Accession Number : AD0688598

Title :   ON THE GAS LAYER SURROUNDING A PROJECTILE BEING FIRED FROM A SMOOTH BORE GUN,

Corporate Author : BOEING SCIENTIFIC RESEARCH LABS SEATTLE WASH MATHEMATICS RESEARCH LAB

Personal Author(s) : Ehlers,F. Edward

Report Date : APR 1969

Pagination or Media Count : 23

Abstract : An analysis of the gas envelope surrounding a projectile being fired from a smooth bore gun is presented. By reducing the equations of stress and strain in an accelerated body to dimensionless form and examining the dimensionless parameters, it is shown that the strains in an accelerated body do not increase with increasing acceleration if the pressure surrounding the body is increased proportionately, provided Poisson's ratio remains constant and Young's modulus increases with the applied pressure. A simple analysis on the assumption of parallel flow is given for the flow in the gap between the moving projectile and the gun barrel. For constant gas properties, the shear stress on the projectile and on the gun barrel and the pressure gradient are constant. For isothermal flow in the slot, the shear stress on the projectile increases toward the low pressure end approaching asymptotically the Couette flow value. For mass flow rate in the slot below a certain value, the shear stress acts as a thrust on part of the projectile near the high pressure end and a drag on the leading edge or low pressure end. (Author)

Descriptors :   (*GUN BARRELS, INTERIOR BALLISTICS), STRAIN(MECHANICS), PROJECTILES, ROCKETS, SHEAR STRESSES, SKIN FRICTION, GAS FLOW, LAMINAR FLOW, ACCELERATION, DRAG, PRESSURE

Subject Categories : Ballistics
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE