Unsteady Flow of Gas in Long Circular Tube

Abstract

Analysis is performed, considering the energy equation, of the unsteady flow of gas in a long circular tube. Exact solutions of the pressure, axial velocity, radial velocity, density and temperature distribution on the cross section of the tube are obtained under the acoustic approximation. It is proved that the transfer constant of the pressure wave varies with the boundary conditions for the temperature. For the two typical boundary conditions, namely the adiabatic wall and the isothermal wall, numerical calculation is performed assuming the sinusoidal input. An important practical example of the above stated flow is the transfer characteristic of the pneumatic instrument line. To describe the transfer characteristics of the pneumatic instrument line, the transfer matrix is calculated and the graphs of numerical examples are given.