WO2014042671A1

WO2014042671A1 - Gas stream generating system

Info

Publication number: WO2014042671A1
Application number: PCT/US2013/000212
Authority: WO
Inventors: Jayden David Harman; Thomas Gielda
Original assignee: Pax Mixer, Inc.
Priority date: 2012-09-14
Filing date: 2013-09-16
Publication date: 2014-03-20

Abstract

An artificially created atmospheric circulation system comprising at least one pulse detonation engine (211) adapted to generate a rapid series of gas pulses directed into the atmosphere, each gas pulse adapted to entrain surrounding atmosphere after exiting the pulse detonation engine to provide an entrained gas pulse adapted to travel in the atmosphere.

Description

Gas Stream Generating System Field of the Invention

The present invention relates to the circulation of atmospheric gas. More particularly, this invention seeks to provide an artificially generated system of circulation within the atmosphere.

Background Art

Thermal stratification in the lower atmosphere is a naturally occurring phenomenon resulting from a specific combination of land/water geography, general climate, recent weather conditions, and wind presence and direction. The resulting inversion layers can pose several problems, the most detrimental of which is poor air quality trapped in the lowermost strata where humans reside.

Currently available techniques for air quality improvement are limited. Filtration systems are effective for buildings and smaller contained areas, though they use a significant amount of power. City-wide air quality improvement can be impacted by reducing pollution, but currently this is not sufficient in certain areas of the world.

Certain geographical scenarios make inversion layer forming more common. Many low-lying cities are mainly or completely surrounded by mountains, which protect formed inversion layers from being broken up naturally by wind. Cities exhibiting this phenomenon include Los Angeles, California, USA; Tehran, Iran; and Beijing, China.

In preparation for the 2008 Olympics, there was a comprehensive study completed on the Beijing-area inversion layers in relation to air quality. Researchers found a semi-contained "air dome" around the urban center of Beijing. This "dome" was characterized by multiple inversion layers, each of which had very different wind speed and pollution levels, in addition to the differences in temperature (Reference: Zu, Xiangde. The Beijing City Air Pollution Observation Experiment (BECAPEX) and Some Preliminary Results.)

In these large cities, the pollution is generated at or near the Earth's surface and can get trapped inside the lowest inversion layer, effectively "capped" by the higher temperature layer above it. And because there is very little mixing between layers, the pollution is unable to escape into the higher atmosphere and disperse. The poor-quality air is trapped near the Earth's surface, where the city's inhabitants must breathe it. Breathing in polluted air has been shown to contribute to several health- related problems including lung cancer and asthma. The Great Smog of 1952, during which a very severe and persistent inversion layer developed over London, was blamed for 1 1 ,000 to 12,000 deaths. (Bell and Davis, "Reassessment of the Lethal London Fog of 1952", Environmental Health Perspectives, 2001) Attempts by cities to reduce pollution production can improve the air quality, but a short-term solution is needed to break up inversion layers and improve air quality until large- scale pollution reduction is achieved.

Few industrial methods have been devised to cause the desired atmospheric circulation. In nature, however, we see many examples such as tornados, hurricanes, waterspouts, dust devils and the like. All of these cyclic motions act as atmospheric circulators.

The most significant prior art is that of Louis Marc MICHAUD. His disclosure in US 7,086,823 provides a detailed review of the prior art including certain publications made by him explaining the thermodynamics that are involved. A further disclosure by him in WO 2008/0 4596 describes certain improvements to his invention. These disclosures are hereby incorporated by reference.

One difficulty with Michaud's proposal is that his facility is extremely large and expensive. While the facility promises several advantages, including more efficient cooling towers, low cost operation of wind turbines, as well as possible atmospheric circulation advantages, it is not entirely clear what is the primary purpose, or whether the system would perform any of the tasks effectively. The large area of land that would be required to put the system in to effect would make it impractical near cities where the atmospheric circulation may be of the greatest importance.

