Abstract
Conventionally, the use of an orifice for flow measurement is restricted within the range of Reynolds number as is prescribed by the standard to which our reference is made for flow coefficient, gas expansion correction factor, and so on. It is however necessary to have knowledge of the coefficient at lower Reynolds numbers, when the rate of flow to be measured possibly varies over an extensively wide range of the number.
This paper describes an experimental determination of the flow coefficient of an orifice for the steady flow whose rate is made to change over a considerably wide range of Reynolds number by the use of air, water and aqueous solutions of glycerine as fluid of flow.
By the use of the data obtained, an empirical formula is derived which expresses the coefficient as a function of the Reynolds number corresponding to the flow. This formula is found to be also applicable to direct calculation of the flow from the measurement of differential pressure without going through estimating thereof Reynolds number as long as only kinematic viscosity of the fluid at the time is known.
