Effect of eccentricity and inner pipe motion on flow instability for flow through annulus

Abstract

Present work implements the Energy gradient method (EGM) to study the effect of variation in eccentricity, radius ratio and inner pipe movement on the fully developed flow of Newtonian fluid through an annulus for the flow instability. The formula for the flow stability parameter has been derived considering the eccentricity and radius ratio of the annulus. Results have been plotted for flow stability parameter (K) for annulus of various eccentricity and radius ratio. Further, the relationships for the critical flow parameter have also been obtained. Flow instability is very crucial parameter in oil well drilling process as turbulent flow is desirable for the transportation of rock cuttings to the surface generated during the process.