Other prior art of some significance are US 3,589,603 (Fohl), US 3,940,060 (Viets) and US 2005/0039626 (Yi). Fohl discloses a means of transporting polluted gas high into the atmosphere. It comprises a device which produces a toroidal vortex or vortex ring which envelopes a volume of polluted gas and carries it into the upper atmosphere. It can be seen to be an alternative to a conventional tall chimney. It is not capable of raising a large volume of atmospheric gas to the upper atmosphere to alleviate general pollution in the atmosphere at ground level.

The disclosure of Viets is directed primarily at a means of providing a tunnel through a fog mass around an airport so that a beacon light can shine through it. It does so by generating vortex rings.

The disclosure of Yi is directed to a system for preventing damage from tornados and other harmful naturally occurring weather phenomenon uses multiple jet devices which are distributed in a ground array to produce man made tornados.

A recent application WO2013/070254 by the first of the present inventors is also of importance. This application discloses an artificially created atmospheric circulation system comprising a plurality of vortex generating units, wherein each vortex generating unit is configured to generate an upwardly directed vortex within the atmosphere and wherein the plurality of vortex generating units are configured and associated so that all of the vortices produced combine to provide a single atmospheric vortex. This application is also incorporated by reference. The present disclosure provides a means and method of pumping substantial volumes of polluted atmosphere from ground level to a height above the thermal stratification layers. This allows the polluted air to be dispersed using natural wind currents in the upper atmosphere. This natural dispersion process occurs in locations which do not exhibit lower atmosphere thermal stratification. The operational costs and capital costs compare very favorably with alternative proposals.

Disclosure of the Invention

According to a first aspect, the invention resides in a gas stream generating system comprising a stationary pulse detonation engine adapted to generate a gas stream of high velocity and high volume into the atmosphere to thereby transfer a substantial quantity of atmosphere from a low level to significantly higher elevation.

According to a preferred feature of the invention the pulse detonation engine is adapted to transfer the substantial quantity of atmosphere from a low level to above a thermal stratification layer within the atmosphere.

According to a preferred feature of the invention the pulse detonation engine is directed to expelling its exhaust as a succession of vortex rings.

According to a preferred embodiment, the exit of the pulse detonation engine is configured to facilitate the gas pulses to form vortex rings upon being ejected from the exit.

According to a preferred feature of the invention the gas stream comprises a continuous series of vortex rings.

According to a preferred embodiment, the pulse detonation engine is configured to generate approximately 20 pulses per second. According to a preferred feature of the invention the vortex rings entrain substantial volumes of surrounding air as the pulse detonation engine exhaust is expelled and the vortex ring created.

According to a preferred feature of the invention the vortex rings also entrain surrounding air as the vortex ring rises through the lower atmosphere.

According to a preferred feature of the invention a plurality of entrained gas pulses merge to form an enlarged gas pulse having sufficient energy and momentum to be projected through the thermal stratification layer.

According to a preferred feature of the invention a plurality of pulse detonation are arranged so that the gas streams from each engine combine into a single stream.

According to a preferred feature of the invention the gas stream transfers sufficient lower atmospheric gas to a level above the thermal stratification layers to be effective at reducing pollution levels in the vicinity of the pulse detonation engine.

According to a preferred feature of the invention operational costs do not exceed a reasonable level justifiable by the benefit obtained in reducing pollution.

According to a second aspect, the invention resides in an artificially created atmospheric circulation system comprising at least one pulse detonation engine adapted to generate a rapid series of gas pulses directed into the atmosphere, each gas pulse adapted to entrain surrounding atmosphere after exiting the pulse detonation engine to provide an entrained gas pulse adapted to travel in the atmosphere.

According to a preferred feature of the invention, a plurality of entrained gas pulses merge to form an enlarged gas pulse having sufficient energy and momentum to be projected through an inversion layer existing in the atmosphere at the time of use. According to a preferred embodiment, an outlet of the pulse detonation engine is directed to expelling its exhaust as a succession of vortex rings.

