Analysis and identification of the flow pattern in a specific high-pressure axial turbine in off-design conditions

The aim of this research is to identify the flow pattern in off-design conditions of a specific high-pressure axial turbine. by writing the preliminary design code, the turbine was designed, Then the geometry of this turbine was designed in CATIA and Ansys Design Modeler softwares, and it is meshed in Turbogrid software. the turbine is analyzed using the Ansys CFX software at 12 points in off-design conditions. with fixed rotor speed ratio, inlet static pressure ratio was changed. Then with fixed inlet static pressure ratio, the rotor speed ratio was changed. With the increase of the inlet static pressure ratio, the Mach number of the flow reached above one and the turbine efficiency dropped significantly. Reducing the inlet static pressure ratio to a certain extent improved the performance of the turbine; But with a further drop in the inlet static pressure ratio, the turbine efficiency began to decline. the working conditions at the inlet static pressure ratio of 0.9 are better compared to other working points and the turbine efficiency reaches 0.93. With changes in the rotor speed ratio, the areas prone to flow separation around the turbine blades increased, especially on the suction surface of the rotor blades.