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 analysis of leakage in relation to the number of rings and pressure.
| Identifier | ExFiles\Box 74\3\ scan0074 | |
| Date | 1st March 1917 guessed | |
| -2- EFC2/T22.3.17. Contd. The amount of leakage attains the same limit eventually independently of the number of rings. The limit is obtained when the ratio of the pressures is n times the limiting pressure ratio for one restriction (ring), where n is the number of rings. Thus the pressure at which the limit is reached is greater for a greater number of rings. If we suppose the pressure to be fixed at a moderate value, say a compression pressure of 125 lbs per sq. inch absolute, and the number of rings to be increased, this corresponds to running down a vertical line AA{D. Abbot-Anderson}, the leakage is greatly reduced by the addition of rings after the first three, but by a diminishing amount for each additional ring added. If the pressure be fixed at a large value, the addition of the first few rings (after the first) (i.e. running down line BB) does not later the leakage and the addition of subsequent rings only reduces it slightly. (The curves have not been drawn from calculation and are therefore somewhat in error). If the explosion pressure is 350 lbs per sq. inch which is 23.8 atmospheres and the limiting pressure ratio for one restriction is .527 = 1/1.90, the number of rings to be added before a reduction in the leakage takes place is given by 1.90^x = 23.8 whence x = 5 nearly and the addition of subsequent rings only reduces the leakage slightly, unless added in great numbers. Similarly for a compression pressure of 125 lbs/sq. inch number of rings before reduction takes place is given by 1.90^x = 125/14.7 whence x = 3 rings. (Contd) | ||