Technical Study Of New Traveling Charge Based On Differential Principle

Significant increase of the muzzle velocity of intelligent ammunition is critical to meet the requirement of modern war. Traveling charge technology is recognized as one of the effective techniques to improve the muzzle velocity of artillery. Current researches on traveling charge technology can be classified, in terms of operation mode, as strap-on mode, projectile base adhered mode, enclosed mode, etc. These techniques have quite some defects although they demonstrate certain effect on velocity increasing. For example, strap-on mode and base adhered mode requires higher burning rate or even very high burning rate than main charge; enclosed mode increases the passive weight. These defects result in formidable difficulties in traveling charge schemes. Especially if we want to substantially increase the muzzle velocity of projectiles for existing traveling charge, the projectiles will consequently appear significant base pressure increase and risk of projectiles overload due to the nature of these traveling charge firing schemes. Overload is not allowed in fire of intelligent ammunition gun.In order to overcome the defects in traditional traveling charge scheme, this thesis studies and explores follow aspects:1. This thesis reviews the feasibilities and restrictions of existing traveling charge schemes on the improvement of muzzle velocity. Based on the review, this thesis focuses the study on enclosed mode of solid traveling charge, then establishes an interior ballistic theoretical model and conducts a series of numerical simulation and analysis. The study result shows that enclosed mode of solid traveling charge is effective to increase muzzle velocity in a certain range, but inevitably encounters the issues of projectiles overload and significant projectile passive weight. The importance of projectiles overload to the intelligent ammunition has not been fully discussed and studied yet in previous similar researches.2. This thesis conducts systematical researches on the coated traveling charge by using combination of theoretical and experimental approaches. The theoretical two-region interior ballistic model with coated traveling charge to 105mm caliber tank gun was established and programming simulation was conducted afterwards. The calculation results show the theoretical model is consistent with the experimental results, therefore demonstrate the corresponding theoretical model is correct and credible. The preliminary study shows that coated traveling charge scheme is able to achieve 4.4% increase of velocity and no passive weight problem occurs under the conditions of not changing the structure of artillery and projectile and nor increasing the maximum bore pressure and projectile overload conditions. The theoretical model demonstrates that coating traveling charge scheme is able to achieve 6.7% increase of velocity if adjust the coating propellant ratio to 30% of main charge.3. This thesis proposes a new type of traveling charge scheme with differential principle and multi-body design to ensure the relative movement between different assemblages of projectile hence to achieve continuous in-bore space jet of missile-borne traveling working medium. The ejected un-combusted mediums will combust in situ with the effect of high temperature inside in-bore space. The energy of combustion can effectively compensate or eliminate the impact of rarefaction wave due to projectile motion. Therefore the new traveling charge scheme is able to improve the utilization rate of gun working volume, hence to significantly increase the muzzle velocity. In the same time, this thesis constructs conditions of design which aims, through optimizing interior ballistic design, not only to increase the muzzle velocity but also to effectively control projectile overload for differential automatic injecting ammunition.4. This thesis establishes an interior ballistic theoretical model with liquid differential traveling charge, which combines differential traveling charge kinetic model and interior ballistic model accompanying increased mass and energy inside in-bore space. Considering two cases, compressible liquid propellant and incompressible liquid propellant, the research simulates the artillery parameters and charging conditions for 155mm caliber artillery via numerical calculation. The results show liquid differential traveling charge can significantly improve muzzle velocity. Under the conditions of rated maximum bore pressure and projectile overload, it is able to achieve 21% more muzzle velocity than conventional charge.5. This thesis establishes an interior ballistic theoretical model with solid differential traveling charge for solid propellant. The calculation results of multiple cases show the model has good compatibility on existing artillery. The research selects two different applications. One application is required for extreme long range such as 160mm or 155mm caliber artillery. The result shows the solid differential traveling charge scheme is able to achieve 17% more muzzle velocity than conventional charge without changing the conditions of maximum bore pressure, tube length, projectile weight and projectile base pressure. Other application is to improve the muzzle velocity and firing range of cannon-launched guided missile for existing 155mm gun-howitzer, hence to optimize long-range strike precision of intelligent ammunition. The results show solid differential traveling charge is able to increase muzzle velocity 200m/s more without changing the conditions of maximum bore pressure and projectile overload and the increasing ratio is 31%. If subcaliber sabot design technique is used simultaneously, projectile mass is 40kg, the muzzle velocity can be increased 260m/s and the increasing ratio is 37.7%.6. This thesis calculates and evaluates the muzzle velocity increase of differential traveling charge scheme by applying modified particle external trajectory model and optimizing aerodynamic parameters. The results show differential traveling charge firing schemes can increase firing range effectively.7. A structure design of core component of missile-borne high-G micro capacitive accelerometer is derived in this scheme. Range of this accelerometer is 13300g and inherent frequency of the accelerometer is 100KHz. The accelerometer possesses preferable static and dynamic response characters.The research achievement of this thesis provides a new thinking, technical approach and development direction for the improvement, innovation and future development of existing gun weapon system. The research delivers practical importance and future development guidance in follow aspects:(1) The coating traveling charge scheme, essentially the improvement of charging structure design, is able to achieve 4.4%-6.8% increase of muzzle velocity on existing artillery without changing existing artillery and projectile structure condition.(2) Without changing the maximum bore pressure, projectile overload, weight and travel of projectile, differential traveling charge scheme can greatly improve the muzzle velocity (from 17% to 21%). In case of combining the differential traveling charge scheme and glide bomb design on existing 160mm caliber artillery, it is able to launch the 50kg projectile 98.85km range, hence to achieve extreme long range firing. Applying the combined technology on existing 155mm intelligent ammunition, it is able to increase 100% firing range.