GB2064010A - Thermal Engine - Google Patents

Abstract

The engine receives air for combustion from a jet type compressor, powered by a number of fluid nozzles 1 and 2 exhausting combustion gas (and/or heated compressed air) and fuel vapour respectively, into the air compression duct 3. <IMAGE>

Description

SPECIFICATION Improvements in or Relating to Thermal Engines Including a Method of Power Generation This invention concerns improvements in or relating to thermal engines and provides a thermodynamic cycle for use with such engines.

Specifically, the improvements relate to for example, jet propulsion units, gas turbine engines and gas generator units comprising one or more combustion chambers receiving air for combustion from a jet type air compressor system powered partly by fuel vapour and partly by another fluid or fluids, such as combustion gas, and the method of operating the air compressor system.

A thermodynamic cycle utilizing heated compressed air to at least partially power the air compressor systems of such engines, is also provided.

This invention provides thermal engines equipped with jet type air compressors of either a single or several stages, each of which stages is powered by a combination of the various power fluids employed to effect the combustion air compression, or with such air compressors having a plurality of stages only some of which are so powered, and a thermodynamic cycle.

Briefly, the air compressor stage or stages have power nozzle systems each consist of several nozzles, some of which are fed with pressurized fuel vapour and others with for example combustion gas under pressure, derived from the fuel burning in the combustion chambers.

Compressed air heated to a temperature higher than that achieved by its compression, alternatively replaces or supplements the combustion gas supplied to some of the power nozzles of each system, or supplements a mixture of said gas and fuel vapour, generated by the injection of liquid fuel into a conduit system conveying such hot gas, so fed to some of said nozzles. Liquid fuel is, in some embodiments of this invention, diffusion vaporized in the compressed hot air supplied to the air compressor power nozzle(s) and perhaps ignited and partially burnt in said hot air prior to its delivery, for example, to said nozzles. The compressed and heated air power fluid supply is obtained either or both from the combustion chamber(s) of the engines and a heater system fed with compressed air and heated directly or indirectly by, for example, the products of the combustion in said chamber(s).The utilization of such heated compressed air power fluid, so obtained, in jet type air compressors for internal combustion engines of the continuous combustion kind, forms a novel thermodynamic cycle not essentially confined in its range of application, solely to thermal engines according to this invention.

The means provided to compress the air to be heated for use as power fluid by the air compressor system, is the air compressor itself or an auxiliary unit, usually of jet type operated by some of the heated air under pressure generated, and incorporated specifically as said means.

Theoretically, the adiabatic efficiency of the main air compressor system of the engine and the overall efficiency of the plant may be improved by this invention, due to the provision in the air compressor of motive fluid jet systems of higher power or/and supplied with pressurized fuel vapour and a comburent medium instead of combustion gas and said vapour, and the greater flow of air induced into the combustor.

According to this invention a thermal engine, such as a jet propulsion unit, a gas turbine engine or a gas generator unit, comprising one or more combustion chambers in which a continuous combustion takes place and receiving air for combustion from a jet type air compressor of one or a plurality of stages, is characterised by the fact that the air compression in the air comressor is effected, in at least one of its several stages in the appropriate instance, by multiple motive fluid jets of pressurized fuel vapour and a further medium or media, for example, combustion gas or such gas mixed with compressed and heated air.

According to a feature of this invention, in such a thermal engine a thermodynamic cycle including the utilization of air compressed and superheated to a temperature above that due only to its compression, as motive fluid in the air compressor or the main air compressor, is employed.

The invention may be applied to various designs of thermal engines of the kinds described, whether the air compressors are single or multiple units in which the multiple motive fluid jets exhaust through single air forcing ducts or whether the air compressors are multiple units in which the motive fluid jets of different media effecting the air compression or a stage of the air compression respectively, in single and multistage such air compressors, exhaust through different air forcing ducts.

The invention will now be described in more detail and by way of non-limitative example with reference to the accompanying drawings in which Figure 1 is a diagrammatic representation of an arrangement according to the invention, in part section, and Figure 2 is an axial part section of a jet propulsion unit working on the new thermodynamic cycle according to the invention.

In Figure 1, combustion gas and fuel vapour expanding through the, respectively, nozzles 1 and 2 into air compression duct 3 of the air compressor, effects the compression of the air for combustion. In the top half of the figure, the nozzle 2 is placed coaxially inside nozzle 1. In the lower half of the figure, nozzle 2 is adjacent nozzle 1. If desired, a ring of said adjacent nozzles 2 or two such nozzles may be provided. Optionally, nozzles 1 and 2 may be supplied with, respectively, compressed and heated air obtained from a heater, such as tube coil 5 or the combustion chamber(s) of the engine, and fuel vapour or vice versa, or fuel vapour and combustion gas. The air heater 5 could be placed in exhaust manifolds, combustion chambers or the flame tubes and be heated by the fuel combustion product.Compressed air can be supplied to heater 5 from combustion chambers or by an auxiliary jet type air compressor operated by some of the heated compressed air from said heater. The nozzle is supplied with combustion gas by conduit 4. Alternative nozzles of a ring of power nozzles could be fed with the various gaseous fluids expanding into duct 3.

