Abstract
A self-designed oxygen-kerosene ablation system was employed to research the ablation properties of silicone rubber-based insulation material under different oxygen-rich conditions, that is, 0%, 5.00%, 7.71%, 17.01%, and 18.50%. The morphology of posttest specimens was analyzed via a scanning electron microscope (SEM), and the ablation rates were calculated. Experimental results showed that when the particle concentration was a fixed value, the mass and the linear ablation rates increased first and then decreased with the rise of oxygen content; the maximum values were 0.572 g/s and 0.933 mm/s, respectively. Under high oxygen-rich conditions, the formation of silicone rubber restricted the further increase of the ablation rates, filling more gaps of the reaction layer with liquid silicone rubber. Meanwhile, the thickness of the liquid glass layer attached to the surface was increased, which acted as a buffer against the impacts and erosion of particles and retarded the consumption and recession of materials. Excess oxygen spread to the edge of the ablation pit and reacted. Finally, these led to the increase in diameter of the ablation pit and the decrease of two types of ablation rates.
Highlights
When a solid rocket ramjet (SRR) engine works, the heat protection component in the combustion chamber will suffer from the thermochemical ablation of oxygen-enriched gas, particle erosion of condensed matter, and aerodynamic erosion of high-speed gas, which brings higher requirements for the thermal protective performance of insulation materials
Because silicone rubber-based insulation material has a simple manufacturing process, low thermal conductivity, and a better resistance to oxygen-enriched eroding and superior smoke characteristic performance than ethylene propylene diene monomer (EPDM) insulation material, it is widely used as a thermal protection material of solid rocket ramjet combustor
Current research shows that researchers of ablation materials have paid more and more attention to silicone rubber-based insulation materials, and many research results have been obtained, which focused on material composition and formulation optimization
Summary
When a solid rocket ramjet (SRR) engine works, the heat protection component in the combustion chamber will suffer from the thermochemical ablation of oxygen-enriched gas, particle erosion of condensed matter, and aerodynamic erosion of high-speed gas, which brings higher requirements for the thermal protective performance of insulation materials. When solid rocket ramjet engines operate at different altitudes, the oxygen-enriched environment will be changed which will influence the ablation behavior of the thermal insulation layer. It is of great practical significance to explore the influence of oxygen enrichment on the ablation behavior of the silicone rubber-based insulation material. In order to explore the influence of an oxygen-enriched environment on the ablation behavior of silicone rubberbased insulation material, this study sets the actual ablation of a solid rocket ramjet chamber insulation material as the research background, where a self-designed oxygenkerosene simulation ablation test system was employed to conduct ablation experiments on the silicone rubber-based insulation material under different oxygen-rich conditions. This work analyzed the relationship between ablation rate and oxygen enrichment, focusing on the effect of oxygen enrichment on the ablation behavior of the silicone rubberbased insulation material by combining the macroscopic and microscopic ablation morphology and characteristics of the material
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