Advances in fan and compressor blade flutter analysis and predictions

1975 ◽  
Vol 12 (4) ◽  
pp. 325-332 ◽  
Author(s):  
A. A. Mikolajczak ◽  
R. A. Arnoldi ◽  
L. E. Snyder ◽  
H. Stargardter
Keyword(s):  
Compressor Blade ◽  
Flutter Analysis ◽  
Blade Flutter

Mechanisms for Wide-Chord Fan Blade Flutter

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Mehdi Vahdati ◽  
George Simpson ◽  
Mehmet Imregun
Keyword(s):  
Flow Separation ◽  
Pressure Wave ◽  
Geometric Features ◽  
The Third ◽  
Reflected Wave ◽  
Flutter Analysis ◽  
Parametric Studies ◽  
Blade Flutter ◽  
Stall Flutter ◽  
Fan Blade

This paper describes a detailed wide-chord fan blade flutter analysis with emphasis on flutter bite. The same fan was used with three different intakes of increasing complexity to explain flutter mechanisms. Two types of flutter, namely, stall and acoustic flutters, were identified. The first intake is a uniform cylinder, in which there are no acoustic reflections. Only the stall flutter, which is driven by flow separation, can exist in this case. The second intake, based on the first one, has a “bump” feature to reflect the fan’s forward pressure wave at a known location so that detailed parametric studies can be undertaken. The analysis revealed a mechanism for acoustic flutter, which is driven by the phase of the reflected wave. The third intake has the typical geometric features of a flight intake. The results indicate that flutter bite occurs when both stall and acoustic flutters happen at the same speed. It is also found that blade stiffening has no effect on aero-acoustic flutter.

Cascade Blade Flutter and Wake Excitation

1954 ◽  
Vol 58 (523) ◽  
pp. 505-508 ◽  
Author(s):  
J. F. W. Parry ◽  
H. Pearson
Keyword(s):  
Turbine Blade ◽  
Compressor Blade ◽  
New Method ◽  
Blade Vibration ◽  
Blade Cascade ◽  
Blade Flutter ◽  
Anglo American ◽  
Basic Equations

A new method of presenting the aerodynamic data for a compressor or turbine blade cascade is shown, with particular reference to flutter excitation or damping. The application of these results to wake excitation is demonstrated.The basic equations for flutter excitation or damping are derived in the paper “The Aerodynamics of Compressor Blade Vibration” presented by H. Pearson at the 1953 Anglo-American Conference (London). No new equations are derived but the method of plotting the relevant data leads to a simpler appreciation of the criteria.

Influence of Intake on Fan Blade Flutter

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Mehdi Vahdati ◽  
Nigel Smith ◽  
Fanzhou Zhao
Keyword(s):  
Correct Prediction ◽  
Blade Vibration ◽  
Reflected Waves ◽  
Reflection Model ◽  
Flutter Analysis ◽  
Flutter Boundary ◽  
Blade Flutter ◽  
Computational Fluid Dynamics Cfd ◽  
Fan Blade ◽  
Insight Into

The main aim of this paper is to study the influence of upstream reflections on flutter of a fan blade. To achieve this goal, flutter analysis of a complete fan assembly with an intake duct and the downstream outlet guide vanes (OGVs) (whole low pressure (LP) domain) is undertaken using a validated computational fluid dynamics (CFD) model. The computed results show good correlation with measured data. Due to space constraints, only upstream (intake) reflections are analyzed in this paper. It will be shown that the correct prediction of flutter boundary for a fan blade requires modeling of the intake and different intakes would produce different flutter boundaries for the same fan blade. However, the “blade only” and intake damping are independent and the total damping can be obtained from the sum of the two contributions. In order to gain further insight into the physics of the problem, the pressure waves created by blade vibration are split into an upstream and a downstream traveling wave in the intake. The splitting of the pressure wave allows one to establish a relationship between the phase and amplitude of the reflected waves and flutter stability of the blade. By using this approach, a simple reflection model can be used to model the intake effects.

The Effect of Bending-Torsion Coupling on Fan and Compressor Blade Flutter

1982 ◽  
Vol 104 (3) ◽  
pp. 617-623 ◽  
Author(s):  
O. O. Bendiksen ◽  
P. P. Friedmann
Keyword(s):  
Supersonic Flow ◽  
Incompressible Flow ◽  
Equations Of Motion ◽  
Leading Edge ◽  
Compressor Blade ◽  
Pronounced Effect ◽  
Design Parameters ◽  
Structural Damping ◽  
Current Technology ◽  
Blade Flutter

A study of the effects of bending-torsion interaction of the flutter boundaries of turbomachinery blading is presented. The blades are modeled as equivalent sections, and the equations of motion allow for the general case of structural, inertial and aerodynamic coupling, in the presence of structural damping. Two different speed regimes are investigated: incompressible flow, and supersonic flow with a subsonic leading edge locus. Flutter boundaries are presented for cascade design parameters representative of current technology fan rotors. These results illustrate that bending-torsion interaction has a pronounced effect on the flutter boundaries for both speed regimes, although the mode frequencies show no appreciable tendency to coalesce as flutter is approached. Several cases of bending branch instability were observed, without incorporating the effects of finite mean lift or strong shocks in the analysis.

Influence of Upstream and Downstream Stator Blades on the Rotor Blade Flutter Characteristics

2018 ◽  
Author(s):  
Zhang Xiaojie ◽  
Wang Yanrong ◽  
Han Le ◽  
Zhao Jiazhe ◽  
Luo Yanbin
Keyword(s):  
Rotor Blade ◽  
Systematic Research ◽  
Plane Method ◽  
Aerodynamic Damping ◽  
Flutter Analysis ◽  
Blade Flutter ◽  
Time Marching ◽  
Mp Method ◽  
Marching Method ◽  
Rotor Model

One of the important issues in turbomachinery flutter analysis is the intra-row interaction effects. The present work is aimed at a systematic research of the adjacent rows effects on aerodynamic damping. Three models, the isolated rotor, the IGV-rotor and the rotor-stator model, are performed to identify the upstream and downstream stator effects on the rotor blade. It is found that the aerodynamic damping from the stage flutter simulations are quite different from that from isolated rotor. In addition, the mixing-plane method is also applied to calculate the stage flutter characteristics and its accuracy of flutter predictions is compared with the time-marching method. It is indicated that the main difference of aerowork density between MP and TM is in the tip area, and in some cases the result from MP method can be misleading. Furthermore, study with different axial gaps illustrates that there is a nonmonotonic relationship between the rotor blade aerodynamic damping and the gap in the rotor-stator model, while the rotor blade aerodynamic damping monotonically increases with the gap in the IGV-rotor model.

Influence of Intake on Fan Blade Flutter

2014 ◽  
Author(s):  
Mehdi Vahdati ◽  
Nigel Smith ◽  
Fanzhou Zhao
Keyword(s):  
Correct Prediction ◽  
Pressure Waves ◽  
Blade Vibration ◽  
Reflected Waves ◽  
Reflection Model ◽  
Flutter Analysis ◽  
Flutter Boundary ◽  
Blade Flutter ◽  
Fan Blade ◽  
Insight Into

The main aim of this paper is to study the influence of upstream reflections on flutter of a fan blade. To achieve this goal, flutter analysis of a complete fan assembly with an intake duct and the downstream OGVs (whole LP domain) is undertaken using a validated CFD model. The computed results show good correlation with measured data. Due to space constraints, only upstream (intake) reflections are analyzed in this paper. It will be shown that the correct prediction of flutter boundary for a fan blade requires modeling of the intake and different intakes would produce different flutter boundaries for the same fan blade. However, the ‘blade only’ and intake damping are independent and the total damping can be obtained from the sum of the two contributions. In order to gain further insight into the physics of the problem, the pressure waves created by blade vibration are split into an upstream and a downstream traveling wave in the intake. The splitting of the pressure wave allows one to establish a relationship between the phase and amplitude of the reflected waves and flutter stability of the blade. By using this approach, a simple reflection model can be used to model the intake effects.

Flutter of Swept Fan Blades

1985 ◽  
Vol 107 (2) ◽  
pp. 394-398
Author(s):  
R. E. Kielb ◽  
K. R. V. Kaza
Keyword(s):  
Detrimental Effect ◽  
Structural Model ◽  
Aerodynamic Loads ◽  
Unsteady Aerodynamic ◽  
Aeroelastic Analysis ◽  
Flutter Analysis ◽  
Blade Flutter ◽  
Fan Blade ◽  
Element Technique ◽  
Nonuniform Beam

The purpose of the research presented in this paper is to study the effect of sweep on fan blade flutter by applying the analytical methods developed for aeroelastic analysis of advanced turboprops. Two methods are used. The first method utilizes an approximate structural model in which the blade is represented by a swept, nonuniform beam. The second method utilizes a finite element technique to conduct modal flutter analysis. For both methods, the unsteady aerodynamic loads are calculated using two-dimensional cascade theories that are modified to account for sweep. An advanced fan stage is analyzed with 0, 15, and 30 deg of sweep. It is shown that sweep has a beneficial effect on predominantly torsional flutter and a detrimental effect on predominantly bending flutter. This detrimental effect is shown to be significantly destabilizing for 30 deg of sweep.

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