Coupled Fluid-structure Flutter Analysis of a Transonic Fan

This paper describes the calculation of flutter stability characteristics for a transonic forward swept fan configuration using a viscous aeroelastic analysis program. Unsteady Navier-Stokes equations are solved on a dynamically deforming, body fitted, grid to obtain the aeroelastic characteristics using the energy exchange method. The non-zero inter-blade phase angle is modeled using phase-lagged boundary conditions. Results obtained show good correlation with measurements. It is found that the location of shock and variation of shock strength strongly influenced stability. Also, outboard stations primarily contributed to stability characteristics. Results demonstrate that changes in blade shape impact the calculated aerodynamic damping, indicating importance of using accurate blade operating shape under centrifugal and steady aerodynamic loading for flutter prediction. It was found that the calculated aerodynamic damping was relatively insensitive to variation in natural frequency.

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Flutter Prediction of a Transonic Fan With Travelling Wave Using Fully Coupled Fluid/Structure Interaction

Volume 7B: Structures and Dynamics ◽

10.1115/gt2013-94341 ◽

2013 ◽

Cited By ~ 2

Author(s):

Hong-Sik Im ◽

Ge-Cheng Zha

Keyword(s):

Time Lag ◽

Fluid Structure Interaction ◽

Travelling Wave ◽

Weno Scheme ◽

Normal Shock ◽

Phase Lag ◽

Fluid Structure ◽

Structure Interaction ◽

Transonic Fan ◽

Fully Coupled

This paper uses a fully coupled fluid/structure interaction (FSI) to investigate the flutter mechanism of a modern transonic fan rotor with a forward travelling wave. To induce an initial travelling wave for the blade structure, an initial BC that can facilitate each blade to vibrate with a time lag by a given nodal diameter (ND) is implemented. Unsteady Reynolds-averaged Navier-Stokes (URANS) equations are solved with a system of structure modal equations in a fully coupled manner. The 5th order WENO scheme with a low diffusion E-CUSP Riemann solver is used for the inviscid fluxes and a 2nd order central differencing is used for the viscous terms. A half annulus sector is used for the flutter simulations with a time shifted phase lag boundary condition at the circumferential boundaries. The present FSI simulations show that the shock instability causes the flutter. When the detached normal shock moves further upstream in a direction normal to the blade chord, the interaction of the detached normal shock with tip leakage vortex creates more serious blockage to the blade passage that can introduce an aerodynamic instability to the blade structure due to the incoming flow disturbance, resulting in flutter. The flutter of the transonic fan observed in this study occurs at the 1st mode before the stall. The predicted flutter boundary agrees well with the experiment.

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A High Efficient Fluid-Structure Interaction Method for Flutter Analysis of Mistuned

Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University ◽

10.1051/jnwpu/20183650856 ◽

2018 ◽

Vol 36 (5) ◽

pp. 856-864

Author(s):

Zhanhe Liu ◽

Jinlou Quan ◽

Jingyuan Yang ◽

Dan Su ◽

Weiwei Zhang

Keyword(s):

Fluid Structure Interaction ◽

Reduced Order Model ◽

Interaction Method ◽

Order Model ◽

Fluid Structure ◽

Reduced Order ◽

Structure Interaction ◽

Bladed Disk ◽

High Efficient ◽

Flutter Analysis

The time cost is very high by direct fluid-structure interaction method for mistuned bladed disk structures, so aerodynamic loads generally are ignored or treated as small perturbations in traditional flutter analysis. In order to analyze the flutter characteristics of mistuned blade rapidly and accurately, this paper presents an efficient fluid-structure interaction method based on aerodynamic reduced order model. system identification technology and two basic assumptions are used to build the unsteady aerodynamic reduced order model. Coupled the structural equations and the aerodynamic model in the state space, the flutter stability of mistuned bladed disk can be obtained by changing the structural parameters. For the STCF 4 example, the response calculated by this method agrees well with the results obtained by the direct CFD, but the computational efficiency is improved by nearly two orders of magnitude. This method is used to study the stiffness mistuned cascade system, and the stability characteristics of the system are obtained by calculating the eigenvalues of the aeroelastic matrix. The results show that the stiffness mistuning can significantly improve the flutter stability of the system, and also lead to the localization of the mode. The mistuning mode, mistuning amplitude and fluid structure interaction can influence the flutter stability obviously.

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An energy method for flutter analysis of wing using one-way fluid structure coupling

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410016667146 ◽

2016 ◽

Vol 231 (14) ◽

pp. 2560-2569

Author(s):

Jize Zhong ◽

Zili Xu

Keyword(s):

Energy Method ◽

Stokes Equations ◽

Navier Stokes ◽

Navier Stokes Equations ◽

Fluid Structure ◽

Aerodynamic Damping ◽

Wing Vibration ◽

Flutter Analysis ◽

Flutter Boundary ◽

Reynolds Averaged Navier Stokes

In this paper, an energy method for flutter analysis of wing using one-way fluid structure coupling was developed. To consider the effect of wing vibration, Reynolds-averaged Navier–Stokes equations based on the arbitrary Lagrangian Eulerian coordinates were employed to model the flow. The flow mesh was updated using a fast dynamic mesh technology proposed by our research group. The pressure was calculated by solving the Reynolds-averaged Navier–Stokes equations through the SIMPLE algorithm with the updated flow mesh. The aerodynamic force for the wing was computed using the pressure on the wing surface. Then the aerodynamic damping of the wing vibration was computed. Finally, the flutter stability for the wing was decided according to whether the aerodynamic damping was positive or not. Considering the first four modes, the aerodynamic damping for wing 445.6 was calculated using the present method. The results show that the aerodynamic damping of the first mode is lower than the aerodynamic damping of higher order modes. The aerodynamic damping increases with the increase of the mode order. The flutter boundary for wing 445.6 was computed using the aerodynamic damping of the first mode in this paper. The calculated flutter boundary is consistent well with the experimental data.

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