Q&A with Feroz Ahmed, Senior Aeroacoustics Engineer at the University of Bristol
13/08/2024
What will you be presenting at the Aerospace Test & Development Show?
My presentation will cover the fundamental physics of noise generation and propagation mechanisms in electric embedded engines, technically known as Boundary Layer Ingesting (BLI) ducted fans. These fans, which are similar to the large engines found in modern airplanes but are partially embedded into the plane's main body rather than being mounted under the wings, offer significant potential for reducing fuel consumption. By ingesting air from both the front and the surface of the airframe, BLI ducted fans require less effort to propel the plane, leading to reduction in fuel consumptions. However, their impact on noise levels can vary significantly depending on their specific designs and configurations.
The core of my presentation will be based on detailed flow and noise measurements conducted at the University of Bristol’s National Aeroacoustic Wind Tunnel Facility. This first-of-its-kind study reveals, for the first time, how noise is generated and propagated from BLI ducted fans. A key focus will be the novel source decomposition method we developed, which dissects the complexities of noise interaction mechanisms among various sources. This method is crucial for understanding the fundamental physics of noise origin and how it changes as the fan operates at different thrust levels. Additionally, the study dissected the problem into three main areas (or physics): aerodynamics, aeroacoustics, and psychoacoustics. It investigated how the interactions among these three physics change under different fan thrust levels and operating conditions, providing a clear understanding of the underlying physics of noise origin, propagation, and human annoyance, as well as their variation with different thrust levels in BLI ducted fans.
What are the key challenges in the Aerospace Test & Development sector, and how will your presentation address them?
The development of next-generation eVTOL vehicles faces a critical challenge with noise emissions, which impact passenger acoustic comfort, public acceptance, and complicate the certification process. To address these challenges, Distributed Electric Propulsion (DEP) systems and Boundary Layer Ingesting (BLI) ducted fans have become integral components of next-generation aircraft in the Urban Air Mobility Sector (UAM). These technologies offer the potential to enhance both aerodynamic efficiency and noise reduction. However, despite these advancements, noise remains a significant hurdle.
Identifying the physical sources of noise is crucial for effective noise reduction. Current industry practices for noise control often rely on trial and error rather than a deep understanding of the underlying physics. This is where our study comes in. Our research addresses the urgent issue of noise, which poses a major obstacle to obtaining certifications for future aircraft, by uncovering the physics behind noise origin, propagation, and human annoyance associated with BLI ducted fans. The findings indicate that both duct and fan noise must be considered at both low and high thrust levels during the design of noise control devices.
A key challenge in the Aerospace Test & Development sector is effectively applying advanced academic research to real-world industry needs. Our research seeks to bridge this academic industry gap by offering actionable insights into the noise mechanisms of BLI ducted fans. By demonstrating a thorough understanding of how these systems generate and propagate noise, our study offers valuable insights for the industry to develop advanced noise reduction strategies, enhance human acoustic comfort, and ultimately simplifying the certification process.
Why is it important to participate in this event?
Participating in the Aerospace Test & Development Show is essential because it provides a unique platform to present and discuss my research on BLI ducted fans with a global audience of industry leaders. This event fosters collaboration between academia and industry, which is crucial for bridging the gap between fundamental research and practical application. By engaging with experts and stakeholders, we can accelerate the adoption of new technologies and strategies aimed at reducing noise emissions and improving the overall efficiency of next generation aircraft. Furthermore, this collaboration provides a critical foundation for advancing quieter and more efficient propulsion systems, contributing to the broader goal of sustainable aviation.
