Wind Tunnel Wall Interference.
Abstract
Behavior of isolated holes and slots in wind tunnel walls was studied. The aerodynamic characteristics of these individual wall elements can be used to help understand the behavior of walls with multiple perforations. Potential flow analysis similar to that employed in the kernel function approach to lifting surface theory was used to determine the pressure differential versus flowrate relationship for various hole planforms in high speed subsonic flow. The effect of an imposed pressure gradient was also analyzed. Good agreement with slender-body theory results was obtained for low aspect ratio planforms. Although the finite hole problem resembles the lifting wing problem, there are significant differences: the pressure differential is known and the free surface shape is unknown; the Kutta condition is applied to the hole leading edge; and there are no wake effects in the hole out-flow problem. The analysis was extended to include the effect of an inviscid rotational power law boundary layer over the hole by using a shear flow aerodynamics kernel function. The effect of the boundary layer was determined for transverse slots and holes with various planform shapes. Presence of a wall boundary layer tends to reduce the flow resistance coefficient and, since the layer thickness may be comparable to the hole size, the effect is reasonably strong.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1984
- Accession Number
- ADA151212
Entities
People
- D. B. Bliss
- P. J. Lu
Organizations
- Princeton University