Validation of a Numerical Model for Predicting Stalled Flows in a Low-Speed Fan—Part II: Unsteady Analysis

Lee, Kuen-Bae; Dodds, John A.; Wilson, Mark; Vahdati, Mehdi

doi:10.1115/1.4039052

Cited by 27 publications

(8 citation statements)

References 19 publications

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“…The model was chosen to achieve good numerical accuracy for large length scale disturbances (multi-cell rotating stall and surge) within practical computational resource requirement. The resulting CFD code has been used over the past 20 years for flows at off-design conditions with a good degree of success (Vahdati et al 2008;Choi et al 2012;Lee et al 2018;Zhao et al 2018).…”

Section: Methodology 3d Urans Model -Au3dmentioning

confidence: 99%

Three-dimensional low-order surge model for high-speed axial compressors

Righi¹,

Pachidis²,

Könözsy³

et al. 2020

Proceedings of Global Power &Amp; Propulsion Society

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Surge in modern aero-engines can lead to violent disruption of the flow, damage to the blade structures and eventually engine shutdown. Knowledge of unsteady performance and loading during surge is crucial for compressor design, however, the understanding and prediction capability for this phenomenon is still very limited. While useful for the investigation of specific cases, costly experimental tests and high-fidelity CFD simulations cannot be used routinely in the design process of compressor systems. There is therefore an interest in developing a low-order model which can predict compressor performance during surge with sufficient accuracy at significantly reduced computational cost. This paper describes the validation of an unsteady 3D through-flow code developed at Cranfield University for the low-order modelling of surge in axial compressors. The geometry investigated is an 8-stage rig representative of a modern aero-engine IP compressor. Two deep surge events are modelled at part speed and full speed respectively. The results are compared against high-fidelity, full annulus, URANS simulations conducted at Imperial College. Comparison of massflow, pressure and temperature time histories shows a close match between the low-order and the higher-fidelity methods. The low-order model is shown capable of predicting many transient flow features which were observed in the high-fidelity simulations, while reducing the computational cost by up to two orders of magnitude.

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Section: Methodology 3d Urans Model -Au3dmentioning

confidence: 99%

Three-dimensional low-order surge model for high-speed axial compressors

Righi¹,

Pachidis²,

Könözsy³

et al. 2020

Proceedings of Global Power &Amp; Propulsion Society

View full text Add to dashboard Cite

show abstract

“…These modified SA models include the one with a quadratic constitutive relation (SA-QCR) [15] and one with rotation and curvature correction (SA-RC) [16], both of which have been widely implemented in several computational fluid dynamics (CFD) solvers and tested in a broad range of cases (i.e., reaching model readiness rating level 3 [17]). In addition, emerging modifications using helicity (SA-H) [18] and pressure gradient (SA-PG) [19] are also evaluated since they were found useful in fan rotor stall prediction [20,21].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Spalart-Allmaras Turbulence Model Forms for a Transonic Axial Compressor

He¹,

Zhao²,

Vahdati³

2020

Proceedings of Global Power &Amp; Propulsion Society

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A comparative study of the state-of-the-art modified Spalart-Allmaras (SA) model forms has been conducted on the transonic axial compressor NASA Rotor 67. The models studied include the SA-QCR model that improves the Boussinesq assumption, the SA-RC model that tunes turbulence production considering rotation and curvature, the SA-H model that enhances turbulence source using helicity, and the SA-PG model that boosts turbulence source using adverse pressure gradient. By comparing the results in performance characteristics and radial, circumferential and chordwise profiles, the original SA model is found to over-predict the tip blockage size and thus cause large discrepancies in the near-stall performance. The SA-QCR and SA-RC models show limited effects on the tip blockage and the near-stall performance, whereas the SA-H and SA-PG models show improved predictions, although still not near perfection. The findings suggest the requirement of a new model for better prediction of compressor tip blockage.

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“…The situation becomes worse for blades which have flat characteristics such as a lowspeed fan. In order to suppress unnecessarily large separation zones, the production term is modified based on the pressure gradient and velocity helicity [10][11]. The parameters in the modified SA model are held constant in all the present work.…”

Section: Flow Solvermentioning

confidence: 99%

A Review of Computational Aeroelasticity Of Civil Fan Blades

Vahdati

Lee²,

Sureshkumar

2020

JGPP

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This paper presents a review of aeroelasticity research concerning fan blades in modern civil aircraft engines. It summarises the research carried out at the Rolls-Royce Vibration University Technology Centre (VUTC) at Imperial College over the past 25 years. The purpose of this paper is to gather information on all the aeroelastic issues observed for civil aero-engine fan blades into one document and provide a useful synopsis for other researchers in the field. The results presented here are based on numerical methods but wherever possible data from experiments are used to verify the numerical findings. For cases where such datasets do not exist fundamental principles, engine observations and engineering judgement are used to support the numerical results. Numerical methods offer a cheaper alternative to rig tests, especially in cases of blade failure, and can also provide more information about the nature of instabilities, which can be useful in the design of future civil aircraft engines. In fact, in cases such as crosswind testing that use smaller rig-scale blades, such results can even be more representative of real engine flows.

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Validation of a Numerical Model for Predicting Stalled Flows in a Low-Speed Fan—Part II: Unsteady Analysis

Cited by 27 publications

References 19 publications

Three-dimensional low-order surge model for high-speed axial compressors

Three-dimensional low-order surge model for high-speed axial compressors

Evaluation of Spalart-Allmaras Turbulence Model Forms for a Transonic Axial Compressor

A Review of Computational Aeroelasticity Of Civil Fan Blades

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