0
Research Papers

Stability Increase of Aerodynamically Unstable Rotors Using Intentional Mistuning

[+] Author and Article Information
Carlos Martel

E.T.S.I. Aeronáuticos, Universidad Politécnica de Madrid, 28040 Madrid, Spainmartel@fmetsia.upm.es

Roque Corral1

 Industria de Turbopropulsores S.A., 28830 Madrid, Spainroque.corral@itp.es

José Miguel Llorens

E.T.S.I. Aeronáuticos, Universidad Politécnica de Madrid, 28040 Madrid, Spainjmillor@fmetsia.upm.es

1

Also Associate Professor at E.T.S.I. Aeronáuticos, Universidad Politécnica de Madrid, 28040 Madrid, Spain.

J. Turbomach 130(1), 011006 (Dec 19, 2007) (10 pages) doi:10.1115/1.2720503 History: Received July 18, 2006; Revised August 08, 2006; Published December 19, 2007

A new simple asymptotic mistuning model, which constitutes an extension of the well known fundamental mistuning model for groups of modes belonging to a modal family exhibiting a large variation of the tuned vibration characteristics, is used to analyze the effect of mistuning on the stability properties of aerodynamically unstable rotors. The model assumes that both the aerodynamics and the structural dynamics of the assembly are linear, and retains the first-order terms of a fully consistent asymptotic expansion of the tuned system where the small parameter is the blade mistuning. The simplicity of the model allows the optimization of the blade mistuning pattern to achieve maximum rotor stability. The results of the application of this technique to realistic welded-in-pair and interlock low-pressure-turbine rotors are also presented.

FIGURES IN THIS ARTICLE
<>
Copyright © 2008 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Geometry of an interlock (left) and welded-in-pair (right) LPT bladed disks

Grahic Jump Location
Figure 2

Tuned vibration characteristics versus number of nodal diameters for the first family of modes of an interlocked rotor (15)(N=84): (top) normalized vibration frequency (active modes encircled); (middle) aerodynamic damping relative to the critical damping; (inset) zoom of the unstable modes (shading indicates instability); and (bottom); aerodynamic frequency correction (see Eq. 23)

Grahic Jump Location
Figure 3

Tuned vibration characteristics versus number of nodal diameters for the first family of modes of a welded-in-pair rotor (15)(N=42): (top) normalized vibration frequency (active modes encircled); (middle) aerodynamic damping relative to the critical damping (shading indicates instability); and (bottom) aerodynamic frequency correction (see Eq. 23)

Grahic Jump Location
Figure 4

Damping variation for a pair of isolated modes as the mistuning amplitude ∣δ∣ is increased

Grahic Jump Location
Figure 5

(Top) Fourier coefficient distribution of the mistuning pattern required to stabilize the mode family in Fig. 2 according to Eq. 38; (bottom) corresponding physical mistuning pattern

Grahic Jump Location
Figure 6

Critical damping of the optimum mistuned configuration for the active modes indicated in Fig. 3 as a function of the maximum frequency deviation ∣ΔωBkF∣max: (thick line) minimum damping envelope; (dotted lines) damping of all active modes

Grahic Jump Location
Figure 7

Normalized Fourier coefficients of the optimal blade frequency deviation patterns for several different maximum frequency deviations in Fig. 6, ∣ΔωBkF∣max=0.2, 0.3, and 0.4 (thick, medium, and thin line, respectively)

Grahic Jump Location
Figure 8

Minimum damping as a function of the standard deviation, σ, of the natural frequencies of an interlock (top) and a welded pair (bottom) bladed disk (taken from Ref. 15)

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