A Two-Dimensional Model of Sound Transmission Through Curved and Staggered OGV: Effect of Inter-Vane Channel Mode Transitions

The present work extends a recent two-dimensional analytical model for sound generation and transmission in an axial-flow outlet guide vanes row, by taking into account vane camber and stagger, as well as cut-on/cut-off or cut-off/cut-on transitions of inter-vane channel modes. It is aimed at demonstrating that such transitionsmay have a significant role in turbomachinery aeroacoustics, typically by changing the balance of upstream and downstream scattered waves. The model is based on a mode-matching procedure and generates a uniformly valid description of the sound field. Previous implementations neglecting the vane curvature have shown significant limitations at high frequencies compared to numerical simulations performed with a finite element method code. The extension presented in this paper introduces curvature by a slowly-varying duct formalism. Comparison with numerical simulations show substantial improvements at the cost of a reasonably higher computation time.

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