Abstract:
A ramjet engine power generator. Supersonic ramjets are provided along a portion of the circumference of a low aerodynamic drag rotor. The rotor is affixed at a central hub to a rotating shaft. The rotor acts as a structural member which transmits to the shaft the thrust generated by the ramjets. In the preferred embodiment, a ramjet inlet captures and compresses an inlet air stream by utilizing the rotor edge profile, the confining strakes which are affixed on the rotor adjacent the thrust module, and an adjacent peripheral and preferably stationary housing sidewall. The compressed air inlet stream provides oxygen for mixing with a fuel, such as natural gas, other suitable hydrocarbons, or hydrogen. The fuel is oxidized in the ramjet combustion chamber(s) to produce expanding combustion gases. Such combustion gases escape by acting against the ramjet outlet throat, adjacent strake structures and the adjacent peripheral housing sidewall, rotating the ramjet at supersonic velocities, and producing shaft energy. A helical strake effectively separates the incoming fuel air mixture from the outgoing combustion gases. In one embodiment, the strake further includes a plurality of cooling orifices which allow passage through the strake of cooling gas, and also reducing boundary layer thickness, thus reducing drag.

Description:
This application claims the benefit of U.S. Provisional Application(s) Ser. No(s).: 60/089,674 filling date Jun. 17, 1998. 
    
