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).
Analysis of steam pocket formation and air trapping in engine cylinder jackets under various operating conditions.
| Identifier | WestWitteringFiles\V\December1930-February1931\ Scan172 | |
| Date | 15th January 1931 guessed | |
| - 5 - water commencing to build up in the tank. This we think is aggravated by all the air not being driven out of the jackets when the engine is started. In Curve (2) of 211F. the tank was mounted in such a position that when full there should not be any air in the cylinder jackets before starting up. The effect of this is that the level in the tank remains constant until a temperature of 65°C. is reached before any building up starts and after which it is gradual up to a point and then remains constant even when the boiling is general. This shows formation of local steam pockets which do not after reaching certain proportions, increase. (b) AIR SPACE IN THE CYLINDER JACKETS. The greater the air space in the jackets at the commencement the more pronounced is the building up through the risk of air being trapped. Curves on 212F. illustrate this point. They compare the 'Fury' and 'Hart' tanks which were mounted as in the respective aircraft. The position of the 'Fury' tank is such that (Curve (1) of 212F) there is a greater air space in the cylinder jackets than with the 'Hart' tank (Curve (2) of 212F.); the result being that pockets form more readily and a rapid displacement of water takes place. (The engine speed was constant). (e) ENGINE SPEED. Curves on 213F. show that if an engine is run fast immediately after starting up there is a rapid accumulation of steam up to a certain point and then remains constant, and the final amount of steam generated when general boil occurs is much less than when an engine is warmed up at a slower speed. This means that the increased water flow checks the formation of steam pockets which once formed require a lot of moving. Curve 210F. illustrates the quantity of water displaced when warming up in the normal way and after the temperature reaches the normal figure of 80°C keeping it under control. When the temperature is under control and kept constant the water level remains constant. (This curve was quoted in a previous report) CONCLUSION. (1) In doing repeat tests during the investigation the volume of water displaced varied and the curves show the mean figures. This shows variation of steam pockets formed in the jackets. contd | ||