Comparative closed vessel tests : influence of ignition and loading conditions on propellant burning rate

The most widely used experimental method to determine and to compare energetic and ballistic properties (force, co-volume, coefficients of burning rate law) of different propellants is burning a specific amount of propellant in a closed chamber. The procedure of determining the values of the individual material constants recommends similar conditions of closed vessel investigations like limited range of loading density and determined mass of black powder (igniter material) for determined loading density. There also often occurs the need for performing of closed vessel comparative tests (carried out for two or more numbers of propellants), where one of them serves the role of a reference propellant and in relation to which described are the differences between the characteristics of the remaining propellants are described. Comparative tests of propellants should be understood to be such tests performed for identical loading conditions, including firstly the same closed chamber capacity, mass of the propellant burned (thereby the identical loading density) as well as identical ignition conditions which are understood as the same mass and the same type of igniter material. In the present paper the influence of ignition and combustion conditions during closed vessel tests on possible deviations in determination of burning rate is analysed as a function of incident heat flux.