Vortex pumps are widely used in wide range of hydro-transportation applications. Main disadvantage of this type of pump design is low efficiency. Despite ongoing effort to improve vortex impeller performance precise algorithm for their optimal design doesn't exist. One of the ideas is to use winglets (super-vortex) on the tip of the impeller blades. Conducted literature studies have shown that there is not yet clarified principle of winglet design. Authors have performed numerical simulations and measurements for three different arrangements of winglets with varying impeller coverages. From the obtained results recommendation for optimal winglet placement is deducted.

This work focuses on methods of submersible sewage mixer performance evaluation comparison. In the paper an experiment with a submersible mixer with a published and known geometry has been presented. The authors measured thrust, torque rotation speed and electric power. Experiment was compared with results obtained with a steady state numerical simulation. Next CFD results were checked with a theoretical approach for the mixing range. Both theoretical and numerical methods showed good applicability for the industry.

The article presents the results of experimental and numerical tests of a water turbine. As the object of the research the middle size Francis turbine, characterized by a middle value of specific speed, was taken into consideration. The primary aim of the realized project was to explain the occurrence of a high vibration level in a partial load operation. It was realized by the application of the superposition of experimental methods and a numerical simulation. The numerical results were verified on the basis of comparison with experimental results obtained for the real turbine. The numerical models were built with great accuracy to the reality and the flow was recognized, which allows to explain the reasons for random occurrence of high vibration in a draft tube and indicate a possibility of improvement of the analyzed object. The results of the numerical research such as distributions of velocity, pressure and vapor volume fraction in the passages were taken into consideration. The flow inside the Francis turbine and an outflow chamber were conscientiously analyzed. Pressure and velocity distribution as well as water surface structure were presented in the paper. Furthermore, the results numerical investigations helped to describe a cavitation rope vortex creation in the draft tube and the development of the air vortexes in the outlet chamber. Finally, the superposition of those phenomena was responsible for the deterioration of the turbine operation.