RESEARCH IN RESISTANCE AND PROPULSION PART 3: BLOCKAGE CORRECTION IN A SHIP MODEL TOWING TANK AND SCALE EFFECT ON PROPULSIVE PARAMETERS

The most important parameter governing the blockage effect is that of blockage ratio. Blockage ratio is simply defined as the ratio of the maximum cross sectional area of the model to that of the towing tank. The lower limit of blockage ratio below which the blockage effect has normally been considered to be negligible is 0.006. Results of experimentation indicate however, that in addition to blockage ratio both the speed-length ratio and the block-coefficient play an important role in the determination of the blockage effect. At the inception of self-propulsion testing, the model sizes were chosen to be 14 feet, in order to avoid serious scale effect on the propeller performance. The first three self-propulsion tests were made with Series 60 forms of block-coefficients Cb = .60, .75, and .80. The blockage ratio for these models ranged from .0072 to .0100.(See also PB-163815)

• Corporate Authors:

  University of Michigan, Ann Arbor

  College of Engineering
  Ann Arbor, MI  United States  48109
• Authors:
  • Kim, H C
  • MOSS, J L
  • Couch, R B
• Publication Date: 1963-3

Media Info

• Pagination: 54 p.

Subject/Index Terms

• TRT Terms: Engine efficiency; Model basins; Propulsion; Tests
• Uncontrolled Terms: Blockage
• Old TRIS Terms: Propulsion tests; Propulsive efficiency
• Subject Areas: Design; Marine Transportation;

Filing Info

• Accession Number: 00027647
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: 04542-3-F Final Rpt
• Contract Numbers: MA-2564
• Files: TRIS
• Created Date: Jul 9 1973 12:00AM