부산대학교 도서관

Modern radial-axial turbines operate in a wide range of operating points. One of the most interesting modes for research is the partial load operating point. This mode is accompanied by the formation of a precessing vortex rope in the draft tube cone, which causes pulsations. Previously the authors proposed a 1D-3D two-phase model and numerical method for investigation of this phenomenon. In this work, the previously developed model was extended in several ways. Two approaches are used to simulate the effect of air injection. The first approach is to assume that air is incompressible. The second model uses the assumption that the air intake process is adiabatic, i.e., there is no heat exchange between air and liquid. This assumption makes it possible not to add the energy conservation equation to the original model. The air density, in this case, obeys the barotropic law. Calculations of air injection were performed using two models. The amplitude-frequency characteristics were compared with each other and with experiment. It is shown that the proposed models can be used to predict changes in the amplitude-frequency characteristics of pulsations associated with air injection under the turbine runner. [ABSTRACT FROM AUTHOR]