DRAG, FLOW TRANSITION, AND LAMINAR SEPARATION ON NINE BODIES OF REVOLUTION HAVING DIFFERENT FOREBODY SHAPES

Resistance has been measured of nine bodies of revolution, having equal volume but varying forebody shapes. Forebody shapes ranged from extremely blunt to extremely fine and included two that were flat faced. The forebodies were altered by changing their length-to-diameter ratios (l/d's) and prismatic coefficients. Drag results indicate that when the prismatic coefficient is fixed and the L/D is decreased, the residual resistance will increase modestly. Increasing the prismatic coefficient at small L/D's increases residual resistance; however, at moderate L/D's it does not. The results suggest that a flat-faced shape in itself does not increase resistance. In addition to resistance experiments, transition regions on the models were located, using hot film probes. Calculations predicted laminar separation on five of the model forebodies. The hot film measurements confirmed that separation did occur at the locations predicted; downstream of the separation locations, turbulent flow occurred immediately. The remaining four forebodies exhibited well-defined natural transition regions. Flow properties in the transition regions, measured by the hot film gages, have been compared with predicted spatial amplification ratios of disturbances, calculated by linear stability theory. Results have failed to show a single relationship between measured flow properties and computed spatial amplification ratios. Correlation of amplification factors with flow regimes varied, both with forebody shape and Reynolds number. (Author)

• Corporate Authors:

  David Taylor Naval Ship R&D Center

  Bethesda, MD  United States  20084
• Authors:
  • Power, J L
• Publication Date: 1977-12

Media Info

• Pagination: 55 p.

Subject/Index Terms

• TRT Terms: Bluff bodies; Bodies of revolution; Boundary layer; Boundary layer flow; Boundary layer separation; Diameter; Drag; Flow; Laminar flow; Length; Measurement; Ratios; Resistance (Electricity); Reynolds number; Shape; Submarines; Turbulence
• Candidate Terms: Turbulent flow
• Old TRIS Terms: Blunt bodies; Boundary layer transition; Drag measurement; Laminar boundary layer; Residual resistance
• Subject Areas: Design; Marine Transportation;

Filing Info

• Accession Number: 00174784
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: DTNSRDC-77-0065
• Files: TRIS
• Created Date: Apr 26 1978 12:00AM