Optimal design of wide viscosity range turbine flow sensor based on flow field analysis

Abstract

Viscosity of liquid is the main factor affecting the performance of turbine flow sensors. The influential mechanism is explained by analyzing the turbine flow sensor's internal flow field within a wide viscosity range. The results suggest that the velocity profile at the impeller inlet and the fluid leakage, affected by the viscosity, significantly influence the turbine flow sensor performance. Therefore, two methods were proposed to optimize the structure of turbine flow sensors. One was optimizing the ratio of the sensor hub radius to the housing inner radius to reduce viscosity's influence on the velocity profile. The other was optimizing the impeller length according to the velocity profile at the highest viscosity to minimize the impact of leakage flow. A new evaluation index was proposed to evaluate the turbine flow sensor's performance in the wide viscosity range. A series of 10 mm diameter turbine flow sensors were designed and manufactured. CFD simulation and experiments were carried out to verify the optimization design. The results show that within a kinematic viscosity range of 1 × 10−6 m2/s～50 × 10−6 m2/s, Ecvwas less than 5%. The comparison of test results before and after optimization showed that the optimized structure was more suitable for flow measurement with a wide viscosity range.