Gas regeneration tesla-type turbine

Abstract

A gas turbine is disclosed. The turbine comprises a casing and a rotor mounted on bearings within the casing. The rotor is of a Tesla-type configuration. Means are provided on the rotor to conduct cooling air to alternate spaces between sets of disc-like blades of the rotor and to conduct a working fluid to opposite alternate spaces between the blades. The air cools the blades and is correspondingly heated. A collecting chamber receives the heated air and conducts it ultimately to a combustion chamber.

Description

BACKGROUND OF THE INVENTION

The invention relates to gas turbines, and more particularly to a Tesla-type spiral flow turbine having a gas regenerator.

The basic Tesla turbine is described in Tesla U.S. Pat. No. 1,061,206. Combustion gases or other pressurized working fluid enter the turbine chamber through a nozzle directed generally tangentially to the outer periphery of a plurality of spaced apart flat disc-like turbine blades. The fluid travels in an inwardly spiraling path while effecting rotation of the turbine blades, and is axially exhausted from openings defined in the blades close to the center of rotation. The efficiency of this type turbine lies in its elimination of sudden changes in the velocity and direction of movement of the fluid which generally occur with turbines having conventional vanes or blades.

Gas regenerators, i.e., means for utilizing the heat present in the exhaust gases from a turbine to heat intake air for combustion, are well known. The regenerators, however, are generally external to the turbine and merely effect a heat exchange between the gases finally exhausted from the turbine and intake air for combustion. See, for example, U.S. Pat. No. 2,784,552. Such a gas regeneration system cannot utilize heat exchange to the full extent with a Tesla-type turbine.

SUMMARY OF THE INVENTION

The invention provides an apparatus which utilizes heat exchange in a Tesla-type turbine to increase nozzle output temperature, system power output, and system efficiency. In addition to an external regenerator, the apparatus includes a second regeneration system amoung the turbine blades themselves. The system facilitates the attainment of very high intake air temperatures at the entrance to the combustion chamber while providing a means for cooling the turbine blades. The cooling of the outer peripheral area of the blades raises the maximum permissible working gas temperature at the nozzle by protecting the blades from adverse effects of high temperature such as melting. With higher gas temperatures at the nozzles, greater power output and efficiency of the turbine is achieved. With the regenerator parameters properly designed and adjusted, cooling of the turbine blades can be accomplished without appreciable cooling of the working gas exiting the nozzles.

According to the present regeneration and cooling system, a plurality of flat, disc-like Tesla turbine blades are stacked in spaced relation on a hollow cylindrical shaft which is mounted for rotation on bearings. Spaces are thus defined between each pair of adjacent blades. Turbine or combustion gas spaces alternate with regeneration or air spaces. Each peripherally sealed turbine space receives expanding combustion gases tangentially from a nozzle. While driving the turbine, these gases spiral inwardly to exhaust ports defined in the hollow rotor shaft. The gases are thus exhausted axially through the rotor shaft toward the external regenerator. Each turbine blade has oppositely disposed openings adjacent the rotor shaft. Spacer ducts around these openings within the turbine spaces provide air commmunication from one air space to the next. Initially compressed air is caused to enter the first such air space and is distributed amoung all the air spaces without being intermingled with exhaust gases, which are sealed in the turbine spaces between pairs of air spaces. The air thus introduced, moves axially along the rotor shaft, then travels spirally and radially outwardly in each air space, being heated as it cools the turbine blades. The cooling of the outer periphery of the blades is most important, since this is the area within the turbine spaces where temperatures are highest. Each blade is cooled from one side. The heated air of the air spaces is collected circumferentially within the turbine housing for admission into an external regenerator for further heating, by interaction with exhaust heat. From the external regenerator, the hot air enters a combustion chamber. In this way, fuel is conserved by the admission of very hot air to the combustion chamber, while at the same time the turbine blades are cooled to allow extra high gas temperatures at the nozzles. With such higher temperatures possible, turbine efficiency is generally increased along with power output.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially sectioned elevational view of a gas regeneration turbine engine according to the invention, indicating gas and air flow paths;

FIG. 2 is a sectional view of the regeneration turbine engine taken along the line 2--2 of FIG. 1, further indicating gas and air flow paths;

FIG. 3 is an elevational view of the engine looking along the line 3--3 of FIG. 1;

FIG. 4 is a diagrammatic view of the turbine and rotor shaft, indicating gas flow paths; and

FIG. 5 is a sectional view of the turbine and rotor shaft taken along the line 5--5 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a gas regeneration turbine engine is diagrammatically shown, generally indicated by the reference number 10. Atmospheric air first enters an air compressor 11 preferably operably connected to a rotor shaft 12 where it is compressed at a ratio of about 2:1. The compressor 11 also introduces a circumferential whirling motion to the air.

