Corrections for Lift, Drag, and Moment of an Airfoil in a Supersonic Tunnel Having a Given Static Pressure Gradient
Abstract
Reports from supersonic tunnels indicate that sometimes there exist in the working section undesired static pressure gradients due to design or construction flaws, which are difficult to eliminate. As a consequence, force measurements made upon models have to be corrected to agree with the forces to be expected in rectilinear flow. For incompressible flow the correction to be applied to the drag, in the case of a longitudinal pressure gradient is well-known. Because of the occurrence of a "horizontal buoyancy," the correction turns out to be equal to the product of the pressure gradient and the sum of volume and "apparent volume" of the test body, the apparent volume, like the real volume, depends only on the geometrical shape. The present analysis is an attempt to solve the analogous problem in supersonic flow under the most general conditions, which require corrections to be applied also to the lift and moment. A two-dimensional pressure gradient in both the longitudinal and transverse directions is considered, which is equivalent to a stream-angle variation along the tunnel axis. In the first approximation the computations must be expected to yield a superposition of well-known results. Hence, it is important to carry the calculations up to the second approximation, which includes a term characterizing the interaction between the airfoil field and that of the given pressure gradient.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1952
- Accession Number
- ADA377265
Entities
People
- H. F. Ludloff
- M. B. Friedman
Organizations
- New York University