Quantification of the Influence of Unsteady Aerodynamic Loading on the Damping Characteristics of Airfoils Oscillating at Low-Reduced Frequency—Part I: Theoretical Support

  1. Corral, Roque 12
  2. Vega, Almudena 2
  1. 1 Advanced Engineering Direction, Industria de TurboPropulsores S.A., Madrid 28108, Spain;
  2. 2 Universidad Politécnica de Madrid
    info

    Universidad Politécnica de Madrid

    Madrid, España

    ROR https://ror.org/03n6nwv02

Revista:
Journal of Turbomachinery

ISSN: 0889-504X,  1528-8900

Año de publicación: 2016

Volumen: 139

Número: 3

Tipo: Artículo

DOI: 10.1115/1.4034976 GOOGLE SCHOLAR lock_openAcceso abierto editor

Otras publicaciones en: Journal of Turbomachinery

Resumen

The effect of the unsteady aerodynamic loading of oscillating airfoils in the low-reduced frequency regime on the work per cycle curves is investigated. The theoretical analysis is based on a perturbation analysis of the linearized Navier–Stokes equations for real modes at low-reduced frequency. It was discovered that a new parameter, the unsteady loading, plays an essential role in the trends of the phase and modulus of the unsteady pressure caused by the airfoil oscillation. Here, the theory is extended in order to quantify this new parameter. It is shown that this parameter depends solely on the steady flow-field on the airfoil surface and the vibration mode-shape. As a consequence, the effect of changing the design operating conditions or the vibration mode onto the work-per-cycle curves (and therefore in the stability) can be easily predicted and, what is more important, quantified without conducting additional flutter analysis. The relevance of the parameter has been numerically confirmed in the Part II of the paper.

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