JET ENGINE USING EXHAUST GAS
TECHNICAL FIELD
The present invention relates to a jet engine such as a turbo
engine, and more particularly to a jet engine using exhaust gas which
obtains propulsive force by rotating a fan within exhaust gas burned
and discharged in the engine.
BACKGROUND ART
Generally, a jet-propelled engine means a heat engine which
ejects high temperature gas burned in the engine and then uses its
repulsive force to advance. This jet-propelled engine is commonly
called 'jet engine', and may include a rocket engine having oxygen
source necessary for combustion in a broad sense.
The jet engine is mostly used as a prime mover of an airplane,
and classified into four types depending on its structure and function.
Firstly, there is a Turbojet, which compresses air inhaled from the
atmosphere with an axial-flow type or centrifugal-flow type compressor,
draws this compressed air into a burner so that fuels injected into the
burner are burned, and then discharges high-temperature and
high-pressure combustion gas toward a compression-driving turbine.
That is, Turbojet is a prime mover which obtains propulsive force by
jetting the gas, which has passed through the turbine, through jet
nozzles.
This engine receives a great deal of air so as to control the
temperature of combustion gas lower than a certain point in aspect of
heat resistance of the turbine material, and thus there remains a lot of
oxygen among the combustion gas. Therefore, in order to increase
propulsive force, some turbojet engines are equipped with a long tail
pipe and inject secondary fuel into the pipe for the purpose of
after-burning.
Next, there is Turboprop which is a jet-propelled engine having a
structure that a propeller is attached to the turbojet. Turboprop has
similar configuration to the turbojet. But, energy of combustion gas in
Turboprop is mostly converted into driving force of the propeller. Thus,
Turboprop uses propulsive force of the propeller and jetting force
together. Turboprop has performance between a propeller and a
turbojet, and is suitable for an engine of a passenger airplane or a
transport plane not requiring a high-speed flight.
There is also Bypass Jet which has an axial compressor instead of
the propeller of turboprop. Bypass Jet ejects a part of compressed air
through outer circumference of the combustion chamber together with
combustion gas. This does not need a reduction gear, which is a factor
of demerit of the turboprop. Bypass Jet also consumes very small fuel
and is suitable for relatively fast transport planes.
As another type of jet-propelled engines, there is Ram Jet. If
flying speed increases, atmosphere air is relatively flowed into the
engine and then compressed due to its inertia. This is called "Ram
effect", and Ram Jet introduces the compressed air into the combustion
chamber by using this Ram effect and then injects fuel thereto. Ram
Jet ejects combustion gas through jet nozzles and then uses its
repulsive force to advance.
In fact, Ram Jet is equipped with a diffuser to help inflow air to
move slowly. Slowly moving air increases pressure in the diffuser, and
thus the air is easily compressed to very high pressure. This engine
has very simple structure and its performance is better as the plane
moves faster. Thus, Ram Jet is suitable for a prime mover of a
supersonic airliner moving at two or three times the speed of sound.
However, to obtain motive power, high-speed air is applied to Ram
Jet from outside. Thus, there is designed a hybrid engine called "Turbo
Ram Jet' which operates as a turbojet at a low speed and as a ramjet at
a high speed.
As another type of jet-propelled engines, there is Pulse Jet. Pulse
Jet has an automatic valve at the front of air inhalator. When a plane
is flying, atmosphere air pushes the automatic valve to be opened and
enters the diffuser. The air entering the diffuser loses its speed and
makes the pressure in the combustion chamber increased. Then, the
fuel is injected and burned, which makes the pressure in the
combustion chamber more increased. This makes the automatic valve
is closed. The combustion gas is ejected through jet nozzles to give
propulsive force. If the combustion gas is ejected, the pressure in the
combustion chamber is decreased and then air can be flowed in the
combustion gas through the automatic valve.
This Pulse Jet has a feature that combustion is intermittently
generated, compared with other engines in which combustion is
continuously generated. Pulse Jet has simple structure, but it has
disadvantages such as large fuel consumption and short lifecycle.
In such a jet engine, most needed is reliability. When evaluating
its performance, there are considered three main factors: the propulsive
force of engine should be great, compared with its weight; the
propulsive force should be great, compared with its front surface area;
and the fuel consumption should be low.
