特征结构对复合式石蜡基药柱燃烧特性的影响研究

Effects of Characteristic Structure on Combustion Characteristic of Composite Paraffin-Based Grain

关键词:  固液混合火箭发动机  复合式药柱  特征结构  尺度  燃烧特性

Key words:  Hybrid rocket motor  Composite grains  Characteristic structure  Scale  Combustion characteristic

摘要:

凹槽状特征结构是复合式石蜡基药柱相对于传统石蜡基药柱燃烧性能有效改善的重要因素，该特征结构因螺旋基底与石蜡基燃料退移速率不同而产生。研究了预设0，2mm尺度的特征结构（初始凹槽深度为0，2mm）对于燃烧室压强、退移速率、特征速度的影响规律。点火实验以气氧作为氧化剂，平均流量分别为11.6，18.5，23.1g/s，同时选择传统圆孔石蜡基药柱作为对比分析。实验结果表明：在相同氧化剂质量流量下，预设2mm尺度的复合式药柱点火到室压稳定所需的时间最短，退移速率和特征速度也最高。采用计算流体力学（CFD）分析了不同尺度的特征结构对燃气流动特性的影响规律，冷流结果表明尺度越大的特征结构引导旋流强度更高，且影响范围更大。

Abstract:

The characteristic structure consisting of grooves is an important factor in improving the combustion performance of the composite paraffin-based grain compared to the conventional paraffin-based grain， which results from the different regression rates of the helical substrate and the paraffin-based fuel. The effect regulation of pre-characteristic structure with 0mm and 2mm scales （the depth of grooves） was investigated， including the combustion chamber pressure， regression rate， and characteristic velocity. The firing tests used gas oxygen as oxidizer with average flow rates of 11.6， 18.5， and 23.1g/s， respectively， and the conventional round-hole paraffin-based grain was selected as a baseline test. The tests result show that the 2mm scale pre-set characteristic structure composite grains take the shortest time from ignition to pressure stabilization and have the highest regression rate and characteristic velocity at the same oxidizer mass flow rate. Computational fluid dynamics （CFD） was used to analyze the effect regulation of characteristic structure with different scales on gas flow characteristics. The cold flow results show that the larger scale of the characteristic structure guides the swirl flow field with higher intensity， and influences a wider region.