Non-steady, isothermal gas pipeline flow

Abstract

What has been done in this thesis is to derive a numerical method to solve approximately the non-steady gas pipeline flow problem by assuming that the flow is isothermal. Under this assumption, the application of this method is restricted to the following conditions: (1) A variable rate of heat transfer through the pipeline is assumed possible to make the flow isothermal; (2) The pipeline is very long as compared with its diameter, the skin friction exists in the pipe, and the velocity and the change of velocity are small. (3) No shock is permitted. The isothermal assumption takes the advantage that the temperature of the entire' flow is constant and therefore the problem is solved without introducing the energy equation. After a few transformations the governing differential equations are reduced to only two simultaneous ones containing the pressure and mass flow rate as functions of time and distance. The solution is carried out by a step-by-step method. First, the simultaneous equations are transformed into three sets of simultaneous difference equations, and then, solve them by computer (e.g., IBM 1620 Computer which has been used to solve the examples in this thesis). Once the pressure and the mass flow rate of the flow have been found, all the other properties of the flow can be determined. Therefore the entire problem can be solved.