Experimental study of piano key side weir with oblique keys

Side weir has many applications in water distribution and regulation in irrigation and flood control. For a constant opening length, weir crest can be design as labyrinth or piano key shape to increase the developed length and discharge coefficient. Another way to increase the side weir efficiency is oblique design, which make the weir crest aligned with the diverted flow. Combining the two noted approach leads to design a side weir with longer developed crest length and aligned with flow which has high performance. In this study, piano key side weirs with different key angles were studied. Flow characteristic including deflection angle and streamlines and also discharge coefficient were studied. Results show that angled keys aligned with the flow direction, increases performance of the piano key side weir up to 12 percent in high Froude numbers. Oblique keys can reduce the turbulence usually occurs in symmetric piano key side weir and results in higher discharge coefficient. The results can be used to design a side weir with which applied in conditions with high Froude numbers such as flood control.