Research On Drag Reduction Of Artificial Hail And Rainfall Projectile And Study On Its Dynamic Characteristics Of Fuze Mechanism

Aiming at old projectile which has the problems of low firing height, high fuze dud rate,taking the new developed 37 mm caliber artificial hail-suppression and rainfall projectile and its fuze as the study object,with the method of finite element analysis and dynamic simulation combining with the relevant design requirements,the aerodynamic characteristics of the contour of projectile were optimized,the fragmentation of projectile was simulation analyzed, the dynamic performance of fuze chamber ignition mechanism was systematically and deeply studied.4 contour optimization schemes based on the contour of original Liu-1 fuze were put forward,the drag coefficient of the projectile equipped with the fuze of 5 contour schemes was simulated by using simulation software Fluent, and the data was fitted to rational function,then the centroid trajectory was calculated and the maximum firing height of each scheme was obtained.The parabolic scheme has the best effect in reducing resistance,which increases the firing height by about 4%.On the basis of bullet contour optimization^ drag-reduction improved schemes of the bottom structure of projectile were proposed according to the drag reduction principle of contour and hollow base.By using Fluent, the aerodynamic characteristics of the projectile were analyzed and the centroid trajectory was calculated.It was found that the scheme of hollow base with fillet and hole and parabolic contour has the similar effect in drag reduction which can increase the firing height up to more than 9% through the simulation and calculation.With the help of AUTODYN the blast fragmentation of base contour optimized projectile was simulation analyzed,it was found that the structure of aerodynamic optimization both can not fully meet the design criteria of fragmentation and need to be further optimized.Combining with the impact overload of fuze (or projectile) getting from the ANSYS/LS-DYNA simulation,simulating the motion of chamber ignition mechanism in drop test,shock test,firing process,hammering test and throw-out process of detonation completeness test by using ADAMS,and would be compared with the test results to verify that the model is correct.The influence of striker spring’s stiffness and initial compression, pin-piercing primer’s mass,impact overload’s peak and duration to the motion of chamber ignition mechanism was analyzed by using the simulation model,and it was found that increasing the striker spring’s stiffness and appropriately selecting initial compression are both beneficial to ensure the logistic handling safety.Increasing the mass of pin-piercing primer(or stab body) is helpful to improve the firing reliability of fuze.According to the response of the chamber ignition mechanism to the peak and duration of impact overload,the fuze would fire when dropping to soft object(the peak of the impact overload is small,but the duration is long)rather than rigid object(the peak of the impact overload is big,but the duration is short) in service handling process,which would lead to the accident,so the design of in-bore ignition mechanism should be given special consideration and attention.