There is a winglet outside the engine of the passenger plane. What is it used for?

This winglet is called a vortex generator. As the name implies, it is what produces vortex. The vortex generator at that position is called nacelle vortex generator, which is what produces vortex behind the engine nacelle; The airflow bypassed the top of the wing. The civil aviation engine is a turbofan engine from Dobby, Gao Han. It is impossible to put it in the belly of a passenger plane and it is not suitable to be attached to the fuselage. The best thing is to hang it under the wing, so the aircraft designer added an engine nacelle under the wing and then stuffed the engine into the nacelle. Then the question comes: how high should this nacelle be hoisted? Of course, the higher the better, but not higher than the wing. In this way, the engine can not only inhale enough air, but also can not inhale foreign objects on the runway, and will not bump easily. At the same time, hanging on both sides of the wing increases the moment of inertia in the rolling direction of the aircraft, making the aircraft more stable. This seems to be enough.