Hydrazine’s carcinogenic and toxic nature makes its use in space propulsion expensive and necessitates careful launch campaign planning, which may cause delays. One already established alternative is to use energetic salt-based ionic solution propellants. However, the costs remain high because these salts are costly and highly regulated energetic materials. Additionally, propellants based on these energetic salts produce much higher temperatures during decomposition and combustion, as is the case for hydrazine. Consequently, expensive refractory metal-based alloys and high-temperature oxidation-resistant catalytic reactors must be used, which further drives up the costs. Alternatively, hydrogen peroxide may be used, though only in applications with a low specific impulse requirement. This study explores an alternative approach: using nitromethane, a commonly available laboratory solvent. NMP-001 is a nitromethane-based monopropellant that contains additives that allow for low-pressure combustion and reduce sensitivity to mechanical stimuli. Multiple combustion chamber configurations with varying characteristic lengths were tested in rocket combustion experiments. With the 11.5 m -configuration, a 15.1 bar low-pressure limit could be determined. The 7.3 and 5.0 m -configurations yielded a 16.2 and 28.3 bar low-pressure combustion limits, respectively. These outcomes are significantly below the 30 bar limit reported in the literature. Despite using only a simple heat-sink combustion chamber with a non-sophisticated injector element and a non-optimized propellant formulation, combustion was 83 to 95 % efficient with a C* ranged between 1133 to 1302 m/s. These figures are higher than for hydrogen peroxide and are comparable to the theoretical performance of state-of-the-art green liquid monopropellants.

中文翻译：

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硝基甲烷基绿色火箭推进剂NMP-001的燃烧行为


联氨的致癌性和毒性使其在太空推进中的使用成本高昂，并且需要仔细的发射活动规划，这可能会导致延误。一种已经确定的替代方案是使用高能盐基离子溶液推进剂。然而，成本仍然很高，因为这些盐是昂贵且受到严格监管的含能材料。此外，基于这些高能盐的推进剂在分解和燃烧过程中会产生更高的温度，就像肼的情况一样。因此，必须使用昂贵的难熔金属基合金和高温抗氧化催化反应器，这进一步推高了成本。或者，可以使用过氧化氢，但仅适用于比冲要求较低的应用。本研究探索了另一种方法：使用硝基甲烷（一种常用的实验室溶剂）。 NMP-001 是一种基于硝基甲烷的单组元推进剂，含有可实现低压燃烧并降低对机械刺激的敏感性的添加剂。在火箭燃烧实验中测试了具有不同特征长度的多个燃烧室配置。通过 11.5 m 配置，可以确定 15.1 bar 的低压限制。 7.3 和 5.0 m 的配置分别产生 16.2 和 28.3 bar 的低压燃烧极限。这些结果明显低于文献报道的 30 bar 限制。尽管仅使用简单的散热器燃烧室和不复杂的喷射器元件以及未经优化的推进剂配方，但燃烧效率为 83% 至 95%，C* 范围为 1133 至 1302 m/s。 这些数字高于过氧化氢，并且与最先进的绿色液体单组元推进剂的理论性能相当。