Turbine flowmeter response to transitional flow regimes

In this paper, acceleration and deceleration performance of turbine flowmeters was investigated in transitional flow regimes. Different flow meters and peak gas flow rates were used, with a step flow transition induced by rapid closing and reopening of the pipeline valve. Hotwire anemometry was employed as a reference method to assess the dynamic response of turbine flowmeters. Results of this study suggest a good dynamic response of turbine flowmeters in accelerating flows, with only a slight delay of the turbine rotation. However, in decelerating flows, the response of the flowmeter turbine was found to be slow, with characteristic time constants up to 35 s and large resulting over-registration of transferred gas volume. Our findings were quantified by multiple regression models for flowmeter response times and over-registered volumes, which were both find to drop with Reynolds number and increase with the flowmeter size. Understanding dynamic response is essential to evaluate dynamic errors and evaluate overall measurement uncertainty.