Prediction Of Performance Of Rotameter With Different Fluids Using CFD

Abstract Rotameter is a variable area flow meter in which the position of the float indicates the flow rate of the fluid. Normally rotameter is calibrated with standard fluids (water and air). However when this meter is used with other fluids correction factors are applied to account for the change in the density of the fluid. In the present study a rotameter existing in the institute has been modelled and flow is analysed using the CFD software ANSYS FLUENT 14. The accuracy of CFD methodology is established for water flow by comparing the computed flow rate with the indicated flow rate over the entire range of the meter. Subsequently analyses have been carried out with four different fluids having different density and viscosity. It was observed that not only density of the fluid but also the viscosity of the fluid affects the performances of the rotameter. I t is concluded that if the viscosity of the fluid is higher than that of a standard fluid , the actual flow rate by the meter will be lower than the indicated flow rate by the meter even after applying the correction factor for density. The reverse is true for lower viscosity. A parametric study has been carried out by systematically varying density and viscosity of the fluid. It is concluded that for the rotameter analysed , the accuracy of measurement(after applying standard density correction factor)will be within ±2% as long as the density and viscosity of the fluid are within -20% to +15% and -25% to +35% of the corresponding properties of the standard fluid respectively