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).
Tests on fuel boiling and temperature changes within a carburetter floatchamber under various engine conditions.
| Identifier | ExFiles\Box 179b\3\ img045 | |
| Date | 17th January 1933 | |
| -3- Anglo D.T.D.134 fuel, which was used on Exp.3 engine, may have some influence, so the fuel was changed to Anglo and further tests carried out. For definite observations of the fuel boiling a thermometer was inserted in the floatchamber drain plug to observe the actual temperature of the fuel when running. The tests take the form of a rated boost curve 2700 - 3000 R.P.M. and observations made with both ignitions and single ignition, to conform with the same conditions under which Exp.3 gave trouble. The appended curve shews the results. It should be noted that the fuel temperature in the floatchamber remains practically constant. The lower restriction washer .125 dia. of the carburetter water jacket was then removed and replaced by a washer having .095 orifice, in order to prove if the different restriction was the root of the trouble. The results which are plotted on the same curve show identical results to the .125 restriction. Further tests were then made in conjunction with the fuel boiling investigations, by removing all the restrictions from the carburetter jacketing system, allowing full bore flow, and maximum heating to the carburetter, a rated boost curve was taken and observations made of the fuel temperature in the carburetter floatchamber. Results appended. It will be noted that the temperature is only increased by 9ºC under these conditions and is far from approaching fuel boiling temperatures. Tests were then continued to prove where boiling does occur with a full bore water system and the necessity for restricting. In this respect a throttle curve was taken starting from 2500 R.P.M. at rated boost and throttling down to slow running. It will be noted from the curve that the temperature rise of the fuel is only slight at first, and then increases as the smaller throttle positions occur, and after 10 minutes running, the fuel temperature reaches 57ºC and the effect is only to richen the mixture from its original setting. This richening gradually increases and running becomes unstable but no trace of flooding occurs. | ||