Experimental investigation of Centrifugal Flow in Rotor—Stator Cavities at High Reynolds Numbers > 10⁸

Authors

Tilman Raphael Schröder - Chair of Turbomachinery, University of Duisburg-Essen
Sebastian Schuster - Chair of Turbomachinery, University of Duisburg-Essen
Dieter Brillert - Chair of Turbomachinery, University of Duisburg-Essen

Abstract

The designers of radial turbomachinery need detailed information on the impact of the side chamber flow on axial thrust and torque. In a previous paper centripetal flow through narrow rotor—stator cavities was investigated and axial thrust, rotor torque and radial pressure distribution was compared to the case without through-flow. Consequently, in this paper the investigations are extended to centrifugal through-flow as it may occur in the hub side chamber of radial turbomachinery. This case is investigated here at conditions representative of high-pressure centrifugal compressors used in, for example, carbon capture and storage applications as well as hydrogen compression.To date, only the Reynolds number range up to Re=2×10⁷ is investigated for centrifugal through-flow, which is extended in this paper to Reynolds numbers of Re=2×10⁸. Results of experimental and numerical investigations are reported, focusing on the axial thrust generated by the radial pressure distribution in the rotor—stator cavity and the friction exerted on the rotor. The influence of Reynolds number, cavity width and centrifugal mass flow rate is shown, therefore extending the range of available valid data that can be used to design radial turbomachinery. The results are compared to results and models from scientific literature that are valid up to Reynolds numbers of Re=2×10⁷, showing that in the higher Reynolds number range a new correlation is needed. Finally, the analysis of velocity profiles and wall shear shows the switch from Batchelor to Stewardson type flow at high Reynolds numbers in comparison to the results reported by others for Reynolds numbers up to Re=2×10⁷.