Installation effects on the acoustics of low-pressure axial fans aspects of source, environment and receiver
Doctoral thesis, 2025
Low-pressure axial fans are employed in a wide range of applications, from industrial systems to domestic appliances. Their operation in proximity to
humans necessitates the mitigation of noise emissions to prevent adverse health effects and promote comfort. The acoustic characteristics of these fans are influenced by installation effects, considered here in terms of inlet geometry, upstream obstructions, parallel fan operation, and the acoustic field of the test environment. Installation effects associated with the fan’s local flow field modify the underlying aeroacoustic source processes, while the test environment influences sound propagation. Furthermore, the assessment of installation effects must consider human perception of noise.
In this work, installation effects on the acoustics of low-pressure axial fans are investigated experimentally. A round robin test of a benchmark fan is
first conducted to evaluate both the aerodynamic and acoustic measurement capabilities of a bespoke fan performance facility. In addition, the influence of room-acoustical effects is examined, along with the estimation of sound power and directivity using a spherical harmonics scheme of the half-space.
A series of case studies on a low-pressure axial fan with rotating ring, investigates the effects of inlet geometry, upstream obstructions, and spacing in parallel fan operation on the system’s acoustic performance. Psychoacoustic metrics are also evaluated with respect to the installation conditions.
Finally, seven 3D-printed fans are employed to investigate the influence of blade loading distribution and hub-to-tip ratio on aeroacoustic performance.
The interaction between the examined rotor design parameters and installation effects, in particular inlet geometry and upstream obstructions, is also studied.
This work advances the understanding of installation effects on the acoustics of low-pressure axial fans, considering the aspects of source, environment, and receiver. The findings provide guidance for the evaluation and abatement of noise emissions from installations of low-pressure axial fans.
humans necessitates the mitigation of noise emissions to prevent adverse health effects and promote comfort. The acoustic characteristics of these fans are influenced by installation effects, considered here in terms of inlet geometry, upstream obstructions, parallel fan operation, and the acoustic field of the test environment. Installation effects associated with the fan’s local flow field modify the underlying aeroacoustic source processes, while the test environment influences sound propagation. Furthermore, the assessment of installation effects must consider human perception of noise.
In this work, installation effects on the acoustics of low-pressure axial fans are investigated experimentally. A round robin test of a benchmark fan is
first conducted to evaluate both the aerodynamic and acoustic measurement capabilities of a bespoke fan performance facility. In addition, the influence of room-acoustical effects is examined, along with the estimation of sound power and directivity using a spherical harmonics scheme of the half-space.
A series of case studies on a low-pressure axial fan with rotating ring, investigates the effects of inlet geometry, upstream obstructions, and spacing in parallel fan operation on the system’s acoustic performance. Psychoacoustic metrics are also evaluated with respect to the installation conditions.
Finally, seven 3D-printed fans are employed to investigate the influence of blade loading distribution and hub-to-tip ratio on aeroacoustic performance.
The interaction between the examined rotor design parameters and installation effects, in particular inlet geometry and upstream obstructions, is also studied.
This work advances the understanding of installation effects on the acoustics of low-pressure axial fans, considering the aspects of source, environment, and receiver. The findings provide guidance for the evaluation and abatement of noise emissions from installations of low-pressure axial fans.
inlet geometry
low-pressure axial fans
upstream obstructions
aeroacoustics
room-acoustical effects
installation effects
psychoacoustics
lecture hall HA3, Hörsalsvägen 4, Chalmers
Opponent: Prof. Stefan Becker, Department of Chemical and Biological Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany.
Author
Michail Vourakis
Chalmers, Mechanics and Maritime Sciences (M2), Fluid Dynamics
A round robin test of a lowpressure axial fan.
International Congress on Fan Noise, Aerodynamics, Applications and Systems 2022, 27-29 June, Senlis, France, 2022.,;(2022)
Paper in proceeding
AEROACOUSTIC INTERACTION EFFECTS BETWEEN PARALLEL LOW-PRESSURE AXIAL FLOW FANS
Proceedings of Forum Acusticum,;(2023)
Paper in proceeding
Impact of distorted inlet flow on axial fan psychoacoustics
International Congress on Fan Noise, Aerodynamics, Applications and Systems 2025, 9-11 April, Antibes/Juan-les-Pins, France, 2025.,;(2025)
Paper in proceeding
Aeroacoustic source characterization at fan test facility with spherical harmonics of the half-space
Jasa Express Letters,;Vol. 5(2025)
Journal article
Installation effects on axial fans: Combined aeroacoustic and psychoacoustic perspective
Applied Acoustics,;Vol. 240(2025)
Journal article
Vourakis, M., Ghosh, D., Andersson, N., Etemad, S., Karlsson, M., & Zea, E. (2025). Experimental investigation of installation effects on the aeroacoustics of low-pressure axial fans: on the impact of blade loading distribution and hub-to-tip ratio. Manuscript.
Low-pressure axial fans are used in many everyday applications, from industrial ventilation systems to the cooling units of household devices. Because these fans often operate near people, reducing unwanted noise is important for health and comfort. One factor that influences fan noise is installation conditions, such as inlet geometry and surrounding space.
This research investigates how such installation conditions affect the noise produced by low-pressure axial fans. Initially, measurements of a benchmark fan were repeated to evaluate the measurement capabilities of the test facility and to identify the influence of room acoustics. Subsequent case studies explored generic installation scenarios, including variations in inlet geometry, upstream obstructions, and the spacing of fans arranged in parallel. These scenarios were also evaluated based on human’s perception of sound. In the final part of the work, seven 3D-printed fan designs were tested to study how rotor geometry interacts with installation conditions and alters noise emissions of low-pressure axial fans.
The findings of this work provide guidance for evaluating and reducing noise emissions of low-pressure axial fans installations.
This research investigates how such installation conditions affect the noise produced by low-pressure axial fans. Initially, measurements of a benchmark fan were repeated to evaluate the measurement capabilities of the test facility and to identify the influence of room acoustics. Subsequent case studies explored generic installation scenarios, including variations in inlet geometry, upstream obstructions, and the spacing of fans arranged in parallel. These scenarios were also evaluated based on human’s perception of sound. In the final part of the work, seven 3D-printed fan designs were tested to study how rotor geometry interacts with installation conditions and alters noise emissions of low-pressure axial fans.
The findings of this work provide guidance for evaluating and reducing noise emissions of low-pressure axial fans installations.
eFan, a key enabler for eMobility, part II
Swedish Energy Agency (2020-016065), 2020-10-01 -- 2024-09-30.
Areas of Advance
Transport
Energy
Subject Categories (SSIF 2025)
Fluid Mechanics
Vehicle and Aerospace Engineering
DOI
10.63959/chalmers.dt/5790
ISBN
978-91-8103-333-5
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5790
Publisher
Chalmers
lecture hall HA3, Hörsalsvägen 4, Chalmers
Opponent: Prof. Stefan Becker, Department of Chemical and Biological Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany.