抄録
The use of pneumatic transmission lines in automatic control and instrumentation reqires accurate knowledge of their dynamic response. Many researchers have dealt theoretically and experimentally with the frequency, step and/or impulse responses of fluid lines. The basic differential equations expressing the dynamics of the fluid lines are continuity, equation of motion, energy equation and equation of state for gas or liquid. These equation are very complex, so many researchers have made some assumptions and solved these equations by use of the methods corresponding their own objects.
In this paper, these assumptions, procedures for solutions and solutions are compared with each other. The approximately basic equations are classified into two large groups. The first group consists of the Navier-Stokes equation and the linearized equation of energy equation with respect to fluid velocity, and the solutions derived from these equations express the radial distributions of temperature and fluid velocity as well as the axial deviation of pressure and velocity. But the physical considerations with regard to dynamic response are very difficult, because the solutions consists of Bessel functions. The equations of second group are the linearized ones of Euler's equation of motion and continuity. By this solution it is found that the behaviour of pneumatic transmission lines is comparable to an electric cable involving distributed constants, thouth only the axial deviations of pressure and fluid velocity are specified by the solution.
The dynamics yet to study on the pneumatic transmission lines are as follows:
(1) the effects of end-point's impeadances of transmission lines
(2) theoretical examinations of resonance phenomena in pressure attenuation curve
(3) the change of various factors by large disturbance
