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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).
Copy of an article from 'Automotive Industries' discussing constants for air orifices and Fliegner's formula.

Identifier  ExFiles\Box 27\2\  Scan296
Date  6th November 1934
  
x/775
COPY - FROM "AUTOMOTIVE INDUSTRIES"
JULY 19, 1930.
6.11.34.

CONSTANTS FOR AIR ORIFICES CHECKED.

Drop in pressure of air on flowing through circular orifice with rounded approach is used to determine rate of flow.

An investigation on the flow of air through circular orifices with rounded approach has been made at the Engineering Experiment Station of the University of Illinois, Urbana, by Joseph A.{Mr Adams} Polson, Joseph G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Lowther and Benjamin J.{Mr Johnson W.M.} Wilosn, and is reported in Bulletin No. 207 of the Station. There has been much work done on rates of air flow through orifices in the past, and the specific purpose of this investigation was to determine, by a precision method, the coefficients to be applied to Fliegner's formula for the flow of air. The method consists in weighing the air discharged per unit of time while controlling the pressure on the inlet side of the orifice.

Fliegner's formula is as follows :

M = 63.6 * (a / sqrt(T)) * sqrt(P2 * (P1 - P2))

where M is the amount of air discharged, in lb. per minute;
a, area of the smallest section of the orifice in sq.in.
P1, absolute pressure of the air at the entrance to the orifice in lb. per sq. in.
P2, absolute pressure of the air on the outlet side of the orifice.
T1, absolute temperature of the air on the entrance side of the orifice, deg. F.{Mr Friese}
  
  


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