Approach to Unidirectional Coupled CFD–FEM Analysis of Axial Turbocharger Turbine Blades

2001 ◽  
Vol 124 (1) ◽  
pp. 125-131 ◽  
Author(s):  
D. Filsinger ◽  
J. Szwedowicz ◽  
O. Scha¨fer
Keyword(s):  
Turbine Blades ◽  
Fem Analysis ◽  
Turbine Stage ◽  
Time Resolved ◽  
Nodal Diameter ◽  
Numerical Investigations ◽  
Bladed Disk ◽  
Steady State Responses ◽  
Bladed Rotor ◽  
State Responses

This paper describes an approach to unidirectional coupled CFD–FEM analysis developed at ABB Turbo Systems Ltd. Results of numerical investigations concerning the vibration behavior of an axial turbocharger turbine are presented. To predict the excitation forces acting on the rotating blades, the time-resolved two-dimensional coupled stator–rotor flow field of the turbine stage was calculated. The unsteady pressure, imposed on the airfoil contour, leads to circumferentially nonuniform and pulsating excitation forces acting on the rotating bladed disk. A harmonic transformation of the excitation forces into the rotating coordinate system of a single blade was elaborated and the complex Fourier amplitudes were determined. The bladed rotor was modeled by a single symmetric segment with complex circumferential boundary conditions. With respect to different nodal diameter numbers, free vibration analyses of the disk assembly were then effectively performed. For calculated resonance conditions, the steady-state responses of the turbocharger bladed disk were computed. By using this coupled CFD–FEM analysis, the dynamic loading of the turbine blades can be determined in the design process.

Approach to Unidirectional Coupled CFD – FEM Analysis of Axial Turbocharger Turbine Blades

2001 ◽  
Author(s):  
D. Filsinger ◽  
J. Szwedowicz ◽  
O. Schäfer
Keyword(s):  
Turbine Blades ◽  
Fem Analysis ◽  
Two Dimensional ◽  
Turbine Stage ◽  
Time Resolved ◽  
Nodal Diameter ◽  
Numerical Investigations ◽  
Steady State Responses ◽  
Bladed Rotor ◽  
State Responses

This paper describes an approach to unidirectional coupled CFD – FEM analysis developed at ABB Turbo Systems Ltd.. Results of numerical investigations concerning the vibration behavior of an axial turbocharger turbine are presented. To predict the excitation forces acting on the rotating blades, the time resolved two-dimensional coupled stator - rotor flow field of the turbine stage was calculated. The unsteady pressure, imposed on the airfoil contour, leads to circumferentially non-uniform and pulsating excitation forces acting on the rotating bladed disc. A harmonic transformation of the excitation forces into the rotating co-ordinate system of a single blade was elaborated and the complex Fourier amplitudes were determined. The bladed rotor was modeled by a single symmetric segment with complex circumferential boundary conditions. With respect to different nodal diameter numbers free vibration analyses of the disc assembly were then effectively performed. For calculated resonance conditions, the steady state responses of the turbocharger bladed disc were computed. By using this coupled CFD - FEM analysis, the dynamic loading of the turbine blades can be determined in the design process.

Investigation of Alternate Mistuned Turbine Blades Non-Linear Coupled by Underplatform Dampers

2013 ◽  
Author(s):  
S. Tatzko ◽  
L. Panning-von Scheidt ◽  
J. Wallaschek ◽  
A. Kayser ◽  
G. Walz
Keyword(s):  
Turbine Blades ◽  
Forced Response ◽  
Mode Shapes ◽  
Nodal Diameter ◽  
Frictional Contacts ◽  
Bladed Disk ◽  
Engine Order ◽  
Bladed Disk Assembly ◽  
Last Stage ◽  
Software Code

Freestanding turbine blades have typically low structural damping and thus require additional friction damping devices, such as underplatform dampers. The friction coupling between neighboring blades reduces response amplitude and increases resonance frequency. Along with forced response excitation large blades, especially of last stage, could be excited by fluid structural interaction (flutter). To prevent such excitation alternate mistuned blade patterns are beneficial disturbing traveling waves in the stage. In this paper the influence of alternate mistuning is investigated with a simplified oscillator chain as well as a bladed disk assembly coupled by frictional contacts. It is pointed out that the performance of friction coupling can be improved by alternate mistuning as long as the engine order of the excitation is below quarter of the number of blades. Alternate mistuning causes a mode coupling between two nodal diameter vibration mode shapes allowing for energy transfer. The in-house developed software code DATAR is enhanced and alternate mistuning can be applied to the blades as well as to the damping elements. For validation the DATAR code was applied to an alternate mistuned last stage blade of a Siemens gas turbine and compared with available field engine measurement.

Vibration Modes of Packeted Bladed Disks

1984 ◽  
Vol 106 (2) ◽  
pp. 175-180 ◽  
Author(s):  
D. J. Ewins ◽  
M. Imregun
Keyword(s):  
Natural Frequencies ◽  
Turbine Blades ◽  
Vibration Modes ◽  
Nodal Diameter ◽  
Vibrational Behavior ◽  
Bladed Disk ◽  
Methods Of Analysis ◽  
Receptance Coupling ◽  
Modal Interference ◽  
Series Of Experiments

This paper presents the results of investigating the vibrational behavior of turbine blades when grouped into packets. Two methods of analysis based on substructuring via receptance coupling have been developed and used with success to predict the natural frequencies of a 30-bladed disk with various packeting arrangements. A series of experiments have been conducted on a special testpiece to confirm these predictions. It is found that, unlike its continuously shrouded counterpart, the packeted bladed disk has modes which are always complex in shape, containing several nodal diameter components, a feature which can be predicted from the modal interference diagrams introduced in this work.

Reduced-Order Modeling of Bladed Disks With Friction Ring Dampers

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Seunghun Baek ◽  
Bogdan Epureanu
Keyword(s):  
Steady State ◽  
Dry Friction ◽  
Friction Model ◽  
Contact Friction ◽  
Bladed Disks ◽  
Transient Dynamic Analysis ◽  
Reduced Order ◽  
Bladed Disk ◽  
Steady State Responses ◽  
State Responses

An efficient methodology to predict the nonlinear response of bladed disks with a dry friction ring damper is proposed. Designing frictional interfaces for bladed-disk systems is an important approach to dissipate vibration energy. One emerging technology uses ring dampers, which are ringlike substructures constrained to move inside a groove at the root of the blades. Such rings are in contact with the bladed disk due to centrifugal forces, and they create nonlinear dissipation by relative motion between the ring and the disk. The analysis of the dynamic response of nonlinear structures is commonly done by numerical integration of the equations of motion, which is computationally inefficient, especially for steady-state responses. To address this issue, reduced-order models (ROMs) are developed to capture the nonlinear behavior due to contact friction. The approach is based on expressing the nonlinear forces as equivalent nonlinear damping and stiffness parameters. The method requires only sector-level calculations and allows precalculation of the response-dependent equivalent terms. These factors contribute to the increase of the computational speed of the iterative solution methods. A model of a bladed disk and damper is used to demonstrate the method. Macro- and micro-slip are used in the friction model to account for realistic behavior of dry friction damping. For validation, responses due to steady-state traveling wave excitations are examined. Results computed by ROMs are compared with results from transient dynamic analysis (TDA) in ansys with the full-order model. It is found that the steady-state responses predicted from the ROMs and the results from ansys are in good agreement, and that the ROMs reduce computation time significantly.

Estimating the Audiogram Using Multiple Auditory Steady-State Responses

2002 ◽  
Vol 13 (04) ◽  
pp. 205-224 ◽  
Author(s):  
Andrew Dimitrijevic ◽  
Sasha M. John ◽  
Patricia Van Roon ◽  
David W. Purcell ◽  
Julija Adamonis ◽  
...  
Keyword(s):  
Steady State ◽  
Correlation Coefficients ◽  
Behavioral Threshold ◽  
Behavioral Thresholds ◽  
Sensorineural Hearing Impairment ◽  
Steady State Responses ◽  
Auditory Steady State Responses ◽  
Tonal Stimuli ◽  
Conductive Hearing ◽  
State Responses

Multiple auditory steady-state responses were evoked by eight tonal stimuli (four per ear), with each stimulus simultaneously modulated in both amplitude and frequency. The modulation frequencies varied from 80 to 95 Hz and the carrier frequencies were 500, 1000, 2000, and 4000 Hz. For air conduction, the differences between physiologic thresholds for these mixed-modulation (MM) stimuli and behavioral thresholds for pure tones in 31 adult subjects with a sensorineural hearing impairment and 14 adult subjects with normal hearing were 14 ± 11, 5 ± 9, 5 ± 9, and 9 ± 10 dB (correlation coefficients .85, .94, .95, and .95) for the 500-, 1000-, 2000-, and 4000-Hz carrier frequencies, respectively. Similar results were obtained in subjects with simulated conductive hearing losses. Responses to stimuli presented through a forehead bone conductor showed physiologic-behavioral threshold differences of 22 ± 8, 14 ± 5, 5 ± 8, and 5 ± 10 dB for the 500-, 1000-, 2000-, and 4000-Hz carrier frequencies, respectively. These responses were attenuated by white noise presented concurrently through the bone conductor.

Weighted averaging of steady-state responses

2001 ◽  
Vol 112 (3) ◽  
pp. 555-562 ◽  
Author(s):  
M.Sasha John ◽  
Andrew Dimitrijevic ◽  
Terence W Picton
Keyword(s):  
Steady State ◽  
Weighted Averaging ◽  
Steady State Responses ◽  
State Responses

Investigation of the 3D Unsteady Rotor Pressure Field in a HP Turbine Stage

2002 ◽  
Author(s):  
E. Valenti ◽  
J. Halama ◽  
R. De´nos ◽  
T. Arts
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Pressure Field ◽  
Pressure Ratio ◽  
Turbine Stage ◽  
Time Resolved ◽  
Mach Number Distribution ◽  
Rotor Surface ◽  
Exit Mach Number ◽  
Unsteady Pressure Measurements

This paper presents steady and unsteady pressure measurements at three span locations (15, 50 and 85%) on the rotor surface of a transonic turbine stage. The data are compared with the results of a 3D unsteady Euler stage calculation. The overall agreement between the measurements and the prediction is satisfactory. The effects of pressure ratio and Reynolds number are discussed. The rotor time-averaged Mach number distribution is very sensitive to the pressure ratio of the stage since the incidence of the flow changes as well as the rotor exit Mach number. The time-resolved pressure field is dominated by the vane trailing edge shock waves. The incidence and intensity of the shock strongly varies from hub to tip due to the radial equilibrium of the flow at the vane exit. The decrease of the pressure ratio attenuates significantly the amplitude of the fluctuations. An increase of the pressure ratio has less significant effect since the change in the vane exit Mach number is small. The effect of the Reynolds number is weak for both the time-averaged and the time-resolved rotor static pressure at mid-span, while it causes an increase of the pressure amplitudes at the two other spans.

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