Optimum forebody shaping for axisymmetric submersibles with turbulent boundary layers and BLO (Boundary Layer Control) afterbodies
Abstract
One objective of the Advanced Undersea Vehicle (AUV) program is to design a low drag vehicle. The approach in this investigation is boundary layer control by means of an annular suction slot located on the afterbody. Although wind tunnel data showed significant reduction in propulsive power over conventional shapes, an attempt was made to achieve further reduction by means of forebody shaping. Two methods were used to vary the geometric parameters for this analysis. The direct method, based on the mathematical development of the Series 58 bodies, allows the definition of a shape by a fifthorder polynomial based on the four fundamental parameters of fineness ratio, nose radius of curvature, location of maximum thickness, and prismatic coefficient. The inverse method allows various velocity distributions to define the body shape. The shapes derived by this method have flat velocity distributions and show similar trends to the polynomial shapes (about 3percent reduction in propulsive power). The range of fineness ratios analyzed was from 1 to 10 at a volumebased Reynolds number of 3.2 million. In the range of 2.5 to 8, fineness ratio did not affect propulsive power more than 6 percent. A maximum improvement of 3 percent as shown by varying the meridian section.
 Publication:

Final Report
 Pub Date:
 July 1983
 Bibcode:
 1983nsrd.rept.....N
 Keywords:

 Boundary Layer Control;
 Drag Reduction;
 Mathematical Models;
 Shapes;
 Structural Design;
 Underwater Vehicles;
 Afterbodies;
 Hydrodynamics;
 Pressure Distribution;
 Submerged Bodies;
 Turbulent Boundary Layer;
 Fluid Mechanics and Heat Transfer