    
     A portion of the disclosure of this patent document contains material which is subject to copyright protection. The owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
     This invention uses ramjet technology for power generation. The fundamentals the technology were set forth in detail in my prior application Ser. No. 07/945,228, filed Sept. 14, 1992, now U.S. Pat. No. 5,372,005, issued Dec. 13, 1994. Certain embodiments were also provided in U.S. patent application Ser. No. 08/480,663, filed Jun. 7, 1995, now U.S. Pat. No. 5,709,076, issued Jan. 20, 1998. Specific embodiments were also earlier disclosed in my U.S. Provisional Patent Application, Ser. No. 60/028,311, filed Dec. 16, 1996. The disclosures of such patent applications, and the issued U.S. patents, all as just indentified in this paragraph, are incorporated herein by this reference. 
     This invention is based on, and the benefit of priority under 35 U.S.C. Section 119(e) is claimed from, U.S. Provisional Patent Application No. 60/089,674 filed Jun. 17, 1998. 
     TECHNICAL FIELD 
     My invention relates to a high efficiency, novel ramjet driven rotary engine, and to a method for the generation of electrical and mechanical power with the engine, while minimizing emission rates of nitrogen oxides. More particularly, my invention relates to a power plant driven by a ramjet engine, and to structures which are designed to withstand the extremely high tensile stress encountered in a rotating device with distally located ramjets operating at supersonic speeds. Power plants of that character are particularly useful for generation of electrical and mechanical power. 
     BACKGROUND 
     A continuing demand exists for a simple, highly efficient and inexpensive thermal power plant which can reliably provide low cost electrical and mechanical power. This is because many electrical and/or mechanical power plants could substantially benefit from a prime mover that offers a significant improvement over currently practiced cycle efficiencies in power generation. This is particularly true in medium size power plants—largely in the 10 to 100 megawatt range—which are used in many industrial applications, including stationary electric power generating units, rail locomotives, marine power systems, and aircraft engines. 
     Medium sized power plants are also well suited for use in industrial and utility cogeneration facilities. Such facilities are increasingly employed to service thermal power needs while simultaneously generating electrical power at somewhat reduced overall costs. Power plant designs which are now commonly utilized in co-generation applications include (a) gas turbines, driven by the combustion of natural gas, fuel oil, or other fuels, which capture the thermal and kinetic energy from the combustion gases, (b) steam turbines, driven by the steam which is generated in boilers from the combustion of coal, fuel oil, natural gas, solid waste, or other fuels, and (c) large scale reciprocating engines, usually diesel cycle and typically fired with fuel oils. 
     Of the currently available power plant technologies, diesel fueled reciprocating and advanced aeroderivative turbine engines have the highest efficiency levels. Unfortunately, with respect to the reciprocating engines, at power output levels greater than approximately 1 megawatt, the size of the individual engine components required become almost unmanageably large, and as a result, widespread commercial use of single unit reciprocating engine systems in larger sizes has not been developed. Gas turbines perform more reliably than reciprocating engines, and are therefore frequently employed in plants which have higher power output levels. However, because gas turbines are only moderately efficient in converting fuel to electrical energy, gas turbine powered plants are most effectively employed in co-generation systems where both electrical and thermal energy can be utilized. In that way, the moderate efficiency of a gas turbine can in part be counterbalanced by using the thermal energy to increase the overall cycle efficiency. 
     Fossil fueled steam turbine electrical power generation systems are also of fairly low efficiency, often in the range of 30% to 40% on an overall net power output to raw fuel value basis. Still, such systems are commonly employed in both utility and industrial applications for base load electrical power generation. This is primarily due to the high reliability of such systems. 
     In any event, particularly in view of reduced governmental regulation in the sale of electrical power, it can be appreciated that significant cost reduction in electrical power generation would be desirable. Fundamentally, particularly in view of long term fuel costs, this objection can be most effectively accomplished by generating electrical power at a higher overall cycle efficiency than is currently known or practiced. 
     SUMMARY 
     I have now invented an improved power plant based on the use of a supersonic ramjet as the prime mover to rotate a power shaft. In using this method to generate electrical power, the supersonic ramjet is directly or indirectly coupled with an electrical generator. By use of a metered fuel feed arrangement, the power output of the ramjet can be turned down as necessary to maintain constant rotating velocity, such as is necessary in synchronous power generation apparatus, at minimal output loads. Throughout its operating range, the supersonic ramjet power plant has greatly increased efficiencies when compared to those heretofore used power plants of which I am aware. 
     The designs incorporated into my power plant overcomes four significant and serious problems which have plagued earlier attempts at ramjet utilization for efficient electrical power production: 
     First, at the moderate mach number tip speeds at which my device operates (preferably, Mach 2.5 to about Mach 4.0), the design minimizes aerodynamic drag. This is accomplished by both reducing the effective atmospheric density that the rotor encounters, and by use of a boundary layer control and film cooling technique. Thus, the design minimizes parasitic losses to the power plant due to the drag resulting from rotational movement of the rotor. This is important commercially because it enables a power plant to avoid large parasitic losses that undesirably consume fuel and reduce overall efficiency. 
     Second, the selection of materials and the mechanical design of rotating components avoids use of excessive quantities or weights of materials (a vast improvement over large rotating mass designs), and provides the necessary strength, particularly tensile strength where needed in the rotor, to prevent internal separation of the rotor by virtue of the centrifugal forces acting due to the extremely high speed rotor. 
     Third, the design provides for effective mechanical separation of the cool entering fuel and oxidizer gases from the exiting hot combustion gases, while allowing ramjet operation along a circumferential pathway. 