However, three conditions are rarely satisfied. Particularly, the
turbojet generates serious noise and consumes too much fuel, so not
frequently used in these days. The ramjet primarily used in high-speed
airplanes has an advantage that it has simple configuration and gives
great propulsive force, compared with its front surface area, but it
consumes too much fuel.
In addition, the turbofan and the turboprop lower its fuel
consumption rate by converting the energy generated in its basic
turbojet engine into rotary energy of fan or propeller installed at the
front. However, the turbofan and the turboprop disadvantageously give
not to great propulsive force, compared its front surface area, since the
fan or the propeller rotates among atmosphere air having low density.
It is because there are generated many losses in the forwarding
propulsive force when the fan or the propeller rotates among the
low-density atmosphere air.
Furthermore, since giving the propulsive force toward the
atmosphere air straightly flowing from the front, the turbofan and the
turboprop demonstrate its function only at or below supersonic speed.
At a speed above the supersonic speed, the fan or the propeller does not
push the rushing atmosphere but disturb the flow of atmosphere air.
In addition, the fan and the propeller used in the turbofan and
the turboprop have relatively big diameter, so the engine becomes
bigger and heavier. In addition, its big size becomes an obstruction to
its advancing due to friction with the atmosphere, and its weight also
works as a burden of the engine itself.
Therefore, there still remains a need for a jet engine having small
weight, great propulsive force to a front surface area and low fuel
consumption rate.
DISCLOSURE OF INVENTION
The present invention is designed to solve such problems of the
prior art, and an object of the invention is to provide a jet engine using
exhaust gas, which may obtain greater propulsive force through simple
structural change that rotates a fan among exhaust gas having high
density.
In order to accomplish the above object, the present invention
provides a jet engine which includes a body, a burner installed in the
body to inject and burn fuel in compressed air, a high-pressure turbine
having a plurality of rotors, the high-pressure turbine being rotated by
high-pressure exhaust gas discharged from the burner, a low-pressure
turbine having a plurality of rotors, the low-temperature turbine being
rotated by low-pressure exhaust gas passing through the high-pressure
turbine, a rotary shaft combined to gyratory centers of the
high-pressure turbine and the low-pressure turbine, and a propulsive
force providing unit which rotates together with the rotary shaft in order
to change lateral component of velocity of the exhaust gas, discharged
through the low-pressure turbine from the burner, to be directed
backward.
Preferably, the propulsive force providing unit is a fan combined
to the rotary shaft at a rear of the last rotor of the low-pressure turbine,
and the fan is curved to a direction opposite to a bent portion of the last
rotor in order to change the lateral component of velocity of the exhaust
gas, passing through the low-pressure turbine, to be directed backward
to the utmost when rotating.
As an alternative, it is also preferable that each rotor of the
low-pressure turbine has a bent portion elongated backward at a tail,
and the bent portion of each rotor changes the lateral component of
velocity of the exhaust gas, passing through the near rotor, to be
directed backward to the utmost so as to provide propulsive force.
In addition, the fan preferably has a diameter substantially
similar to a diameter of the last rotor of the low-pressure turbine.
Preferably, the jet engine of the present invention can be realized
in various types: a turbojet type in which a compressor is installed in
the body, the compressor being connected to the rotary shaft and
rotating by the rotating force of the turbine to compress air supplied
into the burner; a ramjet type in which a compressing chamber is
installed at the front of the body so as to naturally compress air which
is flowed therein when the body advances; and a rocket type in which a
front portion of the body is sealed, and an oxygen storage area is
prepared in the body in order to store oxygen to be supplied to the
burner.
The jet engines of various types can be equipped with a cooling
device, and this cooling device cools the fan by using air compressed in
the diffuser or other coolant. At this time, the cooling device can be
designed to cool the turbine and the stators together with the fan, and
particularly the cooling device may cool even bearings used in the
turbine.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of preferred
embodiments of the present invention will be more fully described in the
following detailed description, taken accompanying drawings. In the
drawings:
FIG. 1 is a sectional view showing a jet-propelled engine according
to the present invention;
FIG. 2 shows a flow path of exhaust gas passing through a
turbine and a fan in the jet-propelled engine of FIG. 1;
FIG. 3 shows a turbine and a flow path of exhaust gas passing
through the turbine according to another embodiment of the present
invention;
FIG. 4 is a sectional view showing another type of jet-propelled
engine applying the principle of the present invention; and
FIG. '5 is a sectional view showing still another type of
jet-propelled engine applying the principle of the present invention.
