Accession Number : AD0663747

Title :   ACOUSTIC AND BOUNDARY LAYER FLOW CHARACTERISTICS OF A FREE-FALL STREAMLINED BODY IN THE OCEAN.

Descriptive Note : Final rept. Sep 64-Nov 67,

Corporate Author : NORTH AMERICAN ROCKWELL CORP ANAHEIM CALIF OCEAN SYSTEMS OPERATIONS

Personal Author(s) : McNay,D. E. ; Plane,V. C. ; Hall,J. O. ; Cleveland,G.

Report Date : NOV 1967

Pagination or Media Count : 49

Abstract : Acoustical data on vehicle boundary layer flow was obtained on a 19-inch diameter, negatively buoyant body of revolution in free-fall through the upper layers of the ocean. The extent of laminar flow over the forward portion of the laminar airfoil shaped body varied from near zero to more than 55 percent of the basic body length of 63 inches. The extent of laminar flow was varied both by design, using boundary layer trips at different locations on the surface, and by the natural environmental conditions of the ocean. The most significant environmental influence was the varying relative ambient turbulence encountered by the vehicle as it passed with increasing speed through regions of differing characteristics, in its vertical dive from the surface. Within the experimental evidence, there is significant correlation between the sudden increase in the extent of laminar flow and the discontinuities in the temperature profile with depth as indicated by the bathythermograph record. The sound pressure spectrum level received at the nose of the vehicle as a self-noise measurement also shows significant correlation with the indicated extent of laminar flow. The analysis of the limited sound data leads to the conclusion that the sound levels in the 20 to 40 kHz range, received at the nose-mounted hydrophone, decrease as the transition zone from laminar to turbulent flow moves aft on the body. (Author)

Descriptors :   (*UNDERWATER VEHICLES, ACOUSTIC PROPERTIES), (*UNDERWATER SOUND, TEST EQUIPMENT), (*LAMINAR BOUNDARY LAYER, FREE FALL MODELS), BODIES OF REVOLUTION, HYDROPHONES, SEA WATER, DRAG, SONAR EQUIPMENT, DETECTORS, TURBULENCE, BOUNDARY LAYER TRANSITION, NOISE, HYDRODYNAMICS

Subject Categories : Test Facilities, Equipment and Methods
      Acoustics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE