Section
2
Invention No. 1:
A New Isentropic Air Motor and Clean
Energy Source
Abstract A new air motor is described which uses
isentropic linear acceleration to enormously increase the power of an air flow from
a vacuum pump source plus a new reaction
rotor to efficiently extract the power for useful work. The fuel used is ordinary air - no heat is supplied.
The exhaust is clean air. The invention
is described in excerpts from the Patent Application. The process can be made
to be quasi-self-sustaining if desired, that is to say, a species of ‘Perpetual
Motion’ can be achieved.
Contents
2.1
Extracting Flow Energy and Flow Power : Turbo-machines
2.2
Calculating the Power Curve of Air Flows and of Power Take-off Rotors
2.3 A
New Method and Apparatus for Greatly Increasing and Extracting Power from an
Air Flow
2.4 Invention No. 1: Excerpts
from a
Method
Apparatus
Perpetual Motion Operating Mode
Design Steps
Testing
Design
Safety Considerations
2.5
Conclusions
References
2.1 Extracting Flow Energy
and Flow Power : Turbo-machines
.
Turbines are used to extract energy from fluid flow. Those that involve rotors (and usually blades ) are often called turbo-machines. Examples are steam
turbines, gas turbines, jet engines and
so. Rotary lawn sprinklers are an example
of simple reaction turbines.
Windmill propellers are flow turbines which extract power from the
wind flow by slowing it down. This
extraction of flow kinetic energy by
inserting a windmill or ducted fan into a wind flow is governed by what is called the Betz Limit
which states that only 59.3% of the
total flow kinetic energy available in the air approaching the
propeller can be extracted. [ 1].
Here,
we describe a new invention which first, greatly increases the power of an air
flow, and then extracts a portion of the increased power without at the same
time reducing the flow power. It does so
by a reaction force method .
2.2 Calculating the Power
Curve of Air Flows and of Power Take-off
Rotors
In Section 1.4 above we
calculated the power of an air flow in
terms of the mass flow and the velocity squared ( P = ½ m-dot x V2 ). The power can also be calculated in other
equivalent ways.
For
example, we can take the product of the
pressure drop −Δp over
the flow path, multiplied by the volume flow rate VA, since energy per unit volume multiplied by
volume per second gives energy per second or power in watts. Thus, we have
P = Δp
x VA = ( force x velocity = energy per second = joules per second = watts ).
Vin
This relation between air
flow VA ( m3 /s) and pressure drop ( Pascals, Pa) is shown in Figure 1.
Figure 1. Power output in air watts for
a vacuum source drawing in a linear flow
of air, expressed in terms of pressure drop and flow rate.
Here
we note that the maximum power available in any flow system comes at neither
the maximum flow rate nor at the maximum
pressure drop point, but rather at some
intermediate values which give the
maximum product of the two flow
variables.
In
the case of rotating turbo-machinery, the power can be calculated as the
product of the torque To and the rotation rate ω. This yields
the power formula:
P = Torque x Rate of rotation = To ω (
watts)
This
is plotted in Fig. 2 and is seen to be
similar in form to that calculated from air flow and pressure drop (Fig.
1).
Fig. 4.
Power Curve of a Rotor in terms
of Torque and Rate of Rotation
We
may note here that at maximum torque the rotation rate is zero and so the power
output is zero. At maximum rotation the
torque becomes zero and again there is no power. It is at the intermediate rotation and torque
that the maximum in rotational power output is reached.
[We
also note that the maximum power transferred to the rotor by the flow thrust is
only one half the nozzle thrust power. This is because as the rotor speeds up,
its thrust speed measured relative to the rotor itself decreases. Consequently, only one half of
the nozzle power can be extracted by the
rotor power take-off means. However, because the power amplification by the
acceleration of the flow in the nozzle throat
is so great, the net power produced
by the invention is still very much larger than any prior art. ]
Now
that we have outlined the principles of flow acceleration, power increase and
power curve calculation, we turn to a new
practical method and apparatus for implementing these principles to
produce clean, renewable, economical energy
2.3 A New Method and
Apparatus for Greatly Increasing and Extracting Power from an Air Flow
In the course of experimental investigation into methods of
accelerating air flow to achieve increased power, a new method of extracting
the increased power was also discovered
(Fig. 3) and is now described.
