A METHOD OF ANALYZING PERFORATED MUZZLE BRAKE PERFORMANCE.

摘要

Excessive blast overpressures are adversely affecting the safety and performance of artillery crews. Recent trends are the production of higher blast overpressures necessitated by the need for greater range for these weapons. Tank cannons are now producing blast overpressures of the same magnitude as large artillery pieces. The need for reduced recoil characteristics of these weapons has led to the use of muzzle brakes to attenuate the recoil momentum. One adverse effect of using a muzzle brake is the shifting of the blast field rearward, thus elevating the blast overpressure in the crew area. One method of providing a braking force without the high blast overpressure is the perforated muzzle brake. This device is an extension of the gun tube with vent nozzles to discharge the propellant gas radially, hence recovering a finite amount of recoil momentum. The method of characteristics is used to predict the performance of perforated muzzle brakes. The muzzle brake interior flow is assumed to be one-dimensional and inviscid. The muzzle brake is configured with constant diameter nozzles to vent the propellant gases perpendicular from the axis of fire. An axisymmetric inviscid Godunov finite-difference scheme is used to model the external flow field produced by the perforated muzzle brake. Comparisons of the flow fields generated by the bare muzzle, a double baffle brake and a perforated brake were made for a 20 mm gun. A firing test was conducted to experimentally verify the numerical predictions of the MOC and Godunov scheme. Recoil impulse, free field blast overpressure and muzzle velocity were measured and spark shadowgraphs were obtained. The agreement between the numerical predictions and experimental results was very good.