Research On 37mm Grenade Bottom Row Range Increase Technology

The small-caliber artillery has the characteristics of high initial velocity,fast firing rate,strong anti-jamming capability,rapid response and flexible maneuverability.It can effectively complete the tasks of ground defense,short-range anti-missile,and ship-to-ship defense.At this time,small-caliber artillery seems a bit weak.In order to meet the needs of modern air defense operations,it is necessary to optimize the structure of small-caliber artillery and increase its range.Among various artillery range-extending technologies,bottom-row range-extending technology is widely used because of its high range-extending rate,no reduction in power,and small projectile dispersion.It is an ideal choice to apply it to 37 mm grenade.In this paper,the static analysis method,internal and external ballistic modeling,bottom flow field simulation and external ballistic simulation research methods are used to conduct an in-depth study on the internal and external ballistic characteristics and bottom flow field characteristics of the 37 mm grenade with bottom row device.The main research content as follows:Firstly,this paper analyzes the principle of the increase of the bottom emission reduction,and expounds the method of expressing the bottom emission reduction.According to the design requirements,the overall design of the 37 mm bottom-row grenade was determined,including the structural design of the bottom-row device,the selection of the bottom-row medicament,and the choice of the ignition device;The research requires that the bottom row device meet the strength requirements during the launch process to ensure the safety of the projectile during launch.Secondly,The internal and external ballistic models of the 37 mm bottom-row grenade were established.According to the combustion characteristics of the bottom row of chemicals,the ballistic equations in the bottom row device were established using formula derivation and other methods;by analyzing the forces and moments received by the projectile in the air,the formula derivation and other methods were used to establish the 37 mm bottom row grenade modified particles Ballistic equation.Thirdly,fluent was used to analyze the bottom flow field of the 37 mm bottom row grenades.Study the change law of bottom flow field with and without exhaust gas,and analyze the principle of bottom discharge resistance reduction from the change of bottom flow field.Under different Mach number conditions,the influence of the Mach number on the range extension of the 37 mm bottom row grenades is studied.The results show that with the increase of the Mach number,the larger the recirculation area of the bottom of the projectile,the lower the pressure at the bottom of the projectile,and further increase the row.The gas parameter and the increase of the bottom pressure can effectively reduce the bottom pressure and achieve the purpose of increasing the range and reducing the resistance.Fourthly,use MATLAB to simulate the exterior ballistics of 37 mm bottom row grenade.First,perform the external ballistic calculation for a 155 mm bottom row projectile,and compare the calculation result with the test data.The calculation result is slightly different from the test data,which verifies the accuracy and feasibility of the external ballistic calculation program;the external ballistic calculation is adopted.The program analyzes the external ballistics of 37 mm bottom row grenade when the bottom row device is working and the bottom row device is not working.The results show that for 37 mm bottom row grenade with different firing angles,at the highest point of the flight trajectory,the higher the firing angle,the larger the vertical displacement difference(the height difference)between the bottom row working and the bottom row not working because the bottom row reduces drag.According to the principle,the drag coefficient when the bottom row is working is smaller than when the bottom row is not working,which shortens the flight time to reach the effective fire height and improves the interception probability of the 37 mm anti-aircraft gun;it also increases the storage speed of the projectile and the height of the vertical displacement.The difference gradually increases.The feasibility of the bottom row extended range technology on 37 mm grenade was verified.