Blade Row Interaction Effects on Flutter and Forced Response

1995 ◽  
Vol 11 (2) ◽  
pp. 205-212 ◽  
Author(s):  
Daniel H. Buffurn
Keyword(s):  
Interaction Effects ◽  
Forced Response ◽  
Blade Row ◽  
Blade Row Interaction

scholarly journals Navier-Stokes and Potential Calculations of Axial Spacing Effect on Vortical and Potential Disturbances and Gust Response in an Axial Compressor

1995 ◽  
Author(s):  
Meng-Hsuan Chung ◽  
Andrew M. Wo
Keyword(s):  
Lower Order ◽  
Spacing Effect ◽  
Axial Compressor ◽  
Interaction Effects ◽  
Moving Frame ◽  
Navier Stokes ◽  
Blade Row ◽  
Vortical Disturbance ◽  
Blade Row Interaction ◽  
Gust Response

The effect of blade row axial spacing on vortical and potential disturbances and gust response is studied for a compressor stator/rotor configuration near design and at high loadings using 2D incompressible Navier-Stokes and potential codes, both written for multistage calculations. First, vortical and potential disturbances downstream of the isolated stator in the moving frame are defined; these disturbances exclude blade row interaction effects. Then, vortical and potential disturbances for the stator/rotor configuration are calculated for axial gaps of 10%, 20%, and 30% chord. Results show that the potential disturbance is uncoupled; the potential disturbance calculated from the isolated stator configuration is a good approximation for that from the stator/rotor configuration for all three axial gaps. The vortical disturbance depends strongly on blade row interactions. Low order modes of vortical disturbance are of substantial magnitude and decay much more slowly downstream than do those of potential disturbance. Vortical disturbance decays linearly with increasing mode except very close to the stator trailing edge. For a small axial gap, lower order modes of both vortical and potential disturbances must be included to determine the rotor gust response.

Interaction Effects in a Transonic Turbine Stage

2000 ◽  
Author(s):  
J. W. Barter ◽  
P. H. Vitt ◽  
J. P. Chen
Keyword(s):  
Analytical Techniques ◽  
Interaction Effects ◽  
Phase Lag ◽  
Turbine Stage ◽  
Reflected Waves ◽  
Blade Row ◽  
Transonic Turbine ◽  
Unsteady Loading ◽  
Unsteady Pressure Measurements ◽  
Blade Row Interaction

A 3D, viscous, time-accurate code has been used to predict the time-dependent flowfield in a transonic turbine stage. Two analytical techniques are used to understand the unsteady physics. One technique takes into account interaction effects associated with reflected waves bouncing between blade rows while the other neglects them. Both techniques model the exact blade counts using phase-lag boundary conditions. The analytical techniques are validated by comparing to unsteady pressure measurements which have been made on the vane and blade surfaces at midspan. The analytical results are then used to understand the importance of interaction effects when the blade rows are close-coupled and when they are more widely spaced. The results show that interaction effects must be taken into account in order to accurately predict the unsteady loading on the upstream blade row. However, for the downstream blade row, interaction effects are second order and do not routinely need to be taken into account in the design process.

Blade-Row Interaction Effects on Unsteady Stator Loading in an Embedded Compressor Stage

2017 ◽  
Vol 33 (1) ◽  
pp. 248-255 ◽  
Author(s):  
Natalie R. Smith ◽  
Nicole L. Key
Keyword(s):  
Interaction Effects ◽  
Compressor Stage ◽  
Blade Row ◽  
Blade Row Interaction

scholarly journals Non-Axisymmetric Blade Row Interaction in Axial Turbomachines

1980 ◽  
Author(s):  
N. A. Mitchell
Keyword(s):  
Three Dimensional ◽  
Interaction Effects ◽  
Numerical Calculations ◽  
Relative Importance ◽  
Streamwise Vorticity ◽  
Wake Interaction ◽  
Blade Row ◽  
Blade Row Interaction

A three-dimensional non-axisymmetric theory is presented to analyze the interaction effects due to wakes between two blade rows in an axial turbomachine. The relative importance of potential and wake interaction with varying row separations and the contribution to the flow of shed radial and shed streamwise vorticity from the first row are examined. Numerical calculations of turbine and compressor stages are presented to illustrate the theory.

