Abstract
Large Eddy Simulation is performed using the NASA Source Diagnostic Test turbofan at approach conditions (62% of the design speed). The simulation is performed in a periodic domain containing one fan blade (rotor-alone configuration). The aerodynamic and acoustic results are compared with experimental data. The dilatation field and the dynamic mode decomposition (DMD) are employed to reveal the noise sources around the rotor. The trailing-edge radiation is effective starting from 50% of span. The strongest DMD modes come from the tip region. Two major noise contributors are shown, the first being the tip noise and the second being the trailing-edge noise. The Ffowcs Williams and Hawkings’ (FWH) analogy is used to compute the far-field noise from the solid surface of the blade. The analogy is computed for the full blade, for its tip region (outer 20% of span) and for lower 80% of span to see the contribution of the latter. The acoustics spectrum below 6 kHz is dominated by the tip part (tip noise), whereas the rest of the blade (trailing-edge noise) contributes more beyond that frequency.
Highlights
The latest noise standards imposed by International Civil Aviation Organization (ICAO) [1] have further restricted the maximum noise level for an aircraft certified after 2018
The hybrid Lattice–Boltzmann Method (LBM)–Very Large Eddy Simulation (VLES) [13,14] and the hybrid unsteady Reynolds-Averaged Navier–Stokes–LES [15,16] computations give a reliable prediction of the rotor–stator interaction (RSI) noise, as it may not require such a high grid resolution around the rotor blades
The results show that the wake width is well captured in LES
Summary
The latest noise standards imposed by International Civil Aviation Organization (ICAO) [1] have further restricted the maximum noise level for an aircraft certified after 2018. The rotor–stator interaction noise is generated by the interaction between the turbulent wakes of the rotor and the outlet guide vanes (OGV) This is currently the most studied noise source as the rotor wakes can be well resolved by using various numerical methods. The hybrid Lattice–Boltzmann Method (LBM)–Very Large Eddy Simulation (VLES) [13,14] and the hybrid unsteady Reynolds-Averaged Navier–Stokes (uRANS)–LES [15,16] computations give a reliable prediction of the RSI noise, as it may not require such a high grid resolution around the rotor blades. The previous studies showed that the modeling of the trailing-edge and turbulence-interaction noise sources is not enough to correctly predict the total rotor broadband noise spectrum [17,18]. The current study aims at providing a deeper understanding of these noise sources and their contribution to the overall rotor broadband noise.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
