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).
Page from a document discussing the coefficient of contraction and discharge for fluid flow through various orifices.
| Identifier | ExFiles\Box 36\1\ scan 015 | |
| Date | 16th February 1916 | |
| R.R. 82A a (400) T(S.C. 656 16-2-16) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 1546. Contd. -3- (3) The contraction is imperfect and Cc is increased if the orifice is placed in a confined part of the vessel or if the water approaches the orifice through a channel. (4) Ditto. if the inner edge of the orifice is rounded. Cc between .63 & 1.00 Vena contracta orifice. Cc = 1 (5) See notes concerning value of C. Notes concerning the value of C :- (1) C diminishes as the head increases, but at a diminishing rate. Thus for a circular sharp edged orifice 1/16 sq inch area. C = .62 at 1 foot head. C = .61 " 2 feet " C = .60 " 10 " " (2) C is slightly greater (about 4%) for rectangular orifices of the same area at the same head. (3) C increases slightly as the area of the orifice. (4) C may be made nearly equal to Cv (i.e. Cc = 1) by properly shaping the orifice to suit the natural stream line flow. (5) C for a cylindrical orifice is about .825. Loss by shock occurs. Cv = C or Cc = 1. EFC. | ||