DETERMINATION OF THE DESIGN PARAMETERS FOR OPTIMUM HEAVILY LOADED DUCTED FANS
Abstract
A single-rotation ducted fan of highest induced efficiency is characterized by an ultimate wake vortex system shed from the blade trailing edges whose apparent motion is that of rigid helical surfaces. In addition and concentric with this inner sheet system there is a cylindrical surface of helical vortex filaments shed from the duct trailing edge. For zero hub diameter and neglecting compressibility, viscosity, and tip clearance, a consistent mathematical model of the constant-diameter vortex wake is developed and the compatibility relationships to be satisfied are presented. It is shown that the wake vorticity and the velocity distribution in the wake, for all loadings from the lightly loaded limit to the heavily loaded static thrust condition may be extracted from the lightly loaded result through the use of a simple algebraic scale factor. The performance parameters, thrust, power and blade bound vortex strength, are thus expressed in terms of a lightly loaded solution for a given freestream velocity, blade tip speed, blade number and the loading parameter. The lightly loaded case is compared to existing theoretical and experimental results. Some sample results for heavily loaded performance parameters and design parameters are presented and compared to the exact results for a heavily loaded ducted fan with an infinite number of blades. Results for the heavily loaded system over a broad range of conditions are presented.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1969
- Accession Number
- AD0697802
Entities
People
- Terry Wright
Organizations
- Georgia Tech