Abstract
Applicability of the conventional discharge equation for estimating water abstraction by a torrent intake of bar screen type is experimentally investigated. The experiments carried out under a variety of hydraulic and bar screen conditions indicate that depending on length, slope and clearance of the bar, the discharge coefficient defined may take uneven values that are outside of its normal design range of 0.50 to 0.55. This implies that the conventional discharge equation is less versatile in designing a torrent intake. An alternative discharge equation is thus proposed which is expressed in terms of diameter, clearance and modified length of the bar, and its applicability is also experimentally tested. The results show that though use of the equation is limited to the intake with a bar sloping of less than 50°, it gives an appropriately even value of the discharge coefficient, i. e., 0.62, for different configurations of the bar. Experiments also show that in case that a deflector or an upright stoplog are installed in a water cushion to enhance the water abstraction form the intake, value of the coefficient should be taken as 0.68.
