Accession Number:

AD0840750

Title:

DRAG AND PROPULSIVE EFFICIENCY OF SHROUDED AIR PROPELLERS IN AXIAL FLOW. AN ANALYTICAL REVIEW OF EXPERIMENTAL INVESTIGATIONS,

Descriptive Note:

Corporate Author:

DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD AVIATIO N AND SURFACE EFFECTS DEPT

Personal Author(s):

Report Date:

1968-07-01

Pagination or Media Count:

31.0

Abstract:

Experimental investigations of shrouded air propellers in which propulsive efficiency in axial flow was measured have been reviewed. A simple, semi-empirical formula, using either measured or estimated shroud drag, gives good predictions of the propulsive efficiency at Mach numbers below the drag rise Mach number, provided the shroud does not have appreciable drag due to separation or interference between its various parts. For each shrouded propeller, there is a range of thrust coefficients in which near-maximum efficiency occurs that helps determine that shrouded propellers applicability to a given aircraft propulsion requirement. Because of this characteristic, shrouded propellers for VTOL aircraft with good efficiency in both hover and cruise will probably have to have either variable intake lip geometry or variable disc area. Author

Subject Categories:

  • VSTOL
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE