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).
Continued report on fan testing, discussing available fans, methodology, and the relationship between fan thrust and cooling efficiency.
| Identifier | ExFiles\Box 75\3\ scan0015 | |
| Date | 19th November 1924 | |
| Contd. -2- A curve of a small ventilator fan is also given. It is understood that there will be available for the tests a further 40/50 fan with hanging back blades. There is further a special fan being made for these experiments on lines suggested to us by Prof. H.C. Watts of Ogilvie & Patners, Ltd. and a copy of his recommendations is attached. This fan is not yet ready but together with the 40/50 fan with hanging black blades will first be put through the thrust tests, following which, for reasons described below, all the fans which have not been subjected to power to drive determination tests will be so subjected. On the thrust speed curves the scale of thrust is in lbs. weight. The thrust of a fan is necessarily a measure of the rate at which momentum is generated in the air stream, but it does not follow that it is a proportional measure of the efficiency of the air stream from the point of view of cooling. It can be said with certainty, however, that it is a measure of this effect in the sense that an increase of one must necessarily be accompanied by an increased of the other, and vice versa, and in this sense we can look upon the thrust of the fan as a measure of the effect which it is the function of the fan to produce. Supposing always that the dimensions of the radiator are larger than those of the fan, it must be a fairly reasonable assumption to say that this still applies with | ||