     Fourth, the design provides for effective film cooling of rotor rim components, including rim segments, rim strakes, and ramjet thrust modules. This novel design enables the use of lightweight components in the ramjet combustor and in the ramjet hot combustion exhaust gas environment. 
     To solve the above mentioned problems, I have now developed novel rotor designs which overcome the problems inherent in the heretofore known apparatus and methods known to me which have been proposed for the application of ramjet technology to stationary power generation equipment of primary importance, I have now developed a low drag rotor having an axis of rotation, and which has one or more unshrouded ramjet thrust modules rotatably mounted on the distal edge thereof. A number N of peripheral, preferably partially helically extending strakes S partition the entering gas flow sequentially to the inlet to a first one of one or more ramjets, and then to a second one of one or more ramjets, and so on to an Nth one of one or more ramjets. Each of the strakes S has an upstream or inlet side and a downstream or outlet side. For rotor balance and power output purposes, I prefer that the number of ramjets X and the number of strakes N be the same positive integer number, and that N and X be at least equal to two. More preferably, I find it desirable that N and X be equal to five. The exhaust gases exiting from each of the one or more ramjets is effectively prevented from “short circuiting,” or returning to the inlet side of subsequent ramjets. In the area of each ramjet combustor, this is effectively accomplished by the strakes S, due to overpressure in the ramjet combustor. Downstream from the ramjet exhaust area, and extending until just before the inlet to the next of the one or more ramjets, the prevention of bypass of the hot exhaust combustion gases to the cool entering fuel air mixture is effectively accomplished by the design of my one or more ramjet thrust modules, as it is preferred that the exhaust gases from each ramjet be expanded to approximately atmospheric pressure, so the strakes S merely act as a large fan or pump to move exhaust gases along with each turn of the rotor. 
     I have provided several embodiments for an acceptable high strength rotor. In a preferred embodiment, the rotor section comprises a carbon fibre disc. In another , it comprises a steel hub with high strength spokes. In each case, rim segments and ramjet thrust modules are preferably releasably and replaceably affixed to the rotor. 
     A rotor operating cavity is provided, at least part of which has a lowered atmospheric pressure, preferably in the 1 psia range, in order to eliminate aerodynamic drag on the rotor. The vacuum conditions are assured by use of a vacuum pump to evacuate the operating cavity, and by the use of appropriate seals (a) at the rotor output shaft where it penetrates the operating cavity walls (b) at the rim segments, and (c) at the ramjet thrust modules. 
     The rim segments and the ramjet thrust module each include a cooling air receiving chamber. The chambers each have radially extending, preferably substantially parallel sidewalls, a radially proximal wall, and a radially distal wall, through which cooling gas outlets penetrate. Such outlets may be cylindrical orifices, or slots, or other desirable shapes. The cooling air receiving chamber functions as a centrifugal compressor for delivery of cooling gas to cooling gas outlet orifices. The exit of the cooling gas orifices is located on the surface of the rim segments and the ramjet thrust modules. The radial dimension at the start of each individual air receiving radially proximal wall determines the distance over which that air receiving chamber operates for compression, and thus determines the pressure of air delivered at the exit of a particular boundary layer cooling outlet orifice. 
     Attached at the radial end of the rotor are one or more of the at least one ramjets, each ramjet preferably having an unshrouded thrust module construction. The ramjet engines are situated so as to engage and to compress that portion of the airstream which is impinged by the ramjet upon its rotation about the aforementioned axis of rotation. Fuel is added to the air before compression in the ramjet inlet. The fuel may be conveniently provided through use of fuel supply passageways located in an annular ring, with fuel injection passageways communicating between the fuel supply passageways and the inlet air passageway. Fuel injected into the inlet air stream is thus well mixed with the inlet air before arriving at the ramjet engine combustion chamber. The combustion gases formed by oxidation of the fuel escape rearwardly from the ramjet nozzle, thrusting the ramjet tangentially about the axis of rotation, i.e., about the output shaft portions, thus turning the rotor and the coupled output shaft portions. The power generated by the turning output shaft portions may be used directly in mechanical form, or may be used to drive an electrical generator and thus generate electricity. The operation of my ramjet engine may be controlled to maintain synchronous operation, i.e., vary the power output from the ramjet, while maintaining constant speed shaft operation. 
     When the ramjet power plant is used in a co-generation configuration, the exhaust combustion gases from the ramjet are transported to a heat exchanger, where the gases are cooled as they heat up a heat transfer fluid (such as water, in which case the production of hot water or steam results). The heat transfer fluid may be utilized for convenient thermal purposes, or for mechanical purposes, such as for driving a steam turbine. Ultimately, the cooled combustion gases are exhausted to the ambient air. 
     Finally, many variations in the air flow configuration and in provision of the fuel supply, secondary fuel supply, and in providing startup ignitors, may be made by those skilled in the art without departing from the teachings hereof. Finally, in addition to the foregoing, my novel power plant is simple, durable, and relatively inexpensive to manufacture. 
     OBJECTS, ADVANTAGES, AND FEATURES OF THE INVENTION 
     From the foregoing, it will be apparent to the reader that one important and primary object of the present invention resides in the provision of a novel ramjet powered engine which can be cost effectively used to generate mechanical and electrical power. 
     More specifically, an important object of my invention is to provide a ramjet driven power generation plant which is capable of withstanding the stress and strain of high speed rotation, so as to reliably provide a method of power generation at high overall efficiency. 
     Other important but more specific objects of the invention reside in the provision of power generation plants as described in the preceding paragraph which: 
     have high efficiency rates; that is, they provide high heat and high work outputs relative to the heating value of fuel input to the power plant; 
     in conjunction with the preceding object, provide lower power costs to the power plant operator and thus ultimately to the power purchaser than is presently the case; 