Jet type air compressors continuously operated solely by heated compressed air led e.g.

from heater 5, are obviously practical, the fuel supply to the engine being, for example, directly into the flame tubes of its combustion chambers, in this case. If the hot air to power said air compressors is obtained from the engine's combustion chambers, this air could be directed, by suitable internal or external conduits, from the opposite end of these chambers and from the spaces between their walls and their hot flame tubes, which would heat said air to the power nozzles of these air compressors.

Air compressor power nozzles of some other design, such as slot nozzles, may be embodied.

The nozzles 1 and 2 are of circular cross-sectional shape.

The invention may be applied to thermal engines in accord with my U.K. Specification No.

2,021,201 and the like.

All the fluids supplied to nozzles 1 and 2 would, of course, be at high pressure.

Both nozzles 2 may be embodied, as indicated by the discontinuous lines in the lower half of the drawing but, in fact pipe 6 feeds some vaporized fuel into conduit 4, which mixes with the principal fluid conveyed by said conduit, in this part of the figure.

Referring to Figure 2, the second example comprises a combustion chamber 1 which receives air from a jet type air compressor 2 operated continuously by heated compressed air directed by conduits 3 from said combustion chamber to its single power nozzle 4, a convergent duct 5 connecting said air compressor and combustion chamber and through which nozzle 4 exhausts, thus inducing the air flow, which is entrained through tube 6, into chamber 1, and a combustion chamber outlet constituted by a jet propulsion nozzle 7 the inner walls of which may optionally be formed by or incorporate the fuel vaporizing means. The combustion chamber 1 consists of an outer tube 8 and a flame tube 9 placed inside said outer tube and separated from it by an air space through which air flows into said flame tube through inlets 10 and 11 and into conduits 3.The outlet end of the flame tube 9 is cooled by and heats a coiled tube fuel boiler 12 encircling said tube end and encased in synthetic ruby and sapphire elements 13 which conduct heat rapidly to said fuel boiler from tube 9 with which they are also in close contact. Fuel vapour is led under pressure, continuously to an injector nozzle 14 from the boiler 12 and is expanded through this nozzle into a mixing nozzle 1 5 entraining air through the inlets 10, mixing these two fluids and passing the mixture into flame tube 9 and arranged coaxial with said nozzle 14 and tube 9.When starting the working cycle of this example, some of the fuel vapour is let from the boiler 12, which can be supplied with a pressurized volatile fuel, such as butane or propane during this period through a three way valve not shown, to an auxiliary power nozzle 1 6 which exhausts said vapor through duct 5 and with air which mixes with it, into combustion chamber 1. A stop valve 17 regulates the flow of fuel vapour to the auxiliary nozzle 1 6 which acts as the starting means of air compressor 2 in this embodiment, which needs a supply of compressed fluid to its combustion chamber 1 before fuel combustion can take place in flame tube 9 of said chamber and heated air be passed by conduits 3 to the main air compressor power nozzle 4.

The compressed air, which is heated by the hot flame tube 9, passed to conduits 3 Figure 2, helps to cool the section, which is at incandescent temperature, of said tube downstream of its air inlets 11 and prevents overheating of this tube, the material at which might otherwise not withstand the heat of the combustion flame propagated in said section of tube 9.

Fuel vapour could be led continuously to auxiliary nozzle 1 6 if the power nozzle 4 was fed with heated compressed air derived for example, from a heater placed in or around the hot end of flame tube 9 and supplied with compressed air by an auxiliary air compressor, or with combustion gas from tube 9 which could be extended, as shown by the broken lines 18, in these instances, to exclude fuel combustion in the outer tube 8, nozzle 14 being omitted.

The bottom half of Figure 2 shows one form of an optional baffle 19 directing compressed air over the hot end of flame tube 9, conduit 3 being connected to the outer tube 8 or possibly to said baffle, which is positioned in said outer tube, so as to receive the compressed air heated by passage over said tube 9, in which the actual fuel burning proceeds. The top half of this figure illustrates a different baffle 20 acting similarly to direct hot compressed air from tube 8 into conduit 3, the inlet end of which projects longitudinally into said tube in this design.

Liquid fuel is supplied to the boiler 12 during continuous operation, through a pipe 21 and preferably by a mechanical pump, such as a steam pump, or an ordinary injector driven by some of the vapour generated by said boiler. The exhaust vapour from such a mechanical fuel pump could be passed back to the fuel tank and condensed or directed into the entraining tube 6 of air compressor 2 and burnt in the combustion chamber. The auxiliary power nozzle 16 might conveniently be fed with such exhaust vapour in appropriate cases.

