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).
List of five conclusions from an investigation into air discharge through orifices using Fliegner's formula.
| Identifier | ExFiles\Box 27\2\ Scan297 | |
| Date | 30th October 1934 guessed | |
| -2- The following conclusions were arrived at :- First - The weight of air discharged through orifices with rounded approach agrees very well with that calculated by the use of Fliegner's formula for the range of inlet pressures used in this investigation, namely, 1 in. of water to 35 in. of mercury. Second - The coefficients as applied to Fliegner's formula show a more rapid change for low pressures on the inlet side of the orifice and for small orifices. As the inlet pressure is increased and as the orifice diameter is increased the value of the coefficient tends to become more nearly uniform. Due to the rapid change in the value of the coefficient at low heads, interpolation cannot be made as definite as at the higher heads, where the value of the coefficient is more nearly constant. It is, therefore, not advisable to use this type of orifice for pressures on the inlet side of the orifice less than 10 in. of water, unless the orifice is carefully calibrated for the required condition. The change in the value of the coefficients is slight for inlet pressures above 10 in. of water for pressures up to 35 in. of mercury, the limit of this investigation. Third - It is advisable to use water or oil as the manometer liquid for all pressures within the limit of the manometer. For the higher pressures mercury should be used. However, mercury should not be used in glass tubes of less than 3/8 in. inside diameter. Capillary tubes of 2 to 3 millimeters inside diameter are likely to introduce considerable lag in movement both up and down. Fourth - The use of Fliegner's formula with a coefficient of unity for inlet pressures between 1 in. of water and 35 in. of mercury may introduce errors ranging from 6.2 per cent too high to 0.5 per cent too low. Fifth - The type of orifice used is not difficult to produce, and the results on test on duplicate orifices agree closely. | ||