Compressible Flows with Vortical Disturbances Around a Cascade of Loaded Airfoils

Fang, J.; Atassi, Hafiz M.

doi:10.1007/978-1-4613-9341-2_8

Cited by 26 publications

(14 citation statements)

References 14 publications

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“…Our analysis is focussed on unloaded flat plates, although it is well known that loaded blades have a significant effect on aeroacoustic performance (Fang & Atassi 1993;Evers & Peake 2002;Hall et al 2006). The present work could be merged with our recent solution for scattering by loaded cascades (Baddoo & Ayton 2020) to account for both the effects of complex boundary conditions and non-trivial geometries.…”

Section: Introductionmentioning

confidence: 99%

Acoustic scattering by cascades with complex boundary conditions: compliance, porosity and impedance

Baddoo

Ayton

2020

J. Fluid Mech.

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Section: Introductionmentioning

confidence: 99%

Acoustic scattering by cascades with complex boundary conditions: compliance, porosity and impedance

Baddoo

Ayton

2020

J. Fluid Mech.

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“…In recent years, linearized Euler codes have been developed to solve twodimensional (e.g. Hall & Verdon 1991;Fang & Atassi 1993) and progressively fully three-dimensional annular-cascade problems with mean swirling flow (e.g. Golubev & Atassi 2000;Atassi et al 2004) and loading, and have been successfully applied to broadband computations (e.g.…”

Section: Introductionmentioning

confidence: 99%

On a uniformly valid analytical rectilinear cascade response function

2010

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This paper extends an existing analytical model of the aeroacoustic response of a rectilinear cascade of flat-plate blades to three-dimensional incident vortical gusts, by providing closed-form expressions for the acoustic field inside the inter-blade channels, as well as for the pressure jump over the blades in subsonic flows. The extended formulation is dedicated to future implementation in a fan-broadband-noise-prediction tool. The intended applications include the modern turbofan engines, for which analytical modelling is believed to be a good alternative to more expensive numerical techniques. The initial model taken as a reference is based on the Wiener–Hopf technique. An analytical solution valid over the whole space is first derived by making an extensive use of the residue theorem. The accuracy of the model is shown by comparing with numerical predictions of benchmark configurations available in the literature. This full exact solution could be used as a reference for future assessment of numerical solvers, of linearized Euler equations for instance, in rectilinear or narrow-annulus configurations. In addition, the pressure jump is a key piece of information because it can be used as a source term in an acoustic analogy when the rectilinear-cascade model is applied to three-dimensional blade rows by resorting to a strip-theory approach. When used as such in a true rectilinear-cascade configuration, it reproduces the exact radiated field that can be derived directly. The solution is also compared to a classical single-airfoil formulation to highlight the cascade effect. This effect is found important when the blades of the cascade overlap significantly, but the cascade solution tends to the single-airfoil one as the overlap goes to zero. This suggests that both models can be used as the continuation of each other if needed.

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“…where 0(x) is the mean velocity, and the boundary conditions 0 0 (7) (8) along the surface of the body £ and its wake W. The potential function </ > satisfies the equation (9) Numerical solutions using this approach were obtained for a three-dimensional periodic gust in subsonic flow for a single airfoil by Scott and Atassi [15] and [16], and for a two-dimensional cascade geometry by Hall and Verdon [17], Fang and Atassi [18], and Atassi et al [19]. The computation time required for these solutions is less than a minute on scientific workstations.…”

Section: Mean Potential Flowsmentioning

confidence: 98%

“…Vortical disturbances known as gusts will be superimposed on this mean flow. An inviscid numerical code CASGUST, based on 9 for a cascade geometry was developed by Fang and Atassi [18] . CASGUST calculates all unsteady flow quantities for impinging three-dimensional harmonic gusts of the form Figure 7 shows the magnitude of the unsteady pressure distribution along the suction surface of the blade for cases 1 and 2 at k\ = 2.5.…”

Section: Cascade Near Transonic Speed In a Gustmentioning

confidence: 99%

Aeroacoustics of nonuniform flows

Atassi

1997

35th Aerospace Sciences Meeting and Exhibit

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Compressible Flows with Vortical Disturbances Around a Cascade of Loaded Airfoils

Cited by 26 publications

References 14 publications

Acoustic scattering by cascades with complex boundary conditions: compliance, porosity and impedance

Acoustic scattering by cascades with complex boundary conditions: compliance, porosity and impedance

On a uniformly valid analytical rectilinear cascade response function

Aeroacoustics of nonuniform flows

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