Experimental and numerical investigation of frictional behavior and heat transfer in 3D printed rocket engine cooling channels

An experimental campaign has been conducted at the Space Propulsion Laboratory of Technical University of Munich (TUM) with the goal of characterizing pressure drop and heat transfer performances in new 3D printed segments of a thrust chamber. Four different specimens with different surface qualities in the combustion chamber and in the cooling channels have been tested, at real rocket engines operating conditions. CFD simulations of the cooling channels are performed in order to compare experimental data and numerical results through the use of RANS simulations and state-of-the-art roughness models. It has been found that the roughness in the cooling channels leads to an increment of the heat pick up of about the 10% while a rough chamber brings a more significant increase, up to the 30%. Pressure drops have also shown to be remarkably increased. RANS simulations are able to predict these results, however, proper tuning of the modelling parameters is required.