As indicated in FIG. 1, and in more detail in FIG. 5, compressed air next flows through an opening 3 in a stationary end disc 14 and enters a plurality of spaces defined by turbine blades 15. The turbine blades 15, of which only a few are indicated herein for clarity, are flat, disc-like plates each having a central bore 16 for stacking the blades 15 on the central rotor shaft 12, as best seen in FIG. 4.

Referring again to FIGS. 1 and 5, the turbine blades 15 define two types of interblade spaces: air or regenerator spaces 20, and turbine or expansion gas spaces 21. The air spaces 20 are in common air communication through openings 24 defined in each blade 15, best seen in FIGS. 4 and 5. There are preferably two openings 24 through each turbine blade 15. FIG. 5, showing a greatly reduced number of interblade spaces 20 and 21 for simplicity, indicates stationary end discs 14 and 25 each forming a boundary of an air space 20, with a turbine blade 15 forming the opposed boundary. It should be understood that in a working embodiment of the turbine engine 10, a much larger number of blades 15, turbine spaces 21, and air spaces 20 would be provided, with turbine blades 15 forming both boundaries of all air spaces 20 except those adjacent the stationary end discs 14 and 25.

The air interblade spaces 20 alternate with the turbine interblade spaces 21, as best seen in FIGS. 1 and 5. To provide the required communication amoung the air spaces 20 and to seal the air spaces 20 from the turbine spaces 21, spacer air ducts 26 are provided within the turbine spaces 21 between adjacent blade openings 24. FIG. 4 shows the spacer air ducts 26 in section. The spacer ducts 26 also act as spacers for the blades 15 in turbine spaces 21. They are retained in aligned relationship by tie rods 27 which penetrate the blades 15 as well as the spacer ducts 26.

Spacers are also interposed in the air spaces 20 to maintain proper interblade spacing therein. These spacers, whose sole function is to maintain the blades 15 in spaced relationship, not shown on the schematic representations herein, since not enough air spaces 20 are shown for inclusion of spacers.

As the compressed air from the compressor 11 enters the air spaces 20, it flows spirally and radially outwardly, primarily due to its compression and to a lesser extent to a minor propulsion effect encountered between the rotating turbine blades 15. This propulsion effect must be kept at a minimum in order to prevent a rapid rise in the temperature of the cooling air as it moves through the air spaces 20. In order to avoid the propulsion effect, the air spaces 20 between the blades 15 are made greater than the turbine spaces 21. This increase in space between the blades 15 reduces the tendency of the blades to frictionally compress the cooling air and inhibits a too-rapid velocity increase as the air moves toward the periphery of the blades 15. The calculated temperature of the compressed air as it enters the air spaces 20 is approximately 170.degree. F. This temperature increase above ambient air temperature is caused primarily by the initial compression at the compressor 11.

After the air from the air spaces 20 has had a cooling effect on the blades 15 and passes the periphery of the blades 15, it is directed into a circular path in a peripheral collection chamber 29, as best seen in FIG. 2. The air from the collection chamber 29 is directed through exit parts 30 and ducts 31 into an external regenerator 32 for heat exchange with exhaust gases, as shown in FIG. 3. Further heated in the regenerator 32, the air then passes through ducts 33 and 34 to combustion chambers 36, where it is mixed with fuel and continuous combustion occurs.

In the combustion chambers 36, the combustion gases encounter great increases in temperature. In the preferred embodiment of the present invention, the temperature of the combusted gases at the nozzle exit is preferably 1900.degree. - 2000.degree. F. The high-pressure, high-temperature gases pass through a plurality of nozzles 37 in each combustion chamber 36, as indicated in FIGS. 1, 2 and 5. Each nozzle 37 is disposed at the periphery of a turbine space 21, and is aimed preferably about 10.degree. below the tangent of the turbine blades 15 at the gases' point of entry. Pressure seals 38 are provided around the periphery of the turbine spaces and are interrupted only by the nozzles 37. Thus, the turbine spaces 21 are sealed so that expanding gases from the nozzles 37 can only travel spirally inwardly in the turbine spaces 21. Although for clarity FIGS. 1 and 5 indicate only a single turbine space 21, a much larger number are provided in practice as discussed above.

