Plasma reduces aeroacoustical noise of Aero-trains

As the threat of climate change intensifies, so does the demand for sustainable, efficient transportation. Fueled by renewable energy, high-speed Aero-trains utilize the wing-in-ground (WIG) effect to hover over a walled track.

But the aerodynamic performance of the Aero-trains makes them impractically loud. Lai et al. investigated how plasma can decrease decibels. Such a technique has been successfully implemented for noise reduction at low speeds, and this study demonstrates plasma intervention is effective up to 500 km/h.

Albatrosses, the large seabirds, inspired the Aero-train’s design.

“Research has found that they fly efficiently by taking advantage of the WIG effect, a phenomenon in which the lift of the wing increases dramatically and the drag decreases as it approaches the ground or water,” said author Liangkui Tan.

However, the wings’ proximity to the track walls, which facilitates the WIG effect, makes Aero-trains loud. Adding plasma actuators to the Aero-train wings reduces noise.

“The effect of aeroacoustic reduction is achieved through the suppression of airflow separation and the destruction of large vortex structures by the jet induced by the plasma actuator,” Tan said. “Reducing the strength of the shedding vortex developing downstream into wall-bounded vortices reduces aerodynamic noise.”

The researchers compared two plasma configurations and found that placing actuators on the trailing edge of both the upper and lower airfoils reduces airflow interaction and subsequently noise at high speeds. However, high frequency sound pressure increases slightly as a result.

Aero-trains, once optimized to reduce noise, are a promising alternative for energy efficient, high-speed travel.

Source: “Aeroacoustic control mechanism on near-wall-wing of Aero-train based on plasma jet,” by Chenguang Lai, Liangkui Tan, and Shigeru Obayashi, Physics of Fluids (2023). The article can be accessed at https://doi.org/10.1063/5.0136669 .