According to a preferred embodiment the pulse detonation engine is configured to generate approximately 20 pulses per second.

According to a preferred embodiment the size and rate of operation of the pulse detonation engine are determined to cause the transfer of one cubic kilometre of lower level atmosphere above an inversion layer in approximately one day.

According to a third aspect, the invention resides in a method of transferring polluted ground level atmosphere above an atmospheric inversion layer by use of gas stream generating system as described herein.

According to a fourth aspect, the invention resides in a method of transferring polluted ground level atmosphere above an atmospheric inversion layer by use of an atmospheric circulation system as described herein.

According to a fifth aspect, the invention resides in a method of causing the abatement of tornados or storms by the use of an atmospheric circulation system as described herein. The invention will be more fully understood in the light of the following description of several specific embodiments.

Brief Description of the Drawings

The description is made with reference to the accompanying drawings, of which: Figure 1 is a diagrammatic representation of normal stratification of air within the atmosphere;

Figure 2 is a diagrammatic representation of thermal inversion stratification in the atmosphere; Figure 3 is a diagrammatic representation a vortex ring;

Figure 4 is a diagrammatic representation of a cyclonic heat engine in the atmosphere;

Figure 5a is a diagrammatic representation of an advectional inversion layer in the atmosphere; Figure 5b is a diagrammatic representation of the advectional inversion layer Figure 5a showing the flow provided by a gas stream generating system according to the first embodiment.

Figure 6 is a diagrammatic representation of a pulse detonation engine according to the prior art; Figure 7 a plan view of a rotary shutter-type valve as used in the PDE of Figure 6;

Figure 8 is a diagrammatic representation of a PDE according to a first embodiment;

Figure 9 is sectional view of the PDE of Figure 8, laid perpendicular to normal orientation; Figure 10 is a diagrammatic representation of the computational domain used for the computational simulation of the operation of the PDE of Figure 8; Figure 1 1 is the base line configuration of the computational domain of Figure 10;

Figure 12a is a progressively shaded scale representing the speed of the gas in the computational domain of Figures 10 and 1 1 as used in Figures 12b to 12g;

Figure 12b is diagrammatic representation of the Mach number contours around the exhaust of the PDE of the first embodiment at time 0 s.

Figure 12c is an update of the diagrammatic representation of Figure 12b at time 1 ms.

Figure 12d is an update of the diagrammatic representation of Figure 12b at time 2 ms. Figure 12e is an update of the diagrammatic representation of Figure 12b at time 3 ms.

Figure 12f is an update of the diagrammatic representation of Figure 12b at time 4 ms.

Figure 12g is an update of the diagrammatic representation of Figure 12b at time 5 ms.

Figure 13a is a progressively shaded scale representing the mass fraction of combustion products in the computational domain of Figures 10 and 1 1 as used in Figures 13b to 13g;

Figure 13b is diagrammatic representation of the mass fraction of combustion products around the exhaust of the PDE of the first embodiment at time 0 s.

Figure 13c is an update of the diagrammatic representation of Figure 13b at time 1 ms. Figure 13d is an update of the diagrammatic representation of Figure 13b at time 2 ms.

Figure 13e is an update of the diagrammatic representation of Figure 13b at time 3 ms. Figure 13f is an update of the diagrammatic representation of Figure 13b at time 4 ms.

Figure 13g is an update of the diagrammatic representation of Figure 13b at time 5 ms.

Figure 14 is a diagrammatic representation of velocity vectors near the PDE engine exhaust of the embodiment at time of 5 ms

Figure 15 is an enlargement of a portion of Figure 14;

Figure 16a is an update of the diagrammatic representation of Figure 12b at time 10 ms.

Figure 16b is an update of the diagrammatic representation of Figure 12b at time 20 ms.

Figure 16c is an update of the diagrammatic representation of Figure 12b at time 30 ms.

