Abstract in English:

In the side-chambers of radial turbomachinery, which are rotor-stator cavities, complex flow patterns develop that contribute substantially to axial thrust on the shaft and frictional torque on the rotor. Moreover, leakage flow through the side-chambers may occur in both centripetal and centrifugal directions which significantly influences rotor-stator cavity flow and has to be carefully taken into account in the design process: precise correlations quantifying the effects of rotor-stator cavity flow are needed to design reliable, highly efficient turbomachines. This paper presents an experimental investigation of centripetal leakage flow with and without pre-swirl in rotor-stator cavities through combining the experimental results of two test rigs: a hydraulic test rig covering the Reynolds number range of 4 × 10⁵ ≤ Re ≤ 3 × 10⁶ and a test rig for gaseous rotor-stator cavity flow operating at 2 × 10⁷ ≤ Re ≤ 2 × 10⁸. This covers the operating ranges of hydraulic and thermal turbomachinery. In rotor-stator cavities, the Reynolds number Re is defined as Re = Ωb²/ν with angular rotor velocity Ω, rotor outer radius b and kinematic viscosity ν. The influence of circumferential Reynolds number, axial gap width and centripetal through-flow on the radial pressure distribution, axial thrust and frictional torque is presented, with the through-flow being characterised by its mass flow rate and swirl angle at the inlet. The results present a comprehensive insight into the flow in rotor-stator cavities with superposed centripetal through-flow and provide an extended database to aid the turbomachinery design process.