ESTIMATION OF A CRITICAL PRESSURE RATIO OF A PNEUMATIC PIPE-LINE AND ITS SIMULATION

Abstract

We considered the so-called Fanno flow as a model of flow through pneumatic pipe lines with a constant diameter. The flow is one dimensional, steady and adiabatic. The friction coefficient is constant. We succeeded to express the critical pressure ratio of the flow which is choking at the exit of the pipe line by three parameters, the pipe diameter, the pipe length and the friction coefficient. We compared the theoretically estimated critical pressure ratio to the experimental results. The results showed the good agreements except the case of the short pipe lines less than 10cm. It was confirmed that our method of determination of the ratio was very useful for the flow calculation using ISO choke equation. With these studies we established the simulation program for the Fanno flow on MATLAB_Simulink and show that the program was easily applied to connected pipelines in series.