Application of the Modal Approach for Prediction of Forced Response Amplitudes for Fan Blades

2018 ◽  
Author(s):  
Franziska Eichner ◽  
Joachim Belz
Keyword(s):  
Energy Method ◽  
Natural Frequencies ◽  
Resonant Mode ◽  
Forced Response ◽  
Vibrational Amplitude ◽  
Campbell Diagram ◽  
Modal Approach ◽  
Blade Row ◽  
The Impact ◽  
Blade Row Interaction

Forced response is the main reason for high cycle fatigue in turbomachinery. Not all resonance points in the operating range can be avoided especially for low order excitation. For highly flexible CFRP fans an accurate calculation of vibration amplitudes is required. Forced response analyses were performed for blade row interaction and boundary layer ingestion. The resonance points considered were identified in the Campbell diagram. Forced response amplitudes were calculated using a modal approach and results are compared to the widely used energy method. For the unsteady simulations a time-linearised URANS method was applied. If only the resonant mode was considered the forced response amplitude from the modal approach was confirmed with the energy method. Thereby forced response due to BLI showed higher vibration amplitudes than for blade row interaction. The impact of modes which are not in resonant to the total deformation were investigated by using the modal approach, which so far, only considers one excitation order. A doubling of vibrational amplitude was shown in the case of blade row interaction for higher rotational speeds. The first and third mode-shape as well as modes with similar natural frequencies were identified as critical cases. The behaviour in the vicinity of resonance shows high vibration amplitudes over a larger frequency range. This is also valid for high modes with many nodal diameters, which have a greater risk of critical strain.

CFD Investigation of Aeromechanics

2001 ◽  
Author(s):  
Peter D. Silkowski ◽  
Chae M. Rhie ◽  
George S. Copeland ◽  
James A. Eley ◽  
James M. Bleeg
Keyword(s):  
Experimental Data ◽  
Interaction Analysis ◽  
Forced Response ◽  
Aerodynamic Damping ◽  
Influence Coefficients ◽  
Blade Row ◽  
Parallel Network ◽  
Computational Fluid Dynamics Cfd ◽  
Cascade Flutter ◽  
Blade Row Interaction

A Computational Fluid Dynamics (CFD) tool was developed and applied to a variety of aeromechanics problems, including both forced response and flutter. This 3-D non-linear, viscous, time accurate code, in conjunction with a large parallel network, is used to demonstrate the mature capability of CFD based tools for aeromechanical analysis. An example of multistage blade row interaction analysis is presented and compared against detailed experimental data highlighting the fidelity of current CFD tools. Flutter analyses of isolated blade rows are also compared to data and used to demonstrate several classical aeromechanical concepts such as influence coefficients, the destabilizing effect of neighboring blades in cascade flutter, the depiction of an aerodynamic damping map, and the flutter benefit of frequency mistuning. These two capabilities, multistage and flutter, are then combined to examine the effect of multistage interaction on the flutter problem. Finally the reasons for extending the above modeling to include full-aeroelastic capability are discussed and an example is presented.

Nonaxisymmetric Blade Row Interaction in Axial Turbomachines

1981 ◽  
Vol 103 (1) ◽  
pp. 201-209
Author(s):  
N. A. Mitchell
Keyword(s):  
Three Dimensional ◽  
Interaction Effects ◽  
Numerical Calculations ◽  
Relative Importance ◽  
Streamwise Vorticity ◽  
Wake Interaction ◽  
Blade Row ◽  
Blade Row Interaction

A three-dimensional nonaxisymmetric theory is presented to analyze the interaction effects due to wakes between two blade rows in an axial turbomachine. The relative importance of potential and wake interaction with varying row separations and the contribution to the flow of shed radial and shed streamwise vorticity from the first row are examined. Numerical calculations of turbine and compressor stages are presented to illustrate the theory.

scholarly journals Blade row interaction effects on compressor measurements

1993 ◽  
Vol 9 (4) ◽  
pp. 569-578 ◽  
Author(s):  
T. Shang ◽  
A. H. Epstein ◽  
M. B. Giles ◽  
A. K. Sehra
Keyword(s):  
Interaction Effects ◽  
Blade Row ◽  
Blade Row Interaction

Analysis of Unsteady Blade Row Interaction Using Nonlinear Harmonic Approach

2000 ◽  
Author(s):  
T. Chen ◽  
P. Vasanthakumar ◽  
L. He
Keyword(s):  
Stokes Equations ◽  
Linear Time ◽  
Three Dimensional ◽  
Axial Flow ◽  
Interaction Effects ◽  
Navier Stokes ◽  
Linear Interaction ◽  
Blade Row ◽  
Non Linear ◽  
Blade Row Interaction

An efficient non-linear harmonic methodology has been developed for predicting unsteady blade row interaction effects in multistage axial flow compressors. Flow variables are decomposed into time averaged variables and unsteady perturbations, resulting in time averaged equations with deterministic stress terms depending on the unsteady perturbation. The non-linear interaction between the time averaged flow field and the unsteady perturbations are included by a simultaneous pseudotime integration approach, leading to a strongly coupled solution. The stator/rotor interface treatment follows a flux averaged characteristic based mixing plane approach and includes the deterministic stress terms due to upstream running potential disturbances and downstream running wakes, resulting in the continuous nature of all parameters across the interface. The basic computational methodology is applied to the three-dimensional Navier-Stokes equations and validated against several cases. Results show that this method is much more efficient than the non-linear time-marching methods while still modeling the nonlinear unsteady blade row interaction effects.

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