     allow the generation of power to be done in a simple, direct manner; 
     have a minimum of mechanical parts; 
     avoid complex subsystems; 
     require less physical space than many existing technology power plants; 
     are easy to construct, to start, to operate, and to service; 
     cleanly burns fossil fuels; 
     in conjunction with the just mentioned object, results in fewer negative environmental impacts than most power generation facilities presently in use; 
     have a rotating element with a minimal distally located mass structure, and which thus minimizes and therefore is able to withstand the stresses and strains of rotating at very high tip speeds; and which 
     provides for operation with minimal aerodynamic drag. 
     One feature of the present invention is a novel high strength rotor structure. In one design, a high strength steel inboard section is provided with high strength spokes that at their distal end suspend a rotating rim that has unshrouded ramjet thrust modules integrated therein. This unique structure enables operation at rotational speeds above stress failure limits of many conventional materials, while simultaneously providing for adequate cooling of the rim and ramjet structure, in order to maintain material integrity, at the high temperature operating conditions. In another design, a carbon fiber epoxy composite disc is provided, which simplifies the overall construction while providing an abundance of strength, while still providing a ventilated positive cooling system design to maintain structural integrity of the rotor, and of the rim and ramjet structure. 
     Another feature of the present invention is the use of a unshrouded ramjet design. In this design, a sturdy, stationary, peripheral wall which surrounds the rotating portion of the ramjet functions as part of the ramjet thrust module. This unique design enables use of a minimal rotating mass at the high design tip speeds, thereby enabling the rotor to be designed with lower strength materials and/or a higher margin of safety with respect to overall tensile strength requirements for a given ramjet operational mach number. 
     Still another important feature of the present invention is the use of strakes to partition the ramjet inlet air flow (and preferably in which inlet air flow the fuel and air are pre-mixed) from the ramjet exhaust gas flow. This elegant design feature assures that exhaust gases are directly removed from the engine, and that only the amount of inlet air necessary for combustion in the ramjets is required to be provided. 
     Finally, another important feature is the use of perforations in the strakes to minimize boundary layer buildup, (and accompanying drag) during high speed operation, by passing a small portion of pressurized gas thru such perforations to sweep away an otherwise stable boundary layer zone. 
     Other important objects, features, and additional advantages of my invention will become apparent to those skilled in the art from the foregoing and from the detailed description which follows and the appended claims, in conjunction with the accompanying drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 provides a partial perspective view of my novel power plant apparatus, showing the primary rotor of the power plant rotating within a housing, to drive an output shaft portion which is coupled with a gear box, which is operatively connected to an electric generator. 
     FIG. 2 is a partial sectional view of my ramjet power plant apparatus, showing a rotating output shaft portion affixed to a rotor and rotatably secured therewith, and an unshrouded ramjet thrust module integrally provided with the rotor. Additionally, the inlet air duct is shown, along with the transition to an annular passageway having a peripherial wall section in the combustion zone; the exhaust gas outlet from the combustion zone also shown, along with the exhaust gas ducting. Cooling air, cooling water, and the vacuum lines used to help reduce aerodynamic drag near the rotor are illustrated. 
     FIG. 3 is a perspective view of a rotor with integral (a) rim, (b) unshrouded ramjet, and (c) strake, showing in particular a rim segment with strake segment, and also illustrating cooling air slots in rim segments, as well as boundary layer control orifices in the strakes. 
     FIG. 4 is a circumferential edge view of a rotor, taken as starting at line  4 — 4  on the circumference of the rotor just shown in FIG. 3, with the rotor edge peeled and laid out flat, showing a pair of unshrouded ramjet thrust modules and the relationship of rim segments and integral strake segments. 
     FIG. 4A is a circumferential edge view of a rotor, similar to the view just set forth in FIG. 4, but now showing an embodiment where five ramjets, and their accompanying strakes, are illustrated. 
     FIG. 5 shows, in perspective, a rim segment which includes an unshrouded ramjet thrust module and related integral strake segments, and where the strakes include boundary layer control orifices. 
     FIG. 6 provides a cross-sectional view of a carbon fibre rotor, unshrouded ramjet thrust modules, and the cooperating peripheral wall against which compression occurs. 
     FIG. 7 provides a cross-sectional view of second embodiment of my rotating assembly, showing a steel rotor, unshrouded ramjet thrust modules with strakes, and the cooperating peripheral wall against which compression occurs. 
     FIG. 8 shows a rim segment with integral strake segment, and also clearly shown are the cooling air passageways and a slotted type exit pathway, i.e., the film cooling orifices, as well as the boundary layer control orifices in the strakes. 
     FIG. 9 is a partial cross sectional view, taken as if through a portion of section  9 — 9  of FIG. 8, showing the close fitting relationship of the rotor strake with the interior surface of the cooperating peripheral wall, and indicating the flow of air thru boundary layer control orifices in the strake. 
     FIG. 10 shows, in a partial cross sectional view, one embodiment of an unshrouded thrust module and integral strake with boundary layer control orifices, where compression occurs against a cooperating peripheral wall. 
     FIG. 11 shows a perspective view of the thrust module and integral strake just set forth in FIG.10. 
     FIG. 12 shows a perspective view of one embodiment of a rotor segment with integral strake, revealing details of an embodiment of film cooling using orifices, and showing related radial boundary layer flow on the strake, and the use of boundary layer control orifices. 
     FIG. 13 shows a cross-sectional view of a section of the peripherial wall portion of the engine, taken as if along a portion of line  13 — 13  of FIG. 2 in the region adjacent the strake, showing a gas bypass valve in the form of an annular segment gate valve, with the valve depicted in a closed position. 
     FIG. 14 shows a cross-sectional view of a section of the peripherial wall portion of the engine, similar to FIG. 13 above, but now showing the gas bypass valve in an open position, as used to spill air through the peripheral sidewall during startup of the ramjet thrust modules. 
