scholarly journals Estimating unsteady aerodynamic forces on a cascade in a three-dimensional turbulence field

1986 ◽  
Author(s):  
T. NORMAN ◽  
W. JOHNSON
Keyword(s):  
Three Dimensional ◽  
Aerodynamic Forces ◽  
Unsteady Aerodynamic

Investigation of the Influence of Aerodynamic Coupling on Response Levels of Mistuned Bladed Discs With Weak Structural Coupling

2005 ◽  
Author(s):  
I. Sladojevic´ ◽  
E. P. Petrov ◽  
A. I. Sayma ◽  
M. Imregun ◽  
J. S. Green
Keyword(s):  
Three Dimensional ◽  
Forced Response ◽  
Navier Stokes ◽  
Response Distribution ◽  
Aerodynamic Forces ◽  
Torsional Mode ◽  
Structural Coupling ◽  
Unsteady Aerodynamic ◽  
The Difference ◽  
Statistical Results

The paper summarises the results of a study investigating the correlation between the aerodynamic blade-to-blade coupling in mistuned bladed disc assemblies and the level of forced response. The focus was placed on the torsional mode of vibration, where blades’ coupling through the disc is weak, exposing the effects of aerodynamic coupling. The forced response of a large number of mistuned discs was computed, using whole-annulus finite element (FE) models. The unsteady aerodynamic forces that act upon the disc were calculated using a three-dimensional Reynolds-averaged Navier-Stokes CFD code. The results show the difference in response with and without aerodynamic coupling, exposing higher blade-to-blade interaction in the latter case. The statistical results show the change of the forced response distribution curves with the introduction of aero-coupling and their deviation from Gaussian distribution.

Control of Unsteady Aerodynamic Forces

1990 ◽  
Author(s):  
Chih-Ming Ho ◽  
Ismet Gursul ◽  
Chiang Shih ◽  
Hank Lin ◽  
Mario Lee
Keyword(s):  
Aerodynamic Forces ◽  
Unsteady Aerodynamic

Effect of Wake Passing on Unsteady Aerodynamic Performance in a Turbine Stage

2006 ◽  
Author(s):  
K. Yamada ◽  
K. Funazaki ◽  
K. Hiroma ◽  
M. Tsutsumi ◽  
Y. Hirano ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Three Dimensional ◽  
Suction Side ◽  
Turbine Stage ◽  
Three Dimensional Flow ◽  
Unsteady Aerodynamic ◽  
Unsteady Effect ◽  
Unsteady Rans ◽  
Wake Passing ◽  
Stage Efficiency

In the present work, unsteady RANS simulations were performed to clarify several interesting features of the unsteady three-dimensional flow field in a turbine stage. The unsteady effect was investigated for two cases of axial spacing between stator and rotor, i.e. large and small axial spacing. Simulation results showed that the stator wake was convected from pressure side to suction side in the rotor. As a result, another secondary flow, which counter-rotated against the passage vortices, was periodically generated by the stator wake passing through the rotor passage. It was found that turbine stage efficiency with the small axial spacing was higher than that with the large axial spacing. This was because the stator wake in the small axial spacing case entered the rotor before mixing and induced the stronger counter-rotating vortices to suppress the passage vortices more effectively, while the wake in the large axial spacing case eventually promoted the growth of the secondary flow near the hub due to the migration of the wake towards the hub.

Three-Dimensional Aerodynamic Characteristics of Oscillating Supersonic and Transonic Annular Cascades

1982 ◽  
Author(s):  
M. Namba ◽  
A. Ishikawa
Keyword(s):  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Forces ◽  
Numerical Work ◽  
Dimensional Effects ◽  
Mathematical Expressions ◽  
Strip Theory ◽  
Clear Insight ◽  
Theory Approximation ◽  
Insight Into

A lifting surface theory is developed for unsteady three-dimensional flow in rotating subsonic, transonic and supersonic annular cascades with fluctuating blade loadings. Application of a finite radial eigenfunction series approximation not only affords a clear insight into the three-dimensional structures of acoustic fields but also provides mathematical expressions advantageous to numerical work. The theory is applied to oscillating blades. Numerical examples are presented to demonstrate three-dimensional effects on aerodynamic characteristics. Three-dimensional effects in supersonic cascades are generally small and strip theory predicts local aerodynamic forces as well as total aerodynamic forces with good accuracy. In transonic flow, however, the strip theory approximation breaks down near the sonic span station and three-dimensional effects are of primary importance.

Unsteady Aerodynamic Forces Measured on a Fluttering Profile

2014 ◽  
Author(s):  
Igor Zolotarev ◽  
Václav Vlček ◽  
Jan Kozánek
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Degrees Of Freedom ◽  
Air Flow ◽  
Optical Measurements ◽  
Energy Contribution ◽  
Aerodynamic Forces ◽  
Unsteady Aerodynamic ◽  
New Information ◽  
Drag And Lift

The study presents evaluation of optical measurements of the air flow field near the fluttering profile NACA0015 with two-degrees of freedom, Mach number of the flutter occurrence were M=0.21 and M=0.45. Aerodynamic forces (drag and lift components) were evaluated independently on the upper and lower surfaces of the profile. Using the mentioned decomposition, the new information about mechanism of flutter properties was obtained. The forces on the upper and lower surfaces are phase shifted and are partially eliminated as a result of the circulation around the profile. The cycle changes of these forces cause the permanent energy contribution from the airflow to the vibrating system.

A Time-Domain Fluid-Structure Interaction Analysis of Fan Blades

2008 ◽  
Author(s):  
Seung Ho Cho ◽  
Taehyoun Kim ◽  
Seung Jin Song
Keyword(s):  
Time Domain ◽  
Vortex Lattice ◽  
Interaction Analysis ◽  
Three Dimensional ◽  
Incoming Flow ◽  
Structure Interaction ◽  
Unsteady Aerodynamic ◽  
Aerodynamic Model ◽  
Blade Row ◽  
Fan Blade

This paper presents aerodynamic and aeromechanical analyses for an entire row of fan blades (i.e. tens of blades with a finite aspect ratio) subject to a uniform incoming flow. In this regard, a new unsteady three-dimensional vortex lattice model has been developed for multiple blades in discrete time domain. Using the new model, the characteristics of the unsteady aerodynamic forces on vibrating blades, including their temporal development, are examined. Also, the new aerodynamic model is applied to examine the aeromechanical behavior of fan blades by using a standard eigenvalue analysis. For this analysis, the fan blades have been modeled as three-dimensional plates, and, increasing the number of blades (or solidity) is predicted to destabilize the fan blade row.

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