Mechanism of Interior Ballistic Peak Phenomenon of Guns and Its Effects

摘要

The erosion and wear in the gun barrel will get worse with an increase in the number ofnprojectiles fired. Generally speaking, the ballistic performance of the gun, measurednthrough indicators such as the maximum pressure pm and the muzzle velocity v0, willndecrease gradually due to gun barrel erosion. However, the above analysis does notnagree with the firing test data of certain types of guns, especially of some small-calibernguns. The ballistic performance of such guns will exhibit an increase to their peak valuesnfollowed by a gradual decrease with the number of rounds fired. This is the so-calledninterior ballistic peak phenomenon, also named as the hump effect. Taking several kindsnof guns as examples, such as a 76 mm gun and a 100 mm gun, we calculated thenengraving pressure p0 of the guns by an approximate method and built a lumped-nparameter interior ballistic model of the guns that exhibits the effect, according to theninterior ballistics theory of guns with erosion and wear. The results of the modeling of thenguns under different wear conditions are close to the test data, showing the existence ofnthe peak values of pm and v0. The simulation results of some of the other guns that exhibitnthis phenomenon also show good agreement. Furthermore, it can explain the double-peaknphenomenon for some types of guns with double driving bands. It was proven that thenmismatch of the structure and the dimensions of the gun bore with those of the projectilendriving band is the fundamental cause of this effect. Due to the mismatch, the engravingnpressure will first increase and then decrease with the enlargement of the bore dimensionsncaused by barrel erosion and wear. The variation in the engraving pressure p0 willninevitably lead to the variation in interior ballistic performance in the life cycle of thengun. This observed process appears to explain the interior ballistic peak phenomenon.nu0001 u0002fense Industrial Association, USA.