Transpiration cooling using gaseous hydrogen

For future liquid rocket engines, advanced cryogenic combustion chambers are needed, both for Expandable Launch Vehicles (ELVs) or Reusable Launch Vehicles (RLVs). As a consequence of higher combustion chamber pressures extreme heat loads to the chamber walls, especially to the throat section, make alternatives to conventional regenerative cooling techniques almost mandatory. Transpiration cooling where a small amount of the fuel passes through porous walls into the combustion chamber is a very promising technique [14], [7]. This contribution summarizes both the experimental and the numerical work in the field of transpiration cooling performed at DLR Lampoldshausen. The experiments presented here have been performed using gaseous hydrogen at ambient temperature as coolant flow. Parallel to the experimental approach, some theoretical and numerical work has been carried out. Transient temperature distributions inside the porous wall are predicted modeling the heat transport problem as onedimensional in cylindrical coordinates. The hot gas side heat transfer is described applying a Bartz equation modified to account for the blowing boundary condition. Furthermore, coolant and wall are handled separately.