Measurement and Decomposition of Periodic Flow Structures of a Test Turbine

This paper shows the experimental methodology which has been employed for the simultaneous aerodynamic and aeroacoustic analysis of a test turbine by means of a fast-response aerodynamic pressure probe. Two different phase references are used to resolve the fluctuations in time of the velocity and the pressure of phenomena occurring at different and unrelated periodicity. The phase-averaged fields are further post-processed by decomposing them into spatial-temporal Fourier coefficients. The deterministic unsteadiness is then simply represented by a limited number of Fourier coefficients, the physical meaning of which is discussed in details. In particular, this approach has been used to distinguish between propagating and non-propagating noise sources.