The use of heated air to partially power the air compressors of embodiments permits the combustion of a larger amount of fuel in their combustion chambers than may be practical if combustion gas fed air compressors are employed, and therefore, could increase their thrust or power output. However, air compressors operated partially by fuel vapour and partially by both hot air and combustion gas fluids may be embodied, the supply of such hot air being obtained in both cases, either from the combustion chamber or chambers or from a heater system receiving compressed air from said chamber(s) e.g. from outer tube 8 Figure 2, or from an auxiliary air compressor system incorporated specifically or, for example, as one of the stages of the main jet type air compressor, for this purpose.Air heaters of this kind can be positioned in or around any combustion gas fed assemblies, such as the exhaust or collector manifolds of gas turbine engine and jet propulsion unit embodiments, their tail pipes, and the like, and be heated directly or indirectly by said gas or by such gas derived from a combustion process occurring in a separate combustion chamber or chambers installed as their heat source. In the embodiments employing both combustion gas and hot air power fluid in their air compressors, some combustion gas may be mixed with said hot air unavoidably during their working cycle.

The employment of hot air as power fluid in the main jet type aircompressor systems effecting the compression of the air for fuel combustion in the combustion chambers is a novel method of operation of such air compressors and is not limited in its application, to thermal engines according to the present invention.

In the top half section of Figure 2 the gases generated by the fuel combustion in tube 9 expand through nozzle 7 and an air ejector 22, in which latter assembly extra fuel, possibly in vaporized form and fed into its injectors 23, which are supplied by an annular pipe 24, is burnt, when an increased thrust is required after ignition of said extra fuel by the hot gas stream leaving said nozzle. In the lower half section of this figure, the combustion gas passing from tube 9 is merely expanded through the nozzle 7 to produce a thrust reaction.

Another form of fuel boiler would consist of tube coil, such as that shown at 12 Figure 2, but from both ends of which the vaporized fuel would be passed, for example to nozzle(s) 14 or/and 16.

The liquid fuel would be supplied to the centre coil only or to several such coils of the boiler by suitable pipe connection(s). Both ends of the boiler coil could supply e.g. the nozzle 1 6 and pass through apertures and sealing devices, such as packing glands, in the end cover of the combustion chamber 1 Figure 2, to said nozzle or its equivalent provision.

The fuel boiler 12 Figure 2, might similarly be fed progressively with its liquid fuel supply by several supply pipe connections to its coils, supplementing its fuel supply by pipe 21, throughout a part at least of its length. A more effective vaporization of the liquid fuel supplied to the boiler might be obtained in this way.

In another embodiment, the nozzle 4 Figure 2 would be supplied with combustion gas led to it by a modified conduit arrangement from tube 9 or with both such gas and hot air from tube 8 or the heater 5 Figure 1.

Liquid fuel may be injected continuously through suitable atomizers, which may be incorporated in conduits 3 Figure 2, into the hot air streams flowing to nozzle 4 and vaporized and possibly ignited by said hot air and at least partially burnt therein. This fuel could either supplement or serve as the fuel supply of the unit.

Power nozzle arrangements including or consisting of a ring or rings of such nozzles and auxiliary power nozzles, such as those shown at 2 Figure 1 and 1 6 Figure 2, placed adjacent a main power nozzle coaxial with the air duct e.g. ducts 3 and 5 respectively, into which they exhaust, may preferably be aligned, by setting them at a slight angle, with the throat of said air duct to obtain maximum air compression.

Slotted air forcing ducts would require slotted power nozzle systems or for example, a row of several power nozzles of circular bore fed with the various power fluids. It is practical however in both this case and wherein ducts of circular bore are used, in air compressors provided with a plurality of air ducts in for example, each or one of their stages, to supply particular power fluids, such as fuel vapour, exclusively to the power nozzle(s) exhausting through particular air ducts of any one stage or of the only stage of the air compressor or a combination of any of the power fluids employed or several such combinations of said fluids.

The first compression stage, which would be powered in this case by compressed hot air derived from a separate heater, such as the heater 5 Figure 1, of for example, a two stage air compressor, would, in a further specific embodiment, function also as the means for supplying compressed air to said separate heater.

A second portion of the air compressed by the first stage of such an air compressor for example, might furthermore be bypassed therefrom and ejected through e.g. an annular nozzle, to produce an additional propulsive thrust.

Some compressed air might optionally be bypassed from the outer tube 8 of the combustion chamber of jet propulsion unit embodiment described with reference to Figure 2 and utilized as a propellant.

