A superposition methodology for modeling the multi-directional flow through a non-orthotropic porous combustion chamber wall material

Abstract

As an attractive alternative to the well-established regenerative cooling technology, DLR has spent many years in developing an effusion cooling design that could be used for rocket engine combustion chamber wall cooling. A porous carbon fiber/carbon matric (C/C) composite material that shows a high specific strength and very low thermal expansion over a large temperature range has been tested as a possible substitute for the copper based alloys conventionally used as combustion chamber wall material for highly efficient large thrust rocket engines. Due to the complexity of the structure of the investigated carbon fiber / carbon matrix (C/C) composite material, a superposition methodology, presented in this paper, has been used to:  Determine the Forchheimer model parameters for the permeability of the C/C material from experimental measurements.  Model the multi-directional flow through the nonorthotropic porous thrust chamber wall material. A test bench that uses cylindrical probes of C/C composite material designed in DLR Lampoldshausen has been used to determine the permeability of the material. The predicted mass flow rates for a cylindrical test sample are compared to experimental measurements for wide ranges of pressures and pressure drops in order to demonstrate the accuracy of the optimized permeability parameters. The distribution of the coolant flow throughout a cross section of a subscale combustion chamber wall made from the C/C material and the profile of the flow rate of the coolant flowing out of the combustion chamber surface are simulated performing cold flow CFD analyses.