Studies of Upper Surface Blown Airfoils in Incompressible and Transonic Flows.
Abstract
Asymptotic and computational methods have been utilized to study the incompressible and transonic flow over upper surface blown airfoils. To provide a framework for more approximate simulations which are subsequently discussed, a full potential formulation is given and various numerical treatments are proposed. In this and the other models, the problem has been decomposed into the treatment of the fine structure of the jet and the analysis of the flow outside of it. Asymptotic expansions of limit process type have been used to treat the jet in a thin layer approximation using suitable strained variables. Although vorticity must be accounted for in matching with the external flow, its effect on the Spence boundary conditions derived under irrotational assumptions is nil in regions away from the trailing edge and jet exit. A similar conclusion applies for compressibility. The condition of flow pressure and direction compatibility replacing the Kutta condition for the unblown configuration indicates that a dividing streamline leaves tangent to the upper surface of the airfoil at the trailing edge. Computational results for a USB airfoil indicate significant enhancements in lift with blowing. Comparisons with experiments indicate that viscous wall jet effects, wave interaction phenomena with the mixing zones near the jet exit and trailing edge layers must be incorporated into the model for improved simulation of the flow physics. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1980
- Accession Number
- ADA081179
Entities
People
- E. Cumberbatch
- J. D. Cole
- N. D. Malmuth
- V Shankar
- W. D. Murphy