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).
Explanation of temperature variations in engine induction pipes and the effect on fuel evaporation.
Identifier | WestWitteringFiles\O\2January1926-March1926\ Scan82 | |
Date | 12th February 1926 guessed | |
contd :- -2- to the considerable difference in temperature existing over various parts of the hot spot and even the maximum and minimum temperature positions did not correspond for the water and exhaust.systems. At one time we thought that the rise of temperature in the induction pipe relative to the air at the carburetter intake would afford a simple and reliable method of comparing the various systems, but after tests even with this were found to have limitations which we think may be satisfied by the following explanation :- With a fuel of low volatility the charge in the induction pipe at the low temperatures would consist mostly of unevaporated fuel and any heat supplied by the hot spot would, we should expect, give an increase of temperature in the induction pipe. If however the outside air was near the temperature at which the bulk of the fuel evaporated, the same amount of heat would result in only a small temperature rise and then go to supply the latent heat of evaporation. Although in this latter case the temperature rise would be less than previously, the engine would receive a more homogeneous mixture. Variation in the outside air temperature from test to test was unavoidable and it also naturally increased after the engine had been running for a time. However, we put forward readings for the actual temperatures recorded in the induction pipe and have selected such curves from the tests that have, as near as possible, the same outside air temperatures. contd :- | ||