Component design concerns for deep throttling H2/O2 rocket engines

Limerick, C.

doi:10.2514/6.1991-2209

Cited by 3 publications

(2 citation statements)

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“…Additional methods of avoiding chug are using dual element injectors, gas-gas injection, and high inertia injectors. 21 Chugging is particularly a problem at low thrust on the RL-10 CECE.…”

Section: Chugmentioning

confidence: 99%

A Historical Systems Study of Liquid Rocket Engine Throttling Capabilities

Betts

Frederick

2010

46th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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This is a comprehensive systems study to examine and evaluate throttling capabilities of liquid rocket engines. The focus of this study is on engine components, and how the interactions of these components are considered for throttling applications. First, an assessment of space mission requirements is performed to determine what applications require engine throttling. A background on liquid rocket engine throttling is provided, along with the basic equations that are used to predict performance. Three engines are discussed that have successfully demonstrated throttling. Next, the engine system is broken down into components to discuss special considerations that need to be made for engine throttling. This study focuses on liquid rocket engines that have demonstrated operational capability on American space launch vehicles, starting with the Apollo vehicle engines and ending with current technology demonstrations. Both deep throttling and shallow throttling engines are discussed. Boost and sustainer engines have demonstrated throttling from 17% to 100% thrust, while upper stage and lunar lander engines have demonstrated throttling in excess of 10% to 100% thrust. The key difficulty in throttling liquid rocket engines is maintaining an adequate pressure drop across the injector, which is necessary to provide propellant atomization and mixing. For the combustion chamber, cooling can be an issue at low thrust levels. For turbomachinery, the primary considerations are to avoid cavitation, stall, surge, and to consider bearing leakage flows, rotordynamics, and structural dynamics. For valves, it is necessary to design valves and actuators that can achieve accurate flow control at all thrust levels. It is also important to assess the amount of nozzle flow separation that can be tolerated at low thrust levels for ground testing. Nomenclature

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“…Additional methods of avoiding chug are using dual element injectors, gas-gas injection, and high inertia injectors. 21 Chugging is particularly a problem at low thrust on the RL-10 CECE.…”

Section: Chugmentioning

confidence: 99%

A Historical Systems Study of Liquid Rocket Engine Throttling Capabilities

Betts

Frederick

2010

46th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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“…Throttling has been investigated and several engines were tested in deep and shallow throttled conditions. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Throttling is also necessary for the rocket-based-combined-cycle engine (RBCC) to change its operation to the ramjet mode. 15) In the rocket engine, thrust is proportional to the combustion chamber pressure.…”

Section: Introductionmentioning

confidence: 99%

Conceptual Study of Throttled Operation of Rocket Engine Turbopump

Kanda

2013

Trans. Japan Soc. Aero. S Sci.

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Throttled operation of turbopumps of liquid rocket engines is studied analytically. Two types of pressure drops in the propellant injector are examined, that is, the drop of gas injection and that of liquid injection. Circulation is examined in relation to throttling to operate the pump in the vicinity of the design condition. An enthalpy increase at the pump entrance is derived analytically in the circulation system. With the derived analytical relationships, throttled operating conditions are examined for imaginary LH 2 and LOX turbopumps with a LH 2 /LOX property calculation code. The circulation causes gasification at the entrance of the high-pressure LH 2 pump. This does not occur in the mid-pressure LH 2 pump or the LOX pump. In the liquid propellant injection system, the unstable region becomes narrower than in the gas propellant injection. The ratio of the turbine flow rate to the pump flow rate decreases in line with throttling. Throttling does not degrade the engine specific impulse from the viewpoint of the turbine bleed ratio.

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Summary of Deep Throttling Rocket Engines with Emphasis on Apollo LMDE

Dressler¹

2006

42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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Component design concerns for deep throttling H2/O2 rocket engines

Cited by 3 publications

References 0 publications

A Historical Systems Study of Liquid Rocket Engine Throttling Capabilities

A Historical Systems Study of Liquid Rocket Engine Throttling Capabilities

Conceptual Study of Throttled Operation of Rocket Engine Turbopump

Summary of Deep Throttling Rocket Engines with Emphasis on Apollo LMDE

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