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 discharge coefficients for nozzles, considering factors like bore size, length ratio, and skin friction.
| Identifier | ExFiles\Box 36\1\ scan 049 | |
| Date | 23th May 1917 guessed | |
| Contd. (3) (3) A column of average coefficients of discharge will be found in the table already given. It will be seen that the smaller the bore, the more rapidly is the coefficient of discharge lowered by increasing the length bore ratio. (4) We can judge from this that for still smaller bores than 3/64", the effect of skin friction in lowering the coefficient of discharge would be noticeable even with smaller length bore ratios than 10. Curves have been plotted as suggested in Mr. Elliott's memo E2/D16217, and in our memo EFC1/AT31.817, but these curves do not well show up the deviations from the law of cross sectional areas, and we are therefore not publishing them, believing that the simple set of "coefficients of discharge" already given will give all the information required in the design of petrol jets, and enable Mr. Elliott to judge the extent of the deviation from the law of areas in any particular case. The above results are for sharp edged entry to the nozzle. We will now have these edges rounded off to a radius equal to the bore and find if the discharge is appreciably increased. EFC. | ||