Back Cicle de gasogen Catalan Ciclo con generador de gas (cohete) Spanish Cycle générateur de gaz French Siklus generator gas ID Ciclo a generatore di gas Italian ガス発生器サイクル Japanese 가스발생기 사이클 Korean Ciclo gerador de gás Portuguese Жидкостный ракетный двигатель открытого цикла Russian Газогенераторний цикл Ukrainian
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The gas-generator cycle, also called open cycle, is one of the most commonly used power cycles in bipropellant liquid rocket engines.
Propellant is burned in a gas generator (or "preburner") and the resulting hot gas is used to power the propellant pumps before being exhausted overboard and lost. Because of this loss, this type of engine is termed open cycle.
The gas generator cycle exhaust products pass over the turbine first. Then they are expelled overboard. They can be expelled directly from the turbine, or are sometimes expelled into the nozzle (downstream from the throat) for a small gain in efficiency.
The main combustion chamber does not use these products. This explains the name of the open cycle. The major disadvantage is that this propellant contributes little to no thrust because they are not injected into the combustion chamber. The major advantage of the cycle is reduced engineering complexity compared to the staged combustion (closed) cycle.