Model Experiments for the Design of a Sixty Inch Water Tunnel Par III

Abstract

A study of the test section for a water tunnel was made at the St. Anthony Falls Hydraulic Laboratory as part of the research program for the design of the proposed 6o-in. water tunnel of the David Taylor Model Basin, Bureau of Ships, Department of the Navy. It was determined that the variation in velocity across the test stream would be less than one per cent everywhere except in the boundary layer, which would have a maximum thickness of ten per cent of the diameter of the test section. The pressure gradient and energy loss in the test section were computed assuming the test section boundary layer to be analogous to that of a plate in a uniform stream. The critical cavitation area in the tunnel circuit was found to be at the transition from the test section to the diffuser, and the corresponding critical cavitation indexes were calculated for several points in the test section.