REYNOLDS NUMBER DEPENDENCE ON THE EFFECT OF AXIAL STRESS ON UNSTEADY POLYVINYL CHLORIDE PIPELINE FLOW

Abstract

This paper studies the Reynolds number dependence on the effect of axial stress on unsteady pipeline flow. The unsteadiness is caused by sudden and gradual closure of the valve situated at the downstream end of the pipe. The effect generated by the unsteadiness is controlled by varying the Reynolds number (Re). Measurements were taken at different part of the pipe for a full and half closure of the valve at various Reynolds numbers. The pressure head obtained increase as Reynolds number (Re) increases, measurement clearly shows that Reynolds number majorly control the response of the pressure head although other factors like pipe geometry and wave speed which is a function of material properties and working fluid also contribute. Reynolds number control the magnitude but the wavelength of oscillation is unaltered. For all values of Reynolds numbers considered in this study (3750, 4125, 4750, 5250, 6000) with Polyvinyl Chloride (PVC) material used as pipe, its variation caused pressure head to increase, decrease with time until another steady state is reached which make it constant after a particular time for the Reynolds number considered.