GB2237069A - Gas turbine engine - Google Patents

Abstract

A gas turbine engine comprises a single or multi-stage air turbine 2 rotated by air drawn through a tubular case 1 by a fluid jet ejected e.g. from combustor or other heating means 4 through the outlet of said case. An air compressor 3 supplying compressed air to said combustor or to an equivalent apparatus is driven by said air turbine or optionally by both air turbine 2 and a second such turbine 8 fed with motive fluid derived from a superheater. A propulsive fan may be driven by either or both said turbines, or a gas turbine driven by the products of combustion can drive a mechanical power generator and a means to utilise excess power from the air turbines may also be provided. A hybrid air compressor may also be used embodied. Closed or open cycle operation is referred to as is the use of electrical heaters and steam or carbon dioxide. <IMAGE>

Description

TITLE Improvements in, or relating to, Jet ProPulsion Units This invention is concerned with improvements in or relating to jet propulsion units. Conventional turbojet engines usually employ a fuel combustion air compressor driven by a coupled gas turbine fed by a combustor with the products of the fuel combustion.

This gas turbine is a comparatively heavy construction, the blades of which work at a very high temperature in a corrosive gas (air and combustion gas) working fluid stream. The disadvantages of this system are excessive weight and unreliability in the gas turbine.

My present invention avoids the use of an air compressor driving gas turbine, by this inclusion: in a jet propulsion engine having an air by-pass facility the by-pass air is drawn through the blades of an air turbine provision coupled to and driving the air compressor, which rotates in used by-pass air stream air, to effect the compression of some of this air and its delivery, for example to the combustor of the engine in the appropriate instance or to another heat expansion device, the working fluid of which is finally exhausted downstream of said air turbine and said air compressor and acts as a motive fluid jet system inducing the by-pass airflow through said air turbine. Alternatively, a hybrid by-pass air compressor is provided.

The accompanying drawings are purely diagrammatic illustrations of the main features of examples according to my invention which will now be described further with reference thereto.

In Figure 1, ambient air drawn through an open ended cylindrical tubular case 1 rotates an air turbine 2 positioned in the inlet end of said case and driving an air compressor 3 which receives a portion of the used air leaving said air turbine, compresses this air portion and directs it into a combustor 4 burning liquid fuel in said compressed air and the combustion products from which combustor exit, via nozzle 5, through the outlet end of said case and, after the manner of an ejector, induce said air flow, which is drawn past said air compressor and combustor assembly via an annular space 6 separating this said assembly and the inner wall of case 1.

The second example differs only in the respect that a hybrid air compressor supplies the air for combustion to the combustor 4.

With this hybrid air compressor (Figure 2) the air compressed by air compressor 3 expands therefrom through a nozzle or tail pipe 7 into an axial convergent divergent air inlet (8a) provision of the cornbustor 4, thus entraining extra air from case 1 and feeding the mixture into said combustor.

The mixed air and gas medium in either example generated exhausts from case 1 to utilisation, e.g. to exert a reactive thrust.

The air turbine 2 also provides power to drive ancillary equipment such as fuel pumps, electric generators and, in the jet propulsion configuration, perhaps a propulsive fan optionally positioned forward of case 1 and coupled to said air turbine by an extension shaft.

Extra fuel may be burnt in the air by-passed around combustor 4 in the tail end of case 1. The combustor flame exiting via nozzle 5 ignites this extra fuel which, at high altitude, is preferably burnt in a liquid oxygen enriched airstream, and increases the thrust.

Rings of radial struts (not shown) support the combustor 4 and the air compressor 3 in case 1.

If desired, the compressed air supply to nozzle or pipe 7 is superheated in a heater placed, for example, in the fuel combustion zone of case 1 or combustor 4 or around nozzle 5 in the second example, prior to the delivery of said air to said nozzle or pipe 7. A refinement of this design also uses the superheated compressed air, before its expansion through device 7, Figure 2, to drive a second air turbine coupled to and helping to rotate the rotor of air compressor 3. In this instance the air turbine 2 provides only a portion of the power required to drive said air compressor 3.

Variants of the heat-engines now disclosed with reference to the drawings work partly or exclusively according to the thermodynamic cycles I have previously devised. The air turbine 2 could be fabricated from light alloy or even thermosetting plastic material, thus reducing the total weight of the engine considerably. The air compressor drive shaft could be short, further reducing the engine's total weight and complexity.

The propulsive fan of the first example conversely is rotated partly or exclusively by the second air turbine referred to concerning the second example, a shaft drive to said fan from a said second air turbine placed as shown at 8, Figure 2, through a hollow air compressor (3) shaft being used.

It is practical furthermore to feed the exhaust air of a second air turbine, such as 8, Figure 2, at its reduced pressure directly, i.e. without the use of nozzle or pipe 7, Figure 2, into combustor 4.

Referring again to Figure 2, closure of a ring of louvres 9 obstructs the flow of ambient air past combustor 4, whereupon air turbine 2 is driven only by the such air drawn through case 1 by the action of the compressed air jet expanding through nozzle or pipe 7, this air jet necessarily being superheated air, such as that exhausting from turbine 8, with this method of working, which might be the sole such method used.

Superheated compressed air derived directly from a heater might be fed, to the exclusion of additional air from case 1, into combustor 4 but there is little advantage in this system of working unless a provision to e.g. spray liquid oxygen into said compressed air (to vaporise said liquid oxygen) exists.

The air turbine 2 is mounted on the forward end of the shaft of air compressor 3 which latter assembly has an air intake 10.

Guide vanes 11 direct the ambient air stream induced through case 1 into the blades of air turbine 2, a ring of said vanes being provided.

An air superheater included to e.g. superheat the compressed air supplied to nozzle or tail pipe 7, Figure 2, could be of various design, for example a tube coil, possibly even placed in combustor 4.