Figure 16d is an update of the diagrammatic representation of Figure 12b at time 40 ms. Figure 16e is an update of the diagrammatic representation of Figure 12b at time 50 ms. Figure 17a is an update of the diagrammatic representation of Figure 13b at time 10 ms.

Figure 17b is an update of the diagrammatic representation of Figure 13b at time 20 ms. Figure 17c is an update of the diagrammatic representation of Figure 13b at time 30 ms.

Figure 17d is an update of the diagrammatic representation of Figure 13b at time 40 ms.

Figure 17e is an update of the diagrammatic representation of Figure 13b at time 50 ms.

Figure 18 depicts the velocity vectors around the engine plume 50 ms after detonation.

Detailed Description of Specific Embodiments

Under typical conditions, the atmosphere's temperature decreases with a gain in altitude from the Earth's surface. The air temperature is always hottest near the surface. These typical conditions are shown in Figure 1. As shown in Figure 1 , under typical conditions, a city 21 located proximate a mountain 22 acquires a surface layer 23 of warm air 23 adjacent the ground 24 due to heating from the sun's radiation during the day. An intermediate air layer 25 above the surface layer 23 receives little heating from the sun's radiation and therefore remains cool. Above the cool layer is an even cooler upper atmosphere layer 26 that is not associated directly with surface effects. As a result of the temperature variation between the layers and the consequential variations in density, convection currents 28 are established in the atmosphere transporting the warmer air from the surface layer 23 to the intermediate layer 25 and in stronger conditions into the upper atmosphere layer 26. However, certain conditions can lead to a divergence in this typical behavior and result in temperature inversion, or a temperature increase over an increase in altitude, in certain atmospheric regions. This condition is shown in Figure 2 where the surface layer 33 is cool air and the intermediate layer 35 is a warm inversion layer, having a layer of cooler air 36 above it. Any convection currents that may be established in the surface layer 33 cannot penetrate into the intermediate layer 35 as the air is denser and so mixing between the layers is prevented. These pockets of high temperature also have a different density than the surrounding air_T which causes the air to form discrete layers instead of mixing together.

One main cause of temperature inversion layer formation is when a warmer, less dense mass of air moves over a cooler, denser mass of air near the Earth's surface, often called a warm front. These conditions can lead to weather changes such as fog or thunderstorms. The proposed de-stratification system is built upon the efficacy of ring vortices to efficiently transport stagnant air in the atmosphere near the ground to reduce smog levels during the presence of an advectional inversion layer. Figure 5a depicts an advectional inversion scenario akin to Figure 2, having a city 41 with ocean 42 to one side and barrier mountains 43 to the other, above which a trapped smog layer 44 is locked below an inversion layer 45 of subsiding warming air.

In this scenario an atmospheric circulation system according to the invention must be able to pump the stagnant surface air containing the trapped smog in a stream 46 to a height that will then be convected over the barrier mountains by upper air flow 47. This type of smog layer is typical to regions such as Los Angeles and Beijing. Note both regions are bordered by the ocean and relatively small mountain ranges. The smog layer is trapped between the cooler ocean and the mountains. The goal of the atmospheric circulation system of this invention is to establish an efficient pumping mechanism to form a gas stream generating system to transport air from ground level up through the inversion layer, as shown in Figure 5b. The solution as disclosed herein consists of one or multiple pulse detonation engines that would create a series of ring vortices. This would establish an upward flow to transport the stagnant air in the near surface layer to a level higher than the surrounding mountains. In the case of Beijing and Los Angeles, this would be a level of 1 ,500 to 2,000 meters. At this altitude, the exhaust plumes of the PDEs will combine to create a thermal bloom effect that breaks up the overhead smog layer. In the system that is disclosed ring vortices are used to efficiently transport the stagnant surface layer to the upper atmosphere. Furthermore, these pulses entrain significant amounts of ambient air in the vicinity of the engine into the ring vortexes. The ring vortex is the most efficient transport mechanism due to the near lossless rotation inherent to the structure; they persist for very long periods in the atmosphere.

The key to this design concept is to maximize the amount of entrained air into the jet plume. This must be done as efficiently as possible in order to move the combined engine exhaust and entrained air as high as possible into the atmosphere. This is a unique design problem and requires a specialized propulsive system such as the PDE.

A first embodiment of the invention is derived from the concept of a pulse detonation engine.

A pulse detonation engine is a form of jet engine which generates power by a sequence of pulses caused by the rapid oxidation of fuel and the oxidant (oxygen within the air). It can be distinguished from the pulse jet engine, such as was used in the V1 rocket in World War 2 where the combustion was in the form of deflagration, i.e. subsonic combustion that propagates through thermal conductivity. In pulse detonation engines the combustion occurs supersonically and propagates through shock waves. It has a higher thermodynamic efficiency than alternative engines.

A pulse detonation engine (PDE) has been adopted as the driving force because of the inherent ability of the engine to generate ring vortices. A schematic that demonstrates the operating principles of the PDE engine is shown in Figure 6.

The PDE 11 1 comprises an engine body in the form of a generally cylindrical detonation tube 1 14 having an inlet end 116 and an exhaust end 1 18. The PDE further includes a thrust wall 122 disposed from inlet end 1 16 about one quarter on the length of the PDE. The thrust wall 122 is provided with wall apertures 124 which are able to be successively opened and closed by the rotation of a rotary shutter- type valve 126 having valve apertures 128. The rotary shutter-type valve 126 is configured to rotate about an axis 130 aligned with the central axis of the central detonation tube 1 14. The PDE is further provided with a fuel supply means 132 proximate the inlet end 1 16 and an ignition means in the form of a spark generating means 134 mounted from the detonation tube 1 14 and disposed a short way from the thrust wall 122 towards the exhaust end 1 8.

In use, during the exhaust period of the cycle, the valve 126 will open to the ambient conditions and allow the air and fuel mixture to flow into the combustion chamber 136. The valve 126 is then closed and a spark 142 is generated in the combustion chamber to ignite fuel air mixture. The thrust wall 122 is used to prevent combustion gases from escaping the combustion chamber 136 portion of the detonation tube 122 during detonation when the valve 126 is closed. Ignition causes detonation the propagation of a detonation wave 144 in the fuel air mixture. This results in mixture obtaining a high pressure and temperature within constant volume conditions. A high energy pulse is then ejected at the exhaust end 1 18. Pulse detonation engines are comparatively simple, having minimal moving parts as they don't require compressors or turbines and therefore they can be manufactured at a much lower cost than a traditional fan jet. Pulse detonation engines that have been produced to date have been aimed primarily for use in aircraft and particularly for military aircraft. While PDEs have many advantages which promote their use in aircraft, that application imposes many design restrictions on the PDE. There are still significant design problems which have prevented their adoption as yet for that application. In the present application the PDE is stationary during use and can be designed to operate at a single power output level. It is not required to operate a variable speeds. It is also not as physically constrained as is the case for aircraft use.

A PDE directed to use in connection with an atmospheric mixing system according to the invention has design criteria very different from those of an engine directed for use in an aircraft. Amongst the criteria are these:

1. The PDE must be directed to expelling its exhaust as a succession of vortex rings;

2. The vortex rings must entrain substantial volumes of surrounding air as the PDE exhaust is expelled and the vortex ring created and also as the vortex ring rises through the lower atmosphere;

3. The vortex rings must transfer sufficient lower atmospheric gas to a level above the thermal stratification layers to be effective;

4. Operational costs should not exceed a reasonable level.

Figure 8 depicts a PDE according to the first embodiment. In general, the first embodiment adopts the functional elements of existing technology as described above with reference to Figure 6 and 7. Unlike a PDE for an aircraft, the PDE 21 1 of the embodiment has an extended exhaust portion 212 of the detonation tube. It will be seen that this assists the acceleration of the pulse gas along this portion somewhat in a manner akin to the barrel of a rifle. The exhaust gases are ejected from exhaust end at supersonic speed and entrain a considerable volume of surrounding atmosphere to create a large vortex ring. In addition the exhaust end 214 is configured to promote the formation of ring vortexes. This is done by adopting the formations disclosed by Jayden David Harman in the references WO2003/056228, WO2003/056190 and WO2005/003616. These disclosures are hereby incorporated by reference. The surface structures disclosed in these references promote the formation of ring vortexes because the surface shapes of these disclosures conform with the flow path of fluid within a ring vortex as it is flowing over that surface. It is to be noted that fluid flow within a ring vortex follows a complex three dimensional pathway. The pathways of the surfaces of the disclosures corresponds with the pathway that an element of fluid within a ring vortex will momentarily travel.

During development, a series of CFD analyses have been performed. The goal of these analyses was to utilize PDE technology to induce flow up to 1500 m around the pulse jet. For all of the following simulations methane was used as the combustible gas. A goal of completing an air change of a volume of one cubic kilometer the engine in less than 24 hours was set as being a level which could provide sufficient circulation of atmosphere to have an observable impact on pollution levels in cities such as Los Angeles and Beijing. Figures 10 and 1 1 depict the baseline configuration that was studied.

The computational domain was 500 meters tall and 100 meters in diameter. The actual engine configuration was 3.2 meters long with an exit diameter of 0.38 meters as shown in Figure 9. Figure 9 is a section of the PDE shown in Figure 8, laid perpendicularly for convenience of displaying the results, as is done in Figures 12b to 12g. Figure 12a provides a progressively shaded scale representing the speed of the gas in the computational domain as used in Figures 12b to 12g. The simulations were initiated at the point where the detonation wave reached the converging wall section of the combustion chamber (approximately 0.5 meter). The chemical composition of the detonation products is shown below in Table 1 .

Table 1 Products of detonation for the methane air mixture (stoichiometric conditions)

The temperature, pressure, and flame speed of the mixture was determined by solving the Chapman-Jouget equations. The C-J point (point of tangency) was utilized to set the pressure and temperatures. This condition is conservative since it is the lowest pressure and temperature where strong detonation occurs. Note the weak C-J detonation point is non-physical. The simulation assumes a frozen flow condition.

The first simulation performed represents a single pulse in the engine. This simulation, attempts to establish the operating conditions of the engine. In particular, the thrust/exhaust period and the length of time the pressure in the engine is below ambient. This time is critical since it will set the period of each pulse and the subsequent firing frequency.

Figures 12b-12g depict the Mach number contours around the exhaust of the PDE in 1 ms increments during the firing sequence.

Further analysis of operation of the PDE was obtained by plotting the flow of combustion products mass fraction in and around the PDE. Figure 13a provides a progressively shaded scale representing the combustion products mass fraction in the computational domain as used in Figures 13b to 13g Figures 13b to 13g depict the combustion products mass fraction contours around the exhaust of the PDE in 1 ms increments during the firing sequence.

Comparing Figures 12g and 13g reveal some interesting behaviors. First, the induced flow from the pressure wave exiting the engine generates a large entrained flowfield. Second, the large entrained flowfield consists primarily of ambient air around the engine; this is shown by the lack of combustion products in the plume. Lastly, the induced flowfield has the topology of a ring vortex. This is shown in Figures 14 and 15. It is to be noted that Figures 14 and 15 were originally generated in colour to represent flow rates. The conversion the colour figures into grayscale for presentation in this application has caused loss of the speed representation in the figures. Therefore the representation of the PDE has been designated as regions A to H in Figure 14, and approximate flow rates in the regions is given by Table 1 , below.

In Figure 15, the ring vortex core can be identified at J. The results of these simulations showed the center line velocity was still in excess of 200 ms at the exit of the computational domain (500 meters from the nozzle exit). A salient benefit of operating a PDE engine is reduced fuel consumption . The simulation above was run at a firing frequency of 20 Hz. Even though the detonation wave cleared the engine in 5 ms, the engine will require approximately 45 ms to refill the engine with fuel and oxidant (air). Figures 16a to 16e depict the Mach contours about the engine at 10, 20, 30 40 and 50 ms. It should be noted that the speed scale of Figure 12a applies to these drawings also.

Please note in Figures 16d and 16e the field of view was expanded to capture the full plume. The results shown above clearly demonstrate that the pressure pulse quickly leaves the engine, setting up the ring vortex structure. This behavior is very similar to the vortex cannon developed by Germany in the 1940s, and the Italians in 1917-18. It has been shown that these ring vortex structures can persist for very long periods. The period is a function of the initial pressure ratio. For the PDE we observed peak pressures of 2.4 mPa. Figures 17a to 17e depict the products of combustion mass fraction contours about the engine at 10, 20, 30, 40 and 50 ms. It should be noted that the mass fraction scale of Figure 13a applies to these drawings also.

Please note in Figures 17d and 17e the field of view was expanded to capture the full plume. In Figures 17d and 17e we see the engine back filling with ambient air. This behavior is caused by the low pressures created in the PDE.

Figure 18 depicts the velocity vectors around the engine plume 50 ms after detonation. Note the persistence of the ring vortex.

It is critical to note that the detonation wave clears the engine at 5 ms, while it takes 45 ms to refill the engine. The proposed engine configuration must be self- aspirating for simplicity and cost. The current design will self-aspirate as evidenced by Figures 39 and 40. Figures 39 and 40 depict the surface pressure on the thrust plate of the engine. (Note the thrust plate is located at the far left side of the engine.) For the engine to aspirate, the pressure inside the engine must be significantly lower than the ambient pressure 101 ,303.0 Pa. Note that the engine will aspirate fresh air and fuel while the pressure remains at the red line. The aspiration time and efficiency is a key point of research in PDE development. Since we will statically fire the engine, with no ram effect, it becomes even more critical. It can thus be seen that the optimal firing frequency for this configuration is 20 Hz. Since the PDE is being operated, by the nature of the engine, in a transient mode the fuel flow rate is significantly less than the F100, GE90-84 and Trent 900 engines. Furthermore, because of the high bypass ratio of these engines (amount of air that bypasses the high pressure compressor) these fan jet exhausts will mix out quickly in the plume. This is a serious drawback of this type of engine for our application. The transient nature of the PDE is ideal for the atmospheric application.

A further factor that assists in the propagation of the ring vortex into the upper atmosphere is the release of convective available potential energy (CAPE). It is believed that as the vortex ring rises, CAPE can be released in such a way that it tends to maintain the stability of the vortex ring because it partly replaces kinetic energy that is lost from the ring over time. It is postulated that it can even facilitate the vortex ring entraining further atmosphere as it rises, although that is not yet proven. As the hot vortex ring rises it will encounter colder air at the same pressure. The hot air will be less dense, thus it would rise with respect to the cold air. From the above analyses an overall entrainment rate of the jet plume was quantified. For the above configuration, the entrainment rate for a single engine was approximately 12,000 kg/s. Based on the estimated entrainment rate, it would require less than 23 hours to completely change the air in a one-kilometer cube (1 billion cubic meters).

As previously described with reference to Figure 6, the PDE of the first embodiment utilizes the thrust wall 122 and rotary shutter-type valve 126. According to a second embodiment, the PDE uses aerodynamic flow control to open and close the fuel-air inlets, further simplifying the design. It is easier to adapt the design of the PDE to accommodate this means of aspiration for this application rather than for an aircraft as it need operate at a single operating point only.

In an adaptation of the invention, an array of the pulse detonation engines located around an airport or city to clear or prevent the formation of smog layers. It should be noted that these devices would be run only when necessary, as dictated by local climate conditions.

