Calculating secondary nonviscous gas flows in spatial cascades of turbines

The flow of an ideal gas in the stationary channels of turbine machines in the presence of an overall pressure gradient in the channel cross section is accompanied by secondary flows, which must be considered when optimizing the efficiency of the blading. The flow through a ring cascade which consists of the blading of a high pressure nozzle stage is studied numerically. The vorticity of the flow is specified in terms of the total pressure distribution at the input to the region being analyzed. The spatial flows modeled in this way are compared with a set of two dimensional flows at the axially symmetric surfaces of rotation (the main flow) for various total flow pressures and temperatures. The spatial flow of the gas is treated as the superposition of this main flow and the secondary flow which appears at surfaces with current lines orthogonal to the main flow. The total pressure in this numerical example is assumed to have a parabolic distribution with a maximum of 117 KPa and a minimum of 100 KPa; the temperature is 315 K and the flow entrance angle is 90 deg. The structure of the secondary flow is illustrated in different channel cross sections.