Parametric Investigation of the EESC-USP Aeroacoustic Fan Rig

Abstract: The study of turbofan aeroacoustics has become important in academia and industry as noise from other sources in aircraft have been reduced. Rotor-stator interaction noise, which is generated by the impingement of fan wakes on stator vanes, is considered the most prominent sources within engine noise. The pressure oscillations over these stator vanes have two distinct components: tonal and broadband. Knowledge in broadband component is still incipient and experimental methods can provide insights and data for on-going research. In this work, a instrumented stator vane was designed using recently available technologies, as 3D printing and the use of MEMS microphones, to measure this pressure fluctuations. Phase-averaging and the signal from a hall sensor were used to separate broadband content in time series. Broadband level distribution were analyzed for two span lines of the instrumented stator vane and for a reference microphone located in the inlet antenna. Broadband levels increased with the increase in fan speed and its distribution over these span lines maintained its shape for different speeds. Cross-correlation of the microphones were calculated and showed decay of zero-delay cross-correlation with increase in distance between microphones over the vane. And, finally, the integral length scale, obtained by the integration of zero-delay cross-correlation curve, showed decay with increase in fan speed.

Download paper here

Recommended citation: Rafael G. Cuenca, Bernardo Martinez R. Jr., Paulo C. Greco. “Parametric Investigation of the EESC-USP Aeroacoustic Fan Rig,” ICAS 2018-0147. 31st Congress of the International Council of the Aeronautical Sciences (ICAS). September 2018.