Application of laser schilieren and monochromatic photography to solid propellant combustion research.

Abstract

Ammonium perchlorate (AP) -binder sandwiches and a composite propellant were burned in a combustion bomb at various pressures. A schlieren system equipped with an argon laser was used to study the flame structure. High speed monochromatic motion pictures of solid propellant were taken during combustion, and ammonium perchlorate-binder interactions were investigated. ' It was found that the laser source combined with a laser line filter allowed examination of the density gradient in the flame front. However, a good schlieren record could not be obtained at high power levels. The major problems were: (1) a "speckle" background effect on the high speed recording film, and (2) severe fringe pattern interference due to knife-edge problems and turbulence effects caused by the burning propellant. The monochromatic pictures demonstrated that propellants without opacifiers cannot be effectively examined for surface interactions during combustion when using high intensity laser light.