Study On Flow Field With Gas Leakage And Temperature Field Of Chromiun-plating Barrel

Gun barrel damage is an extremely complicated problem,which involves multidisciplinary intersection and coupling,and is of large technical difficulty.The temperature field of gun barrel is studied in this paper,which occupies the dominant position in factors of gun barrel damage,and lays a theoretical foundation for the study of gun barrel erosion mechanism.Three problems are mainly studied in this paper,i.e.core flow with leakage bore in gun barrel,turbulent boundary layer developing at times and nonlinear heat conduction,and obtains some research results.(1)The comprehensive test of gun barrel life and the chamber pressure test have been carried out.Several test items,such as muzzle velocity,firing accuracy,internal bore size and external surface temperature are carried out in the process of the comprehensive test.The above tests provide the basis for the study of this paper,and verify the theoretical model established in this paper.(2)The ablation model of gun barrel's internal bore is established by measurement test of internal bore size in the comprehensive test of gun barrel life.Based on the ablation model of internal bore,interior ballistics' mathematical model of quasi two-phase flow with leakage is established combining with interior ballistics' model of quasi two-phase flow,and its finite scheme is derived.Combined with definite solution conditions,the numerical solution of the core flow parameters of gun barrel's internal bore without leakage and with leakage are solved by Fortran program.The calculation results of chamber pressure and muzzle velocity are verified separately by chamber pressure test and muzzle velocity test in the comprehensive test,and the test demonstractes that the model is accurate and reliable.Core flow's distribution law without leakage and with leakage in chamber is analyzed in detail,core flow fields in chamber are analyzed comparatively under 4 statuses,and the influence law of gun barrel erosion on core flow field in chamber is obtained.(3)The mathematic model of heat transfer on turbulent boundary layer is established by boundary layer theory,and its finite difference scheme is derived on the basis of Taylor expansion.The distribution laws of velocity boundary layer and temperature boundary layer are solved by adopting Fortran program.And convective heat transfer coefficient of boundary layer is solved by simplified engineering method.(4)Based on the calculation results of core flow and boundary layer's heat transfer,a two-dimensional nonlinear heat conduction model of gun barrel with leakage and chromium-plating plated is established by applying heat transfer theory,and its linerization is in progress with the Kirchhoff transform.The numerical analysis of the heat conduction model after linearization is carried out,and the temperature field of the barrel bore is obtained under 4 different leakage states by applying Fortran program.Aiming at the error caused by the difference between the model hypothesis and the actual working state of the gun barrel,the correction coefficient of composite heat transfer coefficients of internal and external bore are introduced in this paper.By comparing the calculated temperature field of external surface with the tested temperature field of external surface in the comprehensive test of gun barrel life,the axial distribution laws of the composite heat transfer coefficient's correction coefficient are obtained and the calculation accuracy of the corrected model reaches 90%.The temperature fields of gun barrel under 4 different leakage conditions are obtained by applying the revised model,and the influence law of gun barrel erosion on the temperature field of gun barrel is gained by analyzing.(5)A two-dimensional nonlinear heat conduction model and its simplified model of a chromium-palting barrel with leakage are used to analyze the factors that affect the temperature field of gun barrel.The influence laws of the presence or absence of chromium layer,linear or not,thermal conductivity of chromium layer,thermal conductivity of matrix material,shooting regulation,cooling interval,environmental temperature and wind speed on gun barrel's temperature field are obtained.