The vortex dissipators are aimed at preventing the engines from forming vortices that would suck up gravel from directly below, like the ones you see in this vi

The vortex dissipators are aimed at preventing the engines from forming vortices that would suck up gravel from directly below, like the ones you see in this video: https://www.youtube.com/watch?v=cEgiqCZLJqQ&feature=youtu.be&t=3m11s https://www.youtube.com/watch?v=cEgiqCZLJqQ&feature=youtu.be... On the 737-200, I think the engines sit far enough back in the nacelles that the won't be able to suck in anything form below if the vortices don't form: https://upload.wikimedia.org/wikipedia/commons/0/04/Boeing_737-200_%28Brasilia_Air_Base%29_JT8D.jpg?1567178864795 https://upload.wikimedia.org/wikipedia/commons/0/04/Boeing_7...