The turbine blades 15 defining these turbine spaces 21 encounter extremely high temperatures from the burned gases, especially in the areas close to the outer periphery of the blades 15. The primary purpose of the air spaces 20 is to cool each turbine blade 15 from one side, thus permitting, without damage to the blades 15, higher gas exit temperatures at the nozzles 37. With higher gas exit temperatures permissible, a higher rate of combustion may be maintained in the chambers 36, thus facilitating higher gas temperatures and pressures in the chambers 36, a higher gas exit velocity from the nozzles 37, and greater engine power output. A secondary purpose of the air spaces 20 is to effect heating of the air as it passes through the air spaces 20 toward the collection chamber 29 to additionally heat the air for combustion.

FIG. 4 schematically indicates the path of expanding combustion gases. As the gases spiral through the turbine spaces 21 toward the rotor shaft 12, they perform work on the turbine blades 15, effecting their rotation. This principle is discussed in Tesla U.S. Pat. No. 1,061,206. As distinguished from the Tesla turbine, the spent, decelerated gases approaching the rotor 12 are not exhausted through blade spaces. Instead, the rotor shaft 12 is hollow, with exhaust ports 40 provided directly therein. Preferably two oppositely disposed exhaust ports 40 are located in the rotor 12 in each turbine space 21, between the spacer air ducts 26. Exhaust gases entering the exhaust ports 40, as shown in FIGS. 1, 2, 4 and 5, flow axially through the rotor shaft 12 into an exhaust chamber 41 and duct 42 toward the regenerator 32, which is best seen in FIG. 1. Here its heat is exchanged with air passing through the regenerator 32 from the air spaces 20, as discussed above. The cooled combustion gases are finally exhausted at 43.

As shown in FIGS. 4 and 5, keys 44 are provided in the outer surface of the rotor shaft 18 for engaging the turbine blades 15, which have complementarily shaped openings adjacent the rotor 12. The keys 44 are not continuous along the rotor 12, but are interrupted by the exhaust ports 40, so that they do not block exhaust flow into the hollow rotor shaft 12. The keys 44 may be of a "dove-tail" or "firtree" configuration for gripping the blades 15 against both circular and radial movement with respect to the rotor 12.

In addition to the pressure seals 38 provided around the periphery of the turbine spaces 21, pressure seals must also be provided at points 45 and 46 indicated in FIG. 1, to prevent loss of air or pressurized gases from the system 10.

As shown in FIG. 1, the rotor shaft 12 is supported by bearings 48 which must be as remote as possible from the hot exhaust portion of the rotor shaft 12. The rotor shaft may be somewhat cantilevered from the support bearings 48, as shown in FIG. 1. However, it should be understood that the various components of the turbine engine 10 may be arranged in any convenient manner, FIG. 1 indicating only a preferred arrangement.

The above-described preferred embodiment provides a gas regeneration turbine and turbine engine capable of operating at very high temperatures without damage to the turbine blades, thus generally increasing power output and efficiency over that of most prior art turbine engines. Various other embodiments and alterations to this preferred embodiment will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the following claims.

Claims

We claim:

1. A gas turbine, comprising:

a housing;

a hollow, cylindrical rotatable shaft within said housing and having a plurality of spaced-apart exhaust ports therein;

a plurality of flat, circular turbine blades within said housing and concentrically disposed in spaced relation upon said shaft, defining a plurality of interblade spaces circumjacent said shaft, every second space defining a turbine space disposed about at least one of said exhaust ports, remaining spaces defining air spaces alternating with said turbine spaces, each blade having openings therethrough;

ducts in said turbine spaces sealingly connecting said openings in said blades from one blade to the next, thereby establishing communication among said air spaces;

at least one combustion gas nozzle disposed at the periphery of each turbine space substantially tangentially thereto;

sealing means on said housing in circumferential relationship to said blades for peripherally closing each turbine space from nozzle to nozzle and for isolating the flow of working fluid from each nozzle into the turbine space;

a combustion chamber connected to said nozzles; and

a collection chamber defined by said housing about the periphery of said air spaces leading ultimately to an air inlet of said combustion chamber.

