The noise emitted by airplanes sounds as if it is coming from the engine, but it is basically airflow over the plane’s wings, flaps and landing gear, according to University of Florida researchers.
Engineers hoping to reduce the racket have just completed construction of a wind tunnel that simulates flight conditions and is enabling researchers to figure out exactly why airplanes often cause so much noise.
He explained that the phenomenon is comparable to a hand stuck outside the window of a fast-moving car. If the hand is tilted, the lift and drag due to the wind fluctuates. This resulting unsteady airflow then often produces sometimes audible noise.
Yet another source of airplane noise results from turbulence, such as small vortices or eddies in the air flow, that interact with parts of the plane to create what the researchers call aerodynamic noise.