This set of Rocket Propulsion Quiz focuses on “Liquid Propellant Rocket Engine – Turbopump Feed Systems and Engine Cycles”.
1. In turbopump feed systems, the pressurization of the propellants is done by ____________ and they are driven by ____________
a) turbines; pumps
b) pumps; turbines
c) pumps; pumps
d) turbines; turbines
Explanation: Pumps pressurize the propellants while they are driven by turbines. The turbines are run by propellants fed from the main propellant tank, separate propellant tank or by some other means.
2. In turbopump feed systems, the turbines derive their power from _______________
a) expansion of hot gases
b) expansion of cold gases
c) compression of hot gases
d) compression of cold gases
Explanation: The power derived by the turbines come from the expansion of hot gases. This power is in turn used to run the turbopumps.
3. Closed cycles in turbopump feed systems are also called as ____________
a) open cycle
b) engine cycle
c) topping cycle
d) bottoming cycle
Explanation: Closed and open cycles are both engine cycles. Closed cycle is also called topping cycle. In this cycle, the working fluid from the turbine is injected into the combustion chamber so that the energy of this working fluid is also utilized in the engine cycle.
4. Open cycles perform better than closed cycle in a turbopump feed type rocket engine.
Explanation: Closed cycle tends to perform a little better than closed cycles. This is mainly because the exhaust gas from the turbine expands through the thrust chamber nozzle in its full pressure ratio. For open cycles, this expansion process happens across a smaller pressure ratio.
5. In gas generator cycles, the turbine inlet gas is obtained from a portion of exhaust gases about to pass through the rocket nozzle.
Explanation: For gas generator cycles, the turbine inlet gas is obtained from a separate gas generator. The propellants used to generate the gas may be stored in separate tanks or it may be fed from the main propellant tank.
6. Which of the following cycles is used in RL10 hydrogen/oxygen rocket engine?
a) Expander cycle
b) Gas generator cycle
c) Staged-combustion cycle
d) Combustion tap-off cycle
Explanation: Expander cycle was used in RL-10 hydrogen/oxygen rocket engine. In this cycle, fuel used for cooling the thrust chamber is used as the working fluid in the turbine used to power the turbopumps. The exhaust from the turbine is fed to the combustion chamber and burned.
7. Which of the following engines uses a staged combustion cycle?
b) Pratt & Whitney RL10
c) Ariane 6
d) SpaceX Raptor
Explanation: SpaceX Raptor uses a full flow staged combustion cycle. Rest of them uses expander cycles. Staged combustion cycles involve the propellant going through multiple combustion chambers to undergo its combustion. In full flow staged combustion cycle, both oxygen-rich and fuel-rich preburners are used.
8. Which of the following is not a characteristic of staged combustion cycle compared to other cycles?
a) High fuel efficiency
b) High engine specific impulse
c) Engineering simplicity
d) Use of preburners
Explanation: Staged combustion cycles involve multiple combustion chambers and its engineering design is complex compared to other cycles. The propellant flows through two kinds of combustion chambers – preburner and main combustion chamber.
Sanfoundry Global Education & Learning Series – Rocket Propulsion.
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