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However, a nozzle designed for sea-level operation will quickly lose efficiency at higher altitudes. In a multi-stage design, the second stage rocket engine is primarily designed for use at high altitudes, only providing additional thrust after the first-stage engine performs the initial liftoff. In this case, designers will usually opt for an ...
The expanding nozzle is a type of rocket nozzle that, unlike traditional designs, maintains its efficiency at a wide range of altitudes. It is a member of the class of altitude compensating nozzles, a class that also includes the plug nozzle and aerospike. While the expanding nozzle is the least technically advanced and simplest to understand ...
It excludes problems with flow separation at sea level and increases efficiency of the engine in vacuum. [3] For example, application of nozzle extension for liquid rocket engine NK-33 improves the value of specific impulse up to 15-20 sec for near-space conditions.
The nozzle is usually over-expanded at sea level, and the exhaust can exhibit visible shock diamonds through a schlieren effect caused by the incandescence of the exhaust gas. The shape of the jet varies for a fixed-area nozzle as the expansion ratio varies with altitude: at high altitude all rockets are grossly under-expanded, and a quite ...
This is referred as overexpanded flow because in this case the pressure at the nozzle exit is lower than that in the ambient (the back pressure)- i.e. the flow has been expanded by the nozzle too much. [13] A further lowering of the back pressure changes and weakens the wave pattern in the jet.
Altitude compensating nozzles address this loss of efficiency by changing the shape or volume of the rocket nozzle as the rocket climbs through the atmosphere. There are a wide variety of designs that achieve this goal, with the aerospike being perhaps the most studied among them. Aerospike engine; Plug nozzle; Expanding nozzle
Expander rocket cycle. Expander rocket engine (closed cycle). Heat from the nozzle and combustion chamber powers the fuel and oxidizer pumps. The expander cycle is a power cycle of a bipropellant rocket engine. In this cycle, the fuel is used to cool the engine's combustion chamber, picking up heat and changing phase.
The ED nozzle has been known about since the 1960s and there has been several attempts to develop it, with several reaching the level of static hot-firings. These include the 'Expansion-Deflection 50k' [2] (Rocketdyne), the 'Expansion-Deflection 10k' [3] and the RD-0126 [4] (CADB). Rocketdyne also developed a third, smaller E-D nozzle.