Engine Treatment Can Reduce the Noise Produced by Jets
Those residing in close proximity to an airport or directly beneath the flight path of incoming and outgoing jets often yearn for the opportunity to listen to Simon and Garfunkel’s “The Sound of Silence.”
The impact of airplane noise is severe, as demonstrated by various studies and reports. In a 2022 study conducted in New Jersey, scientists highlighted that individuals living in noise-polluted areas, including those near airports, experience a 72% higher rate of heart attacks compared to those in quieter regions. Professor Abel Moreyra from Rutgers Robert Wood Johnson Medical School emphasized that noise pollution should be recognized as a contributing factor to heart disease.
Impacts of Aircraft Noise on Health and Well-being
The Aviation Environmental Federation in London recently stated that aircraft noise can affect children’s memory and learning abilities, disrupt sleep, and lead to long-term health problems. An environmental group in Belgium estimated that the health costs for residents exposed to airport noise exceed 1 billion euros (1.07 billion USD). They found that approximately 51,000 people face an increased risk of developing high blood pressure, while 2,000 people have a heightened risk of heart disease due to disrupted sleep and constant daytime noise from airports.
To address these concerns, the European Union has implemented a directive to prevent excessively loud airlines from flying in European airspace. Belgium has also taken steps to reduce jet noise by implementing taxes on short-haul flights and private jets. Additionally, Baltimore’s BWI Airport has initiated a multiyear project worth $35 million to install soundproofing measures for over 400 homes surrounding the busy and noisy terminal.
Amid growing concerns about the negative effects of noise pollution, Shanghai University researchers have made a significant breakthrough. They have developed a groundbreaking model that aims to significantly reduce the deafening noise generated by jet engines. Their research, published in Advances in Aerodynamics, involved simulations in areas such as air turbulence, aeroacoustics, and hydrodynamics, relying on established equations like the Ffowcs Williams-Hawkings equation, commonly used to assess sounds produced by aircraft propellers, helicopter rotors, and turbo machinery.
Revolutionizing Jet Engine Noise Reduction with Wavy Inner Wall (WIW) Treatment
The Shanghai team introduced a jet engine treatment known as wavy inner wall (WIW), which involves replacing the smooth inner wall near the nozzle exit with walls featuring wavy patterns. This concept, initially proposed by MIT researchers in 2019, allows for control of fine-scale turbulence and results in a reduction of mid- to high-frequency noise. The Shanghai WIW solution outperforms previous methods that either impeded engine thrust or required additional devices to achieve noise reduction and thrust objectives.
The Shanghai remedy offers minimal thrust loss and does not rely on other structures to achieve significant noise reduction. By introducing subtle geometrical modifications and enhancing shear layer mixing, the wavy wall control method shows promise for flow and noise control in subsonic jets.
With further refinement and eventual implementation, the Shanghai WIW concept may bring us closer to a peaceful rendition of Simon and Garfunkel’s “The Sound of Silence,” resonating with the experiences of the pop duo who grew up near one of the world’s busiest airports, JFK in Queens, New York.
Read the original article on Phys.
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