On the aerodynamic improvement of aircraft gas-turbine engine air intakes

This work is devoted to the development of approaches to the aerodynamic improvement of aircraft gas-turbine engine inlet devices. Air intakes, which are the main components thereof, must provide a sufficiently uniform flow at the compressor inlet. The goal of the work is to computationally assess the effect of the shape of the air intake duct midline on nonuniformity in the distribution of the flow parameters over the outlet cross-section. As the basic tool, a numerical simulation of 3D turbulent gas flows on the basis of the complete averaged Navier–Stokes equations and a two-parameter turbulence model was used. For one of the air intake configurations for an aircraft turboprop engine, the effect of the shape of the air intake duct midline on nonuniformity in the flow parameter distribution over the outlet cross-section was assessed. A numerical simulation of a 3D turbulent flow in the air intake duct showed a significant effect of midline shape variation on the coefficient of nonuniformity of the Mach number and pressure distribution over the outlet cross-section even in the case of fixed coordinates of two chosen points of the line at the duct inlet and outlet and a fixed direction of the line at those points. This makes it possible to reduce the coefficient of nonuniformity by choosing an appropriate midline shape. On the whole, this work shows that the shape of the air intake duct midline is an important factor, accounting for which allows one to reduce nonuniformity in the flow parameter distribution at the duct inlet without going beyond the design constraints on the air intake dimensions and flow inlet and outlet angles. The reliability of the results is provided by the consideration of a real-life air intake design and the use of the authors’ repeatedly verified method of numerical simulation. The results may be used in the aerodynamic improvement of aircraft gas-turbine engine inlet devices.