Transmission of Oscillatory Pressures through Instrument Pipe Lines (1)

Abstract

The amplitude of the oscillatory pressures, at in the course to be transmitted to the manometer through a long pipe, will be diminished and at the same time be accompanied with a phase lag owing to the inertia of the fluid (air) existing in the pipe and the frictional resistance of the pipe wall.
In my experiments a basic theory was developed at first in which the fluid in the pipe line as an incompressible tube was considered. The results of the experiments coincided, although very roughly, witsh the basic theory at the resonance frequencies and amplitudes. Rigorously speaking, however, it goes without saying that the velocity distribution of the fluid in the pipe and the variation of the frictional resistance with increasing frequencies had to be considered.
The theory of the oscillatory flow of fluid (air) in the circular pipe was developed and the velocity distribution, the increase of the frictional resistance and the total resistance coefficient including the inertia were calculated accordingly.
The corrected basic theory showed that the resonance frequencies coincided very well with the experiments, but the resonance amplitudes did not do so well.