Problem: The viscosity of a fluid is to be measured by a viscometer constracted of two 40-cm-long concentric cylinders. The diameter of the inner cylinder is 15 cm, and the gap between the two cylinders is 0.12 cm. The inner cylinder is rotated at 300 rpm, and the torque is measured to be 1.8 N. m. a) Derive clearly an expression of the torque T (show all your steps to get full credits) (15 points) b) Determine the viscosity of the fluid in Pa.sec c) Calculate the approximate power lost in friction (5 points) (5 points) 300 rpm 0.12cm Fluid Stationary cylinder Hint: Use the below equation to derive the viscosity Assumption: linear velocity profile in fluid, viscous flow, negligible end effects =300 rpm Shaft Viscometry Stationary cylinder . • . How is viscosity measured? A rotating viscometer -Two concentric cylinders with a fluid in the small gap e - Inner cylinder is rotating, outer one is fixed. Use definition of shear force: F=TA=μA- du dy If E/R cc 1, then cylinders can be modeled as flat plates. Torque T-FR, and tangential velocity VOR Wetted surface area Ax2RL • Fluid . Measure Tand to compute Wednesday 4 October 2017 b) FTA- MA d