A NEW APPROACH TO PREDICT THE CASCADE EFFECT IN TURBINE FLOWMETERS APPLIED TO LIQUEFIED PETROLEUM GAS

The measurement of transferred quantities of liquid products is essential in multiple industrial activities. Turbine flowmeters are largely employed, especially in custody transferring applications, due to their high accuracy and wide operational range. Analysis and improvement of turbine meters behaviors require specialized mathematical tools, once the constructive characteristics of multiple blades impose challenges to the determination of lift and drag coefficients. The appliance of the integral method Blade Element Theory (BET) without the evaluation of the cascade effect can lead to overestimation of turbine performance. The present work proposes an innovative and semi empirical cascade effect correction within the BET model to estimate the hydrodynamic behavior of turbine flowmeters in a Liquefied Petroleum Gas (LPG) plant. The model provides a strategy to correct the cascade effect on the rotor annular section, accurately predicting lift and drag coefficients at various blade sections. Operational parameters of the studied turbines, obtained from computer modeling, are compared to field data of an existent plant, in several conditions. Computational fluid dynamics (CFD) techniques are employed for the analysis. The validation of CFD model comprises the comparative analysis between numerical results and in-situ data acquired in the regular operation of the measurement system. The results indicate that the proposed model based on BET is able to predict the turbine flowmeter performance and provides precise estimative for field results of angular velocity and linearity.