First a basic mass flow rate of air is set up,
say by a vacuum pump source. Then, the new method involves inducing the desired
acceleration of the air flow by passing the air flow through a set of concentric, converging nozzles in a cylindrical rotor; the flow is accelerated through the nozzles to increase the flow
power, and at the same time the nozzle thrust imparts reaction rotation to the
rotor so that power can efficiently be taken off to do useful work.
Fig. 3. Flow-Accelerator/ Power Take-off Rotor
Means
The thrust from the accelerated flow through the nozzles
induces a rotation of the rotor in the reverse or reaction sense to the thrust
direction. The invention both greatly increases the power of a basic mass flow
air through the rotor while at the same
time inducing rotation energy to the
rotor for easy and efficient take- off
of power for doing useful work. This
new method and apparatus are described
in detail in a recent patent application
from which the following excerpts are taken.
2.4 Invention No. 1: “ A Method for efficiently generating and extracting power from an air flowfor useful work “ . Inventor: Bernard A. Power. Opened-to public inspection by Canadian Intellectual Property Office on 2011/06/07 at :
(www.cipo.gc.ca)
Method
(
1).
A method
of efficiently generating and extracting power from a flow of air for useful
work comprising the steps of::
: (a) inducing a chosen mass flow of air or other compressible fluid, preferably ambient atmospheric air by a vacuum pump;
b) conducting said chosen mass flow of air into and through a set of two or more conical internally converging nozzles formed within a cylindrical rotor disc, said rotor rotating freely on a central shaft or axle, said rotor having its rotation axis aligned at right angles to the longitudinal axes of said conical nozzles; said chosen mass flow of air thus becoming partitioned into a set ot equal portions of said mass flow of air among said set of conical converging nozzles;
(c) arranging said conical nozzles circumferentially and symmetrically in said rotor, with their flow entrance ports situated on the outside rim of said rotor, said nozzles leading through said rotor into an inner central circular air chamber of designed radius inside said rotor, each of said nozzles having its longitudinal axis aligned at right angles to the rotation axis of said rotor, each of said nozzles being also aligned so as to be essentially tangent at its exit port to said inner air chamber at said designed radius so that the air flow through each said converging nozzle exits tangentially into said inner chamber at said designed radius from said inner air chamber’s longitudinal axis;
(d) constructing each said converging nozzle to have a minimum throat cross- sectional area so as to pass through each said throat an equal portion of the total said chosen mass flow of air at near sonic speed; said chosen mass air flow thus undergoing a quasi-isentropic acceleration to near sonic speed through said converging nozzles, and with the total of all of the partial flow of air through all said nozzles taken together being equal to the total of said chosen mass flow of air;
(e) accelerating said chosen mass flow of air through said converging nozzles and thus exerting a reverse thrust on said rotor as said sonic flow passes out from said nozzles and into the said inner air chamber, said thrust direction being offset from the centre of rotation at said designed radius from the central rotation axis of said rotor and thus also exerting a torque on said rotor; said torque causing said rotor to rotate in the opposite direction to the direction of the nozzle exit flow into said inner air chamber, said rotor thereby acquiring by reaction force a rotational energy from the thrust force of the nozzles’ accelerated air flow;
(f) said inner air chamber having a downstream exit port of cross- sectional area equal to the combined throat area of the said nozzles taken together, said mass air flow then exiting from said inner chamber through said downstream exit port into a flow diffuser or diverging duct; said flow diffuser decelerating said air flow and leading it towards a flow exit port and back into the ambient atmosphere.
Apparatus
(2) An air motor apparatus, consisting of a substantially cylindrical rotor, said rotor being mounted on a central shaft or axis, said rotor having two or more converging nozzles molded, cast, machined or otherwise formed into said rotor and situated symmetrically in said rotor so as to conduct a chosen mass air flow drawn in by a vacuum pump source through said converging nozzles from said nozzles entrance openings on the said rotor‘s circumference or rim, said nozzles having their smaller inner exit opening in an inner circular air chamber within said rotor, said nozzle exit openings in said inner circular air chamber being situated at a designed radial distance from the axial centre of said inner air chamber, said accelerated chosen mass flow of air thereby exerting a thrust when said air flow leaves said nozzle’s exit ports and enters said rotor’s inner air chamber; said thrust then in turn exerting a torque on said rotor so as to rotate said rotor in the opposite sense to the direction of the exiting flow thrust, said flow then passing through said inner air chamber and exiting through a chamber exit port of approximately the same area as the sum total area of the nozzles exit port areas; said inner chamber’s exit port leading said air flow into a flow diffuser connected to a vacuum pump that provides and sustains said chosen mass air flow through said air motor; said rotor thereby acquiring power from the reaction force accompanying said accelerating air flow produced by said converging air flow nozzles; said rotor power at its maximum being one half of the air power of the flow when accelerated through the nozzles to sonic speed; said power in said rotating rotor being then exportable to the exterior as shaft power by coupling to any rotary power transfer means such as belt, gear, hydraulic, magnetic or other means. .
Figure 1
0007 Figure 1 shows
an air flow source 1, such as a
vacuum pump, drawing a mass flow of air in through a cylindrical rotor 2 via a set of air nozzles 3
which accelerate the mass flow through them to near sonic speed without
any heat being added or extracted, that
is to say the change is isentropic. The accelerated air flow exerts a thrust
and torque on the rotor and causes it to rotate. The mass flow then is
decelerated efficiently through a flow diffuser 8 to the vacuum pump source
and exhausted to the atmosphere out
through the pump exit. The acceleration of the air flow adds
great air power to the flow; the
resulting thrust and torque is transmitted reactively to the rotor for exaction via a power take-off
means.
(Figures 2 to 4 not reproduced here) show details of a inner air chamber 5 in the rotor into which the nozzles pass the accelerated air flow and in which the thrust and torque are produced; Figure 3 shows the chamber exit plug 6 which forms one side of the said inner air chamber, The exit plug 6 and diffuser tube 8 efficiently slow down the accelerated air flow coming from the nozzles and inner air chamber with minimum loss and delivers it to the vacuum source for exhaustion back to the ambient atmosphere.
0009 In one preferred embodiment of my invention, shown in Figures 1 to 4. I first produce (see Figure 1) from a vacuum source 1 a flow of air having a fixed mass flow rate m-dot = ρVA. I then accelerate said mass flow by passing it through a set of two or more converging nozzles 3 in a substantially cylindrical rotor 2 , said rotor being mounted on an axle or shaft 10, said nozzles being molded , cast , machined or otherwise formed into the material of which the said rotor is made and being situated circumferentially and symmetrically in said rotor so as to conduct an air flow in through said rotor entrance openings 3 on the said rotor ‘s circumference or rim, said nozzles having their smaller inner exits 4 ( see Figure 2) opening into an inner annular air chamber 5 within said rotor; said nozzles 3 being positioned circumferentially and symmetrically so that their exit openings 4 into said inner circular air chamber 5 are situated at a designed radial distance from the axial centre of said inner air chamber 5, said converging nozzles 3 accelerating said air flow through them and said acceleration thereby exerting a thrust when said accelerated air flow leaves said nozzles’ exit ports 4 and enters said inner rotor chamber 5 at the said designed radial distance from the centre of said inner air chamber; said thrust then in turn exerting a torque on said rotor so as to rotate said rotor in the opposite sense to the direction of the exiting flow thrust, said exiting or thrust flow then passing through said inner air chamber 5;, said air chamber having an tapered exit plug 6 (see Figure 3), said tapered exit plug being of such a diameter as to fit inside said inner air chamber 5 leaving a resulting annular clearance space between said exit plug 6 and said inner air chamber 5 through which the nozzle exit flow can exit at approximately the same total cross- sectional flow area as the sum total of the nozzle exit areas, so as to maintain the near sonic flow velocity that supplies the thrust; said tapered exit plug 6 moreover having a shaped groove 7 in its larger end (see Figure 3 ) into which the nozzle thrust flow discharges before then exiting through the said annular clearance space; said exit plug 6 in turn fitting inside a flow diffuser tube 8 with the resulting clearance space between said exit plug 6 and said diffuser tube 8 (see Figure 4) forming thereby a diverging flow duct for the air flow from the inner air chamber 5, said resulting annular flow duct initially having approximately the same cross sectional area as the sum total of the exit areas of the rotor nozzle exits combined so as not to slow down such air flow suddenly and inefficiently, said duct area formed annularly between said tapered exit plug and said diffuser tube then gradually increasing in area along said tapered plug 6 of diminishing cross sectional area inside said diffuser tube 8 so as to gradually and smoothly increase the effective annular flow duct’s cross-sectional area thus allowing the said diverging air flow to slow down efficiently and match the design intake flow velocity of the vacuum pump 1; said diffuser being connected to the intake port of said vacuum pump 1, which sustains the said mass air flow through said air motor system and delivers the final exhaust flow to the apparatus air flow exit port 9, said tapered exit plug 6 being positioned so as to fit at its larger end centrally into said inner air chamber 5 and at its tapered portion to be centrally positioned inside said diffuser tube 8 by being securely attached to said diffuser tube 8 by two or more smoothly shaped mounting and centering pins 11 or similar mounting brackets.
My invention thus passes the flow through the nozzles, causing an isentropic acceleration of the flow in the nozzles up to sonic or near sonic speed at the nozzle throat or exit so as to generate the desired maximum thrust at the exit from the nozzles and exert a desired torque on the rotor causing it to rotate and take up the power being generated by the torque. The rotor turns in the direction opposite to that of the thrust flow as required by the law of conservation of momentum or Newton’s Law of Action and Reaction.
Thus, the torque generated by the reaction force opposite to the flow thrust through the nozzles transfers power to the rotor without in any way impeding the mass flow itself, which simply passes out through the nozzle exits 4, into the air chamber exit channel 7 , then into the diffuser 8 and on to the vacuum system flow exit 9. In this manner, rotational energy is transferred by the thrust/ torque reaction force to the rotor 2 automatically, and so it becomes readily available as shaft turning power to be extracted economically and efficiently from the said rotor by any suitable coupling or rotary power transfer means ( not diagrammed) to do useful work, for example by a belt or chain power takeoff, a cog or gear take off, a hydraulic take off or other suitable power take-of means.
The present invention is thus a novel isentropic method of efficiently accelerating a linear air flow through a converging nozzle or nozzles situated in or on a freely turning rotor, while simultaneously and efficiently transforming said flow’s increased linear kinetic energy into flow thrust and torque and into rotational energy of the rotor which then becomes readily available to produce work. It is indeed startling in its economy, its simplicity and its improvement on any existing energy source or method for the generation and supply of clean, economical energy.
The “fuel” or energy source for the present invention is typically air, and so, for continuous operation of the method, a continuous flow of air is required. In the embodiment just described the source of the said mass flow of air is a vacuum pump. In another embodiment the air flow source is a compressor or compressed air supply reservoir. In yet another embodiment the air flow is the relative air flow moving past the air motor when it is mounted on a moving vehicular platform such as on an automobile, a truck, train, ship, airplane, rocket or the like. In another embodiment the air flow is supplied by the wind with suitable ducting to conduct the air to the cylindrical rotor of the invention. The source of the air flow may also be a convective up-current of warmer or less dense air, a hot gas rising through a chimney, or a natural convective up-current in the atmosphere, and so on.
It is pointed out that, while the present disclosure and application deals specifically with air, the invention disclosed applies equally to any compressible fluid.
In any actual device there will frequently be some inefficiency so that the flow may be actually quasi- isentropic, but the disclosed invention covers these situations as well as isentropic devices and means.
Perpetual Motion Operating Mode
As to efficiency, for example, a certain vacuum device which produces a mass flow rate of 0.074 kg/s can only produce a maximum suction power of about 625 watts, but requires an input power of 1690 watts, so that the device is only about 37% efficient with respect to the transformation of internal air energy into linear flow energy. In the present invention, however, the same mass rate of air flow of 0.074 kg/s at 100% efficiency results in an air flow power output of 3625 watts and a rotor take-off useable power output of 1812 watts for the same power input of 1690 watts. The present invention thus appears to be uniquely “self sustaining” in that it apparently can, if desired, be configured, by feeding back sufficient generated rotary power to the vacuum pump, to provide a unique Perpetual Motion ( Perpetuum Mobile) achievement. It is repeated, however, that it is not a heat engine system and so such self-sustaining operation does not involve violation of the second law of thermodynamics [1,2,3].
It is also pointed out that if there are substantial flow losses , that is if the efficiency is less than 100%, the method may not then be self sustaining , but it will still be very much more efficient than prior art flow devices.. For example, at 76% efficiency a flow of 0.074 kg/s becomes 0.056 kg/s which will produce 2743 watts or air flow power and 1371 watts of useable take off rotor power. for the same input power of 1690 watts. While this would not be self sustaining, it will still be several hundred per cent more efficient than existing prior art flow devices.
In the self sustaining mode of operation, once the base mass flow is initiated, the atmospheric air is the only ‘fuel’ or energy input needed, while the exhaust is the same air that entered the nozzles from the atmosphere substantially unaltered. .
