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International Journal of Energetic Materials and Chemical Propulsion

ISSN Print: 2150-766X
ISSN Online: 2150-7678

International Journal of Energetic Materials and Chemical Propulsion

DOI: 10.1615/IntJEnergeticMaterialsChemProp.v9.i4.10
pages 285-304

RADIATIVE IGNITION OF SOLID PROPELLANTS: A PRACTICAL APPROACH

Franck Cauty
ONERA
retired
Yves Fabignon
ONERA−The French Aerospace Lab, Palaiseau, France
Charles Erades
ONERA−The French Aerospace Lab, Palaiseau, France

ABSTRACT

We were interested in studying solid propellant time-to-ignition determination from two perspectives. First, we experimentally determined the sensitivity of composite propellants to ignition by using CO2 laser radiation instead of the classical convective heat generator used at Onera for many decades. Second, we validated the propellant degradation data using a one-dimensional (1D) simulation model based on a classical relationship set. The setup and the associated measurement systems are described in detail in this paper. High-speed video images were obtained, and surface luminance temperature evolutions from optical-fiber pyrometers were determined. The results showed the inert heating of the sample, then the start of binder degradation, and upon ignition of a first ammonium perchlorate (AP) grain ("first light"), rapid rise of temperature to the stationary combustion level. We comment on the different ignition delay times corresponding to criteria and the physical process of the AP propellant grain ignition. The first AP grain large enough to propagate heat to other grains around it, and close enough to the surface, is the starting element of the ignition process. These experimental results were then compared to a 1D numerical simulation model. The solid propellant thermal and reaction parameters were determined from the literature values of the ingredients [AP, hydroxyl terminated polybutadiene (HTPB), and aluminum (Al)] and their mixture ratio. The model gives the surface temperature evolution and the burning rate variation from 0 to the stationary value. The experimental and numerical results showed that the pre-exponential factor of the Arrhenius law governs the delay time and the ignition surface temperature level.

REFERENCES

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