Post Graduate Department Irrigation and Hydraulics, Punjab Engineering College, Chandigarh-11.
The Howell-Bunger valve is often installed in high dams and other control structures as a terminal regulating valve. It has a unique feature that it functions also as an automatic energy dissipator. When this valve discharges into a tunnel, a knowledge of the amount of the hydraulic energy dissipated by it and the type of flow in the tunnel is very important to the engineer. To study these aspects and also its discharge characteristic, an experimental study was made with a 222-mm Howell-Bunger valve discharging into at unnel of 1 m. I. D. Dimensionless graphs are given to determine the discharge coefficient, energy dissipation and the type of flow in the tunnel. Flow sections in the tunnel at different valve settings are also given. The efficiency of energy dissipation by the Howell-Bunger valve is compared with that of a hydraulic jump in a rectangular channel. It is found that except in the case of a large valve opening, flow in the tunnel remains supercritical in which case a device for further dissipation of energy is required and also there can be a danger of the valve being submerged by the hydraulic jump.
