Optimization, Based On The Numerical Simulation Of Non-structured Grid Flow Field And The Nozzle Surface

In this thesis a strategy applying the CFD for the generation of tetrahedral unstructured viscous grid on two-dimensional configurations has been introduced, and flow numerical simulation of steady or unsteady N-S equations under unstructured grids is researched in emphasis. In addition, a vector nozzle shape design method that couples viscous flow analysis, a complex method is described in this paper.The unstructured grids are generated by using the combination of Delaunay and advancing front techniques. Using the Dulaunay method, the grids is compartmentalized and updated. New inner nodes are created based on the concept of advancing front techniques.A computational program based on the 2-D unstructured grids is developed to solve the steady or unsteady N-S equation. The solution of steady flow employs a finite-volume method with the Badwin-Lomax turbulent model, an algebra model, which can' t add the number of the equations and easy to solve. The 4-step Rung-Kutta scheme is adopted and the techniques of artificial dissipation, local time stepping and residual smoothing are used to increase the convergence rate. With respect of the unsteady flow, implicit dual-time stepping method is employed to reduce the calculating time, and in preudo-time region, the method of solving steady flow, as presented above, is applied. Finally, examples of grid generation and flow calculation are presented. The numerical results are in well accord with the published data, which show that the numerical solution method is correct and robust.The optimum method is studied in this paper, a vector nozzle shape design method that couples viscous flow analysis; a complex method is described additionally. The optimum program is developed by using the complex optimum method, which is an effective method to solve the restraining problem, and widely used.The optimum process is started by a base shape of vector nozzle. the unstructured grids of the vector nozzle is generated first and then the numerical flow is simulated by solving the N-S equations to gain the Aerodynamic parameters such as the coefficient of thrust force which is defined as design as the objective function, then the optimum program is executed by the Complex optimum method and the most aerodynamically favorable geometry that can be provide with the better aerodynamic performance is obtained.In this paper, the flow in the oxygen cavity of a rocket engine thrust chamber is investigated by using CFD methods, and the distribution of total and static pressure on exit of the oxygen cavity is determined. A new concept to design the orifice plate for flow uniformity in oxygen cavity is developed, and new orifice plates for flow uniformity are designed based on this concept and the results of flow characteristics. The detailed flow analysis and experiment validation is also performed, it shows that the newly designed orifice plate reduces 11.5% of pressure distortion on oxygen cavity exit, also shows that the concept and method provided in this paper are reasonable.