Simulation of Three-dimensional Inviscid Flow Inside Rocket Engine Nozzles

摘要

A computer code is developed to simulate the three-dimensional, inviscid flow inside the rocket nozzle, which numerically solves the underlying compressible, unsteady Euler equations to obtain the steady state solution. Conservative form of Euler equations is discretized using a first-order upwind scheme (flux difference splitting) for an unstructured mesh composed of tetrahedrons, in connection with a cell-centered finite volume method. Three-stage multi-step explicit Runge-Kutta method is used for time integration and local time stepping is used to accelerate the convergence to steady state. Solutions at vertex nodes are updated by a node reconstruction process after cell center calculations. Inlet and outlet boundary conditions use one-dimensional method of characteristics and flow tangency condition is imposed on the walls. No flux through the walls is accomplished by equating the left and right states at the wall. The solver is developed with C++ programming language, using Object Oriented features. This allowed easier handling of the complicated data structures required by the three-dimensional geometry. The application, TUNES-3D is developed for the Windows environment with a Graphical User Interface (GUI). The geometry is drawn by a CAD software, imported into ANSYS and meshed into tetrahedrons. The code is tested on a three-dimensional Ni-bump channel for various flow regimes, a conical 45°-15° convergent-divergent nozzle, a parabolic convergent-divergent nozzle with various flow regimes, a 90° bent elbow with an inlet velocity profile and finally a divergent nozzle with supersonic flow and injection.