Study Of Discontinuous Finite Element Numerical Scheme And Numerical Simulation On Complex Impinging Flow Field

Investigation object of this dissertation is multiple launch rocket system based on the project supported by the National Defense Key Pre-Research Foundation. A series of groundbreaking research and exploration including the flow field characteristics of complex gas jet and dynamic variety of multiple launch rocket system impinging flow field are carried out respectively and some beneficial results are obtained as follows:1. Three representative problems including sod shock tube, forward-facing step and focusing of toroidal shock wave are calculated numerically by using Runge-Kutta Discontinuous Galerkin Finite Element Method (RKDG-FEM) that is developed to solve axisymmetric Euler equations. The computed results indicate that the theoretical derivation is validity, the program is efficient, and the presented method is robust.2. High underexpanded free jet, supersonic coflowing and impinging jet on flat are studied respectively by using RKDG-FEM. More detailed flowfield wave structures, flow properties distributions along the jet axis and the pressure distributions along the impinging wall are obtained. Moreover, the comparisons between the computed results and those of other experiments and numerical schemes show thata) Flowfield wave structures captured at high underexpanded free jet by using RKDG-FEM are very distinct. The comparisons between the computed results and those of other numerical schemes are good agreement. But as for Mach disk location, the computed results shows relatively better agreement between our numerical results and those of experiment and theoretical estimate under the same flow conditions. The relative errors are less than 1%.b) Wave structures of flow field captured at supersonic coflowing by using RKDG-FEM reflect more detailed flow characteristics. The comparisons between the computed results and those of other numerical schemes are good agreement. For Mach disk, the diameter of which is obviously shortened but not disappear. It is better agreement with the results of experiment image.c) Shock wave evolution progresses of impinging jet on flat are simulated correctly by using RKDG-FEM and pressure variations on the flat surface and the moving of pressure peak are coincident with existed results.3. Discontinuous galerkin finite element method is futher developed to solve compressible multimedia flows based on the present work. A series of numerical experiment demonstrate that this method is capable of capturing moving interface precisely and numerical solutions have high resulation, which establish the foundation for simulating multiphase gas jet using discontinuous galerkin finite element method.4. Dynamic mesh generation technique is studied in this dissertation. Dynamic simulation of rocket impinging jet flow field is performed through CFD software connecting user defined function(udf) based on dynamic mesh technique, where mesh is readjusted continuously according to the rocket projectile movement at each time step.5. Impinging jet flow field of multiple launch rocket system are simulated numerically under the different launch state by using dynamic grid technique, and the variations of impingement force and impingement moment of rocket exhaust with movement distance of rocket projectile are obtained under a specified launch state. Furthermore, the characteristics of impinging jet flow field structure are compared under the different launch state and thermal impact effect of rocket plume to launch device are analyzed.These computed results may provide some theoretical guidance for rigidity and intensity designing of large components and gearing of the weapon system and the next model mechine making. Moreover, they may provide some necessary parameters for corrosion protection of gas jet.