Research on Wave Phenomena in Hydraulic Lines : 11th Report, Harmonic Waves in a Coaxial Double Pipes

Abstract

As a new one of the line elements employed to control and suppress wave transmission in hydraulic lines, the coaxial 'double' pipe is treated in the present report. The equation for a viscous wave flow between two cylindrical walls of different radii with the same axis is solved. for the case of periodical waves, the complicated solutions including many-valued complex Bessel functions of the 2nd kind are rigorously computed and conveniently approximated as well. In terms of wave transmission there exists an equivalent single pipe which well simulates the properties of a double pipe. Frequency response tests were successfully carried out in actual oil-hydraulic double pipes to verify the validity of the analysis. The experiment reveals that the wall elasticity works to reduce the velocity of sound much more in double pipes than in single ones.