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An investigation of low pressure turbine blade—vane interaction noise: Measurements in a 1.5-stage rig

Abstract This article presents the investigation of the acoustical features of a 1.5-stage low pressure (LP) turbine rig, designed in cooperation with MTU Aero Engines Munich. The rig diameter and the rotating speed are approximately half of those of a commercial aeroengine LP turbine. The acoustic measurements were performed in a rotatable measurement section downstream the last blade row. The measurement section was equipped with microphones flush mounted at both the inner and the outer duct walls. This set-up enables the decomposition of the sound field into azimuthal and radial duct modes up to a frequency of 17 kHz. Thus the dominant sound generation mechanisms, caused by the aerodynamic interaction of rotor blades with the fixed blade rows, could be identified and the amount of sound power transported in and against the flow direction evaluated.