Seeking further insights? Check out these articles:
Aeroacoustics of a ducted fan ingesting an adverse pressure gradient boundary layer
Experimental Identification of Noise Mechanisms Present in a Partially Buried BLI Ducted Fan
Boundary layer ingested ducted fans: an experimental aeroacoustics study
Boundary Layer Ingestion Ducted Fan: Aeroacoustic and Psychoacoustic Insights
Author: Feroz Ahmed
My presentation will cover the fundamental physics of noise generation and propagation mechanisms in electric embedded engines, technically known as Boundary Layer Ingesting (BLI) ducted fans. These fans, which are similar to the large engines found in modern airplanes but are partially embedded into the plane's main body rather than being mounted under the wings, offer significant potential for reducing fuel consumption. By ingesting air from both the front and the surface of the airframe, BLI ducted fans require less effort to propel the plane, leading to reduction in fuel consumptions. However, their impact on noise levels can vary significantly depending on their specific designs and configurations.
The core of my presentation will be based on detailed flow and noise measurements conducted at the University of Bristol’s National Aeroacoustic Wind Tunnel Facility. This first-of-its-kind study reveals, for the first time, how noise is generated and propagated from BLI ducted fans. A key focus will be the novel source decomposition method we developed, which dissects the complexities of noise interaction mechanisms among various sources. This method is crucial for understanding the fundamental physics of noise origin and how it changes as the fan operates at different thrust levels. Additionally, the study dissected the problem into three main areas (or physics): aerodynamics, aeroacoustics, and psychoacoustics. It investigated how the interactions among these three physics change under different fan thrust levels and operating conditions, providing a clear understanding of the underlying physics of noise origin, propagation, and human annoyance, as well as their variation with different thrust levels in BLI ducted fans.
What are the key challenges in the Aerospace Test & Development sector, and how will your presentation address them?
The development of next-generation eVTOL vehicles faces a critical challenge with noise emissions, which impact passenger acoustic comfort, public acceptance, and complicate the certification process. To address these challenges, Distributed Electric Propulsion (DEP) systems and Boundary Layer Ingesting (BLI) ducted fans have become integral components of next-generation aircraft in the Urban Air Mobility Sector (UAM). These technologies offer the potential to enhance both aerodynamic efficiency and noise reduction. However, despite these advancements, noise remains a significant hurdle.
Identifying the physical sources of noise is crucial for effective noise reduction. Current industry practices for noise control often rely on trial and error rather than a deep understanding of the underlying physics. This is where our study comes in. Our research addresses the urgent issue of noise, which poses a major obstacle to obtaining certifications for future aircraft, by uncovering the physics behind noise origin, propagation, and human annoyance associated with BLI ducted fans. The findings indicate that both duct and fan noise must be considered at both low and high thrust levels during the design of noise control devices.
A key challenge in the Aerospace Test & Development sector is effectively applying advanced academic research to real-world industry needs. Our research seeks to bridge this academic industry gap by offering actionable insights into the noise mechanisms of BLI ducted fans. By demonstrating a thorough understanding of how these systems generate and propagate noise, our study offers valuable insights for the industry to develop advanced noise reduction strategies, enhance human acoustic comfort, and ultimately simplifying the certification process.
Why is it important to participate in this event?
Participating in the Aerospace Test & Development Show is essential because it provides a unique platform to present and discuss my research on BLI ducted fans with a global audience of industry leaders. This event fosters collaboration between academia and industry, which is crucial for bridging the gap between fundamental research and practical application. By engaging with experts and stakeholders, we can accelerate the adoption of new technologies and strategies aimed at reducing noise emissions and improving the overall efficiency of next generation aircraft. Furthermore, this collaboration provides a critical foundation for advancing quieter and more efficient propulsion systems, contributing to the broader goal of sustainable aviation.
Seeking further insights? Check out these articles:
Aeroacoustics of a ducted fan ingesting an adverse pressure gradient boundary layer
Experimental Identification of Noise Mechanisms Present in a Partially Buried BLI Ducted Fan
Boundary layer ingested ducted fans: an experimental aeroacoustics study
Boundary Layer Ingestion Ducted Fan: Aeroacoustic and Psychoacoustic Insights
Author: Feroz Ahmed