Perforated Brake Efficiency Measurements Using a 20-mm Cannon
ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
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Over the past few years, several field experiments have been performed using 105-mm and 120-mm cannons having perforated muzzle brakes. Significant differences in impulse reduction and gasdynamic efficiency have been reported in tests using the same 105-mm cannon-brake system but different measurement techniques. In the 120-mm experiments, efficiencies considerably above those for the 105-mm cannon have been reported, even though the latter has a large brake. Because the efficiency is a measure of the load produced by the brake, these inconsistencies introduce some uncertainty as to the stresses generated within the brake. In the present study, five brakes, geometrically similar to those used in the field experiments, were tested in the laboratory using a 20-mm cannon. The purpose was to provide a common basis for comparing the performance of the brakes using the standard parameters of gasdynamic efficiency for impulse and the overpressure ratio for the blast field.