PRELIMINARY CONSIDERATIONS IN THE DESIGN OF A LUDWIEG TUBE FOR HIGH REYNOLDS NUMBERS
Abstract
Larger aircraft operate at Reynolds numbers above 10 to the 7th power which happens to be the upper limit of experimental information. Designers depend heavily on extrapolating available test results for minimum drag, maximum lift, and boundary-layer phenomena. Estimation of the last item is least reliable and involves the higher risks. There is a real need to extend experimental information to higher Reynolds numbers. Reynolds numbers of 10 to the 8th power are needed now; 4 x 10 to the 8th power can be projected as a need for 1980; and (10 to the 9th power) is a possibility for 2010. If air is used as the wind tunnel fluid, the higher Reynolds numbers can be obtained almost exclusively by high pressures, static and dynamic. This causes the wind tunnel dimensions to be directly proportional to the Reynolds number. Practically, the wall thickness depends essentially on the Reynolds number and the diameter depends on model stresses. If a Ludwieg tube is contemplated, a minimum pressure of about 4 atm simultaneously establishes a maximum tube diameter and a minimum model stress. The length of a Ludwieg tube depends on specified time for a run and attaining uniform flow.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1968
- Accession Number
- AD0665115
Entities
People
- L. J. Fila
Organizations
- Arnold Engineering Development Complex