Experimental and computational investigation on flow characteristics of rotating cavities with high inlet pre-swirl axial throughflow: Flow characteristics of rotating cavities with high inlet pre-swirl axial throughflow

As an integral part of the internal air system of aero-engines, the axial throughflow of the cooling air can interact with the cavity flow between the rotating compressor disks, forming a three-dimensional, unsteady, and unstable flow field. The flow characteristics in an engine-like rotating multi-stage cavity with throughflow were investigated using particle image velocimetry, flow visualization technology and three-dimensional unsteady Reynolds-Averaged Navier-Stokes (RANS) simulations. The focus of current research was to understand the distribution of the mean swirl ratio and its variation with a wide range of non-dimensional parameters in the co-rotating cavity with high inlet pre-swirl axial throughflow. The maximum axial Reynolds number and rotational Reynolds numbers could reach 4.41 × 10⁴ and 1.24 × 10⁶, respectively. The velocity measurement results indicate that the mean swirl ratio is greater than 1 and decreases with an increase in the radial position. The flow structure is dominated by the Rossby number, and two different flow patterns (flow penetration and flow stratification) are identified and confirmed by flow visualization images. In the absence of buoyancy, the flow penetration caused by the precession of the throughflow makes it easier for the throughflow to reach a high radius region. Satisfactory consistency of results between measurements and numerical calculations is obtained. This study provides a theoretical basis and data support for toroidal vortex breakdown, which is of practical significance for the design of high-pressure compressor cavities.