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).
Bench tests to ascertain the effect of air cooling on the output of a Bentley dynamo.
| Identifier | ExFiles\Box 62\3\ scan0438 | |
| Date | 24th July 1934 | |
| Ha/Wat.5/MA.24.7.34. DYNAMO COOLING TESTS. Tests have been carried out on the Bench to ascertain to what extent the output of a Bentley dynamo could be raised when the commutator and brush gear were cooled by an air stream. The hottest part of our dynamo is usually the brush gear and commutator, so for the purpose of this preliminary experiment a special end cover was constructed with a pipe or orifice attached which could be connected to an air supply under pressure. The cover was also supplied with two additional ventilating windows to allow the hot air to escape. (1) As a basis of comparison, the amount of cooling obtained by allowing free access to the commutator and brush-gear of still air at atmospheric temperature, (as represented by running with the end-cover off) was taken as standard. An idea was then obtained of the air flow necessary to produce a similar cooling with the commutator etc., almost totally enclosed. The extent of cooling was measured in terms of increase in output for the same temperature rise of 55°C. Tests were made at minimum and maximum speeds, with a maximum air temperature of 33°C. TESTS. Output at 13.0 Volts. Condition. At Min. speed (1380RPM) At Max.Speed (5250RPM) Normal (end-cover on) 17.0 amperes. 11.7 amperes. End cover removed 20.0 amperes. 13.5 amperes. Ventilated end-cover 20.0 amperes. 13.5 amperes. on and low rate of flow of air; roughly equiva- lent to very light breeze. | ||