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Evaluation of the possibilities of adapting a constant volume combustion chamber for research on ignition of hypergolic propellants under low and high-pressure conditions

Krzesicki M., Boruc Ł., Kapusta Ł. J.

Combustion Engines

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2018

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R. 57, nr 2

9--13

EN

In this study, the adaptation possibilities of a constant volume combustion chamber (CVCC) for research on the ignition of hypergolic propellants are presented. The application of hypergolic bipropellants and crucial parameters regarding their ignition behaviour are discussed. The initial studies on ignition delay measurements presented here does not cover the whole range of conditions present in practical systems where hypergolic ignition occurs. In the study, a need for an evaluation of the influence of pressure on the ignition delay was indicated as the reason to conduct research on hypergolic ignition in low and high-pressure environments. Moreover, the study reviews the state-of-the-art experimental methods of investigating the ignition under atmospheric, low and high-pressure conditions, including those utilizing a constant volume combustion chamber. The drop test was pointed out as the most commonly used method; this makes it advantageous in terms of comparing the results with those obtained by other researchers. Therefore, the drop test was selected as a method to be used in a CVCC. The test rig developed here was designed based on a CVCC initially designed for diesel sprays’ visualization in high-pressure conditions. All the required modifications, especially the design of the oxidizer dosing unit, are presented in the study.

2

Novel liquid compounds as hypergolic propellants with HTP

Rarata G., Florczuk W.

Journal of KONES

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2016

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Vol. 23, No. 1

271--278

EN

The paper presents both an experimental investigation and an up-to-date literature review over the hypergolicity of highly concentrated hydrogen peroxide with various liquid mixtures or novel chemical compounds that may be a potential candidate for rocket applications. Moreover, the coverage contains both, a historical and modern approach to hydrogen peroxide based hypergolic propulsion systems. In addition, the advantages of the oxidizer, especially in the form of 98% solution of hydrogen peroxide, are profiled in detail against the toxic ones that are currently utilized. Equally, the potential replacements for hydrazine, monomethyl hydrazine, unsymmetrical dimethyl hydrazine, dinitrogen tetroxide or their combinations, as propellants in rocket applications, are collected and discussed thoroughly in terms of their propulsive performance, availability on the market, storability, handling and general safety conditions for the technical staff as well as environmental compatibility. The ignition mechanism of the two main fuel groups, catalytically and energetically promoted, that reveal fast, spontaneous ignition with the highly concentrated hydrogen peroxide , is described too. Furthermore, the example that results from the simple drop tests are shown with special focus laid on the comparison of the minimum ignition delay time as the key parameter for the discussed fuel compositions. Lastly, the most prospective fuel combinations are discussed as desirable alternatives for the near-future bipropellant propulsion systems for the rocket or satellite applications, or other that demand high energy density.

3

Zapłon hipergoliczny stabilizowanego nadtlenku wodoru z węglowodorami promowanymi katalitycznie

Rarata G., Surmacz P.

Prace Instytutu Lotnictwa

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2011

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Nr 12 (221)

173-181

PL

W artykule zwrócono uwagę na możliwość wykorzystania sężonych, stabilizowanych roztworów nadtlenku wodoru (H2O2) w celu wypracowania jak najprostszej oraz skutecznej metody zapłonu węglowodorów ciekłych. Zastosowanie odpowiednio stężonego, stabilizowanego fosforanami, nadtlenku wodoru jako utleniacza (o stężeniu 85% i powyżej) oraz stałego katalizatora jego rozkładu (np. w postaci jego zawiesiny w paliwie) pozwala na uzyskanie samozapłonu spełniającego cechy tzw. zapłonu hipergolicznego (ang. hypergolic). Rzeczywiste układy hipergolowe (np. dwuskładnikowy układ ciekłego paliwa rakietowego oraz utleniacza) ulegają samoczynnemu zapłonowi w chwili, gdy ich składniki ulegną wymieszaniu. Są one jednak dość kłopotliwe w przechowywaniu i transporcie, ale raczej niezawodne w użytkowaniu w silniku rakietowym - gdyż nie wymagają dodatkowych systemów zapłonowych. W określonych warunkach stężony nadtlenek wodoru również może stanowić ciekły utleniacz, który posiada jednocześnie cechy hipergolika w stosunku do odpowiednio spreparowanych paliw weglowodorowych. Jedną z metod wykorzystywaną w tym celu może być dodatek katalizatora do paliwa węglowodorowego w postaci jego drobnokrystalicznej soli. Dalsze prace badawcze wymagane sa w kierunku określenia różnic w zachowaniu się układu przy zastosowaniu HTP (zamiast silnie stabilizowanego H2O2) czy też w warunkach odpowiadających pracy prawdziwego silnika rakietowego.

EN

The paper presents a simple and effective approach towards receiving the hypergolic ignition of a potential environmentally friendly liquid propellant consisting of stabilized hydrogen peroxide as a oxidizer (with a concentration of 85% or higher) and hydrocarbon fuels for use in rocket engines. Simple tests conducted up to now prove positive effect of relatively small amount of metal salt catalyst in fuels for elicitation of the hypergolic ignition. Such bipropellant formulation may be utilized in a real rocket engine environment - for instance in a pressure-fed liquid propellant rocket engine. However, to establish such technology more tests are needed to perform to find what kind of effects exerts the amount of catalyst and the initial temperature of the fuel on the ignition delay of such hypergolic bipropellants. An experimental program aimed at determining the effects of initial ambient pressure, initial ambient gas properties, and hydrogen peroxide concentration on ignition delay. Results show that ignition delay can be reduced by increasing the hydrogen peroxide concentration. The applicability of traditional vaporization and ignition theories to the ignition of a catalytically promoted fuel with rocket grade hydrogen peroxide are shortly discussed as well. However, the paper emphasizes that there are also many other important issues that must be taken into account, such as the level of stabilizers in the H202 or the difference between the ignition delay times from open cup tests and those from rocket engine static firings.