Determining reverse flows using modified propeller-Type current meters in water turbine tests

Abstract

Short hydraulic turbine intake causes irregular flow velocity distribution, sometimes leading to localized reverse flows in available measurement cross-sections. Standard, propeller type current meters do not have the technical ability to distinguish the direction of flow and therefore, in unfavorable flow conditions, they affect the value of the measured flow rate. The paper presents the technical implementation of the bi-directional fluid velocity measurement method using modified propeller-Type current meters. The flow characteristics for two different current meters in forward and reverse flow directions were investigated, showing the differences. A case study on the hydroelectric power plant was also presented. Computational fluid dynamics (CFD) calculations of the flow conditions in the inlet channels of the Kaplan-Type turbine were carried out, which revealed the areas with reverse flow present in only available measurement cross-section.