Effect of the Rotational Central Shaft on the Flow and Heat Transfer of Rotating Cavity with Axial Throughflow

Flow structure in a rotating cavity with axial throughflow is a conjugate problem and strongly depends on the geometric parameters and boundary conditions. Due to the complexity of the actual aero-engine structure, the rotation ratio of the compressor discs and the central shaft changes within a certain range. In order to obtain the effect of the rotation ratio and hydraulic diameter on the flow and heat transfer, three-dimensional unsteady RANS simulations were conducted. The range of rotation ratio is −0.66 ~ 1, and the range of non-dimensional radius of central shaft is 0.221 ~ 0.287. The numerical results indicates that the rotation ratio has a significant impact on the region dominated by throughflow. Under the influence of different central shaft behaviors, the radial mixing extent of throughflow and cavity flow is different, which successively affects the mean swirl ratio and throughflow pressure drop. With the decrease of rotation ratio, mean swirl ratio decreases at a low radius and increases at a high radius. The heat transfer of the shroud increases significantly with the increase of the hydraulic diameter, but is not sensitive to rotation ratio.