Gust load alleviation by normal microjet

This paper presents an investigation on the capability of gust load alleviation by normal microjet. The numerical method integrates the unsteady Reynolds averaged Navier-Stokes (URANS) solutions, structural dynamic equations of motion and the Field Velocity Method. The method is verified for gust responses of rigid and elastic models. The numerical results of microjet are validated against experimental and previous numerical data. Load control capabilities of normal microjet are evaluated on the 2D NACA0012 airfoil and the 3D BAH wing with constant and dynamic momentum coefficients under steady subsonic and transonic incoming flow conditions. Thereafter, gust load alleviation effects using microjet are tested on the airfoil and the BAH wing with and without the consideration of aeroelasticity. The results show that normal microjet has a strong capability for load control for transonic incoming flow. This is due to the jet effect on the shock strength on the airfoil upper surface. For the 3D BAH wing, significant load control effects can be shown for jet deployment on the span near the wing tip. Load reduction has also been observed near the wing root away from the jet region. The test cases show that normal microjet is a promising approach for gust load alleviation with a fast frequency response characteristic. A near constant lift response under gust condition can be achieved by adaptively adjusting the blowing momentum coefficients.