Memorias de investigación
Research Publications in journals:
Linear instability analysis of low-pressure turbine flows
Year:2009
Research Areas
  • Fluid mechanics
Information
Abstract
Three-dimensional linear BiGlobal instability of two-dimensional states over a periodic array of T-106/300 low-pressure turbine (LPT) blades is investigated for Reynolds numbers below 5000. The analyses are based on a high-order spectral/hp element discretization using a hybrid mesh. Steady basic states are investigated by solution of the partial-derivative eigenvalue problem, while Floquet theory is used to analyse time-periodic flow set-up past the first bifurcation. The leading mode is associated with the wake and long-wavelength perturbations, while a second short-wavelength mode can be associated with the separation bubble at the tralling edge. The leading eigenvalues and Floquet multipliers of the LPT flow have been obtained in a range of spanwise wavenumbers. For the most general configuration all secondary modes were observed to be stable in the Reynolds number regime considered. When a single LPT blade with top to bottom periodicity is considered as a base flow, the imposed periodicity forces the wakes of adjacent blades to be synchronized. This enforced synchronization can produce a linear instability due to long-wavelength disturbances. However, relaxing the periodic restrictions is shown to remove this instability. A pseudo-spectrum analysis shows that the eigenvalues can become unstable due to the non-orthogonal properties of the eigenmodes. Three-dimensional direct numerical simulations confirm all perturbations identified herein, All optimum growth analysis based on singular-value decomposition identifies perturbations with energy growths O(10(5)).
International
Si
JCR
Si
Title
JOURNAL OF FLUID MECHANICS
ISBN
0022-1120
Impact factor JCR
2,315
Impact info
Volume
628
Journal number
0
From page
57
To page
83
Month
JUNIO
Ranking
Participants
Research Group, Departaments and Institutes related
  • Creador: Grupo de Investigación: Mecánica de Fluidos Computacional
  • Departamento: Motopropulsión y Termofluidodinámica