Aero‐Acoustic Optimisation of Airflow Components in Gas Turbines

Abstract

AbstractThere is always a great interest in the improvement of the efficiency of gas turbines. This requires the reduction of energetic losses like pressure losses induced by vortices, turbulence and secondary flow. In the current investigation, effects caused by aero‐acoustic oscillation are of interest. The possibility to control these effects or to make them usable has several advantages, for example reducing pressure losses, reducing noise, and influencing the heat transfer and charging effects. This concerns potentially oscillatory flow systems in gas turbines like pipes, cavities and annuli. In particular annuli can not be considered theoretically using one‐dimensional pipe acoustic. The start of oscillation occurs due to turbulent shear stress, solid oscillating surfaces and time fluctuating pressure fields as well as thermal stimulation. This study focuses on the impact of aero‐acoustic oscillation caused by shear stress and rotating pressure fields on the through flow. A numerical study of axial, radial and circumferential acoustic eigen‐modes and a time harmonic analysis have been done with several boundary conditions. The achieved results have to be proved in a further experiment. An improvement in the aero‐acoustical design of gas turbine flow components will be possible thanks to the results gained from both the numerical study and planned experiment. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)