BEST MODES FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will
be described in detail with reference to the accompanying drawings.
First, a jet-propelled engine, commonly called 'jet engine', means
a heat engine which ejects high temperature gas burned in the engine
through jet nozzles and then uses its repulsive force to advance, and it
should be understood that principle and features of the present
invention described later could be applied to various heat engines such
as turbojet, turbofan, turboprop, ramjet, pulsejet and rocket.
FIG. 1 is a sectional view showing configuration of the
jet-propelled engine according to the first embodiment of the present
invention. The first embodiment of the present invention adopts a
turbojet engine, which is the most ordinary type, in a modified shape
according to the principle of the present invention.
Referring to FIG. 1, the jet engine 10 of the present invention has
a body 12 constituting an overall outward shape. The shape of the
body 12 can be modified depending on the kind of engine and required
parts, and the body 12 approximately has a cylindrical shape which
inhales air at the front and discharges exhaust gas at the rear.
A burner 14 is installed in the body 12. The burner 14 gives a
space for mixing fuel with compressed air and burning them. In
addition, after burning the air and fuel in the burner 14, exhaust gas of
high temperature and high pressure is discharged backward.
At this time, if the jet engine is a turbojet engine as in this
embodiment, there is installed a compressor 40 for compressing the
atmosphere flowed in the burner 14. The compressor 40 includes a
plurality of rotors and stators, and rotates by means of driving force of a
turbine 16, described later. This compressor 40 is used in an engine
for low-speed flying, and not used in a ramjet engine for high-speed
flying.
A nose cone 44 is mounted at the front of the compressor 40.
The nose cone plays a role of lessening resistance of air when the body
12 advances and helping the atmosphere air be flowed into the
compressor 40 to the maximum.
At a rear of the burner 14, installed are a high-pressure turbine
16 and a low-pressure turbine 20. Though it is shown that two-stage
high-pressure turbine and three-stage low-pressure turbine are used in
this embodiment, the kind and the number of turbines can be modified
variously, not limited to that case.
The high-pressure and low-pressure turbines 16 and 20 have a
plurality of rotors 22 formed at outer circumference of a rotating body
thereof, and are rotated at a high speed by means of high-temperature
and high-pressure gas discharged from the burner 14. These turbines
16 and 20 convert kinetic energy of the fluid into useful mechanical
energy. Rotation energy generated in the high-pressure turbine 16 is
transmitted to the above-mentioned compressor 40, and rotation energy
generated in the low-pressure turbine 20 is transmitted to a fan 30,
described later.
There are mounted stators 24 at the front of each rotor 22 in
order to control flow of the gas supplied to each rotor 22 to a direction
suitable for angle and shape of each rotor 22. The stators 24 are fixed
to an inner circumference of the body 12, and not rotated.
The jet engine constructed as above is equipped with a propulsive
force providing means for providing propulsive force in addition to the
basic propulsive force obtained by fuel ejection. As an example of the
propulsive force providing means, there is mounted a fan 30 at the rear
of the turbine 20. The fan 30 is connected to the turbine 20 through
the same rotary shaft 26, and rotated by the turbine 20. The fan 30
has a plurality of blades, which are curved in a direction substantially
opposite to a bent portion of the last rotor turbine 20. Particularly,
each blade of the fan 30 has a head portion substantially parallel to an
advancing direction of exhaust gas discharged through the last rotor of
the turbine 20 with a lateral component of velocity, but each blade of
the fan 30 is gradually curved backward at its tail. This shape of the
fan blade converts a direction of the exhaust gas passing through the
last rotor of the turbine 20 with a lateral component of velocity to be
directed backward.
Preferably, the fan 30 is configured to convert a direction of the
exhaust gas as closer to an axial direction as possible in order to reduce
energy loss and improve efficiency.
A curved shape of the fan 30 and an advancing direction of the
gas passing through the turbine 20 and the fan 30 are described in
detail with reference to FIG. 2. The stators 24 and the rotors 22 of the
turbine 20 are schematically shown in FIG. 2.
Referring to FIG. 2, the exhaust gas is initially flowed to the
low-pressure turbine 20 in a straight direction. Generally, the rotor 22
generating a rotation force by the gas is inclined to the gas advancing
backward. The stator 24 also changes an advancing direction of the
gas so that the gas moving toward the rotor 22 may be more effectively
collided with a surface of the inclined rotor 22.
