Model Experiments for the Design of a Sixty Inch Water Tunnel Part V

Abstract

A study of vaned elbows was made at the St. Anthony Falls Hydraulic Laboratory as part of the research program for the design of the proposed 60-in. water tunnel of the David Taylor Model Basin, Bureau of Ships, Department of the Navy. The shape, size, and spacing of the vanes to be used in the elbows were determined from the work of previous investigators, and model studies of the vane cascade were performed at the Laboratory as part of a broad research program in fluid flow diversion. Additional model studies of the assembled elbow were performed on a 1:10 scale model of the 6o-in. tunnel. From the model studies on the vane cascade, the optimum angular setting of the vanes was obtained, as well as data regarding pressure distribution and energy loss. The validity of the application of model results to a prototype was examined in the additional studies on the elbows in the model water tunnel. On the basis of this study, a cascade of vanes of the proportions shown in Fig. 44 of this report is recommended for use in the prototype tunnel. The vanes are to be used at a spacing-chord ratio of 0.48 and a stagger angle of 99 to 101 degrees. The miter line is to cross each vane at about 37 1/2 per cent of the chord from the leading edge. Structural analysis of these vanes indicates that they may be of either solid or hollow cross section without detrimental effects on stresses, deflections, or vibrations. The studies also indicate that the vaned elbows in the prototype tunnel will be free from cavitation.