Design Steps
To illustrate the elements of the method as clearly as possible, we may consider the following design steps:
(1) The mass flow rate selected or available m -dot = ρVA, from the vacuum or pressure source, will determine a maximum design air power output, Pair to be obtained at the sonic velocity flow limit, under the condition of no flow velocity losses, ( that is, under 100 % efficiency of flow), which is given by
Pair = ½ m-dot Vsonic2 = ½ m-dot x (313)2 watts
For example, under this condition of 100 % assumed flow efficiency ( no flow velocity losses), a chosen flow of 0.74 kg/s, for example, will produce a maximum air power at the sonic limit of Pair = ½ x 0.074 x (313)2 = 3625 watts.
(2) The design throat area A* of the nozzle, needed to accelerate a selected design mass flow rate m-dot to the sonic flow speed ( 313 m/s), is given by
A* = m-dot /ρ*V*.
(2a) For example, for a mass flow rate of m-dot = 0.074 kg/s, and no flow losses, the nozzle throat area A* must be 0.074/ 1.2 x 063394 x 313 = 3.11 x 10-4 m2 to pass the mass flow at sonic speed of 313 m/s through the throat area A* to produce the designed air power of 3625 watts.
(2b) If there are flow losses (which is the usual case) then they must be calculated or estimated. For example if the flow velocity losses are estimated to be, say, 24%, then the design mass flow rate in the case above will be m-dot = [0.074 – 0.24 x 0.074] = .056 kg/s. In this reduced mass flow case the throat area A* must be designed to be 2.35 x 10-4 m2 . At this area the maximum designed air power will be 2743 watts.
(3) The Thrust Fthr. produced in the rotor at the nozzle exit by the throat flow of 313 m/s speed will be
Fthr. = m-dot x Vexit = m-dot x 313
For example, a flow of 0.074 kg/s will produce a sonic nozzle thrust of Fthr. = 0.074 x 313 = 23.16 Newtons, whereas a flow rate of 0.056 kg/s will produce a thrust of 17.53 Newtons.
(4) The Torque To that will be produced in the rotor by the thrust Fthrust of a nozzle flow exiting at a radial offset distance of r meters from the centre of the rotor , will then be
To = Fthrust x r (Newton .meters)
For example, a thrust of 17.53 Newtons, exiting tangentially from the rotor nozzles at a nozzle exit radius of 0.04 meters from the rotor centre, will produce a torque of To = 17.53 x .04 = 0.72 N. m.
(5) This torque To will then produce a rotor power Protor given by Protor = To x ω where ω is the rotation speed in radians per second. ( ω in radians/sec = (ω/2π) x 60 in rpm).
For example, at a rotation speed of ω = 1000 radians per second (9549 rpm) and a torque of 0.72Newtons we will have Protor = 0.72 x 1000 = 720 watts. The rotor power will go up as the rotation rate ω is increased to some maximum value and then diminish to zero, To determine this maximum rotor power we need to take into account the fact that there is a reduction in thrust and torque that occurs as the rotor speeds up. In the case of air power Pair we need only use the gas exit velocity from the nozzle relative to the nozzle. However, in the case of the rotor power, the appropriate velocity is the net velocity difference between the gas exit velocity from the nozzles and the rotor turning speed. This is because as the rotor speeds up it gradually overtakes the exiting gas flow and at some ultimate rotation speed it reduces the power to zero since there is then no net thrust. The rotor power formulae are as follows:
Protor = To x ω = (Torque) x (rotation)
Protor = (Vnet x m-dot x r) x ω
Protor = [Vexit -Vrotor ] x m-dot x r x ω
Furthermore, since {Vexit - Vrotor] = Vnet = r ω , then when Vrotor = Vexit /2 = 313/2 = r ω , we have the important result
Protor = [Vexit/2 x Vexit /2 ] m-dot = 1/4 m-dot Vexit 2 = 1/2 Pair
that is to say, at a rotor speed of one-half the sonic speed [ 313/2 = 156.5. m/s ], the rotor power is one-half the maximum or sonic air power.
This can clearly be seen if we look at the rotor power curve data in Table 1.for one particular design example:
Design Specifications
Mass flow m-dot = 0.074 kg/s
Input vacuum power needed to supply 0.074 kg/s flow = 1690 watts
Nozzle exit radial offset distance r = 0.04 m
Nozzle exit flow speed = Vexit = sonic = 313 m/s
Rotor speed at radius r = Vrotor = r ω
Rotor rotation ω = Vrotor /r
Maximum air power at sonic throat flow : P air.max = ½ 0.074 Vexit2 = ½ x0.074 x 3132 = 3624 watts
Table 1
Rotor Power
Data
Vexit Vrotor [Vexit – Vrotor] ω
Torque To Protor
= [Vexit – Vrotor] x 0.074x r x ω
m/s m/s m/s rad/s N.m watts
313 0 0 0 0.074 0
313 100 213 2500 0 .63 1576
313 120 193 3000 0.57 1714
313 150 163 3750 0.48 1809
313 156.5 156.5 3912.5 0.463 1812.4 watts (peak rotor power point)
313 170 143 4250 0.42 1798
313 313 0 7825 0 0
Notes: (a) At maximum rotor velocity ( 313 m/s and ω = 7825 radians/s) the rotor power is zero because the net flow absolute velocity measured relative to the test bed , developed thrust and torque have all fallen to zero. (b) The maximum power ( 1812.4 watts) occurs at some lower rotor speed; that is to say at Vrotor = 156.5 m/s and ω = 3912.5 rad./s. i.e. at a rotor velocity half the nozzle exit velocity of 313 m/s.. The maximum rotor power 1812.4 watts is thus seen to be one-half the rated sonic air power ( i.e. one half of 3624 watts air power). (c) In the case of the vacuum source specification of the cited test, the maximum rotor power ( assuming 100% efficiency) also exceeds the vacuum source input power of 1690 watts by 122.4 watts – clearly a Perpetual Motion possibility. However, since the invention is an isentropic system and does not involve heat injection or rejection, it accomplishes this without at the same time infringing the second law of thermodynamics [5]. (d) In the laboratory test case cited here, the level of net power output is small ( 122.4 watts) but the invention can be readily scaled –up by those skilled in the art to the level of much higher net power output. (e)Even when operated at less than maximum rotor power, the present invention can produce power at far higher efficiency than any previous air motor system. If practiced on a moving platform or in the atmospheric wind flow to provide the basic air flow, the economics obviously become even more attractive since there is much lower cost in providing the base flow of air than with a vacuum pump or compressor motor.
(6) The rotor power can also be expressed in terms of the moment of inertia I of the rotor and the angular acceleration of the rotor ∂ω/∂t . First we have
Protor = To x ω
and since To = I x ∂ω/dt, then also
Protor = = I x ∂ω/dt x ω
(7) The design Moment of Inertia I is calculable from the mass of the rotor, plus its shape and dimensions from standard formulae of rotational mechanics [1,2,3,6]. With the moment of inertia, we can then go on to calculate the design angular acceleration ∂ω/∂t from the torque To and the moment of inertia I as follows
I x ∂ω/∂t = To , so
∂ω/∂t = To/I
(8) Testing: Finally, once the design values are calculated, and the rotor assembled, the system can be operationally tested. First, the mass flow can be measured at the exit port and compared with the design value. Second, the power produced can be verified by measuring the angular acceleration ∂ω/∂t at various values of rotation ω, and comparing the observed results with the design values through the equation Protor = = I x ∂ω/dt x ω. Similarly the maximum rotor power produced can be observed by running the rotor at its peak power rotation speed. (In this final test the safety concerns for high rotation speeds must be kept in mind).
If the measured mass flow in the test matches the design mass flow, then clearly any losses are not greater than the design value chosen and the design will then produce the expected sonic throat flow speed and the design air power to be delivered to the rotor. If, on the other hand, the measured mass flow in the test is less than the design mass flow, the power will decline markedly. This is so because the air power equation is P = ½ m-dot x V2 , so that the deficiency in mass flow lowers the power linearly, but the accompanying lower flow velocity at the throat also comes into the power equation as an additional quadratic loss. We can then either attempt to reduce the large losses and so raise the mass flow to its design value, or we can redesign the rotor nozzles to accommodate the reduced flow at sonic speed and accept a lower power output.
The basic mass flow, m-dot = ρVA , which sets the scale of the whole design and the power output, can be furnished by either an air flow “push” or by a “pull”, that is to say, either by a compressive air flow source or by a vacuum air flow source. It can also be set up by a natural “push” flow source such as the wind. Each case will require a different configuration of the elements of the invention such as the rotor orientation, but the claimed method will be the same in all. In the vacuum or “pull’ case, the rotor will typically be orientated with its axis of rotation parallel to the general air flow through the vacuum source, that is to say the rotor itself will rotate in a plane of rotation at right angles to this said general flow. In the compressive air flow source case, the rotor axis of rotation may conveniently be at right angles to the general flow from the pressurized flow source, but various other orientation options are also possible. If the source of the mass flow of air is either the wind or the relative air flow past a moving vehicle, then the general category will be the compressive or “ push” type source flow.