     FIG. 15 shows a vertical elevation view of one embodiment of an engine bearing plate frame for my power plant, taken along line  15 — 15  and  15 A- 15 -A of FIG. 1 (see also FIG.  2 ), showing the bearing plate frame, combustion exhaust passageways, passageways for cooling air, cooling water, and vacuum. 
     FIG. 16 is a plan view of combined cycle power plant which uses my novel supersonic ramjet thrust module driven engine as a prime mover, provided as shown using the combination of an electrical generator and a steam turbine, which as shown is also used for electrical generation. 
     FIG. 17 is a side elevation view of a combined cycle plant which uses my novel ramjet thrust module driven engine as a prime mover, provided as shown in FIG. 16, in combination with an electrical generator and steam turbine. 
     FIG. 18 is a partial cross-sectional view of my novel ramjet thrust module driven engine, which shows details of the low drag housing using a vacuum boundary layer control system, the gas bypass valve, and the varying position of strakes as the rotor turns about its axis of rotation. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawing, FIG. 1 depicts a partial cut-away perspective view of my novel supersonic ramjet thrust module driven power plant  100 . Major components shown in this FIG. 1 include the supersonic ramjet engine assembly  102  and gear set  104  on ramjet engine skid  106 . The ramjet engine assembly  102  has a driven output shaft  108 , which is coupled with gear set  104  for power transfer therethrough. Gear set  104  has power output shaft  110 , which is coupled with and rotates at a desired rate of rotation to drive electrical generator  112 . Electrical power is output from electrical generator  112  via cable in conduits  116   A ,  116   B , and  116   C . Alternately, mechanical power output can be provided from the engine assembly  102 . 
     The structure of the supersonic ramjet engine which is housed in ramjet engine assembly  102  can be understood by review of related FIGS. 2,  3 ,  4 ,  7 ,  8 ,  10 ,  11 , and  18 . I have now developed a high strength rotor  120  (also, see rotor  120 ′) which has output shaft portions 108 and  124 . The output shaft portions  108  and  124  turn in inlet and outlet bearing assemblies  126  and  128 , respectively, which bearing assemblies are housed in bearing plate frames  130  and  132 , respectively. In FIGS. 2,  7 ,  8 ,  10 , and  11 , one embodiment  120  of my high strength rotor design (and/or components thereof), is shown, illustrating rotor construction using a rotor hub  134  (preferably high strength steel), to which is secured radially extending spokes  136 , and from which are secured ventilatable rim segments  138 , or alternately, a ventilatable unshrouded ramjet  142  such as depicted in FIGS. 11 and 18. 
     For ease of construction, I prefer to use an interlocking hinge type attachment arrangement, as can be seen in FIGS. 2 and 8, for (a) interlocking hinges  144  between hub  134  and spokes  136 , or (b) interlocking hinges  146  are provided between spokes  136  and each ramjet. As depicted in FIG. 8, interlocking hinges  146  between spokes  136  and rim segments  138  are formed by hinge segments  150  on spokes  136  and complementary hinge segments  152  on rim segments  138 . In one embodiment, a pin  154  is used for insertion in a tight fitting relationship through aperture  156  which is defined by wall  158  in hinge segments  152  in rim segment  138 , and through matching aperture  160  defined by wall  162  in hinge segments  150  in spoke  136 . As provided, any of the rim segments  138  or the ramjet thrust modules (see U 1  or U 2  in FIG. 4) are releaseably affixed as a part of the fully assembled rotor  120 , and thus rim segments  138  and the ramjet thrust modules U 1 , U 2 , etc., (see FIG. 4A) may be easily replaced. 
     FIGS. 3,  5 ,  6 , and  12  depict a similarly functioning design using carbon fibre materials for the rotor  120 ′. A series of T-shaped or bulb shaped attachment tabs AT are cut into rotor  120 ′. During assembly, tabs AT are slipped between Y-shaped tines YT that extend inwardly from each of the rim segments  138  or ramjet thrust modules U 1 , U 2 , etc. 
     As seen in FIG. 4, or FIG. 4A, the circumference of rotor  120  or  120 ′ is made up of a plurality of rim segments  138  (defined between lines M-N, N-O, etc.) and one or more ramjets (see FIG. 4, where U 1 , is defined between lines I-J, and U 2  is defined between lines A-Q, for example) . Importantly, there are also a number of peripherially extending strakes S 1 , through S N . Each of strakes S 1  through S N  has a number of strake segments, each strake segment is preferably integrally formed with a rim segment  138 , or with a ramjet  142 , as appropriate, as further shown in FIG. 4 or  4 A. Each of the strake segments may be defined by their edge pair, as seen in FIG. 4 starting at S 1 (IN-I) at the inlet IN for mixed gas  170 , then on to S 1 (I-H), then to S 1 (H-G), and so on through to S 1 (A-EX), which ends at the exhaust point EX of the strake for combustion gases  176 . Similarly, strake segments for strake S 2  start at S 1 (IN-R), at the inlet IN, then on to S 2 (R-Q), etc., in like manner. The strakes S 1  through S N  partition entering gas  170  (which preferably is mixed to provide both fuel and oxidizer), so that the mixed gas  170  flows to the ramjet inlet throat  174 . This process occurs at a first (U 1 ) of one or more ramjets U and then at a second (U 2 ) of one or more ramjets U and so on to an Xth (U X ) one of the one or more ramjets U which are mounted for rotation at the distal edge of rotor  120 . For operational and rotor balance purposes, I prefer that the number X of ramjets U and the number N of strakes S be the same positive integer number, and that N and X each be at least equal to two. More preferably, I prefer than N and X be five, or at least five. 
     The strakes S 1  through S N  allow feed of mixed gas, i.e, a combustible fuel-air mixture  170 , to each ramjet U X  without appreciable bypass of the entering mixed gas  170  to the exhaust combustion gases  176 . Also, and importantly, the exhaust combustion gases  176  exiting from each of the one or more ramjets U is effectively prevented by the arrangement of strakes S from “short circuiting,” by substantially prevent the return of combustion gases  176  from the exhaust side SEX to the inlet side S I  to the inlet side of subsequent ramjets. This strake feature can be better appreciated by considering the rotor or rotating assembly  120  (at respective portions thereof as seen such as in FIGS.  9  and  18 ). The rotor  120  revolves in close proximity (a) to a fixed, annular shaped inboard housing  198  with inboard wall surface  200 , and (b) to a preferably fixed, annular shaped peripheral wall  202  which has an interior peripheral wall surface  204 . The strakes S have a height HH (substantially radially extending) which extends to a tip end S T  that is designed for rotation very near to the interior peripheral wall surface  204 . As seen in FIG. 9, a wear ring  206  of soft sealing metal is provided as an insert into the fixed peripheral wall  202 , to allow for tight fitting abutment of the tip end S T  of strake S with the wear ring  206  that is provided in the peripheral wall surface  204 . 
