Study On The Aerodynamic Characteristics Of A Small-diameter Armor-piercing Projectile And Its Dynamic Characteristics Of The Fuze Mechanism

For the problems of the old projectile' low range and the fuze's low safety and reliability,taking the new developed 35 mm antiarmor&antipersonnel rifle grenade and its fuze as the object.And trying to use the methods of theoretical analysis,numerical simulation and test to analyze 4 aspects of the problem,such as the aerodynamic characteristics of projectile,the dynamic characteristics of inclined design of fuze setback arming device,the optimization on centroid position of horizontal rotor of fuze drived by centrifugal force and the design optimization of tapered cone angle of fuze centrifugal self-destroying device.Four kinds of head contour optimization scheme of the grenade were put forward based on the origin contour.Firstly,air resistance characteristics of the grenades were simulated by using FLUEN.Then the drag coefficients obtained were fitted to logistic curve by using Origin Lab.Lastly,the maximum range of each scheme was obtained by calculating the exterior ballistics.The result shows that the contour of quasi-parabolic scheme has best effect in reducing drag and increasing range(increasing by about 7.4%).The inclined design of fuze setback arming device was put forward based on the drop impacting characteristics of the projectile and fuze to solve the contradiction between safe and reliable arming of fuze setback arming device.The program is making the fuze setback arming which paralleled with the fuze axis inclined at an angle relative to the fuze axis.Firstly,simulation characteristics of the projectile's drop impact was analyzed by LS-DYNA.Then dynamic characteristics of the inclined design of fuze setback arming device was analyzed by rigid body dynamics theory,and the example was given.The results showed that the inclined design of fuze setback arming device contributes to improve the fuze safety when the projectile and fuze fall accidentally,which means to improve the performance of preventing fuze arming unexpectedly.But,the performance of normal arming was not affected.The optimal design method of the centroid position of horizontal rotor was put forward to solve the problem of horizontal rotor which was drived by centrifugal force having difficulty to rotate correctness.Optimal relational expression of radius of gyration and initial azimuth was obtained by setting up kinetic equations of rotating of horizontal rotor of fuze.Simulation was made by using ADAMS with specific example.The optimal radius of gyration and initial azimuth make the value of net driving torque comparatively larger during the rotation of horizontal rotor.lt contributes to improve the rotating correctness of fuze horizontal rotor of rolling airframe.Adjusting the tapered cone angle of the fuze centrifugal self-destroying device can increase the self-destroying firing energy to ensure the self-destroying reliability.But,it may change the self-destroying critical angular velocity,which can make self-destroying time changed.However,adjusting stifness coefficient of the self-destroying spring,preloading of the self-destroying spring,the centrifugal radius of centrifugal ball,the quality of centrifugal ball and the quantity of centrifugal ball can balance this change.The results showed that the method of adjusting stiffness coefficient of the self-destroying spring can increase energy about 11%and the method of adjusting preloading of the self-destroying spring can increase energy about 13%with the tapered cone angle increase 1° when the cone angle changes between 40° and 50°.