Combustion-front non-one-dimensionality in single- and double-base propellants

Parameters of transverse waves propagating over the surface of specimens pressed from colloxylin and double-base propellants A and N are studied. By means of microvideofilming and thermocouple measurements, it is shown that the burning sites on the specimen surface are formed by a set of transverse waves. Under atmospheric pressure, the transverse-wave front has the form of a step 0.5–1.1 mm high and decreases with increasing pressure or initial temperature of the specimen. The front propagates with variable velocities in the horizontal and vertical directions. The mean velocity of the transverse wave is three to eight times higher than the normal burning rate of the specimen as a whole (with a wide spread of local values) and increases with increasing pressure. Behind the front, combustion can be interrupted till the arrival of the next transverse wave. As in the SHS process, the reason for the emergence of the transverse waves is combustion-wave spatial instability.