| The gas gun is a test device that uses a sudden jet of high-pressure air to push the projectile body to accelerate instantaneously in the barrel.After the projectile body flies away from the muzzle,it will produce strong impact force with the rapid expansion of high-pressure gas in the gun barrel,which harms the support structure of the launching system.The installation of muzzle brake can reduce the recoil force of the gas gun during firing and reduce the design load on the gun frame,providing guarantee for the aiming accuracy of the gas gun.Based on this,this paper designs a reaction muzzle brake suitable for the first stage gas gun,and conducts in-depth research on the performance of muzzle brake-the brake efficiency and the change mechanism of flow field from three aspects: theoretical analysis,flow field simulation and experimental test.The specific research contents include the following aspects:According to the weapon industry standards and the brake design criteria,a structural model of the first-stage gas gun brake with a side hole angle of 120 ° and a side hole diameter of 16 mm was designed.Based on the American Engineering Design Manual method and the internal ballistic theory,a theoretical model of the first-stage gas gun brake efficiency was established,the influences of key parameters such as the initial pressure of the high-pressure gas chamber,the volume of the high-pressure gas chamber,the mass of the projectile body,the angle of side hole and the diameter of side hole on the brake efficiency were analyzed.Based on 3D unsteady Navier-Stokes equation and standard k-ε turbulence model,combined with dynamic grid technology,the formation,development and attenuation mechanism of the flow shock wave during the post-effect period with/without muzzle brake was studied by using the Fluent software.The influence of the recoil force of the first-stage gas gun with/without muzzle brake was analyzed,and the brake efficiency was calculated.At the same time,the key parameters of the brake,such as the angle of the side hole,the diameter of the side hole and the initial pressure,are numerically simulated,and the change rule and action mechanism of muzzle shock wave formation,development and attenuation under different parameters were analyzed.The influence of different structural parameters on the brake efficiency is obtained through simulation calculation.An experimental test platform of the first-stage gas gun launch system was built,and the flow field characteristics and brake efficiency of the muzzle brake were tested.The instantaneous acceleration values with/without brake are collected by the three-axis acceleration sensor when the initial pressure is 5MPa,7MPa and 10 MPa,and the brake efficiency is calculated by using the ameliorate recoil resistance method.The change of air flow at the mouth of the brake during launch was captured by a highspeed imaging system,and the flow field characteristics and brake efficiency of the numerical simulation were compared and verified.The results show that the test results of the braking efficiency are highly consistent with the simulation results,and the maximum deviation of the efficiency is less than 1.25%,which can effectively reduce the recoil force to realize the braking of the first-stage gas gun.At the same time,the flow field characteristics of the firststage gas gun recoil are consistent with the test results,indicating that the simulation calculation model can accurately describe the dynamic trend of the flow field of the first-stage gas gun recoil.In summary,the research methods in this paper provides a theoretical basis for the development,simulation calculation,and live fire experiments of a new type of first-stage gas gun brake,and has important guiding significance. |
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