Numerical Simulation Research On The Separation Flow Field With Gasbag And Motion Law Of The Submunitions

In the background of gasbag separation system which was used in the supersonic cluster munitions system,experimental research,theory analysis and numerical simulation was applied to investigate the characteristics of interference flow field.The influence for dynamic characteristics about the submunitions was analyzed with the different initial separation velocities,angles,positions,sequences and Mach numbers.Based on this research the numerical calculation model for jet interaction about the cluster munitions was built,the interaction process of separation between the jet and the flow was reveled and the dynamic characteristics of the submunitions was analyzed.The key works were done in this thesis as follows:1)The gasbag separation experiments and supersonic wind tunnel experiments were designed for the study of separation processes.The whole processes of dynamic characteristics about the gasbag separation system were recorded by the data acquisition system and high-speed photography system.After analyzing the experiment results,the processes and the objective law of the gasbag separation system were revealed.Experimental results indicated that the experimental device was safe and reliable,and the powder charge design was reasonable and feasible.By the single separation and sequential separation wind tunnel experiments,the interference flow field structure was collected.Based on the results,a preliminarily discussion was made on the aerodynamic characteristics with different feature positions,angles and sequences.The results can provide the experimental basis for the unsteady calculation.2)Mathematical models were built according to the gasbag expansion process in combination with relevant theories on combustion,interior ballistics and aerodynamics.The whole separation process was divided into three different periods according to the structural characteristics of the system and the functional characteristics of all modules,namely,the powder burning process in the constant volume phrase,the gasbag inflation process,and the gasbag expansion process.According to the simulation result,the changing characteristics were revealed with the whole separation processes which include internal ballistic process,gasbag expansion process and the movement process of the submunition.The accuracy of the numerical models were verified by comparing with the experimental results.3)Numerical simulation methods and theory were analyzed to simulate unsteady flow field of multi-body sequential separation.The aerodynamic coupled solver was established basing on the rigid body motion equations and fluid control equations.The different dynamic boundaries and separation sequence were controlled based on the macro function.Spring analogy,local remeshing and adaptive mesh refinement method were carried out to resolve the problem of grid distortion and boundary movement.To improve the ability of grid distortion and accuracy of solution,the mesh smoothing and surface exchange method were employed to modify quality of mesh after reconstruction.Based on this method,the unsteady numerical method was verified.4)With the separation velocity and angle of the submunition as the characteristic parameters,the unsteady separation processes were calculated in six separation options.Systematic analysis was made after simulating calculation about the influence for the aerodynamic characteristics and separation stance under the different separation velocities and angles,so as to reveal the influencing mechanism for the separation process by projectile shock wave interaction.According to the simulation results,the gasbag separation parameters were given to ensure the safety of the separation under supersonic conditions.5)The numerical simulation model was built according to the gasbag sequential separation process for the submutions with the feature of axial distribution.The aerodynamic characteristics of the submunitions in different separation bays were presented and the separation trajectories were captured as the results.Based on this research,two types of sequential separation processes were simulated.The interaction processes of separation between the sub-munitions were revealed and the variation of aerodynamic interference characteristics in different sequential separation styles was also discussed.According to the simulation results,the shortest sequential interval between different submunitions was given in this paper.6)To analyze the jet interaction influence after the gasbag was damaged during the separation of submunitions,the jet interaction numerical model was built.After analyzing the numerical simulation results in three typical jet nozzle locations,the jet interaction influence for the flow field and aerodynamic characteristics was revealed.Based on this research,the separation processes of submunitions under the central position were simulated with three-typical separation Mach numbers:0.8Ma?1.2Ma?3Ma.By comparing with no jet interaction simulation results during the separation,the jet influence for the separation velocities,displacements and angular velocities was discussed.This dissertation provides not only experimental and theoretical methods for the study of multi-bay separation processes,but also a reference for the gasbag engineering application which can be used in the supersonic cluster munitions system.