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).
The basis of comparison for orifices and the equations for the flow of liquids.
| Identifier | ExFiles\Box 36\1\ scan 013 | |
| Date | 21th February 1917 | |
| R.R. 25M A (990 T) (S.C. 686 15-2-16) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 1546. X.2907. -1- RE BASIS OF COMPARISON FOR ORIFICES. X.2907L/s-FLOW OF LIQUIDS THROUGH ORIFICES. The flow of a liquid through an orifice is given by the following equation :- Q = C.A, √2gh. or = Cv.Cc.A √2gh . P/σ WHERE Q is the quantity discharged (cubic feet per second). C is the Coefficient of Discharge. A is the area of cross dection of the orifice (sq.feet) g = 32.19 feet per second per second. h = the head over the orifice (feet). Cv is the "Coefficient of Velocity". Cc is the "Coefficient of Contraction". P is the pressure of the liquid just before reaching the orifice (lbw. per sq. foot). σ is the density of the liquid (lbs per cubic foot). The ideal velocity of discharge is √2gh feet per second and the actual is Cv.√2gh ft/sec. where Cv is a coefficient less than unity. The effective area of the orifice is Cc.A square feet, where Cc is a coefficient less than unity. Cv x Cc = C. (Coeff. of discharge). The quantities Cv, Cc, C are not absolute constants for different conditions, but suitable values of these must be selected to suit the particular conditions under consideration. Contd. | ||