LES-based simulation of the time-resolved flow for rotor-stator interactions in axial fan stages
International Journal of Numerical Methods for Heat & Fluid Flow
ISSN: 0961-5539
Article publication date: 30 October 2018
Issue publication date: 8 February 2019
Abstract
Purpose
The purpose of this paper is the development of a CFD methodology based on LES computations to analyze the rotor–stator interaction in an axial fan stage.
Design/methodology/approach
A wall-modeled large eddy simulation (WMLES) has been performed for a spanwise 3D extrusion of the central section of the fan stage. Computations were performed for three different operating conditions, from nominal (Q_N) to off-design (85 per cent Q_N and 70 per cent Q_N) working points. Circumferential periodic conditions were introduced to reduce the extent of the computational domain. The post-processing procedure enabled the segregation of unsteady deterministic features and turbulent scales. The simulations were experimentally validated using wake profiles and turbulent scales obtained from hot-wire measurements.
Findings
The transport of rotor wakes and both wake–vane and wake–wake interactions in the stator flow field have been analyzed. The description of flow separation, particularly at off-design conditions, is fully benefited from the LES performance. Rotor wakes impinging on the stator vanes generate a coherent large-scale vortex shedding at reduced frequencies. Large pressure fluctuations in the stagnation region on the leading edge of the vanes have been found.
Research limitations/implications
LES simulations have shown to be appropriate for the assessment of the design of an axial fan, especially for specific operating conditions for which a URANS model presents a lower performance for turbulence description.
Originality/value
This paper describes the development of an LES-based simulation to understand the flow mechanisms related to the rotor–stator interaction in axial fan stages.
Keywords
Acknowledgements
This work has been supported by the “FPU” predoctoral research scholarship provided by the Spanish Ministry of Education, Culture and Sports.
Citation
Fernandez Oro, J.M., Meana-Fernández, A., Galdo Vega, M., Pereiras, B. and González Pérez, J. (2019), "LES-based simulation of the time-resolved flow for rotor-stator interactions in axial fan stages", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 29 No. 2, pp. 657-681. https://doi.org/10.1108/HFF-10-2017-0421
Publisher
:Emerald Publishing Limited
Copyright © 2018, Emerald Publishing Limited