Assessment of the Impact of Pressure Changes in the Flow Path on the Biological Safety of an Axial Hydraulic Turbine with Increasing Thickness of the Impeller Blade

The issues of improving the environmental safety of energy facilities, in particular small hydroelectric power plants, which make it possible to effectively use local energy resources, including the ones for remote and autonomous consumers, are considered. With the increasing number of small hydroelectric power plants in the world, there is a need to ensure their biological safety in order to reduce the impact on the biological environment of reservoirs. Currently, a number of technical solutions are available, in particular for impellers of hydraulic turbines, which allow reducing possible negative consequences for the environment. However, these proposals are mainly aimed at combating the physical impact of a collision with the mouth, while matters related to energy efficiency and other types of negative impacts, such as barotrauma, remain open. The present article examines the effect of blade thickness on efficiency and biosafety when exposed to a pressure drop. The impeller of an axial hydraulic turbine was created and tested for the study. With the help of CFD and the BioPA technique, the dependences of survivability on different blade thicknesses were determined, and the dependence of the efficiency of a hydraulic turbine on survivability, calculated from the pressure drop, at different blade thicknesses was obtained. The obtained results show the importance of creating biologically safe impellers of hydraulic turbines, taking into account various quality indicators, in order to obtain both effective and safe solutions.