     The construction and operation of my ramjet(s) U is unique. The ramjet thrust modules U, such as seen in FIGS. 5 and 11, are provided in an unshrouded configuration. The structures depicted in FIGS. 5 and 11 and described below provide the necessary elements for compression of incoming gas (preferably, a fuel-air mixture), except for a containment structure against which compression and expansion can occur. In this unique engine, such containment structure for both compression of incoming gas, and expansion of exhaust gas, is provided by the interior peripheral surface  204  of the cooperating peripheral wall  202 . Cooling water CW is provided to outer cooling chambers CCO for cooling the peripheral wall  202  and its surface  204 , and to innner cooling chambers CCI for cooling the inboard housing wall  198  and its surface  200 . 
     The actual ramjet compression area and ramjet structure can be seen in FIGS. 5 and 11. An incoming mixed gas stream  170  is compressed by the ramjet inlet or ramp structure  210 , between the ramjet side RJ of inlet portion of strake S 2 (IN-R) and the ramjet side RJ of inlet portion of strake S 1 (A-EX) . Subsequently, transition section  212  is provided to stabilize the normal shock process, which is followed by a stepdown at flameholder  214  to the combustor  216 . Combustion takes place in combustor  216 , and pressure builds (to about one hundred eighty pounds per square inch or another suitable pressure, depending upon the design criteria chosen in this critical region) . Combustion gas pressure builds up along the geometric throat  218 , to the choke point  220 . After exiting the choke point  220 , via the outflow nozzle  222 , the combustion gases expand to near atmospheric pressure and cool, normally to about 1100° F. or thereabouts. The preferably helical strakes S x  (S 1  and S 2  shown) are thin walled, for example in one design are about 0.15 inches in width (axially) at the root, and about 0.10 inches in width at the tip. With the design illustrated herein, leakage of combustion gases is minimized, and substantially limited adjacent the high pressure region of the combustor  216 . 
     Also shown in FIGS. 8 and 9 is the use of boundary layer orifices in the strake S to allow a small quantity of gas to escape thru the strake, to thereby assist in minimizing aerodynamic drag on the strake. The exact size and spacing of such orifices will depend upon the design speed, strake size, and design pressures, but in one embodiment, I prefer the use of small circular orifices of about 0.020 inches in diameter. 
     Turning now to FIGS. 2 and 18, the overall structure of the ramjet engine in my power plant is further illustrated in these views. Ramjets U 1  and U 2  are suitable for oxidizing a fuel FF continuously supplied thereto and well mixed in an incoming oxidizer stream, normally an air stream. Incoming fuel FF is supplied from a fuel main to fuel supply pressure regulator  230  (see FIG.  1 ). As indicated in FIG. 18, fuel FF is then sent to fuel supply manifold  232 , and finally into an entering airstream  234  via injectors  236 , to provide a well mixed fuel air gas stream  170 . The entering airstream  234  is preferably provided through an annular supply housing SH defined by inner walls IH an outer walls OH, by one or more fans F as driven by fan motor FM, or by other suitable means, for the supply of combustion air supply from an inlet air plenum IAP. The injectors  236  are preferably located sufficiently upstream of the ramjets U 1 , U 2 , etc., so as to provide adequate fuel mixing. The well mixed gas stream  170  is fed to ramjets U, which preferably utilizes oxygen from the incoming airstream  234  (from an ambient air supply at the plant site) as the oxidant source. Ramjets U are provided at the outer, distal reaches of rotor  120  (or carbon type rotor  120 ′) so that the propulsive effect of the ramjets U is utilized to turn rotor  120  or  120 ′ including (preferably directly) the output shaft  108  or  108 ′, respectively. 
     The rotor  120  is rotatably secured in an operating position by a fixed support structure such as inlet and outlet bearing plate frames  130  and  132  in a manner suitable for extremely high speed operation of the rotor  120  (or rotor  120 ′). Ideally, rotation rates in the range of 10,000 to 20,000 rpm, or higher, are achieved. In this regard, inlet side bearing assembly  126  and outlet side bearing assembly  128 , or suitable variations thereof, must provide adequate bearing support for high speed rotation and thrust, with minimum friction. The detailed bearing and lubrication systems may be provided by any convenient means by those knowledgeable in high speed rotating machinery, and need not be further discussed herein. 
     I prefer to use a boundary layer control technique to reduce the parasitic aerodynamic drag on the rotor  120 . As best seen in FIG. 18, one suitable method is to provide a pair of tight fitting housings, including inlet side housing  240   I  and outlet side housing  240   O , each housing having a rotor side surface ( 242   I  on the inlet side and  242   O  on the outlet side) in close proximity to the respective inlet and outlet side surface  120   S  of rotor  120 . More preferably, providing and sealing an operating cavity  250 , behind the tight fitting housings  240   O  and  240   I , so as to enable provision of a vacuum environment having an operating pressure of about 1 psia, allows most gas on the surface  120   S  of the rotor to be suctioned off thru orifices  252  through housings  240   I , and  240   O . 
     An operating cavity  250   I  is formed between interior wall  253   I  of housing  240   I  and inlet wall  256  of inlet bearing plate frame  130 , between radially inward wall  245   I  and radially outward wall  246   I . Likewise, an operating cavity  250   O  is formed between interior wall  245   O  of housing  240   O  and outlet wall  245  of outlet bearing plate frame  132 , between radially inward wall  245   O  and radially outward wall  246   I . As just mentioned, preferably these cavities  250  are evacuated to about 1 psia during normal operation. As also seen in FIG. 18, an outer labyrinth type seal  260  can be provided on the inlet side and another labyrinth type seal  262  is provided on the outlet side of the ramjet thrust module U. These seals hinder “in-leakage” of gas toward the evacuated operating cavities  250 . 
