ERROR SHIFT OF A TURBINE GAS METER AS FUN CTION OF FLOW PROFILE

The paper presents a new empirical model for the calculation of the er ror shift of a turbine gas meter caused by disturbed velocity profiles in front of the gas meter. The model is based on an extensive catalog ue of fluid velocity profiles for different flow rates, perturbations (bends, diffusors, half plates, double bends out of plane) and distanc es between perturbation and turbine gas meter measured by a computer-c ontrolled laser Doppler velocimeter system. The flow profiles can be c haracterized by defining flow field parameters: the momentum-fluxes de scribing the two-dimensional distribution of the axial and tangential velocity component and the asymmetry of the flow characterized by an a symmetry number. These parameters quantify the influence of flow pertu rbations, swirl and deformation of the flow profile, and allow, in add ition, the error shift to be calculated analytically using a simple mo del based on only three flow field parameters. The developed model and the catalogue of flow profiles thus allow the error shift to be predi cted for many applications significant in practice, which is important for the practical use of gas meters.