Experimental Investigation of Centrifugal Flow in Rotor–Stator Cavities at High Reynolds Numbers >10⁸

• Main Authors: Tilman Raphael Schröder, Sebastian Schuster, Dieter Brillert
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: International Journal of Turbomachinery, Propulsion and Power
• Subjects: radial compressor side chamber; rotor–stator cavity; centrifugal through-flow; axial thrust; radial pressure distribution; Batchelor flow
• Online Access: https://www.mdpi.com/2504-186X/6/2/13

The designers of radial turbomachinery need detailed information on the impact of the side chamber flow on axial thrust and torque. A previous paper investigated centripetal flow through narrow rotor–stator cavities and compared axial thrust, rotor torque and radial pressure distribution to the case without through-flow. Consequently, this paper extends the investigated range to centrifugal through-flow as it may occur in the hub side chamber of radial turbomachinery. The chosen operating conditions are 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 <inline-formula><math display="inline"><semantics><mrow><mi>R</mi><mspace width="-0.84998pt"></mspace><mi>e</mi><mo>=</mo><mn>2</mn><mspace width="0.166667em"></mspace><mi>·</mi><mspace width="0.166667em"></mspace><msup><mn>10</mn><mn>7</mn></msup></mrow></semantics></math></inline-formula> has been investigated for centrifugal through-flow. This paper extends the range to Reynolds numbers of <inline-formula><math display="inline"><semantics><mrow><mi>R</mi><mspace width="-0.84998pt"></mspace><mi>e</mi><mo>=</mo><mn>2</mn><mspace width="0.166667em"></mspace><mi>·</mi><mspace width="0.166667em"></mspace><msup><mn>10</mn><mn>8</mn></msup></mrow></semantics></math></inline-formula> and reports results of experimental and numerical investigations. It focuses on the radial pressure distribution in the rotor–stator cavity and shows the influence of the Reynolds number, cavity width and centrifugal mass flow rate. It therefore extends the range of available valid data that can be used to design radial turbomachinery. Additionally, this analysis compares the results to data and models from scientific literature, showing that in the higher Reynolds number range, a new correlation is required. Finally, the analysis of velocity profiles and wall shear delineates the switch from purely radial outflow in the cavity to outflow on the rotor and inflow on the stator at high Reynolds numbers in comparison to the results reported by others for Reynolds numbers up to <inline-formula><math display="inline"><semantics><mrow><mi>R</mi><mspace width="-0.84998pt"></mspace><mi>e</mi><mo>=</mo><mn>2</mn><mspace width="0.166667em"></mspace><mi>·</mi><mspace width="0.166667em"></mspace><msup><mn>10</mn><mn>7</mn></msup></mrow></semantics></math></inline-formula>.