The numerical simulation of the flow within a return channel is reported in this paper. The investigated return channel is typically to join the exit from one stage of a centrifugal machine to the inlet of the next stage. These channel covers the range of extremely low flow coefficients.
Different 3-D calculations with two different turbulence models (low-Reynolds-number k-ϵ and explicit algebraic Reynolds stress model) at the design point and part load range show the strongly three-dimensional flow structure with secondary flows on hub and shroud of the deswirl vanes. There are also significant separations downstream of the 180°-bend at suction and pressure side of the vanes.
The presented numerical results are compared with experimental data in different planes and at the vane contour. The results indicate small differences between the turbulence models in the prediction of losses, flow angles and separation behavior at design point. At off-design conditions the turbulence models begin to deviate notably in their prediction of separation.
