喷注方式和骨架结构对骨架增强石蜡燃料燃烧影响的数值分析

Numerical analysis of influence of injection method and skeleton structure on the combustion of skeleton reinforced paraffin fuel

针对聚合物骨架镶嵌石蜡固体燃料在固-液混合火箭发动机中的燃烧问题,开展螺旋型和六角型骨架增强石蜡燃料在直/旋流喷注固-气掺混燃烧器中的燃烧试验,利用CFD软件对燃烧过程进行数值仿真研究。对四种工况燃烧过程进行比较,分析骨架结构和喷注方式对燃烧室内燃烧的影响。结果表明:骨架材料和石蜡基燃料退移速率差异较大,随着燃烧进行骨架结构逐渐凸显。湍流强度和燃料质量流量共同影响燃烧室温度,燃烧室温度随着燃烧进行呈波动下降趋势。旋流喷注工况的燃烧室温度高于直流喷注工况,燃烧室头部存在高温区,轴向温度分布较直流喷注更加均匀,而直流喷注中燃烧室中段存在温度激增。在直流喷注条件下,相较于六角型骨架,螺旋型骨架更能提高燃烧室湍流强度。在旋流喷注条件下,氧化剂旋流强度对湍流强度提升起主导作用,骨架结构影响较小。

To address the combustion problem of polymer skeleton-reinforced paraffin fuel in hybrid rocket motors,CFD software was used to carry out numerical simulation of the combustion process of helical and hexagonal skeleton-reinforced paraffin fuel in a direct flow/swirling injection solid-gaseous hybrid combustor.The combustion process of the four conditions was compared,and the influences of the skeleton structure and injection method on the combustion were analyzed.The results showed that the regression rates of the skeleton material and the paraffin-based fuel were quite different,and the skeleton structure gradually became prominent as the combustion progressed.The turbulence intensity and fuel mass flow both affected the combustion chamber temperature,and the combustion chamber temperature volatility decreased as the combustion progressed.In the swirling injection condition,the temperature of the combustion chamber was higher than that in the direct flow injection condition,there was a hightemperature area at the head of the combustion chamber,and the axial temperature distribution was more uniform.In the direct flow injection condition,the temperature increased sharply in the middle of the combustion chamber.In addition,compared with the hexagonal skeleton,the spiral skeleton can provide greater turbulence strength under direct flow injection conditions.In the swirling injection conditions,the swirl intensity of the oxidant played a leading role in the increase of the turbulence intensity,and the skeleton structure had little effect.