Mechanism of the electromagnetic force to control hydrodynamic noise from an airfoil model and its action mode

A method is proposed to control the flow and reduce the hydrodynamic noise by applying the constant electromagnetic force into the boundary layer. The flow and sound fields from an airfoil model with and without the electromagnetic force are calculated. Results show that along the flow direction, electromagnetic force can delay the flow separation on the airfoil surface, suppress small discrete vortices, reduce turbulent fluctuation pressure on the airfoil surface, and decrease the hydrodynamic noise. The change law of the hydrodynamic noise effect reduced by the electromagnetic force is summarized in terms of the Reynolds number, attack angle, and electromagnetic effective parameters. Based on the numerical calculation results, an actual model is experimentally measured in the water circulating tank to validate the abovementioned effect. Since the transition area pressure of the airfoil model is the lowest and the area is limited, the application of electromagnetic force into this area can achieve the lowest noise effect. The power consumption decreases and the effect of the magnetic leak is analyzed. The results provide a new method for the suppression of hydrodynamic noise in airfoil models.