An Investigation of Interference Effects on Similar Models of Different Size in Various Transonic Tunnels in the U.K.
Abstract
Details are given of a program of tests being made on similar swept-wing models in transonic tunnels of different types. Force measurement results at subsonic speeds show only small interference effects for models of moderate blockage at low incidence; at higher incidences, the interference effect on lift becomes appreciably greater than estimated by theory, and significant pitching moment differences occur, apparently due to wall interference on the wing flow field. Comparable but smaller effects are evident in the results from the ARA 9ft x 8ft perforated tunnel. At speeds just above M = 1, the force fluctuates as speed is increased, because of wave reflection interference. The magnitude of the fluctuations diminishes as speed is further increased and this reduction is more marked in the perforated tunnel. Pressure measurements along the top of the body at zero incidence show delay in shock movements at high subsonic speeds indicating a blockage effect on speed; the effect is larger in the perforated tunnel though smaller than predicted by theory. Above M = 1, both expansion and shock waves are strongly reflected in the slotted tunnel but considerable alleviation, particularly of shock waves, is achieved in the perforated tunnel, for which an analysis of the effects is given.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1959
- Accession Number
- AD0661953
Entities
People
- A. B. Haines
- F. O'hara
- L. C. Squire
Organizations
- AGARD