Flow State | Episode - 1 | Keeping Rocket Engines Cool | Skyroot Aerospace

Video from the channel Skyroot Aerospace about Skyroot Aerospace, linked on its Above Ten Thousand entry. Duration: 11:29. Language: English. Video type: Documentary.

First episode of "Flow State," an educational series produced by Skyroot Aerospace in which several of its engineers explain regenerative cooling, the method that keeps a rocket engine from melting.

The starting point is a comparison: Inconel, one of the most heat-resistant alloys used in these engines, melts at around 1,300 °C, while temperatures inside the combustion chamber reach about 3,000 °C. A car engine is cooled with a liquid that carries heat to a radiator, but a rocket has no room for such a system, and the radiator could not dissipate that much heat.

The solution is to use the fuel itself as a coolant. Before being burned, it travels through hundreds of thin channels, a millimeter or less across, running through the engine wall from the nozzle to the chamber, and then enters the chamber through the injector; the heat it absorbs also improves performance. A whiteboard is used to explain the Laval convergent-divergent nozzle, the throat, and the geometry of the channels, which is calculated using computational fluid dynamics. Additive manufacturing allows the assembly to be printed as a single piece and a design to be repeated in days or weeks instead of months. The principle is tested at every firing of the Raman 2 engine, and a channel clogged with debris can overheat that area and cause a catastrophic failure.