The above embodiments identify but a few of the potential applications to which the invention may be adapted. It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiments described above.

Claims

The claims defining the invention:

1. A gas stream generating system comprising a stationary pulse detonation engine adapted to generate a gas stream of high velocity and high volume into the atmosphere to thereby transfer a substantial quantity of atmosphere from a low level to significantly higher elevation.

2. A gas stream generating system as claimed at claim 1 wherein the pulse detonation engine is adapted to transfer the substantial quantity of atmosphere from a low level to above a thermal stratification layer within the atmosphere.

3. A gas stream, generating system as claimed at claim 1 or claim 2 wherein the pulse detonation engine is directed to expelling its exhaust as a succession of vortex rings.

4. A gas stream generating system as claimed at claim 3 wherein the exit of the pulse detonation engine is configured to facilitate the gas pulses to form a vortex rings upon being ejected from the exit.

5. A gas stream generating system as claimed at either of claim 3 or claim 4 wherein the gas stream comprises a continuous series of vortex rings.

6. A gas stream generating system as claimed at claim 5 the pulse detonation engine is configured to generate approximately 20 pulses per second.

7. A gas stream generating system as claimed at any one of claims 3 to 6 wherein the vortex rings entrain substantial volumes of surrounding air as the pulse detonation engine exhaust is expelled and the vortex ring created.

8. A gas stream generating system as claimed at claim 7 wherein the vortex rings also entrain surrounding air as the vortex ring rises through the lower atmosphere.

9. A gas stream generating system as claimed at any one of the previous claims wherein a plurality of entrained gas pulses merge to form an enlarged gas pulse having sufficient energy and momentum to be projected through the thermal stratification layer.

10. A gas stream generating system as claimed at any one of the previous claims wherein a plurality of pulse detonation are arranged so that the gas streams from each engine combine into a single stream.

11. A gas stream generating system as claimed at any one of the previous claims wherein the gas stream transfers sufficient lower atmospheric gas to a level above the thermal stratification layers to be effective at reducing pollution levels in the vicinity of the pulse detonation engine.

12. A gas stream generating system as claimed at claim 10 wherein operational costs do not exceed a reasonable level justifiable by the benefit obtained in reducing pollution.

13. An artificially created atmospheric circulation system comprising at least one pulse detonation engine adapted to generate a rapid series of gas pulses directed into the atmosphere, each gas pulse adapted to entrain surrounding atmosphere after exiting the pulse detonation engine to provide an entrained gas pulse adapted to travel in the atmosphere.

14. An atmospheric circulation system as claimed at claim 12 wherein a plurality of entrained gas pulses merge to form an enlarged gas pulse having sufficient energy and momentum to be projected through an inversion layer existing in the atmosphere at the time of use.

15. An atmospheric circulation system as claimed at claim 13 or claim 14 wherein an outlet of the pulse detonation engine is directed to expelling its exhaust as a succession of vortex rings.

16. An atmospheric circulation system as claimed at claim 15 wherein the exit of the pulse detonation engine is configured to facilitate the gas pulses to form vortex rings upon being ejected from the exit.

17. An atmospheric circulation system as claimed at any one of claims 13 to 16 wherein the pulse detonation engine is configured to generate _ approximately 20 pulses per second.

18. An atmospheric circulation system as claimed at any one of claims 13 to 17 wherein the size and rate of operation of the pulse detonation engine are determined to cause the transfer of one cubic kilometre of lower level atmosphere above an inversion layer in approximately one day.

19. A method of transferring polluted ground level atmosphere above an atmospheric inversion layer by use of gas stream generating system as claimed in any one of claims 1 to 11.

20. A method of transferring polluted ground level atmosphere above an atmospheric inversion layer by use of an atmospheric circulation system as claimed in any one of claims 13 to 18.

21. A method of causing the abatement of tornados or storms by the use of an atmospheric circulation system as claimed in any one of claims 13 to 18.