheel Weirs

The effect of applying the crest weir vertical bar at the entrance basin was studied for controling the free vortex,.Experiments were conducted by changing angle of attack inflow to the reservoir α, in order to produce the vortex action. To study the effect of the inlet weir teeth, different scenarios were analyzed. In this study effect of slope of the crown wheel weir keys was evaluated too. The results showed that increasing the angle of approach flow of the intake location increases the strength of the vortex and consequently, reduces the coefficient of discharge flow. In other words by changing the angle of attack of zero flow from zero to 30 degrees and 60 degrees on an average 23.3 and 37.1 percent reduction in oefficient of flow discharge was noticed. . Results also showed that the best weir performance belonged to weir with the relative height of P/D and value of 1.5. Comparison of the results showed that under the terms of eddy current free morning glory spillway, the overflow crowns, can be considered as a viable alternative.