Study on performance improvements of a flow excitation system

Uncertainty of a flowmeter normally changes after long-term service, which brings about a difference both in steady-state and dynamic measurement result by the meter. In this paper, a piezoelectrically-actuated single nozzle flapper valve generates a short-rise time flow change as an excitation for dynamic flowmeter calibration. A commercially available piezoelectric stack is adopted for its fast response. The dynamic performance of the flowmeter is obtained by comparing the time between the pressure difference across the reference restrictor and the indicated flow rate. In order to widen the excitation flow and improve the linearity with the voltage applied, design of the return restrictor is studied. Due to ferromagnetic hysteresis, nonlinear compensation to the piezoelectric stack is implemented based on modeling the hysteresis effect. Simulation and experiments show that proper flow area of the return restrictor allows wider excitation flow rate range. The compensation on the stack can effectively improve the linearity of the excitation flow rate and the input required.