When the rotor, rotating with rotational kinetic energy (Iω2) of the accelerated flow is then coupled to a power transfer system it completely eliminates the need for inserting any supplementary turbine means, propeller means, or the like, to extract the flow power to do useful work. The rotor means is directly able to produce the desired rotational power and to couple it to any exterior motor, generator, or other mechanical machine desired to accomplish useful work. The method of the present invention is thus one of truly remarkable simplicity, efficiency and economy.
If the rotor nozzles are to produce the designed maximum thrust and torque, their exit flow velocity immediately downstream from their exit throat must be as near as possible to the desired sonic speed of 313 m/s. and the flow direction must also be a linear as possible. This requires that any inefficient premature deceleration and back pressure rise must be avoided as the air from the rotor passes through a diverging cone or diffuser cone linking the properly decelerating flow from the rotor to the vacuum suction source which sustains the basic mass flow rate.
(f) Design
Safety Considerations. With sonic nozzle flow speeds, the
rotor typically revolves at very high speeds ( e.g. 20,000 to 40,000 rpm or higher) It therefore develops
extremely high centrifugal stresses at its rim which can cause bursting and
disintegration of the entire rotor if critical rotation speeds are reached or
exceeded.
One working formula for this bursting limit in a solid rotor is [6]
Vburst = [ 10 x s ]1/2
This formula gives the rim speed burst limit in feet per second for
a material having tensile strength s
(in lbs. per square inch). For example, any solid cylindrical rotor made of
aluminum with a tensile strength of 36000 lbs./in2 of any radius will have the same
limiting rim speed from the formula of
600 ft per second. Perforated rotors with the nozzles cast or machined into
them would have a lower burst speed and therefore a lower safe operating speed.
Such safety
concerns require state of the art knowledge and input from mechanical safety
experts.
Figure 4. Example of shrapnel from catastrophic
rupture of rotor ( acrylic) run at
greater than maximum design speed ( 14,500 rpm; 1518 rad/sec) This design
flaw caused serious injury to operator.
At sonic speed the flow
can also produce a high pitched piercing noise that may require use of
ear protectors to avoid hearing damage.
2.5 Conclusion
In
Sections I and II we have disclosed flow amplification, flow energy increase
and a new power take-off means. The new air motor that has been described uses
a vacuum or compressor source for the basic mass flow of air needed to start the
process.
It is also possible, however, to use the
wind or the relative air flow past a moving vehicle to provide the basic mass air flow, and this will now be discussed in Section III, where a new invention for producing large
amounts of clean, economical energy from the wind and moving vehicles by
using conical ducts is disclosed in detail.
References
1. Standard
Handbook for Mechanical Engineers. T. Baumeister,
Ed. Seventh edition , McGraw-Hill
Book Company, New York,1958.
2. Shapiro, A. H., The Dynamics and Thermodyn2amics
of Compressible Fluid Flow. 2 vols. Wiley and Sons, New York, 1953.
3. Munson, Bruce, R., Donald F. Young, and
Theodore H. Okiishi, Fundamentals of
Fluid Mechanics, Wiley and Sons, New
York, 1990.
4. Power, Bernard A., Tornado-
genesis by an Isentropic Energy Transformation. Posted
5.
“Perpetual Motion”. Encyl. Britannica. Vol. 17, p.528, 1959.
6. Machinery’s
Handbook. 27th Edition.. Industrial Press Inc,. New York, 2004.
Figure 5. Acrylic Experimental Rotor with
4 Symmetrical Inlet Nozzles.
Figure 6.
Aluminum Experimental Rotor With 4 Symmetrical Nozzles
Fig. 7. Isentropic Air Motor Showing
( left to right) the Rotor,
Vacuum Line Coupler and Vacuum Pump Mass
Flow Source
Copyright: Bernard A. Power
2011
Section Links:
Section 1: Linear ( streamline) Flow and Flow Power
Amplification
Section 3: To be posted in near future
Section 5: A Note on Isentropic Flow ‘Potential Motion’