STRUCTURE OF GAS FLOWS IN TURBINE STAGE WITH NEGATIVE GRADIENT OF REACTIVITY DEGREE

The study has explored the flow in turbine stages with a negative gradient of degree of reactivity. Stages of this type were created using the tangential inclination of guide blades. The objects of research were two turbine stages. The first stage was a turbine stage with tangential inclination of guide blades. The lines of rounding centers of the radii of output edges of guide blades were rectilinear, lying in the r-u plane of the cylindrical coordinate system and inclined by 23 degrees in the direction of rotation of the rotor at the mean radius. The second turbine stage was created on the basis of the first stage. Тhe two turbine stages differed in that the lines of rounding centers of radii of output edges in the middle part of guide blades were also rectilinear and inclined by 23 degrees at the mean radius in the second turbine stage, but they were smoothly directed to the radius direction r at the root and the periphery. The calculation models of turbine stages were constructed in the Geometry and TurboGrid programs included in ANSYS Workbench. 3D testing gas-dynamic calculations were performed in ANSYS CFX. The pattern of gas flow in the meridian contours of the flow section and the configuration of the current lines on the root, middle and peripheral radiuses were analyzed in nominal mode for the two turbine stages. The graphs of summary characteristics of turbine stages (the efficiency index and the degree of reactivity at the root and periphery) in different modes were presented. The distribution of flow parameters in nominal modes was given by the height of the blade. The conclusion about the rational design of turbine stages with tangential inclination of guide blades were given.