MMH/NTO injection and ignition in vacuum downstream from an Aestus engine single injection element

Lecourt, Renaud; d'Herbigny, François-Xavier

doi:10.1016/j.ast.2003.11.001

Cited by 14 publications

(6 citation statements)

References 7 publications

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“…Therefore, the initial conditions following the first pulse can affect the impulse bit and specific impulse, especially for shortduration ON time. The volume upstream of the injector, the so-called dribble volume, has been shown to affect the time required for propellant to enter the combustion chamber, and thus influences the ignition delay [12,13], which is observed in single-pulse experiments. Brady [14] measured the flow velocity of several propellants into an evacuated injector during a short pulse.…”

Section: Introductionmentioning

confidence: 99%

Visualization of Pulse Firing Mode in Hypergolic Bipropellant Thruster

Fujii¹,

Daimon²,

Inoue

et al. 2020

Journal of Propulsion and Power

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The pulse firing mode of bipropellant thrusters is crucial for the precise attitude control of spacecraft. This research explains how to simultaneously measure the chamber pressure and observe the combustion dynamics in the consecutive pulse firing of the monomethylhydrazine and the mixture of nitrogen tetroxide with approximately 3% nitric oxide bipropellant thruster. This study investigated transient behaviors in the ignition and cutoff of the pulse firing mode of the thruster. There was a delay in measuring the chamber pressure for two reasons: the time needed for the propellant to fill the manifold, and the delay in the response time of the pressure-sensing system. The time needed to fill the manifold depends on the pulse number, whereas the response time of the system factor is constant. This paper also demonstrates that a fuel-rich injection in the pulse firing mode leading to explosive ignition can be realized by prompt evaporation of the oxidizer from the manifold. Nomenclature c = characteristic velocity, m∕s DI = valve inlet current, A DO = valve outlet current, A MEOP = maximum expected operating pressure, MPa Pc = chamber pressure, MPa

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Section: Introductionmentioning

confidence: 99%

Visualization of Pulse Firing Mode in Hypergolic Bipropellant Thruster

Fujii¹,

Daimon²,

Inoue

et al. 2020

Journal of Propulsion and Power

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“…Monomethylhydrazine (MMH) and dinitrogen tetroxide (NTO) is one of the most utilized bipropellant combinations, − with high performance but suffering from the above-mentioned environmental problems. Toward designing “green” hypergolic propellants, Catoire and his colleagues studied the possibility of replacing the toxic MMH fuel with ethanol (EtOH), while keeping the oxidizer NTO unchanged.…”

Section: Introductionmentioning

confidence: 99%

Reactive Dynamics Study of Hypergolic Bipropellants: Monomethylhydrazine and Dinitrogen Tetroxide

et al. 2012

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To gain an atomistic-level understanding on physical and chemical processes occurring at the interfaces of hypergolic propellants, we carried out the first reactive dynamic (ReaxFF) simulations to study the reactive hypergolic mixture of monomethylhydrazine (MMH) and dinitrogen tetroxide (NTO), in comparison with the ethanol (EtOH) and NTO mixture that is reactive but nonhypergolic. Our studies show that the MMH-NTO mixture releases energy more rapidly than the EtOH-NTO mixture upon mixing the fuels and oxidizers. We found that the major early chemical reactions between MMH and NTO are hydrogen abstractions and N-N bond scissions. The MMH-NTO mixture has more reaction channels than EtOH-NTO based on statistical analyses of chemical reaction events and channels at early stages of the dynamics. Analyzing the evolution of product distribution over reaction time shows that the oxidizer (NO(2)) diffuses into the fuels (MMH or EtOH) for the occurrence of reactions, demonstrating the influence of physical mixing on chemical reactions. Our simulations suggest that effective hypergolic systems require fuels with low energy barriers of H abstractions and/or bond scissions and oxidizers with large diffusion mobility for efficient physical mixing.

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“…Investigation of such incidents 3,17,22 revealed that the ignition delay for the hypergolic propellants is affected by the operating conditions. The initial composition and pressure affect the heat and mass transfer processes as well as the reactant concentrations.…”

Section: A Backgroundmentioning

confidence: 98%