A nozzle extension is an extension of the
nozzle
A nozzle is a device designed to control the direction or characteristics of a fluid flow (specially to increase velocity) as it exits (or enters) an enclosed chamber or pipe (material), pipe.
A nozzle is often a pipe or tube of varying cross ...
of a
reaction
Reaction may refer to a process or to a response to an action, event, or exposure.
Physics and chemistry
*Chemical reaction
*Nuclear reaction
*Reaction (physics), as defined by Newton's third law
* Chain reaction (disambiguation)
Biology and ...
/
rocket
A rocket (from , and so named for its shape) is a vehicle that uses jet propulsion to accelerate without using any surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely ...
engine
An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.
Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ge ...
. The application of nozzle extensions improves the
efficiency
Efficiency is the often measurable ability to avoid making mistakes or wasting materials, energy, efforts, money, and time while performing a task. In a more general sense, it is the ability to do things well, successfully, and without waste.
...
of rocket engines in vacuum by increasing the nozzle expansion ratio. As a rule, their modern design assumes use of
carbon-carbon materials without regenerative
cooling
Cooling is removal of heat, usually resulting in a lower temperature and/or Phase transition, phase change. Temperature lowering achieved by any other means may also be called cooling.
The Heat transfer, transfer of Internal energy, thermal energ ...
. Nozzle extensions can be both stationary, for high-altitude engines, or sliding, for engines designed to operate at a range of altitudes.
Description
As of 2009, the search for various schemes to achieve higher area ratios for rocket nozzles remains an active field of research and patenting.
[Extractable nozzle for rocket engine - Russian Patent 2180405]
, ''Russian patents''
, ''Russian patents'' Generally, modern application of these designs can be divided into "air-to-vacuum" engines, which start their work at sea level and finish it at vacuum conditions, and "vacuum" engines, which perform all their operations in a vacuum.
"Air-to-vacuum" engines
For first stage
rocket
A rocket (from , and so named for its shape) is a vehicle that uses jet propulsion to accelerate without using any surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely ...
engines, the
engine
An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.
Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ge ...
works with ''nozzle extension'' in disposed position during the first minutes of flight and expands it at some predefined level of air pressure. This scheme assumes the outer skirt of the bell is extended while the engine is functioning and its installation to working position happens in the upper layers of the atmosphere. It excludes problems with
flow separation
In fluid dynamics, flow separation or boundary layer separation is the detachment of a boundary layer from a surface into a wake.
A boundary layer exists whenever there is relative movement between a fluid and a solid surface with viscous fo ...
at sea level and increases efficiency of the engine in vacuum.
[Work on modifying NK-33]
''News of cosmonautics'', November 2002 For example, application of ''nozzle extension'' for
liquid rocket engine NK-33
The NK-33 ( GRAU index: 14D15) and its vacuum-optimized variant, the NK-43, were rocket engines developed in the late 1960s and early 1970s by the Kuznetsov Design Bureau for the Soviet space program's ill-fated N1 Moon rocket. The NK-33 is am ...
improves the value of
specific impulse
Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine, such as a rocket engine, rocket using propellant or a jet engine using fuel, generates thrust. In general, this is a ratio of the ''Impulse (physics), ...
up to 15-20
sec for near-space conditions. Therefore, this scheme adjusts the system to ambient conditions along the trajectory or, in other words, allows
altitude compensation.
"Vacuum" engines
Rocket engines of
upper stages perform all their operations in space and therefore in a vacuum. In order to achieve maximum efficiency for this class of engines they need high
area ratios. This makes the nozzles a very sizable part of the engine, which must be completely enclosed below the
nose cone
A nose cone is the conically shaped forwardmost section of a rocket, guided missile or aircraft, designed to modulate oncoming fluid dynamics, airflow behaviors and minimize aerodynamic drag. Nose cones are also designed for submerged wat ...
of a rocket. The
payload fairing
A payload fairing or nose fairing is a nose cone used to protect a launch vehicle, spacecraft payload (air and space craft), payload against the impact of dynamic pressure and aerodynamic heating during launch through an atmosphere. An additiona ...
and supporting constructions must endure all stresses and loads during launch and flight. Consequently, the use of an outer
expandable skirt in this case allows the size of the upper stage and
payload fairing
A payload fairing or nose fairing is a nose cone used to protect a launch vehicle, spacecraft payload (air and space craft), payload against the impact of dynamic pressure and aerodynamic heating during launch through an atmosphere. An additiona ...
to be minimized, which in turn decreases the total mass of the nose cone.
[RL10B-2 - NOZZLE EXTENSION ASSEMBLY IMPROVEMENTS FOR DELTA IV](_blank)
/ref> For these reasons, ''nozzle extensions'' are used for rocket engine
A rocket engine is a reaction engine, producing thrust in accordance with Newton's third law by ejecting reaction mass rearward, usually a high-speed Jet (fluid), jet of high-temperature gas produced by the combustion of rocket propellants stor ...
s RL-10
The RL10 is a liquid-fuel cryogenic rocket engine built in the United States by Aerojet Rocketdyne that burns cryogenic liquid hydrogen and liquid oxygen propellants. Modern versions produce up to of thrust per engine in vacuum. RL10 version ...
and RD-58
The RD-58 (, GRAU index: 11D58) is a rocket engine, developed in the 1960s by OKB-1, now RKK Energia. The project was managed by Mikhail Melnikov, and it was based on the previous S1.5400 which was the first staged combustion engine in the wo ...
.
Discussion thread at "''News of cosmonautics''" forum
See also
*
Rocket engine nozzle
A rocket engine nozzle is a propelling nozzle (usually of the de Laval type) used in a rocket engine to expand and accelerate combustion products to high supersonic velocities.
Simply: propellants pressurized by either pumps or high pressure ...
*
De Laval nozzle
A de Laval nozzle (or convergent-divergent nozzle, CD nozzle or con-di nozzle) is a tube which is pinched in the middle, with a rapid convergence and gradual divergence. It is used to accelerate a compressible fluid to supersonic speeds in the a ...
*
Stepped nozzle
*
F-1
*
NK-33
The NK-33 ( GRAU index: 14D15) and its vacuum-optimized variant, the NK-43, were rocket engines developed in the late 1960s and early 1970s by the Kuznetsov Design Bureau for the Soviet space program's ill-fated N1 Moon rocket. The NK-33 is am ...
References
External links
*
Surprises of "Engines-2000" ''News of cosmonautics'', April 2000
*
Patent of NPO Iskra ''Patent department''
*
''Magazine "Engine"''
* {{in lang, ru
ttp://engine.aviaport.ru/issues/02/page08.html Casing for fire ''Magazine "Engine"''
Vulcain-2 Cryogenic Engine Passes First Test with New Nozzle Extension ''European Space Agency''
Nozzles
Rocket propulsion
Spacecraft propulsion