0
Research Papers

Quantification of the Influence of Unsteady Aerodynamic Loading on the Damping Characteristics of Airfoils Oscillating at Low Reduced Frequency—Part II: Numerical Verification

[+] Author and Article Information
Almudena Vega

School of Aeronautics and Space,
Universidad Politécnica de Madrid,
Madrid 28040, Spain
e-mail: almudena.vega@upm.es

Roque Corral

Advanced Engineering Direction,
Industria de TurboPropulsores S.A.,
Madrid 28108, Spain;
Associate Professor
Department of Fluid Dynamics
and Aerospace Propulsion,
School of Aeronautics and Space,
UPM,
Madrid 28040, Spain
e-mail: roque.corral@itp.es

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received June 28, 2016; final manuscript received September 9, 2016; published online December 1, 2016. Assoc. Editor: Li He.

J. Turbomach 139(3), 031010 (Dec 01, 2016) (8 pages) Paper No: TURBO-16-1136; doi: 10.1115/1.4034978 History: Received June 28, 2016; Revised September 09, 2016

This paper numerically investigates the correlation between the so-called unsteady loading parameter (ULP), derived in Part I of the corresponding paper, and the unsteady aerodynamics of oscillating airfoils at low reduced frequency with special emphasis on the work-per-cycle curves. Simulations using a frequency-domain linearized Navier–Stokes solver have been carried out on rows of a low-pressure turbine airfoil section, the NACA65 section, and a flat plate, to show the correlation between the actual value of the ULP and the flutter characteristics, for different airfoils, operating conditions, and mode shapes. Both the traveling wave and influence coefficient formulations of the problem are used in combination to increase the understanding of the ULP influence in different aspects of the unsteady flow field. It is concluded that, for a blade vibrating in a prescribed motion at design conditions, the ULP can quantitatively predict the effect of unsteady loading variations due to changes in both the incidence and the mode shape on the work-per-cycle curves. It is also proved that the unsteady loading parameter can be used to qualitatively compare the flutter characteristics of different airfoils.

FIGURES IN THIS ARTICLE
<>
Copyright © 2017 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Isentropic Mach number distributions along the airfoil chord for the LPT case for different incidences

Grahic Jump Location
Fig. 2

(a) Nondimensional influence coefficient modulus and (b) phase of the central airfoil as a function of the reduced frequency for the LPT case vibrating in flap mode for the different operating conditions

Grahic Jump Location
Fig. 3

Nondimensional damping as a function of the IBPA and the steady flow conditions for the low-pressure turbine case vibrating in flap (M = 0.74 and k = 0.1)

Grahic Jump Location
Fig. 4

Isentropic Mach number distributions along the airfoil chord for the NACA65 compressor for subsonic design and off-design conditions, and for design transonic conditions

Grahic Jump Location
Fig. 5

(a) Nondimensional influence coefficient modulus and (b) phase as a function of the reduced frequency for the NACA65 case vibrating in flap mode for the i=0 deg (filled symbols) and i=−3 deg (open symbols) cases

Grahic Jump Location
Fig. 6

(a) Nondimensional influence coefficient modulus and (b) phase as a function of the reduced frequency for the NACA65 case vibrating in flap mode. M1 = 0.8: filled symbols and M1 = 0.7: open symbols.

Grahic Jump Location
Fig. 7

Real (left) and imaginary (right) part of the unsteady pressure of the NACA65 compressor (Min = 0.8 and k = 0.1)

Grahic Jump Location
Fig. 8

Nondimensional damping as a function of the IBPA and the steady flow conditions for the low-pressure turbine case vibrating in flap, edge, and different torsion modes (M = 0.74 and k = 0.1)

Grahic Jump Location
Fig. 9

(a) Nondimensional influence coefficient modulus and (b) phase as a function of the reduced frequency for the LPT case vibrating in flap mode (filled symbols) and edge mode (open symbols)

Grahic Jump Location
Fig. 10

Nondimensional influence coefficient modulus as a function of the reduced frequency for the NACA65 case vibrating in flap mode (filled symbols) and edgewise mode (empty symbols)

Grahic Jump Location
Fig. 11

Nondimensional influence coefficient phase as a function of the reduced frequency for the NACA65 case vibrating in flap mode (filled symbols) and edge mode (empty symbols)

Grahic Jump Location
Fig. 12

Mean (filled symbols) and minimum (open symbols) damping as a function of the reduced frequency of the LPT and NACA65 (subsonic and transonic) configurations

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In