     For cooling of the rim segments  136  and the ramjet thrust modules U 1  and U 2 , a supply of compressed air is provided through air lines  270 A and  270 B. I prefer to supply air at about  250  psig and about 80° F. to chamber  272 A and  272 B, and allow it to expand through porous metal orifices  274 A and  274 B to about 13.5 psia and about −150° F. (minus 150° F.), before entering distribution chambers  276 A and  276 B, respectively. From distribution chambers  276 A and  276 B, the cooling air is injected into each ventilation chamber VC of the respective rim segment  136  or ramjet thrust module U such as thrust module  142 . Leakage of the cooling air from chambers  276 A and  276 B to the operating cavity  250  is substantially prevented by labyrinth type seals  280  and  282 . Vacuum in cavity  250  is maintained via pump (not shown) acting on ports  290  and  292  to vacuum lines  294  and  296 . 
     A second embodiment for a desirable rotor design is shown in FIGS. 3,  5 ,  6  and  12 . Here, a high strength carbon fibre rotor  120 ′ and complementary rim segments are provided. The rotor  120 ′ has a high strength inboard portion  298  and output shaft  108 ′ which secured to inboard portion  298  and rotatable therewith. 
     As illustrated particularly in FIGS. 4,  5 ,  8 ,  11 , and  12 , I prefer the use of ventilatable, film cooled surfaces, both on rim segments and in combustion chamber  216  on ramjet U. Cooling air is supplied, preferably via compressed air, to a ventilation chamber, such as chamber VC in each portion of the ramjet U. As easily seen in FIGS. 8 and 9, the ventilation chambers VC act as a centrifugal compressor, and the compressed cooling gas is sent outward through cooling passageways  302  in the coolable wall  304  having a hot surface HS to outlets  300 . Preferably, a high density pattern of cooling air passageways  302  is provided. Either orifices or slots are provided for outlets  300 . The exact parameters depend upon the characteristics of a particular design, including the speed (inlet Mach number), capacity (mass flow), and other factors. In this manner the ventilatable rim segments  138  and the ventilatable unshrouded ramjets  142  are provided with a cooling air flow path through a coolable wall  304 . As seen in FIG. 12, cooling air CA is supplied to ventilation chambers VC, which have an inner cold surface CS. A hot surface HS is located on the radially distal side of the rim segments  138  and ramjets  142 . Due to the swirling action of the strakes, the cooling air CA emerging from outlets  300  of passageways or orifices  302  is advantageously swept along the hot surface HSS of the strakes, to assist in cooling of the strakes. Note that in FIG. 8 the cooling air arrows CA are exaggerated to diagrammatically depict the flow of cooling air outward through outlets  300 . In actual practice, the cooling air CA encounters the high speed flow of combustion gas  176  and a very thin, but effective cooling film layer is formed. Of course, one side of each strake S is primarily in contact with cool mixed gas inlet air  170 . The film cooling method just described is important since it allows the use of materials such as titanium in a combustion environment. In this manner, the high temperature generated by combustion gases is prevented from damaging the combustor and other parts subjected to heating by the combustor and by the hot combustion gases along the exhaust pathway. 
     As mentioned above, as a further enhancement to the method just described, illustrated in FIGS. 8,  9  and  12  is the use of orifices  306  through strakes S, to allow cooling gas as depicted by arrows  308  to pass thru the strakes S. The orifices  306  can be effectively sized to control aerodynamic drag on the strake S, by reducing boundary layer thickness on the strake S. 
     A key feature of my power plant is the rotor  120  (or  120 ′). The rotor  120  spins about its axis of rotation due to thrust generated by the ramjets U. Two design parameters of the rotor  120  are extremely important. First, the rotor must be constructed of materials which enable it to survive the extremely high centrifugal loads encountered while the rotor is moving at a rotational rate so that the peripherially mounted ramjet can operate at supersonic speeds, preferably in the Mach 3.5 range, i.e., the rotor must be capable of withstanding extremely high tensile stress. Second, at such speeds, minimizing the overall aerodynamic drag is critical. 
     The structural design and material systems used for the rotor are as important as the aerodynamic performance of the rotor and the propulsive performance of the thrust module discussed above. All three design elements (rotor materials, rotor aerodynamic design, and ramjet thrust module performance) must be properly executed to place into operation a high performance, maximum efficiency ramjet engine as set forth herein. 
     Because of the centrifugal loads induced by the extreme speed with which the rotor turns, the material and structural characteristics of the rotor are vitally important design elements. Thus, it is instructive to consider specific stress of materials, that is, the stress per unit mass of material. The specific stress has units of inches, because the density of a specific material is cancelled out of the mathematical relation. Thus, specific stress varies only with rotation rate. It is important to note that at the rotation rates of importance in the practice of the present invention, extremely high specific stresses are encountered. For example, at a rotation rate of 15,000 rpm, about 1.5 million inches of specific stress would be encountered by a rotating disc, and about 1.8 million inches of specific stress would be encountered by a rotating rod. It can be seen that in addition to the possible aerodynamic advantages discussed above, a rotating disc also may offer a slight advantage with respect to materials requirements. 
     Any given material has associated with it a specific strength which is commonly defined as the ultimate tensile strength of a material divided by its density. Like specific stress, specific strength has the units of inches. The two values are directly comparable; specific strength sets forth the load which a given material can withstand, and specific stress sets forth the load which a given material will encounter when used in a given application. 
     Table I shows the specific strength for various materials, including titanium, advanced metal matrix composites, and carbon based conventional composites. Evaluation of the meaning of the specific strength data is straightforward. It is clear from Table I that as the rotational speed of a rotor is increased, the specific stresses required may ultimately reach the specific strength of a given material. If the speed is increased beyond that point, the load will exceed the specific strength, and as a result, the material will fail. In summary, the specific stress expected to be encountered by rotors for the instant invention exceeds the specific strength of commonly available materials such as low strength steel, magnesium, and aluminum, and thus such materials are not suitable, at least as a single structural material, for use as the primary structural material in the rotor means of the present invention. 
     
