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Vortex energy dissipator for San Diego ocean outfall; laboratory investigations

Brooks, Norman H. and Blackmer, William H. (1962) Vortex energy dissipator for San Diego ocean outfall; laboratory investigations. California Institute of Technology . (Unpublished)

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The sewage effluent from the new sewage treatment plant for the City of San Diego, located on a bluff 95 feet above sea level on Point Lorna, is discharged to the ocean through a long submarine outfall pipe. Under almost all conditions of flow, the hydraulic head at the treatment plant exceeds that required for flow through the outfall. Therefore, the excess energy must be dissipated in a special hydraulic drop structure located on the shoreline between the treatment plant and the ocean outfall. The laboratory model investigation described herein basically sought to find a method for dissipating this excess energy safely without heavy entrainment of air into the flow in the ocean outfall. Such air entrainment could cause unsteady conditions of the pipe flow, and possibly bubbling at the point of discharge in the ocean, both of which must be avoided. The responsibility of this laboratory was to develop the hydraulic principles and a recommended hydraulic configuration which would provide assurance that the prototype to be designed by the sponsors (Holmes and Narver-Montgomery) would give satisfactory hydraulic performance. Investigations From a study of the literature and engineering restrictions for the installation, it was concluded that the most satisfactory configuration would consist of basically a chute and stilling basin for the upper half of the drop, followed by a vortex tube structure with a tangential inlet for the lower half of the drop. First, five small scale models (28.5 : 1 prototype to model) were constructed and tested with various dimensions for the vortex tube and its inlet, and finally, one larger scale one (18 : 1) was built for testing the final recommended geometry (see Figs. 1 and 2). A simple pipe model (27 : 1) was also built for comparison. Models were operated in accordance with Froude's Law.

Item Type:Report or Paper (Technical Report)
Group:W. M. Keck Laboratory of Hydraulics and Water Resources
Record Number:CaltechKHR:KH-R-5
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Usage Policy:You are granted permission for individual, educational, research and non-commercial reproduction, distribution, display and performance of this work in any format.
ID Code:25979
Deposited By: Imported from CaltechKHR
Deposited On:03 Jun 2004
Last Modified:26 Dec 2012 13:50

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