From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Methodology for measuring fan thrust and air velocity using a spring balance and revolving turntable.
| Identifier | ExFiles\Box 75\3\ scan0135 | |
| Date | 18th September 1924 | |
| EFC1/T18.9.24. -5- Contd. In the selected position, the indications of the instrument, duly corrected according to a correction curve supplied with the instrument, are exhibited as curves herewith of air velocity in feet per minute on a fan speed base. It will be seen that the air velocity, as would be expected, is roughly proportional to the speed. (3) Thrust of fan at various speeds, i.e. rate at which momentum is generated in the air stream. Arrangements are being made to carry out a series of tests with various fans in which the thrust of the fan is directly measured by means of a spring balance. A fan and motor rigidly braced together are being mounted on a revolving turntable with little friction, the axis of turning passing vertically through the motor in such a manner that the radius of action of the fan is 2 ft. 11.6". The radial motion of the combination is being limited between suitable stops and the various speeds obtained as desired by suitable electrical control. It is considered that the results obtained in such an experiment will be very much more valuable than those which can be obtained from the observed velocity of the air stream, as this is liable to differ so considerably with the position of the anemometer. EFC. | ||