Nathan Cox, Harold Huff, Robert Einhellig, Connie Svoboda, Warren Frizell. 2010. "It's a Bird, It's a plane, It's a Super-Cavitating Baffle Block - Characteristics of Energy Dissipation". Bureau of Reclamation, Report Number PAP-1024.
Abstract: The proposed Folsom Dam auxiliary spillway will be built near the left abutment of Folsom Dam. Folsom Dam is on the American River about 20 miles northeast of Sacramento, California. The dam was designed and built by the Corps of Engineers (Corps) and transferred to the Bureau of Reclamation (Reclamation) for operation and maintenance in 1956. The dam is a 340 foot high concrete gravity structure and impounds a reservoir of a little more than one million acre-ft. The current flood release capacity of the main spillway is approximately 518,000 ft3/s. The proposed auxiliary spillway control structure houses six 23 feet wide by 34 feet high submerged tainter gates with an additional release capacity of 312,000 ft3/s. The control structure discharges into a 2,100-foot-long chute, which conveys flows to a stepped chute, stilling basin, and exit channel. Velocities entering the stilling basin are about 83 feet per second (fps) and 109 fps, for the design and maximum flow respectively. These are very high velocities for a stilling basin with baffle blocks and cavitation problems would normally be expected if a traditional shaped baffle block were installed. As part of Corps’ overall modeling for the Folsom Dam Joint Federal Project (JFP), several baffle block shapes combined with different schemes for ramps were analyzed in Reclamations Low Ambient Pressure Chamber (LAPC) to come up with acceptable super-cavitating baffle block and ramp combinations. The optimum baffle block shape and ramp combination was then tested in a 1:48 scale Froude scale model of the stilling basin and American River/Auxiliary Spillway confluence area. The 1:48 scale physical model showed that there was a difference in the energy dissipation characteristics of a traditional shaped baffle block and a super-cavitating baffle block and ramp combination. Different ramp shapes for the super-cavitating baffle blocks were also evaluated. The paper will summarize and compare the findings from the physical model with regard to energy dissipation characteristics between a traditionally shaped baffle block and a super-cavitating baffle block and ramp design.
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