Research On Optimal Design Theory And Method Of Muzzle Brake

Muzzle brake is an important muzzle device which can decrease the recoil force andrecoil length. At the same time, it can also increase the overpressure of blast wave in thedirection of the gunners. In this dissertation muzzle brake was studied with numericalsimulation of blast flow, design of experiment, approximation method and optimizationwith GA(Genetic Algorithm). The content of the dissertation includes the analyzing ofthe muzzle brake performance, optimization of muzzle brake and the study of the blastflow development.The inviscid Euler equations were applied to set up the model of the muzzle flowfield with no pill and no initial flow field. The domain of the flow was meshed withunstructured grids and the equations were solved with a finite volume method. Thedistribution of the overpressure was obtained. Then in order to evaluate the overallperformance of the muzzle brake the efficiency was calculated with three methods,method combining with the experimental testing, method combining with flow fieldsimulation and the semi-experiential method. The method combining with flow fieldsimulation includes the steady flow simulation and the unsteady flow simulation.The single objective optimization was developed on a muzzle brake with bevelnozzles based on the 2D numerical simulation of blast flow with an optimization methodof multi-island GA. The optimal design with the given constrains was obtained. Then theoptimal 2D result was applied to build a 3D model to evaluate the improvement of themuzzle brake performance. The improved Non-dominated Sorting Genetic Algorithm(NSGA-Ⅱ) was employed in the multi-objective optimization of the same muzzle brake.The two objectives are the impact force on the muzzle brake and the overpressure at thegiven spot in the gunner's direction. After the optimization the Pareto solution set ofmuzzle brake performance was obtained.The numerical simulation of the 3-D inviscid blast flow and the Latin HypercubeSampling were applied in the simulation experiment of the muzzle brake performance.Then the RSM(Response Surface Method) and the Kriging method were usedindividually to establish the approximate models of the muzzle brake performance basedon the simulation experimental results. The two approximate models were applied insteadof numerical simulation of flow field in the single-objective and multi-objectiveoptimization of the muzzle brake with multi-island GA and NSGA-Ⅱindividually. ThePareto solution set was obtained after the multi-objective optimization. One high performance design with higher efficiency was picked out and named muzzle brake B.The simulation of the muzzle blast flow field with the muzzle brake B indicates highprecision of the approximation model. Finally the static strength analysis was performed,which indicates satisfactory strength performance.The Navier-Stokes equations and the standard high Renault numberκ-εtwo-equation turbulence model were applied to describe the muzzle blast flow with amoving pill and initial flow. The following cases were studied to analyze thedevelopment of muzzle blast flow, 2D axial symmetric model without muzzle brake, 2Daxial symmetric model with a muzzle brake, 3D model with muzzle brake A which isapplied on a gun in service, 3D model with muzzle brake B which is perforated. Clearshock structure was obtained in the simulation results and the development of the muzzleblast flow was analyzed. The comparison of the performance of muzzle brake A andmuzzle brake B was carried on according to the simulation results, which shows theperformance of muzzle brake B was higher in both ways than muzzle brake A. At last thetest of the performance of muzzle brake A was performed in an experiment.