In other words, the gas passing through the stator 24 is ejected at
an angle of about 15° to a horizontal line in the drawing. This gas
pushes the rotor 22 and at the same time its advancing direction is bent
by means of the bent shape of the rotor 22, so advancing somewhat
laterally at about -30 — 50°. In the case shown in the figure, this
process is repeated through three rotors 22 and two stators 24, and in
this process, the gas pushes the rotors 22 and the turbine 20 is rotated.
In addition, the gas passing through the last rotor 22' is flowed
toward the blade 31 of the fan 30. At this time, a tail portion of the fan
blade 31 is curved backward, not elongated to the side as in the case of
the rotor 22 or the stator 24. Thus, the gas passing through the fan
blades 31 are directed toward and ejected through the rear of the engine
according to the curved shape of the fan blades31. In other words,
though the gas passing through the last rotor 22 contains a significant
amount of lateral component of velocity, the lateral component of
velocity is changed to be directed backward as the gas passes through
the fan blades 31.
A head portion of the fan blade 31 is substantially parallel to a
tail portion of the last rotor 22', and other portion of the fan blade 31 is
gradually curved backward. Thus, when flowing into the fan blades 31,
the gas passing through the last rotor 22' does not produce friction with
the fan blades 31. However, when this gas passes through a tail
portion of the fan blade 31, the tail portion of the fan blade 31 pushes
the gas backward since the fan blade 31 rotates in connection with the
rotary shaft 26 of the turbine 20 and the tail portion is curved toward
the rear of the engine. In other words, kinetic energy of the gas
passing through the last rotor 22' is collided with the tail of the fan
blades 31, and the fan blades 31 rotates with overcoming resistance of
such exhaust gas, so pushing the exhaust gas flowed between the fan
blades 31 to be directed backward at a higher speed. Thus, owing to a
repulsive force against the pushed exhaust, the fan blades 31
themselves may generate a great deal of forwarding propulsive force.
The fan 30 mounted at the rear of the low-pressure turbine 20
rotates the blades among the exhaust gas having a higher density than
the atmosphere, so it may gives stronger propulsive force. In addition,
since the blades 31 of the fan 30 changes a significant part of the
velocity component of the gas passing through the turbine 20 to be
straightly directed backward, the exhaust gas passing through the fan
30 may produce a forwarding propulsive force without dissipation of
power. Thus, the jet engine of this embodiment may generate a
forwarding propulsive force by means of the exhaust gas without loss.
In such an embodiment, it is also preferably to adjust an angle of
the rotors 22, particularly the last rotor 22' so that the advancing
direction of the exhaust gas passing through the rotors 22 of the
low-pressure turbine 20 may have an sufficient influence on the blades
32 of the fan 30. At this time, the angle of the rotor 22 is a factor
having a great influence on efficiency and energy loss of the turbine.
Theoretically, the angle of the rotor 22 is recommended to design so
that an advancing direction of the exhaust gas passing through the
rotor 22 may be within a range of 0° ~ 15° to an axial direction. In a
general case, the exhaust gas passing through the rotor 22 is
substantially discharged at approximately near 15° to the axial direction.
Thus, the angle of the fan 30 is also preferably set to be approximately
straight to the axial direction in consideration of the angle of the rotor
22.
This fan 30 is installed in the body 12, and preferably has a
diameter nearly identical to or a bit greater than a diameter of the last
rotor 22' of the turbine 20. A conventional large-scaled fan adopted in
the turbofan or the turboprop has many disadvantages since it
increases a front surface of the jet engine and therefore air friction
during flight and it burdens the engine with additional weight.
However, in the present embodiment manufactures, the fan 30 has so
small diameter to be installed in the body 12, thus the conventional
problems can be solved. In addition, since the jet engine of this
embodiment does its propulsive action through its exhaust gas, the jet
engine can be substituted with an inefficient rocket engine, which can
be used in a weightless state such as in space.
In the figure, reference numeral denotes a strut frame, and
reference numeral 46 denotes an exhaust nozzle.
As another embodiment, the present invention may employ other
manner instead of the above-mentioned fan as a propulsive force
providing means for obtaining an additional propulsive force. In this
embodiment, a tail portion of each rotor mounted in the turbine 20 is
deformed so that each rotor may obtain an additional propulsive force.
