Nacelle design for ultra-high bypass ratio engines with CFD based optimisation

Robinson, Matthew; MacManus, David G.; Christie, Robert; Sheaf, Christopher; Grech, Nicholas

doi:10.1016/j.ast.2020.106191

Cited by 14 publications

(7 citation statements)

References 24 publications

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“…Appropriate values for these key nacelle dimensions are determined with a fully parametric definition that uses the intuitive class-shape transformation (iCST) method [13,14]. The design process is based on a multi-point, multi-objective optimisation routine based on a well-established CFD methodology [4,[15][16][17]. The domain, shown in Fig.…”

Section: Stage 1: Selecting a Representative Nacelle Geometrymentioning

confidence: 99%

“…3d. The mesh independence and validation of this numerical approach have been reported in a number of previous studies [4,16,21], and details of the methodology used for the current optimisation process are set out extensively by Swarthout [11].…”

Section: Stage 1: Selecting a Representative Nacelle Geometrymentioning

confidence: 99%

“…Nacelle design is typically optimised for cruise operating conditions [4]. In certain off-design scenarios, however, the compact nature of UHBR nacelles can result in flow fields which exhibit substantial deviations from the baseline case.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Wind Tunnel Rig to Study the External Fan Cowl Separation Experienced by Compact Nacelles in Windmilling Scenarios

Sabnis

Boscagli

Swarthout

et al. 2023

AIAA SCITECH 2023 Forum

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Ultra high-bypass ratio aircraft engines adopt slim fan cowl profiles which are sensitive to separation on their external surfaces under diversion windmilling conditions, when engine shutdown occurs during cruise. A two-dimensional wind tunnel rig is developed to investigate the separation mechanisms experienced by aero-engine nacelles in such scenarios to establish the detailed aerodynamics. The tunnel flow field with entry Mach number 0.65 broadly replicates the expected diversion windmilling flow behaviour for a full-scale nacelle, featuring a supersonic region which terminates in a normal shock wave on the external fan cowl surface. For the three conditions investigated, which relate to different engine mass-flow rates, the response of the boundary layer in this region progresses from remaining fully attached through to well-established separation. However, the rig Reynolds number based on nacelle lip thickness is about 1.2 × 10 6 , roughly one-third of full scale, resulting in a transitional rather than turbulent shock-boundary-layer interaction. Nevertheless, simple simulations correctly predict the wind tunnel flow field, except for the precise boundary-layer response to normal shock waves, and so experimental data from the rig can be used to validate relevant computational methods.

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Section: Stage 1: Selecting a Representative Nacelle Geometrymentioning

confidence: 99%

Section: Stage 1: Selecting a Representative Nacelle Geometrymentioning

confidence: 99%

See 1 more Smart Citation

A Wind Tunnel Rig to Study the External Fan Cowl Separation Experienced by Compact Nacelles in Windmilling Scenarios

Sabnis

Boscagli

Swarthout

et al. 2023

AIAA SCITECH 2023 Forum

Self Cite

View full text Add to dashboard Cite

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“…Following Figure 2, the reference engine fan radius is set r n = 1.7 m; the sizing is completed comparing different relations presented in the literature [30][31][32]: L n = 1.272r n , r max = 1.252r n , r s = 0.28r n and L s = 1.5r s . The shapes of the inlet section are built using Class Shape Transformation (CST) curves, following [30,33,34]. The metalining is placed on the internal surface of the inlet, starting from z ms with an overall length of L ms ≈ 0.7λ BPF divided into eight cells of equal width w ms = 0.05 m. In the present study, the MS is positioned close to the lip leading edge: the treatment extends in a currently non-lined part of the nacelle as its presence in the nacelle is not intended to be an alternative to the standard absorbing liners.…”

Section: Numerical Modelmentioning

confidence: 99%

Innovative Acoustic Treatments of Nacelle Intakes Based on Optimised Metamaterials

et al. 2021

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Modern turbofans with high bypass ratios, low blade passage frequencies and short nacelles require continuous development of acoustic linings to achieve the noise reductions expected by the international aviation authorities. Metamaterials and metafluids have been recently proposed as promising technologies for designing innovative acoustic treatments dedicated to reducing aeronautic turbofan noise emissions. In this work, a phase-gradient metasurface treatment is investigated as a way to tackle the noise radiation from an axially symmetric nacelle. This paper aims to study the potential benefits of the mentioned technology, and is not an attempt to design a complete new liner or nacelle. The metasurface is modelled through an equivalent metafluid, and a simulation-based optimisation is used in defining the design parameters. The tonal contribution of the blade passage frequency is considered, and the numerical results with the metafluid optimised on one azimuthal mode at a time show a significant effect in terms of acoustic levels and directivity over an arc of virtual receivers.

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“…leading and trailing edge radii, mean camber, thickness distribution, etc. for its resemblance to twodimensional airfoil theory [9][10][11] ) played the role of design variable, participating subsequent design space establishment. [12][13][14] However, the three-dimensionality essential to blade design failed to be reflected in this approach of geometric parameterization, e.g.…”

Section: Introductionmentioning

confidence: 99%

An approach of Proper Orthogonal Decomposition-aided Free-form Deformation with application in compressor blade design

Wang

Qin

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part G:

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Compressor blade design influences aero-engine performance mainly through its total pressure ratio and efficiency. As a volume-based geometric parameterization, Free-form Deformation (FFD) brings three-dimensionality that is essential to blade design. However, the manipulation of control points with respect to simple numeric parametric perturbation renders the use of design space low-efficient. Therefore, an improved FFD with ‘wiser’ control point lay-out is expected to identify those more important design variables. This paper proposes novel design variables that are assigned to grouping of control points’ displacement in FFD lay-out. In short, the approach is realized as: (i) establish a library of sufficient blade shape samples; (ii) filter the database with geometric constraints; (iii) extract dominant modes via (POD) Proper Orthogonal Decomposition; (iv) construct new design variables and apply them in optimization. With geometric constraint filtering, problem-oriented information is injected. With POD, the dominance of new selected geometric parameters in problem description is assured. Perfunctory details of displacement data of each control point in the lay-out can be replaced by grouped data as new design variable candidates. As a proof-of-concept study of the new approach, compressor blade Rotor 37 is selected to be the good platform of testing the feasibility of POD-aided FFD as a global and flexible yet economic geometric parameterization. Result demonstrates the feasibility of proposed POD-aided FFD approach that helps conduct an optimization involving displacement of 6 × 4 × 3 control points with as few as five new design variables, while still being capable of bringing optimization effect in three test cases.

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Nacelle design for ultra-high bypass ratio engines with CFD based optimisation

Cited by 14 publications

References 24 publications

A Wind Tunnel Rig to Study the External Fan Cowl Separation Experienced by Compact Nacelles in Windmilling Scenarios

A Wind Tunnel Rig to Study the External Fan Cowl Separation Experienced by Compact Nacelles in Windmilling Scenarios

Innovative Acoustic Treatments of Nacelle Intakes Based on Optimised Metamaterials

An approach of Proper Orthogonal Decomposition-aided Free-form Deformation with application in compressor blade design

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