It is impractical to describe here all the possible air compressor arrangements embodying the invention, but their multiple power nozzle systems may include a ring or concentric rings of such nozzles or such nozzle ring(s) positioned around a central nozzle, nozzle(s) adjacent each other or adjacent a main power nozzle, slotted nozzles and combinations of these systems, depending on the actual design of said air compressors, and any desired power fluid supply method.

Instead of the coiled tube assembly disclosed, the heater supplying hot air power fluid to the air compressor, may employ the construction of any known heat exchange device or be a multiple unit comprising e.g. several concentric tube coils.

The invention offers new methods of powering the air compressors of thermal engines, such as jet propulsion units and the like, giving a more effective operation of the engine due to factors, such as heat recovery from the exhaust fluid of gas turbine engine examples by compressed air heaters placed in their exhaust manifolds, a reduction in the working pressure and weight of fuel boilers rendered possible by the use of alternative power fluid quantities to help effect the compression of the air for combustion, and the exclusion of combustion products, in appropriate embodiments, from the compressed comburent and fuel vapour mixture fed by the air compressor to the engine's combustor, (combustion chamber(s)).

Where preferred, the fuel supply pipe 21 Figure 2 of the boiler 12 may pass through a suitable fitting or packing gland, which may be provided in the end cover and air duct 5 assembly of the combustion chamber 1, instead of through the wall of tube 8.

Small installations might pressurize their fuel supply by piping either fuel vapour from their fuel boilers, compressed air from e.g. tube 8 Figure 2 or combustion gas from tube 9 of the same figure, back into their fuel reservoirs.

Jet type fuel pumps could utilize fuel vapor led e.g. from boiler 12 Figure 2, air or combustion gas from the combustion chamber 1 Figure 2 or compressed air obtained from an air heater, such as that shown at 5 Figure 1, as their operating motive fluid.

The facts and methods disclosed will readily be understood by anyone with a knowledge of the art.

Claims (12)

Claims

1. A thermal engine, such as a jet propulsion unit, a gas tubine engine or a gas generator unit, comprising one or more combustion chambers in which a continuous combustion takes place and receiving air for combustion from a jet type air compressor of a single or plurality of stages, characterised in that the air compression in the air compressor is effected in at least one of its several stages in the appropriate instance, by multiple motive fluid jets of pressurized fuel vapour and a further medium or media, for example, combustion gas or such gas mixed with compressed and heated air.

2. A thermal engine in accord with Claim 1, wherein the multiple motive fluid jets of fuel vapour and a further medium or media are expanded through a nozzle assembly consisting of two coaxial nozzles placed one inside the other or through several such nozzle assemblies.

3. A thermal engine in accord with Claim 1, wherein the multiple motive fluid jets of fuel vapour and a further medium or media expand through a nozzle assembly or assemblies each consisting of a plurality of adjacent nozzles and, optionally, coaxial nozzles.

4. A thermal engine in accord with Claim 2, or Claim 3, wherein the further medium utilized as motive fluid by the multiple jets is combustion gas.

5. A thermal engine in accord with Claim 2 or Claim 3, wherein the further medium utilized as motive fluid by the multiple jets is heated compressed air.

6. A thermal engine in accord with Claim 5, wherein liquid fuel is injected into the heated compressed air motive fluid of the multiple jets and possibly ignited and partially burnt therein.

7. A thermal engine in accord with Claim 2 or Claim 3, wherein the further media utilized as motive fluid by the multiple jets is both combustion gas and heated compressed air, mixtures of said gas and air and perhaps fuel vapour, heated compressed air mixed with vaporized fuel, or combinations of these fluid quantities.

8. A thermal engine substantially as hereinbefore described with reference to Figures 1 or 2 of the accompanying drawings.

9. A thermal engine in accord with Claim 1, employing a thermodynamic cycle including the utilization by the air compressor of air, compressed and heated to a temperature in excess of that due to its compression as the further motive fluid medium for effecting air compression therein.

10. A thermodynamic cycle for a continuous combustion thermal engine, such as a jet propulsion unit, a gas turbine engine or a gas generator unit, employing a jet type air compressor to compress the air for combustion feeding its combustion chamber or chambers, including the utilization by said air compressor of air compressed and heated to a temperature exceeding that due to its compression, which is effected either by said air compressor, by an auxiliary such air compressor powered by some of said heated compressed air or by both these units, as its or a part of its motive fluid.

11. A thermal engine in accord with Claim 9 or 10, wherein the heated compressed air utilized as motive fluid by the air compressor is derived either directly from the combustion chamber or chambers or from a separate heater, such as a coiled tube, itself heated directly or indirectly by the combustion gases generated in said combustion chamber(s) and either connected to said chamber(s) and receiving air from them, or to the auxiliary air compressor, which may draw its air from said combustion chamber(s) or from the ambient atmosphere.

12. A thermal engine designed and constructed substantially as hereinbefore described with reference to Figures 1 or 2 of the accompanying drawings.