Computational and Experimental Study of a Sector Cascade Consisting of Nozzle Vanes of a High-Pressure Gas Turbine

Experimental studies of blading from cooled gas turbines involve difficulties in simulating actual shape and operating conditions of the blades. Therefore, studies of linear turbine blade or vane cascades composed of blades that usually correspond to plane sections of real spatial turbine rows at the hub, at the middle diameter, and at the tip have received wide acceptance. When investigating linear blade cascades, the spatial effects that are crucial for the formation of the overall flow structure in the blade rows cannot be examined. Application of actual spatial turbine rows enables us to determine more reliably the causes and value of energy losses in turbine blade assemblies even under simulated operating conditions used in an experimental facility. Naturally, a study of a complete annular blade row seems most preferable. However, such studies require high costs associated not only with the manufacture of the turbine blading but also with provision of the required flowrate of the working fluid to conduct tests under conditions simulating the real operating conditions of the experimental object. In this case, the study of a sector cascade composed of full-scale cooled nozzle vanes is an acceptable alternative to testing a full-scale complete annular cascade. A sector cascade was tested at the Central Institute of Aviation Motors in a wide range of the reduced adiabatic velocity at the outlet (0.6–1.3) with cooling air ejection through perforation holes on the airfoil and end surfaces as well as through the trailing edge. The tests were performed under isothermal conditions when the temperatures of the working fluid and cooling air were almost the same. The total pressure fields upstream and downstream of the sector cascade were determined in the tests. The numerical study of the spatial structure of the flow and losses was carried out using the 3D NS and ANSYS CFX codes, which solve the 3D Reynolds-averaged Navier–Stokes (RANS) equations using various turbulence models.