Joseph P. Kubitschek. 2001. "Arrowrock Dam Mid-Level Outlet Works Rehabilitation 48-Inch Clamshell Gate Concept 1:10.67 Scale Physical Model Study". Bureau of Reclamation, Report Number R-01-02.
Abstract: A 1:10.67 Froude-scale physical model of the Arrowrock Dam outlet works clamshell gate concept was constructed at the U.S. Bureau of Reclamation’s Water Resources Research Laboratory in Denver, Colorado. Hydrostatic and Hydrodynamic pressures were measured to evaluate loading on the gate-house structure during submerged operating conditions. In general, the results establish proof-of-concept for use of clamshell gates to replace the existing mid-level outlets at Arrowrock Dam. The maximum static pressure differentials across any part of the structure, for all configurations tested, did not exceed 2.5 ft of H2O (1.2 lb/in2) for the full range of submerged operating conditions tested. Furthermore, the peak external dynamic pressure differentials about the static pressure differentials did not exceed 1.0 ft of H2O (0.44 lb/in2). Thus, a minimum total pressure differential of 3.5-ft of H2O (2.0-lb/in2) represents an adequate design value for the gate-house structure. Internal pressure differentials were also determined for design of the access hatches located on top of the gate-house structure above each gate bay. The results indicate that the maximum internal static pressure across the top of the gate-house structure did not exceed 0.75 ft of H2O (0.32 lb/in2) and the measured peak internal dynamic pressure differential did not exceed 1.0 ft of H2O (0.44 lb/in2.) Thus, the total internal load across the access hatches is not expected to exceed 1.75 ft of H2O (0.75 lb/in2) during submerged operation. Surface vortices were observed during model operation and indicate that air-entrainment is likely to occur for prototype submergences below tailwater elevation 3035 ft. These conditions are not expected to influence prototype performance of the clamshell gates, but are generally considered undesirable.
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