In jet propulsion unit embodiments the ambient air displacement through case 1 is enhanced by ram action, due to the relative wind, in the air intake of said case.

Instead of the single stage air turbine 2 an air turbine having several stages may be embodied. The provision of a shortened case 1, Figure 2, the outlet end of which is merely connected to the air inlet of combustor 4 and through which and air turbine 2, ambient air is drawn, discounting any such air impulsion therethrough by ram action, solely by the superheated compressed air jet expanding through nozzle or tail pipe 7, is also envisaged.

The products of combustion or mixture leaving the embodiments according to Figures 1 or 2 optionally drive a turbine mechanical power generator. Other embodiments use either open or closed working fluid circuits and air or gas, e.g. water steam or carbon-dioxide gas, working medium.

The combustor 4, Figures 1 or 2, is preferably equipped with internally placed electrically energised heaters acting to further heat its entrained compressed air and enabling the relevant embodiments to employ, when required and partially or exclusively, an electrically heated working cycle reducing the pollution of the atmosphere by the exhaust efflux of said engines. In a jet propulsion engine embodiment flying at hypersonic speed, such a working cycle could be very efficient. The outlet end of case 1 may likewise be so equipped.

Further contemplated embodiments use a working cycle in accordance with my U.K. Patent specifications Nos.

1100903 and 2086483 and my present invention. In the former instance a hot tube or chamber system could replace combustor 4 of Figure 1 or 2.

Excess power generated by air turbines 2 and 8, Figures 1 and 2, is utilised remotely for any purpose, where required. Concomitantly, said air turbines 2 and 8 (or the like), if air compressor 3 consists of e.g. two spools, may each drive separate such compressor spools1 or a common spool drive is understood.

The angle of incidence of guide vanes 11, Figures 1 and 2, is variable.

In the claims of novelty to follow, the individual working fluid compressor drivers, such as the air turbines 2 and 8, Figures 1 and 2, will be referred to respectively as the turbine" and "the second turbine".

Claims (12)

1. A jet propulsion unit or an adaptation thereof, such as an engine designed specifically to deliver rotary mechanical power, comprising a heat expansion device, for example a combustor, a means for compressing a gas working fluid, for instance ambient air, for entrainment by said heat expansion device, and a provision to drive said gas working fluid compressing means including a coupled gas/air turbine rotated primarily by ambient air or gas drawn through a tubular case surround and the blades of said gas/air turbine and ejected from said case rearwards of said blades.

2. A thermal engine as defined in Claim 1, wherein the means for compressing the gas working fluid is driven partly by an embodied second turbine fed with superheated compressed working fluid derived from said working fluid compressing means and an associated superheater, the said second turbine exhausting its spent working medium directly or through a means entraining additional working fluid from the case surround, into the heat expansion device.

3. A thermal engine as defined in Claim 1, wherein the heat expansion device receives its compressed gas working fluid directly from said medium's compression means, indirectly therefrom via a means fed with said compressed working fluid and acting to entrain thereby and mix additional gas fluid derived from the case surround with said compressed medium and deliver the mixture to said heat expansion device, or indirectly via a such additional working fluid entrainer and mixer but supplied with compressed working fluid the temperature of which is first raised by its passage through a superheater embodied for this purpose.

4. A thermal engine as defined in any of Claims 1 to 3, including a means for entraining additional gas fluid from the case surround and mixing said fluid with the compressed working fluid delivered to the heat expansion device, comprising a nozzle or tailpipe assembly fed with said compressed working fluid, which expands therethrough into the working fluid inlet provision of said heat expansion device, said compressed working medium being at its compression temperature or superheated or at the exhaust temperature of the second turbine.

5. A thermal engine as defined in any of Claims 1 to 4, wherein additional working medium supplied to the heatexpansion device is the sole such fluid quantity drawn through the case surround downstream of the working fluid compress ion means.

6. A thermal engine as defined in any of Claims 1 to 4, including the utilisation of the working fluid exhausting from the heat expansion device to induce or help induce the working medium flow through the case surround, said working medium flow optionally being controllable by a louvre arrangement obstructing, when required, or partially obstructing said medium flow past said heat expansion device.

7. A thermal engine as defined in any one of Claims 1 to 6, including a provision to utilise surplus power generated by the said turbine or turbines remotely, as appropriate.

8. A jet propulsion unit according to any one of Claims 1 to 7, including a propulsive fan driven by either or both the said turbine and second turbine.

9. A thermal engine as defined in any of Claims 1 to 8, wherein guide vanes direct the entrained ambient working fluid into the turbine blade ring system, said guide vanes optionally having a variable angle of incidence.

10. A thermal engine as defined in any of Claims 1 to 9, including the utilisation of power derived from the said turbine to drive associated auxiliary equipment.

11. A thermal engine as defined in any of Claims 1 to 10, including, as appropriate, a turbine mechanical power generator driven by the single or mixed working media exhausting from said engine; a working fluid compressor having one or more spools variously driven; a compressed working fluid superheating means placed for heating by hot generated working medium; solid or hollow working fluid compressor shafts; the use, in a pure jet propulsion engine embodiment, of a liquid oxygen enriched air supply to burn, at high altitude, extra fuel; radial strut supports for air compressor and heat expansion device assemblies in the case surround; a common or separate drive to multiple working fluid compressor spools; a drive to a propulsive fan provision either by a compressor shaft extension or, through a hollow compressor shaft, by a second turbine shaft; the use of open or closed working fluid circuits and a choice of various said fluids; and the utilisation, to provide motive power, of alternative thermodynamic cycles.

12. A continuous cycle thermal engine designed, constructed and working substantially as hereinbefore described with reference to the drawings.