       
         
               
             
               
               
             
           
               
                 TABLE I 
               
             
             
               
                   
               
               
                 SPECIFIC STRENGTHS FOR VARIOUS MATERIALS 
               
             
          
           
               
                 Material 
                 Specific Strength (inches) 
               
               
                   
               
               
                 Low Strength Steel 
                 176,000 
               
               
                 Magnesium 
                 584,610 
               
               
                 Aluminum 
                 594,060 
               
               
                 Titanium 
                 683,220 
               
               
                 Silicon Carbide Reinforced Titanium 
                     1,300,250 1    
               
               
                 Kevlar Reinforced Polyester 
                 3,752,600   
               
               
                 Monofilament Carbon fibers 
                 15,000,000   
               
               
                   
               
             
          
         
       
     
     The rotor for the proposed power plant must turn at speeds at least up to about 8,000 rpm to 10,000 rpm or more, and more preferably, between 10,000 and 20,000 rpm. It is readily apparent from Table II that not even titanium, with its excellent specific strength characteristics would represent a practical material for rotor construction. However, it is possible to reduce the specific stress encountered, by tapering a rotor element. Nevertheless, it is clear, given the specific stress levels encountered by rotor shapes operating at the speeds required, that commonly utilized metals or metal alloys do not have sufficient specific strength to withstand the loads encountered at the most desirable rotation rates. Newly developed metal matrix composites do provide acceptable strength, however, and can survive the required loads. 
     Carbon fiber reinforced polyester and epoxy composites easily have the specific strength required for service in the instant invention. As indicated in Table II, pure carbon monofilament fiber bundles or “tows” are commercially available with specific strength levels up to 15 million inches, and clearly has a wealth of extra strength capability. Unfortunately, when unprotected, both carbon fiber and epoxy composites lack the capability to resist high temperature exposure. However, if insulated from an oxidizing environment, the carbon tows can accommodate extremely high temperature with only minimal reduction in strength. 
     In one embodiment, the basic rotor structure can be designed and fabricated using both metal matrix composites and carbon or other high strength fiber windings. With proper thermal and oxidative protection, monofilament carbon fiber tows can be combined into a structure with excellent strength and high temperature capability. In the composite design, high strength is provided by continuous monofilament carbon fibers, so as to give the structure sufficient reinforcement to withstand the centrifugal loads encountered. The high specific strengths of the carbon fibers make them quite suitable for the fabrication of stiff, strong, and lightweight composite rotors which can minimize vibrational and static load bending. The carbon fiber windings thus become a central tensile reinforcement element which carries the bulk of all centrifugally induced mechanical loads. As an alternative to use of carbon fiber or other high strength windings, a solid rotor design may be completed utilizing silicon carbide coated carbon fiber metal matrix composite materials. 
     The safety margin for rotor materials can be increased by increased by increasing the material taper ratio. Preferably, in order to minimize the actual loading to the extent practical, the rotor means should be built with high strength materials in shapes which have large material taper ratios. This basically means that at increasing radial station, (further from the axis of rotation), the rotor means should become increasingly slender or thin. Fundamentally, reduction of rotating mass results in reduction of the encountered stress operating at the center of rotation. 
     Attention is now directed to FIGS. 16 and 17, where my power plant is illustrated in conjunction with electrical power generation equipment. The shaft portion  108  acts in conventional fashion to transmit mechanical power to the primary gear-box  104 . The gear-box  104  reduces the speed between shaft  108  and shaft  110  to a sufficiently low level to accommodate the capabilities of the desired application. In FIGS. 1,  16 , and  17 , the primary gear-box  104  is connected by shaft  110  to primary electrical generator  112 , suited to generate electrical power for transmission to a power grid or other electrical load. However, shaft  108  could be applied directly to do desired mechanical work. 
     For starting the ramjet engine, a starter motor  400  is shown connected to gear set  104 . The motor  400  is configured to rotate shaft  108 , and thus rotor  120 , and bring the ramjet thrust modules U up to a convenient tangential velocity so as to enable the start of the ramjets U. Once ramjets U are running, the motor  400  is turned off. 
     Control of fuel supply is also important. Starting, as well as modulating the ramjets U can be accomplished with a secondary fuel  500  supplied via line  502  to injectors  504 . This fuel is lit by a plasma torch  506  or other suitable igniter, preferably in airfoil shape in the inlet air stream, to feed into the ramjet U. Once this secondary fuel supply is started on the ramjet flame holder  214 , the fuel FF is then introduced through injectors  236 . 
     As seen in FIGS. 13,  14 , and  18 , a series of variable position dump valves  600 , here shown as annular gate valves, are provided around the edge of peripherial wall  200 . For starting, the annular gate valve  600  is opened in the direction of reference arrow  602  as shown in FIG. 14, forming a gap  608 , so that a portion of the incoming air which is being compressed against surface  202  of the cooperating peripheral wall  200  can escape outwardly in the direction of arrows  604  and  606 . The unique partially shrouded ramjet U allows the escapement of bypass air  604  and  606 . Once the ramjet U has “swallowed” the shock structure, then the dump valve(s)  600  can be closed by actuator  610 , as illustrated in FIG. 13. I have shown a hydraulic actuator  610  with shaft  612 , mounted by bracket  614   a . However, any convenient dump valve shape, using a mechanical, electrical, or hydraulic actuator, may be utilized as convenient for this purpose. 
     Also shown in FIGS. 16 and 17 is the use, in a combined cycle system, of hot exhaust combustion gases from ramjets U. As shown, the hot exhaust gases are conveniently collected by an exhaust gas duct EXD. The exhaust gas duct EXD is directed to a heat recovery steam generator (HSRG), where steam is produced for driving a steam turbine ST. Steam is generated in the heat recovery steam generator (HSRG) by heating condensate returned from the steam condenser SC via condensate pump CP. This is the commonly encountered design, where the working fluid is water. Although the water is most easily heated to high pressure steam and thereafter used to drive a steam turbine, it can also be used for supply of thermal energy in a co-generation application. Also, as illustrated, the steam turbine ST can be used to produce shaft work for use in electric generator  112 , typically through gear box  104 , or through an alternate electrical generator. Alternately, the steam turbine ST could be utilized to provide shaft work for other purposes. 
     Because the ramjet thrust determines the overall power plant output, the thrust from the ramjet is an important figure of merit for overall plant output levels. The ramjet thrust levels and the overall plant output levels increase in direct proportion with the mass captured and processed by the ramjet. Thus, for the same temperature and pressure conditions, doubling the inlet area and mass capture results in doubling the thrust generated, and thus results in doubling the power output of the system. 
     Finally, even though high combustion temperatures are experienced, my design allows extremely low nitrogen oxide output. This is because of the short residence times at the high combustion temperatures, and because the fuel is extremely well mixed. This shock-boundary layer interaction premixing technique is a unique approach for achieving a near perfectly premixed conditions and low nitrogen oxides emission. Thus, nitrogen dioxide emissions are limited by limiting the size of highly non-equilibrium free-radical zones in the combustor. NOx emissions are estimated to be less than 5 ppm, or EI is less than 0.5 grams of nitrogen dioxide per kilogram of fuel. 
     The method and apparatus for producing mechanical, electrical, and thermal power as described above provides a revolutionary, compact, easily constructed, cost effective power plant. The output from this power plant can be used in conjunction with existing power delivery systems, and represents a significant option for reducing air emissions by combustion of clean burning fuels. Further, given the efficiencies, dramatically less fuel will be consumed per unit of electrical, mechanical, or thermal energy generated. 
     It will thus be seen that the objects set forth above, including those made apparent from the proceeding description, are efficiently attained, and, since certain changes may be made in carrying out the construction of a power generation apparatus and in the execution of the method of power generation described herein, while nevertheless achieving desirable results in accord with the principles generally set forth herein, it is to be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. For example, while I have set forth exemplary designs for a fuel feed arrangement, many other embodiments are also feasible to attain the result of the principles of the apparatus and via use of the methods disclosed herein. 
     All the features disclosed in this specification, including accompanying claims, the drawing, and the abstract, and/or any steps in the method or process so disclosed, may be combined in combination, except combinations where at least some of the features and/or steps are mutually exclusive. 
     Each feature disclosed in this specification (including in the accompanying claims, the drawing, and the abstract), may be replaced by alternative features serving the same or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. 
     Therefore, it will be understood that the foregoing description of representative embodiments of the invention have been presented only for purposes of illustration and for providing an understanding of the invention, and it is not intended to be exhaustive or restrictive, or to limit the invention to the precise forms disclosed. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as expressed in the appended claims. As such, the claims are intended to cover the structures and methods described therein, and not only the equivalents or structural equivalents thereof, but also equivalent structures or methods. Thus, the scope of the invention, as indicated by the appended claims, is intended to include variations from the embodiments provided which are nevertheless described by the broad meaning and range properly afforded to the language of the claims, or to the legal equivalents thereof.