New Developments in Aeroacoustics Research: From Fundamentals to Applications

A special issue of Aerospace (ISSN 2226-4310). This special issue belongs to the section "Aeronautics".

Deadline for manuscript submissions: 31 May 2025 | Viewed by 5026

Special Issue Editors


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Guest Editor
Department of Mathematics, University of York, York YO10 5DD, UK
Interests: aeroacoustics; turbulence; transition; asymptotics

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Guest Editor
Department of Aerospace Engineering, Mississippi State University, Starkville, MS 39762, USA
Interests: receptivity and transition in boundary layers; boundary layer control; theoretical and computational aeroacoustics; turbulence in fluids
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Special Issue Information

Dear Colleagues,

Aeroacoustics is the study of sound generation by fluid motion or aerodynamic forces interacting with surfaces. Over the last few decades, a vast amount of research in the area of aeroacoustics motivated by tightening airport regulations has resulted in a reduction in overall noise by almost 20 EPNdB despite the increase in aircraft size and weight over that time. However, the volume of aircraft in our skies is still growing, raising overall noise levels and making this a prevalent environmental problem. While Lighthill’s acoustic analogy provided the first analytical means to model and predict jet noise, considerable advances have been made in recent years with regard to novel statistical approaches in analysing jet turbulence. This includes using large-Eddy simulations for turbulence correlation function extraction, wave packet modelling, and more recently machine learning. Flow surface interactions have also advanced in both the mathematical modelling of turbulent flow distortions around a solid body and the statistical modelling of turbulence that uses such models as input.

The ultimate goal of this Special Issue is to explore recent developments in aeroacoustics research, ranging from fundamentals and new applications of aerodynamic noise to the use of reduced-order modelling based on modal decomposition or machine learning algorithms. We aim to shed light on the latest technologies, breakthroughs, and cutting-edge advancements targeting a broad range of aeroacoustics applications, using theoretical, numerical, or experimental approaches. We aim to provide a comprehensive platform for the exchange of knowledge, ideas, and developments for those interested in these areas.

As such, this Special Issue seeks to publish research articles and reviews within the domain of aeroacoustics and sound attenuation, including but not limited to fundamental aeroacoustics, aircraft and vehicle noise reduction, architectural acoustics, and innovations in acoustic materials and designs.

We look forward to your submissions.

Dr. Zamir Koshuriyan
Dr. Adrian Sescu
Guest Editors

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Keywords

  • aeroacoustics
  • turbulence modelling
  • statistical analysis

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Published Papers (4 papers)

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Research

16 pages, 23338 KiB  
Article
Passive Rotor Noise Reduction Through Axial and Angular Blade Spacing Modulation
by Chingiz Arystanbekov, Altay Zhakatayev and Basman Elhadidi
Aerospace 2025, 12(3), 167; https://doi.org/10.3390/aerospace12030167 - 20 Feb 2025
Viewed by 605
Abstract
This study investigates the aerodynamic and aeroacoustic performance of a novel two-stage two-bladed coaxial propeller that is axially and angularly spaced. Aerodynamic propulsive thrust and efficiency are validated and evaluated using a Reynolds-averaged Navier–Stokes computational fluid dynamics (CFD) model for the two-bladed APC27x13 [...] Read more.
This study investigates the aerodynamic and aeroacoustic performance of a novel two-stage two-bladed coaxial propeller that is axially and angularly spaced. Aerodynamic propulsive thrust and efficiency are validated and evaluated using a Reynolds-averaged Navier–Stokes computational fluid dynamics (CFD) model for the two-bladed APC27x13 propeller. Aeroacoustic assessment is conducted using a Ffowcs Williams–Hawkings integral model. A four-bladed coplanar APC27x13 propeller is simulated and considered as the baseline propeller. The CFD results suggest that changes in the rotor thrust for the coaxial blades are within 3% for propellers with 0.25D axial spacing (where D is the propeller diameter) and 30 angular spacing for the advance ratio of J=0.30.5. The aeroacoustic assessment for J=0.3 reveals that blades with 30 and 60 azimuthal spacing and 0.25D axial spacing significantly reduce noise compared to the baseline propeller. The reduction is attributed to the redistribution of tonal noise blade passing frequencies, resulting in a reduction in the A-weighted noise levels by up to 2 dBA. Additionally, the study accounts for the effect of the blade tip Mach number, concluding that a tip Mach number ranging between 0.7 and 0.9 is optimal for noise reduction in the 30 configuration. The results highlight the potential noise reduction benefits of uneven axial and angular blade spacing while maintaining similar aerodynamic performance. Full article
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16 pages, 7350 KiB  
Article
Numerical Predictions of Low-Reynolds-Number Propeller Aeroacoustics: Comparison of Methods at Different Fidelity Levels
by Guangyuan Huang, Ankit Sharma, Xin Chen, Atif Riaz and Richard Jefferson-Loveday
Aerospace 2025, 12(2), 154; https://doi.org/10.3390/aerospace12020154 - 18 Feb 2025
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Abstract
Low-Reynolds-number propeller systems have been widely used in aeronautical applications, such as unmanned aerial vehicles (UAV) and electric propulsion systems. However, the aerodynamic sound of the propeller systems is often significant and can lead to aircraft noise problems. Therefore, effective predictions of propeller [...] Read more.
Low-Reynolds-number propeller systems have been widely used in aeronautical applications, such as unmanned aerial vehicles (UAV) and electric propulsion systems. However, the aerodynamic sound of the propeller systems is often significant and can lead to aircraft noise problems. Therefore, effective predictions of propeller noise are important for designing aircraft, and the different phases in aircraft design require specific prediction approaches. This paper aimed to perform a comparison study on numerical methods at different fidelity levels for predicting the aerodynamic noise of low-Reynolds-number propellers. The Ffowcs-Williams and Hawkings (FWH), Hanson, and Gutin methods were assessed as, respectively, high-, medium-, and low-fidelity noise models. And a coarse-grid large eddy simulation was performed to model the propeller aerodynamics and to inform the three noise models. A popular propeller configuration, which has been used in previous experimental and numerical studies on propeller noise, was employed. This configuration consisted of a two-bladed propeller mounted on a cylindrical nacelle. The propeller had a diameter of D=9 and a pitch-to-diameter ratio of P/D=1, and was operated in a forward-flight condition with a chord-based Reynolds number of Re=4.8×104, a tip Mach number of M=0.231, and an advance ratio of J=0.485. The results were validated against existing experimental measurements. The propeller flow was characterized by significant tip vortices, weak separation over the leading edges of the blade suction sides, and small-scale vortical structures from the blade trailing edges. The far-field noise was characterized by tonal noise, as well as broadband noise. The mechanism of the noise generation and propagation were clarified. The capacities of the three noise modeling methods for predicting such propeller noise were evaluated and compared. Full article
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23 pages, 17032 KiB  
Article
Experimental Investigation of Rotor Noise in Reverse Non-Axial Inflow
by Liam Hanson, Leone Trascinelli, Bin Zang and Mahdi Azarpeyvand
Aerospace 2024, 11(9), 730; https://doi.org/10.3390/aerospace11090730 - 6 Sep 2024
Viewed by 1332
Abstract
This paper experimentally characterises the far-field noise emissions of a rotor operating in reverse non-axial inflow conditions. Specifically, experiments were undertaken at a range of rotor tilting angles and inflow velocities to investigate the effects of negative tilting on rotor acoustics and their [...] Read more.
This paper experimentally characterises the far-field noise emissions of a rotor operating in reverse non-axial inflow conditions. Specifically, experiments were undertaken at a range of rotor tilting angles and inflow velocities to investigate the effects of negative tilting on rotor acoustics and their correlation with aerodynamic performance. The results show that the forces and moments experienced by the rotor blades change significantly with increasing inflow velocity and increasing negative tilting angle. Correspondingly, distinct modifications to the far-field acoustic spectra are observed for the negatively tilted rotor when compared to the edgewise condition, with the broadband noise content notably increasing. Moreover, for a given tilting angle, the broadband noise component is accentuated with increasing inflow velocity, similar to when the negative tilting angle is increased. With reference to the flow-field surveys conducted in the literature and a preliminary in-house flow measurement, the increase in broadband content can possibly be attributed to the heightened level of ingestion of blade self-turbulence, i.e., the ingestion of turbulent wake generated by the upstream portion of the rotor by the downstream portion. At lower inflow velocities, the magnitude of the blade passing frequency at each of the observer angles is found to change minimally with negative tilt. In contrast, at higher inflow velocities, the directivity pattern and intensity of both the blade passing frequency and the overall sound pressure level are shown to change with increases in magnitude, particularly at downstream observer locations with negative tilt. These findings have important ramifications for the design and suitable operational profile of aerial vehicles for future urban air mobility applications. Full article
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23 pages, 8690 KiB  
Article
Assessment of Turbulence Models for Cylinder Flow Aeroacoustics
by Xiao Wang, Shanti Bhushan, Adrian Sescu, Edward Luke, Bukhari Manshoor and Yuji Hattori
Aerospace 2024, 11(9), 707; https://doi.org/10.3390/aerospace11090707 - 30 Aug 2024
Cited by 1 | Viewed by 1811
Abstract
Numerical simulations are performed for flows over a circular cylinder at a Reynolds number ranging from 150 to 5000, and Mach number of 0.2, to assess the predictive capability of URANS and hybrid RANS/LES for acoustic waves generation and propagation. Complementary direct numerical [...] Read more.
Numerical simulations are performed for flows over a circular cylinder at a Reynolds number ranging from 150 to 5000, and Mach number of 0.2, to assess the predictive capability of URANS and hybrid RANS/LES for acoustic waves generation and propagation. Complementary direct numerical simulations (DNS) are performed to generate validation datasets and to provide more insight into the problem. DNS predictions show that noise induced by the vortex shedding is radiated primarily at a 90-degree angle with respect to the wake direction and dictates the dominant frequency of the sound pressure waves. Turbulence dominates the noise in the near-field wake, resulting in a broadband pressure spectrum. URANS both underpredicts and overpredicts the noise levels in the wake region and in the direction normal to the freestream flow, respectively, which is attributed to its inability to accurately predict the turbulent kinetic energy content. Hybrid RANS/LES computations, using a second-order low-dissipation optimization-based gradient reconstruction scheme on a grid that is three times coarser than the DNS, provide an accurate prediction of the far-field noise levels, except in the wake region, where they are overpredictive. Full article
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