The Centre-Line Mach-Number Distributions and Auxiliary-Suction Requirements for the A.R.A. 9-ft x 8-ft Transonic Wind Tunnel

摘要

Measurements of the centre-line Mach-number distributions have been made in the Aircraft Research Association 9-ft x 8-ft Transonic Wind Tunnel over the range of Mach numbers from 0•6 to 1• 4. At subsonic speeds up to M = 1.00, a standard of flow uniformity corresponding to △M = ± 0.002 was achieved over a test-section length of about 6 ft. Between M = 1.00 and M = 1.10, when the supersonic stream is generated merely by auxiliary suction through the perforated walls, significant improvements in flow uniformity were achieved by modifications to the open area distributions at the upstream end of the side perforated walls and as a result, △M ≤± 0.005 up to about M = 1.10. At M = 1.10, the uniform flow is generated within a distance of about 0.4 x tunnel height from the start of the perforated plate.