CFD investigation of cooling flow in a rocket nozzle. A concept for one dimensional modeling with subdomains.

Abstract

The main purpose of this work has been to study if it is possible to reduce the mesh resolution but still capture the general flow behavior and heat transfer in a rocket nozzle cooling channels by using a specific type of domain in computational fluid dynamics (CFD). The domain used in this work is a subdomain in the software Ansys CFX by the company Ansys. Ansys CFX is a software used to calculate fluid flow with the Navier-Stokes equations, so called CFD. The geometry that the investigations was conducted on were a square tube with a length of 4.2 [m] connected with a inlet manifold and a outlet manifold and 4 other tubes. In order to verify the results a simulation were preformed in the beginning of the thesis that were compared with Volvo Aero’s in-house code. The validation showed that, with the turbulence model SST k − ! and a friction loss coefficient, the temperature, pressure and velocity where matched with the simulation of the in-house code. After verifying the boundary conditions and mesh, the second part of the thesis were to investigate how well CFX handles the interface between a very coarse mesh and a very fine mesh. These results showed that the interface affects the result but the disturbances are sufficiently low for the purpose of the task. Finally the geometry with inlet manifold and outlet manifold and five tubes were simulated and evaluated in order to get a estimate of the time that it takes for the solution to converge. Comparing this simulation time with the time it takes for a fully resolved tube, the results showed a great improvement.