Wavelet-based decomposition of the tonal-broadband components of propeller noise

The present study reports a novel wavelet-based method aimed at separating the noise emitted by a single propeller into two contributions, tonal and broadband. An assessment using two different experimental investigations of propellers operating in diverse configurations is presented. The first experiment focuses upon near-field polar microphone...

Laminar Separation Bubble Noise on a Propeller Operating at Low-Reynolds Numbers

This paper explains the presence and relevance of noise caused by a laminar separation bubble (LSB) on a propeller operating at low-Reynolds number. Microphone measurements of a propeller with both clean and forced boundary layer transition blades are carried out in an anechoic wind tunnel by varying the propeller advance ratio J from 0 to 0...

Computational study of flow incidence effects on the aeroacoustics of low blade-tip Mach number propellers

This paper presents a computational study of flow incidence effects on the aeroacoustics of a propeller operating at low blade-tip Mach numbers. The numerical flow solution is obtained by using the Lattice-Boltzmann/Very Large Eddy Simulation method, while far-field noise is computed through the Ffowcs-Williams & Hawkings' acoustic...

Aeroacoustic Investigation of a Propeller Operating at Low Reynolds Numbers

This paper presents an experimental investigation of a propeller operating at low Reynolds numbers and provides insights into the role of aerodynamic flow features on both propeller performances and noise generation. A propeller operating at a tip Reynolds number regime of 4.3 × 10⁴ − 4.38 × 10⁴ is tested in an anechoic...

Definition of a benchmark for low Reynolds number propeller aeroacoustics

Experimental and numerical results of a propeller of 0.3 m diameter operated at 5000 RPM and axial velocity ranging from 0 to 20 m/s and advance ratio ranging from 0 to 0.8 are presented as a preliminary step towards the definition of a benchmark configuration for low Reynolds number propeller aeroacoustics. The corresponding rotational tip...

Performance and noise prediction of low-Reynolds number propellers using the Lattice-Boltzmann method

This paper proposes a CFD/CAA-based approach to predict the aerodynamic performances and tonal/broadband noise radiation of low-Reynolds number propellers at engineering level. Broadband self-noise prediction of low-Reynolds number propellers is particularly challenging, due to the requirement for the employed computational method to emulate...

Laminar Separation Bubble Noise on a Propeller Operating at Low Reynolds Numbers

This paper explains the presence and relevance of noise caused by a laminar separation bubble (LSB) on a propeller operating at a low Reynolds number. Microphone measurements of a propeller with both clean and forced boundary-layer transition blades are carried out in an anechoic wind tunnel by varying the propeller advance ratio J from 0 to 0.6...

Towards the definition of a benchmark for low Reynolds number propeller aeroacoustics

Experimental and numerical results of a propeller of 0.3 m diameter operated in quiescent standard ambient conditions at 5000 RPM and axial velocity ranging from 0 to 20 m/s and advance ratio ranging from 0 to 0.8 are presented as a preliminary step towards the definition of a benchmark configuration for low Reynolds number propeller...

Efficient low-fidelity aeroacoustic permanence calculation of propellers

A noise footprint prediction framework for propeller-driven aircraft which couples an aerodynamic model and several aeroacoustic models is presented in this study. The aerodynamic model is based on the blade element momentum theory, while the aeroacoustic models are based on a time-domain compact dipole/monopole Ffowcs-Williams and Hawking's...

Experimental Fluid Dynamic Characterization of Serrated Rotors for Drone Propulsion

The present study reports an experimental investigation regarding one of the most effective and most studied passive control technique in literature to mitigate the noise pollution radiating by a small drone: the Serrated Trailing Edge (STE). 23 quiet propellers have been designed and manufactured in order to identify the most silent...

A wavelet-based separation method for tonal and broadband components of low Reynolds-number propeller noise

Propeller noise generally exhibits a rich mixture of tonal and broadband components related to different physical mechanisms. Specifically, the tones are characterized by having deterministic and persistent characteristics, while the broadband counterpart has random behaviour. The separation is essential for the experimenters as they provide...