Author(s): Ahmed Mahmoud El Dakhakhny, Ehab Abadeer, Saher El Marsafy, Ashraf Fathy Ahmed
Published in: International Journal of Engineering Research & Technology
License: This work is licensed under a Creative Commons Attribution 4.0 International License.
Volume/Issue: Volume. 6 - Issue. 01 , February - 2017
The rocket motor is one of the main types of jet propulsion engines, and the solid rocket motors is one of the chemical propulsion system where the fuel and oxidizer are both incorporated in a single solid, called the propellant grain. The combustion chamber contains the propellant grain and the thermal insulation. The primary function of the thermal insulation which is defined as a layer of heat barrier placed between the internal surface of the case and the propellant grain is to protect the case from reaching temperatures that may endanger its structure integrity. The present study is to develop and characterize rubber thermal insulators for high temperature application for solid rocket motors and to improve the surface life of the insulants. The insulators are based on aramid fiber in the pulp form (Kevlar), Carbon mono fibers and Nano carbon black as fillers for TRILENE liquid polymers which is a family of viscous, low molecular weight ethylene-propylene diene terpolymers, with ammonium polyphosphate as flame retardant and an organic peroxide as crosslinking agent. Different formulations based on these fillers were prepared. The fillers are dispand in the EPDM polymeric matrix to obtain a homogenous master batch for curing. The thermal and ablative properties of insulations were measured. The effect of changing aramid fiber in the pulp form, carbon mono fiber and/or Nano carbon black volume fractions was studied. Prediction of thermal conduction of multiphase thermal insulation composite materials was carried using parallel, Series, Maxwell Euken and Effective medium theory models. Comparison with the measured values allows determining the model which estimates best the thermal conductivity of composite insulation material. For application for solid rocket motor insulation, Reinforcement of EPDM with KP improves the performance of the material with respect to thermal properties ( thermal conductivity) while not improving well the performance with respect to ablation resistance. Using hybrid reinforcement content (KP + CMF+ NCB) inside EPDM improves the performance of EPDM with respect to thermal properties, ablation resistance and decomposition resistance. The best volume fraction which gives the best performance of the insulation material is 10 Phr KP + 5 Phr CMF + 5 Phr NCB. A new type of insulation material using the hybrid reinforcements was developed for the first time.
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