Yes, many. It's widely used on solid rocket motors, but it's considered a bad idea on liquid fuels because regenerative cooling is usually lighter, more efficie

Yes, many. It's widely used on solid rocket motors, but it's considered a bad idea on liquid fuels because regenerative cooling is usually lighter, more efficient and easier to design and build. It's hard to get a rocket nozzle to ablate in such an even and consistent way that you wouldn't have to provide much larger safety margins than you'd really want to in a rocket.