Theory and structure of a modified optical fiber turbine flowmeter

The measurement lower limit of traditional turbine flowmeter is too large to satisfy the measurement requirements of small flow rate. A modified optical fiber turbine flowmeter based on the traditional turbine flowmeter principle was purposed. The front guide vane was specially designed with a helix angle to reduce the measurement lower limit and improve the measurement sensitivity. The theoretical model for the modified flowmeter was established based on planar vector triangle of flow velocities. From theoretical analysis, the conclusion that if the helix angle of front guide vane plus the helix angle of turbine equals to 90°, the starting volume flow rate of turbine can get minimum value and the sensitivity of the flowmeter can get maximum value was found. The correctness of the conclusion was verified by the Computational Fluid Dynamics (CFD) simulation.