Three Dimensional Linearized Navier-Stokes Calculations for Flutter and Forced Response

Holmes, D. Graham; Lorence, Christopher B.

doi:10.1007/978-94-011-5040-8_14

Cited by 49 publications

(24 citation statements)

References 13 publications

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“…Current research emphasis is on the development of linearised Navier-Stokes methods, including the linearisation of the turbulent eddy viscosity (Cizmas and Hall, 1995;Holmes et al, 1997). A viscous three-dimensional formulation on unstructured mixed-element meshes was reported by Sbardella (2000), and Sbardella and Imregun (2001).…”

Section: Frequency-domain Methods For Linearised Unsteady Aerodynamicsmentioning

confidence: 98%

Transonic Rotor/Stator Interaction Using a 3-D Linearised Unsteady Viscous Flow Model

Sbardella

Imregun

2002

International Journal of Computational Fluid Dynamics

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The paper first summarizes the forced response problem in turbomachinery and reviews various numerical methods for the simulation of unsteady flows. A particular technique, based on the linearisation of the unsteady Favre-averaged Navier -Stokes equations on three-dimensional mixedelement grids of tetrahedra, hexahedra and wedges, is described in some detail. The methodology was applied to a NGV/rotor interaction benchmark case for which detailed steady and unsteady flow measurements are available. The steady-state flow, calculated using a non-linear viscous representation, was described in detail with emphasis on features such as separation, horseshoe and passage vortices, tip leakage and shock structure since these are likely to influence the unsteady flow. The sources of unsteadiness on the rotor passage were evaluated from the steady-state solution at the NGV outlet. The disturbances were split into vortical, entropic and potential waves, the Fourier components of which were considered separately. The summation of the vortical and entropic waves was used as a rotor inlet boundary condition in order to assess the wake/rotor unsteady interaction. Similarly, potential waves were used to study the potential/rotor interaction. The results obtained from these two types of unsteady interactions were superimposed and compared with experimental data. Good qualitative and, in most cases, quantitative agreement was obtained, a finding which suggests that the unsteady flowfield generated by the relative blade motion can be considered to be a quasi-linear phenomenon for the particular HP turbine studied. Finally, the mechanisms of wake/rotor and potential/rotor interactions were studied in some detail and it was concluded that the former was strong in the crown of the blade while the latter was dominant in the leading edge region.

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Section: Frequency-domain Methods For Linearised Unsteady Aerodynamicsmentioning

confidence: 98%

Transonic Rotor/Stator Interaction Using a 3-D Linearised Unsteady Viscous Flow Model

Sbardella

Imregun

2002

International Journal of Computational Fluid Dynamics

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“…(5) exactly, but satisfy an approximate set of complex perturbation equations (which will not be repeated here for brevity 10 ). Perturbation products are themselves de ned to be zero under the small perturbation assumption.…”

Section: Dst From Linear Solutionsmentioning

confidence: 99%

Linear Deterministic Source Terms for Hot Streak Simulations

Orkwis

Turner

Barter

2002

Journal of Propulsion and Power

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Steady state surface rothalpy over speci c heat at constant pressure (temperature units) results obtained with a linear unsteady solution-based lumped deterministic source term are compared with results obtained from a traditional, nonlinear, inviscid unsteady solution for an aircraft engine rst stage high-pressure turbine rotor con guration. The relationship between the source terms and traditional solution variables is explored to offer a unique insight into comparing the two approaches. Boundary condition/potential eld effects and the order of accuracy of the available schemes are also explored and show a signi cant effect on surface rothalpy results. The new technique demonstrates a signi cant potential for approximately including unsteady hot streak effects in time average calculations with minimal computer effort.

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“…The time-linearized technique has been extended to three-dimensional inviscid (Euler) flows [9,10] and to two and three-dimensional viscous (Navier-Stokes) flows [11][12][13] in turbomachinery.…”

Section: Linearized Analysis Of Unsteady Flowsmentioning

confidence: 99%

Untitled

Dowell

2015

A Modern Course in Aeroelasticity

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The field of turbomachinery is undergoing major advances in aeroelasticity, and this chapter provides an overview of these new developments in the key enabling methodology of unsteady aerodynamic modeling. Also see the earlier discussions in Chaps. 8 and 9.In this chapter, we review the state of the field of computational unsteady aerodynamics, particularly frequency domain methods used for the calculation of the unsteady aerodynamic forces arising in turbomachinery aeroelasticity problems. While the emphasis here is on turbomachinery aerodynamics, the methods described in this chapter have analogues for the analysis of isolated airfoils, wings, and even whole aircraft, as well as rotorcraft.The two main aeromechanics problems in turbomachinery are flutter and gust response. In the flutter problem, the unsteady aerodynamic loads acting on a cascade of turbomachinery airfoils arise from the motion of the airfoils themselves. In the gust response problem, the original excitation arises away from the blade row in question. Typical sources of excitation are wakes or potential fields from neighboring blade rows or support structures (struts), inlet distortions, and hot streaks from the combustor.More recently, a third class of aeromechanical problems has been identified [1]. This class of problems is akin to galloping of power lines or buffeting of aircraft wings. Examples include so-called separated flow vibrations and non-synchronous vibrations. In separated flow vibrations, the flow over a row of airfoils is separated, or nearly so. The flow itself is unstable, producing unsteady air loads with broadband frequency distributions that excite the airfoil at all frequencies producing a large response at the natural structural frequencies of the airfoil. Non-synchronous flow vibrations, on the other hand, are similar to separated flow vibrations in that the source of the excitation is thought to be a fluid dynamics instability (rather than an aeroelastic instability), except that non-synchronous vibrations can also occur well away from a stalled condition and the response tends to be at a single frequency. If this fluid dynamic natural frequency happens to be close to a structural natural frequency, then the fluid dynamic instability frequency can "lock on" to the structural frequency of the airfoils resulting in a large-amplitude vibration.

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Three Dimensional Linearized Navier-Stokes Calculations for Flutter and Forced Response

Cited by 49 publications

References 13 publications

Transonic Rotor/Stator Interaction Using a 3-D Linearised Unsteady Viscous Flow Model

Transonic Rotor/Stator Interaction Using a 3-D Linearised Unsteady Viscous Flow Model

Linear Deterministic Source Terms for Hot Streak Simulations

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