STATISTICAL-METHOD TO EVALUATE THE CRITICAL REYNOLDS-NUMBER FOR PSEUDOPLASTIC FLUIDS IN TUBES

An experimental, non-intrusive tube system with appropriate instrument ation for measuring pressure drop and mass flow rate was developed to investigate the departure from laminar flow of pseudoplastic fluids (a queous solutions of sodium carboxymethylcellulose). A critical Reynold s number was selected to correspond to the intersection of the two lin es joining the laminar and turbulent flow data on the pressure drop ve rsus Reynolds number plots. The standard deviation of pressure drop in creased at these critical points. Results also indicated large spikes at these points in the plots of variance ratio of pressure drop versus the critical Reynolds number. This phenomenon could form the statisti cal basis for establishing the departure from laminar flow. In the lam inar region, standard deviations were low, suggesting calm, stable flo w of the fluids, a well known characteristic of laminar flow.