Arrangement of the rotor is substantially similar to that of FIG. 1,
except that the fan 30 of FIG. 1 is omitted and each rotor of the turbine
20 is deformed. The deformed rotors 122 of the turbine 20 are well
shown in FIG. 3. Referring to FIG. 3, shape and operating principle of
the rotors 122 according to this embodiment are described below.
First, the rotor 122 of the turbine according to this embodiment
has a head same as or similar to that of the former embodiment, but a
bent portion 123 is elongated backward at a tail of the rotor 122. In
other words, the rotor 122 of this embodiment has the head obliquely
inclined and is gradually bent toward an opposite side to form an arc,
and then is slightly bent backward at the bent portion 123 to form a
reverse arc.
With such configuration, the gas flowing into the rotor 122 is
collided with the head of the rotor 122 so that the rotor 122 is rotated,
and then the gas is directed to an opposite side. At this time, the gas
contains a significant lateral component of velocity. However, this gas
is collided with the bent portion 123 formed at the tail and then rather
slightly directed backward. During this process, the bent portion 123
formed at the tail of the rotor 122 may obtain an additional propulsive
force. The bent portion 123 of this embodiment obtains a small
propulsive force rather than the fan 30 of the former embodiment.
However, since the bent portions can be formed at each rotor formed in
multi stages of the turbine, the jet engine of this embodiment may
advantageously obtain subsequent propulsive forces at several stages.
The exhaust gas advancing in a changed direction is flowed into
the stator 124. At this time, the exhaust gas flowing into the stator
124 has a reduced incidence angle due to the bent portion 123. Thus,
energy loss caused by collision between the exhaust gas and the stator
124 can be significantly reduced. Such movements of the gas are
repeated during passing through each of the rotors 122 and the stators
124, and ejected outside through the last rotor 122'. In particular, the
last rotor 122' also has a bent portion 123' at its tail, so the exhaust gas
passing through the last rotor 122' is directed backward rather than the
conventional one. Thus, the last rotor 122' significantly decreases an
incident angle of the exhaust gas advancing to the strut frame mounted
at the rear, so it may reduce energy loss caused by collision between the
exhaust gas and the strut frame.
In this embodiment, it is also preferred to adjust an angle of the
rotor 122 so that an advancing direction of the exhaust gas passing
through the rotor 122 may have a sufficient effect on the bent portion
123 and 123'. At this time, the angle of the rotor 122 is a factor having
a great influence on efficiency and energy loss of the turbine.
Theoretically, the angle of the rotor 122 is recommended to be designed
so that an advancing direction of the exhaust gas passing through the
rotor 122 may be within a range of 0° ~ 15° to an axial direction. In a
general case, the exhaust gas passing through the rotor 122 is
substantially discharged at approximately near 15° to the axial direction.
Thus, the angle of the bent portions 123 and 123' is also preferably set
to be approximately straight to the axial direction in consideration of
the angle of the rotor 122.
The propulsive force providing means of the above embodiments
can be united. In other words, the fan 30 of the former embodiment
can be applied to a jet engine together with the bent portion 123 of the
later embodiment. In this case, the jet engine may obtain a
subsequent propulsive force by means of the deformed rotors and an
additional propulsive force by means of the fan at the same time, so the
effect of the present invention is maximized. In this case, the last rotor
may not have the bent portion in consideration of the fan.
The features of the present invention may be applied to other
types of jet engines besides the turbojet engine. As another preferred
example, a ramjet and a rocket are taken into consideration. Though it
is described below that the fan 30 is applied as the propulsive force
providing means, it should be understood that the principle of the
present invention can be similarly adopted in the case of the deformed
rotors and in the case that the fan and the deformed rotor are applied
together.
FIG. 4 shows that the principle of the present invention is applied
to the ramjet engine. Referring to FIG. 4, the ramjet 10' generally uses
no compressor since the ramjet 10' is generally used for a high-speed
flight and the air flowing through an inhaling hole is compressed by
itself. In that reason, a compressing chamber 50 for naturally
compressing the inflow air by using a forward movement of the body 12
is installed at a front of the body 12.
The compressed air flowed through the compressing chamber 50
helps combustion of fuel in the burner 14, so rotating the turbine 20
installed at its rear. At this time, since the rotary shaft 26 of the
turbine 20 is positioned at the center of the body 12, several burners 14
are dispersed near inner circumference of the body 12 around the
rotary shaft 26.
