The erosion and wear in the gun barrel will get worse with an increase in the number of projectiles fired. Generally speaking, the ballistic performance of the gun, measured through indicators such as the maximum pressure pm and the muzzle velocity v0, will decrease gradually due to gun barrel erosion. However, the above analysis does not agree with the firing test data of certain types of guns, especially of some small-caliber guns. The ballistic performance of such guns will exhibit an increase to their peak values followed by a gradual decrease with the number of rounds fired. This is the so-called interior ballistic peak phenomenon, also named as the hump effect. Taking several kinds of guns as examples, such as a 76 mm gun and a 100 mm gun, we calculated the engraving pressure p0 of the guns by an approximate method and built a lumped-parameter interior ballistic model of the guns that exhibits the effect, according to the interior ballistics theory of guns with erosion and wear. The results of the modeling of the guns under different wear conditions are close to the test data, showing the existence of the peak values of pm and v0. The simulation results of some of the other guns that exhibit this phenomenon also show good agreement. Furthermore, it can explain the double-peak phenomenon for some types of guns with double driving bands. It was proven that the mismatch of the structure and the dimensions of the gun bore with those of the projectile driving band is the fundamental cause of this effect. Due to the mismatch, the engraving pressure will first increase and then decrease with the enlargement of the bore dimensions caused by barrel erosion and wear. The variation in the engraving pressure p0 will inevitably lead to the variation in interior ballistic performance in the life cycle of the gun. This observed process appears to explain the interior ballistic peak phenomenon.

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In order to study the interaction mechanism of the pipe network, the compressor and the control system in the process of the anti-surge regulation, the simulation model of the overall Closed Cycle System (CCS) is established in this paper. By comparing the simulation results with the target values at the Design Operation and the Maximum Mach Operation, the calculation deviation is less than 1%, which verifies the accuracy of the model. At the Maximum Mach Operation, the analysis of the CCS during the quasi steady process and the dynamic process is carried out respectively. According to the result of quasi steady state analysis, the effectiveness of the designed anti-surge circuit during the normal operating process of the CCS is verified. By opening the Anti-Surge Valve, additional 38.5% surge margin is provided. And the surge margin at the simulation process would be slightly higher than the design value for the variation of the inlet condition from the different operations. Through the dynamic analysis, the changes of the different performance parameters are studied in the process of sudden blockage in the pipe network, and during this process the compressor surge could be induced easily due to the sharp decline of the inlet pressure. To ensure the safety of the compressor during the acceleration and deceleration process, the moving trajectory of the operation point on the Compressor Characteristic Map should be studied by considering the effect of the resistance characteristics of the CCS pipe network. In addition, the anti-surge system should have a high response frequency to deal with the sudden blockage.

Conventional design and analysis of gun system are based on three assumptions of plane, symmetry and static equilibrium, and the consistency between theoretic analysis and experimental results cannot satisfy us despite that varieties of correctional coefficients are introduced. Progressive sensitivity analysis method is presented, and the important degrees of factors with different dimensions are compared. Structural parameters that most affect firing stability are achieved according to sensitivity analysis, and they are optimized with the objective of firing stability by Design Sub-space method (DSM). Finally, a group of structure parameters which can optimize firing stability are obtained. the application perspective of virtual prototyping technology applied in military fields is presented. 3-292