Numerical Study on Varied Vortex Reducer Configurations for the Flow Path Optimization in Compressor Cavities

Abstract

In the internal air system of modern aero-engine, the cooling air is generally taken from the compressor platform, transported radially inwards towards the shaft and further transported to the hot parts. Since strongly swirling air is bled in the compressor rotor to a much lower radius, a means of vortices will be created, which lead to very high pressure losses and limit the cooling flow rate. The present work investigates the fluid flow for twelve kinds of vortex reducer geometries which utilize columnar baffles to divide the cavity into several chambers and avoid extensive vortex formation, therefore the pressure loss decreases and the flow mass increases observably. Based on the numerical study, the pressure loss is closely related to the curvature of the curve and the intersection angle (β) at the entry. Geometries of columnar baffles installed in the cavity include the straight angled degrees (0°,45°,60°) towards the radial and the curved such as Archimedean spirals (ρ = aθ, a = 12,20,30), hyperbolic spirals (ρ θ = a, a = 50,80,100) and logarithmic spirals (ρ = eα θ, α = 0.3,0.4,0.5). For the straight, the attention is focused on six and twelve baffles which are evenly arranged along the circumferential, but six ones for the curved. Otherwise, a key point is that the total volume of baffles is equal for different vortex reducer geometries. The results show that vortex reducer configurations with twelve baffles perform better than those with six baffles for the straight with the same angle. Compared with the straight radial baffle, the other kinds of baffles play better roles with respect to reducing pressure losses and gaining large flow mass. As a rule, the large pressure loss occurs when the curvature for the curved is large, because the flow direction changes greatly. A dedicated investigation about the influence of varied vortex reducer configurations is presented in this paper, particular discussions and conclusions are shown.