The rotary shaft 26 of the turbine 20 is also combined with the
fan 30 positioned at the rear of the turbine 20. Thus, when the
exhaust gas passing through the burner 14 rotates the turbine 20, the
fan 30 is also rotated together. In addition, since the fan 30 is
operated to push the gas discharged through the turbine 20 backward
as described in the former embodiment, the ramjet engine of this
embodiment also obtains a forwarding propulsive force by using the fan
30 in addition to the basic propulsive force. Furthermore, since the
exhaust gas is ejected approximately straightly backward due to
geometric figure of the fan 30, the exhaust gas can also be utilized as a
forwarding propulsive force without loss.
Generally, the jet engine is equipped with a cooling device in order
to prevent the turbine or other parts from being seriously heated. In
the present invention, it is also preferable to cool the fan 30 operating in
the high- temperature exhaust gas. The cooling device can be a
separate one additionally equipped in the jet engine or an existing
cooling device modified as necessary.
This cooling device preferably may use the compressed air
passing through the compressing chamber 50 though a separate
coolant can be used. In addition, though not shown in the figure, as a
cooling device, there can be installed a conduit directed connected from
the compressing chamber 50 toward the fan 30 in order to supply the
compressed air. At this time, the conduit may supply the compressed
air to not only the fan 30 but also the rotors 22 and the stators 24 of
the turbine for cooling. The conduit can be particularly designed to
cool even bearings mounted in the turbine.
FIG. 5 shows that the principle of the present invention is applied
to a rocket. Referring to FIG. 5, a front portion of the body 12 of the
rocket 10" is sealed. In the body 12, there are provided a fuel storage
area 60 and an oxygen storage area 62 respectively containing fuel and
oxygen to be supplied to the burner 14. The fuel storage area 60 and
the oxygen storage area 62 can have various sizes and shapes according
to usage and structural feature of the rocket, and not limited to any
special case.
The fuel and oxygen can be stored in a liquid state in the fuel
storage area 60 and the oxygen storage area 62, and flowed in the
burner 14 through independent conduits.
After flowed in the burner 14, oxygen and fuel are mixed and
burned, and they are exhausted to rotate the turbine 20 installed at the
rear of the burner 14. Since the turbine 20 is connected to the fan 30
mounted at the rear thereof through the same rotary shaft 26, the fan
30 rotates as the turbine 20 rotates. Thus, as described above, the fan
30 pushes the exhaust gas discharged from the turbine 20 backward,
so generating a forwarding propulsive force.
At this time, since the rotary shaft 26 is installed at the center of
the body 12, which is a gyration center of the turbine 20 and the fan 30,
the burner 14 is preferably dispersed around the rotary shaft 26, that is,
near the inner circumference of the body 12.
In addition, a cooling device can also be equipped to cool the fan
30. Though the rocket of this embodiment cannot use compressed air,
different to the former embodiments, the cooling device preferably uses
coolant for cooling the fan 30. The cooling device can also supply the
coolant to not only the fan 30 but also the rotors 22 and the stators 24
of the turbine, and the cooling device can be designed to cool even
bearings mounted in the turbine.
INDUSTRIAL APPLICABILITY
The jet engine using exhaust gas according to the present
invention configured as above has an advantage that it may minimize
loss while the fan rotates since the fan produces a forwarding
propulsive force within exhaust gas having high density rather than the
atmosphere air having low density.
In addition, the jet engine of the present invention uses a fan
having a diameter substantially similar to that of the last rotor of the
turbine, instead of a large fan which has been used in the conventional
turbofan or turboprop engines. So, the jet engine of the present
invention gives advantages that a weight of the fan is reduced and
resistance of the airplane caused by air friction can be dramatically
reduced since a front surface of the engine is decreased.
.Furthermore, the present invention may produce an additional
forwarding propulsive force by deforming tails of the rotors to be
directed backward as another embodiment.
Additionally, this principle can be applied to ramjet and rocket,
and they can also obtain a propulsive force by means of the fan rotating
among exhaust gas as well as a repulsive force generated by ejection of
the exhaust gas. This is helpful in increase of speed and fuel saving
since efficiency of the engine is improved.
The present invention has been described in detail. However, it
should be understood that the detailed description and specific
examples, while indicating preferred embodiments of the invention, are
given by way of illustration only, since various changes and
modifications within the spirit and scope of the invention will become
apparent to those skilled in the art from this detailed description.