Views:0 Author:Site Editor Publish Time: 2021-06-30 Origin:Site
From the practical needs of military rockets with higher readiness requirements, the initial rocket engine uses more stable hydrazine at room temperature, a Methylhydrazine (Mono Methylhydrazine /MMH/CAS 60-34-4), partial dimethylhydrazine (UDMH), hydrazine (50% hydrazine 50% partial dimethylhydrazine), The oxidant uses nitric acid or N₂O₄ (Dinitrogen Tetroxide CAS 10544-72-6).
1. Hydrazine fuel: Hydrazine, highly toxic, but the boiling point of Hydrazine is 113.5℃, liquid under normal temperature, which is attractive to scientists. Hydrazine decomposes into ammonia and nitrogen with the help of catalyst and releases heat. If the endothermic reaction of nitrogen and hydrogen is controlled, the maximum gas temperature of 1650K can be obtained. It is usually used as a low-thrust attitude control engine, and hydrazine is the most suitable for micro-engines with a thrust of about 10N. Hydrazine-fueled gas generators, each weighing just 40 kilograms and producing 135 horsepower, were also used in the shuttle's auxiliary power unit turbo pumps. But hydrazine itself is not very thermally stable. 2.UDMH, also highly toxic, using nitric acid or N₂O₄ as an oxidant, has a wide liquid temperature range and high energy characteristics. It has more convenient military applications, but has a general specific impulse. As the peak proton rocket engine RD-253, the vacuum specific impulse is also only 310S. Since the oxidant N₂O₄ is reddish-brown, it is characterized by an orange-red ₄ when fired.
3.MMH, special purpose for attitude control, boiling point 87.5 ℃, freezing point -52 ℃, ₄ contact with the oxidant N₂O₄ can spontaneously fire, capable of starting multiple times. MMH+N₂O₄, a two-component ₄ with large thrust, addresses the defects of hydrogen peroxide, or hydrazine catalyzed, electro-thermal decomposition attitude control engine fuel specific impulse and low thrust. The AJ10-190 engines of the Shuttle Orbiter Maneuvering System (OMS), mounted on either side of the tail, had a combined thrust of 53.
4. kN. The fuel is also used in the X37B's orbital transformation.
5.Mix hydrazine 50: Aerozine50 is a 50/50 weight component mixture of hydrazine and UDMH. It is developed by the American General Aviation Jet Company at the end of the 1950s. It is high energy and widely used as rocket fuel. It is also allowed to be used as circulating cooling in the engine, using nitrous oxide as an oxidant. The Hercules rocket LR87 was used.
6.Kerosene is characterized by low cost, non-toxic and environmental protection, and high performance. It becomes the best partner with liquid oxygen, representing engines such as F1, RD170/180 and SpaceX's Merlin series engines. The existing shortcomings are: specific impulse 347 seconds compared with hydrogen and oxygen 457 seconds gap is very large; Kerosene combustion will have different degrees of carbon deposition due to sulfur content, which will affect the reuse; Kerosene as a coolant is limited by low coking temperature. At present, the theoretical limit has been approached by increasing the pressure of combustor through fractional oxygen-enriched combustion. The Soviets even achieved higher densities in a fraction of the time by cooling kerosene in the fuel tanks of their rockets.