Investigation of liquid viscosity influence on flow rate measurement by rotary vane meters
Keywords:liquid measurement, rotary vane meter, viscosity, measurement errors, pressure drop, leakage through gap
The influence of liquid viscosity on the flowing volume measurement accuracy by rotary vane meter is investigated experimentally and numerically.
Experiments are performed in 4 different liquid fuel (diesel, petrol and 2 type of kerosene) flows using the volumetric and gravimet-ric methods. Experimental results are summarized considering errors variation with dependence on Reynolds number ReD. It is shown that error curves have peak values, which indi-cate the transition from the dominant laminar flow to the turbulent flow regime or, otherwise, dividing line between low and high ReD number regions. At low ReD, number leakages through the gaps between the meter vanes and housing as well as errors strongly depend on mechanical friction of the meter’s rotor and hydrodynamic friction due to liquid viscosity. In this ReD number range, variation of pressure losses follows the regularity pattern typical for the laminar flow regime. At high ReD number, as a conse-quence of flow turbulization in the meter passage, error variation follows a unique dependence on ReD number. However, liquid viscosity influence on leakages through the gaps remains. When ReD number approaches values 106, the errors approach the constant asymptotic value.
Numerical simulation confirms the basic pre-sumption used, but it also shows urgency to estimate peculiarities of a complicated movement structure in be-tween the vanes spaces and their impact on leakages through the gaps, taking into account Re number.