Part-Speed Flutter Analysis of a Wide-Chord Fan Blade

Chew, John W.; Marshall, J. G.; Vahdati, Mehdi; Imregun, M.

doi:10.1007/978-94-011-5040-8_46

Cited by 14 publications

(8 citation statements)

References 8 publications

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“…Imregun [52,53] did. On the other hand, since the methodologies of each individual discipline have matured independently, each solver has evolved to use a different type of grid generation, a different discretization method and a different time integration scheme so that high accuracy and efficiency can be individually achieved.…”

Section: Motivations Of the Researchmentioning

confidence: 98%

“…In early fluid/structure coupled aeroelastic calculations for external flows, the same surface discretization for the fluid and structural domains with the same size of the surface elements was used to transfer loads and deformations between the two disciplines without the need for any interpolations [89]. The same assumption was made for turbomachinery flow by Imregun and his collaborators [52,53]. The fluid system and the structural systems, however, essentially use different surface discretizations because of differing accuracy requirements in the resolution of the features of each solution.…”

Section: Fluid-structure Interfacementioning

confidence: 99%

“…This difference in allowable time step size is, however, overcome by the dual time stepping scheme in which the fluid system is updated implicitly in physical time, and the pseudo time step is introduced to integrate the fluid equations within the physical time period as discussed in Section 3.1.3. In this way, the same physical time step is used for both solvers [53], because the physical time step of the dual time stepping in fluid calculation can be chosen arbitrary and the structural time step has no limitation. Thus, the overall computational cost can be saved because fewer computations are necessary for the structural solver and communication in exchanging boundary information.…”

Section: Synchronizationmentioning

confidence: 99%

See 2 more Smart Citations

Fluid/Structure Coupled Aeroelastic Computations for Transonic Flows in Turbomachinery

Doi

Alonso

2002

Volume 4: Turbo Expo 2002, Parts a and B

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The unstable, self-excited or forced vibrations of rotor blades must be avoided in designing high performance turbomachinery components because they may induce catastrophic structural failures. In evaluating the stability of such vibrations, computational approaches have been bearing an increasing role due to the surprising progress of both computer technologies and advanced algorithms. They are now at a stage where time domain fluid/structure coupled simulations of aeroelastic phenomena in turbomachinery with realistic geometries can be used in practice. The present study demonstrates the capabilities of a fluid/structure coupled computational approach which consists of an unsteady three-dimensional Navier-Stokes flow solver, TFLO, a finite element structural analysis package, MSC/NASTRAN, and the coupling interface between the two disciplines. The flow solver relies on a multiblock, cell-centered finite volume discretization and the dual time stepping time integration scheme with multigrid for convergence acceleration. Parallelization for multiple processors is also performed to achieve faster computations making use of the Message Passing Interface (MPI). As far as the interface is concerned, high accuracy is pursued with respect to load transfer, deformation tracking and synchronization. As a result, the program successfully predicts the aeroelastic responses of a high performance fan, NASA Rotor 67, over a range of operational conditions. The major contribution to the aerodynamic damping for turbomachinery blade motions is observed to be the unsteady pressure generated at the location of the shock. The results show that the

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Section: Motivations Of the Researchmentioning

confidence: 98%

Section: Fluid-structure Interfacementioning

confidence: 99%

Section: Synchronizationmentioning

confidence: 99%

See 1 more Smart Citation

Fluid/Structure Coupled Aeroelastic Computations for Transonic Flows in Turbomachinery

Doi

Alonso

2002

Volume 4: Turbo Expo 2002, Parts a and B

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“…7,8,15,16,17, shows that the leading edge region makes a decisive contribution to the total stability. In the low-incidence case the leading edge contributes positive damping, whereas in the high-incidence case the flow separation near the leading edge on the upper surface causes a destabilizing pitching moment.…”

Section: Computational Results and Discussionmentioning

confidence: 99%

A Navier-Stokes Analysis of the Stall Flutter Characteristics of the Buffum Cascade

Weber

Platzer

2000

Volume 4: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation;

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Numerical stall flutter prediction methods are highly needed as modern jet engines require blade designs close to the stability boundaries of the performance map. A Quasi-3D Navier-Stokes code is used to analyze the flow over the oscillating cascade designed and manufactured by Pratt & Whitney, and studied at the NASA Glenn Research Center by Buffum et al. The numerical method solves for the governing equations with a fully implicit time-marching technique in a single passage by making use of a direct-store, periodic boundary condition. For turbulence modeling the Baldwin-Lomax model is used. To account for transition, the criterion to predict the onset location suggested by Baldwin and Lomax is incorporated. Buffum et al. investigated two incidence cases for three different Mach numbers. The low-incidence case at a Mach number of 0.5 exhibited the formation of small separation bubbles at reduced oscillation frequencies of 0.8 and 1.2. For this case the present approach yielded good agreement with the steady and oscillatory measurements. At high-incidence at the same Mach number of 0.5 the measured steady-state pressure distribution and the separation bubble on the upper surface was also found in good agreement with the experiment. But computations for oscillations at high-incidence failed to predict the negative damping contribution caused by the leading edge separation.

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“…At present the existing approaches in flutter calculations of 3-D blade rows use the simultaneous integration in time of the equations of motion for the structure and the fluid [3][4][5][6]. However, in these works it is Received June 30, 2005 V.I.…”

Section: Introductionmentioning

confidence: 99%

Numerical modelling of the aeroelastic behaviour and variable loads for the turbine stage in 3D transonic flow

2005

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In this study presented the algorithm proposed involves the coupled solution of 3-D unsteady flow through a turbine stage and the dynamics problem for rotor-blade motion by the action of aerodynamic forces, without separating the outer and inner flow fluctuations. The partially integrated method involves the solution of the fluid and structural equations separately, but information is exchanged at each time step, so that solution from one domain is used as a boundary condition for the other domain. 3-D transonic gas flow through the stator and rotor blades in relative motion with periodicity on the whole annulus is described by the unsteady Euler conservation equations, which are integrated using the explicit monotonous finite-volume difference scheme of GodunovKolgan. The structural analysis uses the modal approach and a 3-D finite element model of a blade. A calculation has been done for the last stage of the steam turbine, under design and off-design regimes. It is shown that the amplitude-frequency spectrum of blade oscillations contains the high frequency harmonics, corresponding to the rotor moving past one stator blade pitch, and low frequency harmonics caused by blade oscillations and flow nonuniformity downstream from the blade row; moreover, the spectrum involves the harmonics which are not multiples of the rotation frequency.

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Part-Speed Flutter Analysis of a Wide-Chord Fan Blade

Cited by 14 publications

References 8 publications

Fluid/Structure Coupled Aeroelastic Computations for Transonic Flows in Turbomachinery

Fluid/Structure Coupled Aeroelastic Computations for Transonic Flows in Turbomachinery

A Navier-Stokes Analysis of the Stall Flutter Characteristics of the Buffum Cascade

Numerical modelling of the aeroelastic behaviour and variable loads for the turbine stage in 3D transonic flow

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