Managing the flow

Stephane Moreau

French

Stephane Moreau studies the acoustics of transportation systems to minimize health risks

Stephane Moreau describes his fields of study as “transportation and ventilation systems” but he admits that when it comes right down to it, he’s a sound man. His research focuses on the acoustics of propulsion and ventilation systems and aircraft airframe noise, including landing gear and high-lift devices. 

His goal? To minimize the noise these systems create while maintaining their proper function.

“I propose models that can simplify and reduce the noise,” Moreau says, from his office in the University of Sherbrooke’s faculty of mechanical engineering. “Everything starts from detailed simulations so I can understand what’s going on from noise in propulsion systems and noise in ventilation systems — that could mean turboengines, propellers, air conditioners, engine cooling, or any cooling ventilators, like in computers, in cars, in trains.”

Noise connected with heart disease

His reasons? Noise from such systems is becoming a major urban annoyance and a health issue, he said. “If you’re exposed to too much noise for too long, your risk of heart disease increases significantly. If you do noise mitigation, you reduce this risk.”

A recent study published in Occupational and Environmental Medicine, showed that people with “bilateral high-frequency hearing loss” were twice as like to have coronary heart disease. This research backed up what previous research into noise exposure had shown.

Those elevated risks, Moreau says, might apply to people living near airports, commercial travelers and those who work alongside noisy systems.

“More and more in big cities, the airports are inside the city,” he says. “Because of that, you have more and more people exposed to the noise.”

Other societal issues

There are other societal ramifications to noise. As much as these systems solve problems, they also end up causing some.

“More and more, firemen are using fans that they use to remove smoke from fires, to save lives, but the noise from those fans causes communication issues sometimes so it slows down the work of the firemen,” he says. In his utopia, the fans would work more quietly.

His work involves finding ways to minimize the unsteadiness and inhomogeneity of the flow in turbomachines,  which will then reduce the noise of engines and turbines.

Demand for computation power

To do that, he relies on the large computing power of Canada’s digital infrastructure.

“If you really want to understand where all this noise comes from, it requires massive simulations,” he says. “If you want to simulate interaction between a rotor and a stator [the basic rotating and static components of any propulsion or ventilation system that transfer mechanical power to the fluid], for example, you need to resolve all the tiny details of the flow. This requires dense computing — you need a very big machine.”

Compute Canada, the guardian and provider of Canada’s large computing systems, “is the star,” he says. “If you don’t do this kind of simulation, you can only have indirect evidence of what’s going on. You never have the full picture.”

Moreau, who has a master’s from École Nationale Supérieure de l’Aéronautique et de l’Espace in France and a PhD from Stanford, began his studies by doing aerodynamic simulations, after which he became an engineer for the automotive sector — working on automotive engine cooling systems for Valeo in Paris.

“I have designed the big fans in the front of the cars for almost 20 years; I was working on the engine-cooling systems as a tier-1 supplier for all major car manufacturers”

In 2008, when there was a financial crash and the automotive sector went into “hibernation,” he decided to move on to academia.

“I’m not a bear,” he says with a laugh. “If there’s nothing much going on in the industry, why not switch? A lot of people from universities contacted me. Université de Sherbrooke had what I wanted — it was the main reason I came to Canada. The facilities allowed me to build my own acoustic wind tunnel.”

He almost got scooped up by the University of Notre Dame in Indiana, but, in the end chose Sherbrooke because his family speaks French. The Parisian says at first the Quebec dialect was a challenge, but it didn’t take long, and now — like the flows of the machines he studies on a daily basis — he’s fully adjusted.

By Jennifer Campbell

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