2. The gas turbine of claim 1 which further includes an air compressor disposed to deliver compressed air to said air spaces.

3. The gas turbine of claim 1 which further includes an external gas regenerator having an air inlet receiving air from said air spaces and an air outlet positioned to deliver air to said combustion chamber, and having a combustion gas inlet receiving exhaust gas from said hollow shaft and an outlet disposing of the exhaust gas after its heat exchange with air from said regenerator air inlet.

4. The gas turbine of claim 3 which further includes an air compressor disposed to deliver compressed air to said air spaces.

5. The gas turbine of claim 1 wherein said turbine spaces are narrower than said air spaces.

6. The gas turbine of claim 1 wherein said ducts and blade openings communicating therewith are located contiguous with said shaft and non-coincident with said shaft exhaust ports in said turbine spaces.

7. A gas turbine, comprising:

a housing;

a hollow cylindrical rotatable shaft having a plurality of spaced apart exhaust ports therein;

a plurality of flat, circular turbine blades concentrically disposed in spaced relation upon said shaft, and defining a plurality of interblade spaces circumjacent said shaft, every second space defining a turbine space disposed about at least one of said exhaust ports, remaining spaces defining air spaces alternating with said turbine spaces, each blade having openings therethrough;

ducts in said turbine spaces sealingly connecting said openings in said blades from one blade to the next, thereby establishing communication among said air spaces;

pressure seals attached to said housing in circumferential relationship to said blades across said turbine spaces, each seal being contiguous around the turbine space periphery except at openings defined for combustion gas nozzles;

a collection chamber defined by said housing about the periphery of said air spaces for conducting air from said air spaces.

8. The gas turbine of claim 7 wherein said ducts and blade openings communicating therewith are located contiguous with said shaft and non-coincident with said shaft exhaust ports in said turbine spaces.

9. A turbine comprising a casing and a rotor within said casing, said rotor comprising a rotatable shaft and blades connected circumferentially to said shaft, said blades defining first and second pluralities of alternating spaces therebetween, said first plurality of alternate spaces having means for generally centrally receiving a low temperature cooling fluid and said second plurality of alternate spaces having means for peripherally receiving a high temperature working fluid, means on said casing for peripherally collecting the cooling fluid from said first plurality of spaces, means on said rotor for exhausting the working fluid from said second plurality of spaces, and means on said casing and on said rotor for isolating said first plurality of spaces from said second plurality of spaces whereby each of said blades receiving the working fluid across one side thereof correspondingly receives a cooling fluid, in substantially counterflow relationship, across an opposite side thereof.

10. A turbine comprising a casing and a rotor within said casing, said rotor comprising a central rotatable shaft and blades connected circumferentially to said shaft, said blades defining first and second pluralities of spaces therebetween for alternately receiving a low temperature cooling fluid in said first plurality of spaces and a high temperature working fluid in said second plurality of spaces, means on said casing for isolatingly delivering the working fluid peripherally into said second plurality of spaces, means on said rotor for exhausting the working fluid, means on said rotor for isolatingly delivering the cooling fluid generally centrally to said first plurality of spaces, and means on said casing for peripherally collecting the cooling fluid whereby each blade receiving the working fluid across one side thereof correspondingly receives the cooling fluid across an opposite side thereof.

11. The turbine of claim 10 wherein said working fluid delivering means comprises nozzles on said casing for introducing working fluid into said second spaces and circumferential sealing means on said casing adjacent opposing blades which define each space of said second plurality of spaces for peripherally closing said spaces and isolating said spaces from said adjacent alternate first spaces, said sealing means being contiguous around each turbine space periphery except at openings defined for the nozzles.

12. The turbine of claim 10 wherein said exhausting means comprises an axial exhaust gallery within said shaft and radial orifices defined in said shaft in communication with each space of said second plurality of spaces.

13. A turbine comprising a casing and a rotor within said casing, said rotor comprising a central rotatable shaft and blades connected circumferentially to said shaft, said blades defining first and second pluralities of spaces therebetween for alternately receiving a low temperature cooling fluid in said first plurality of spaces and a high temperature working fluid in said second plurality of spaces, means on said casing for isolatingly delivering the working fluid to said second plurality of spaces, means on said rotor for exhausting the working fluid, means on said rotor for isolatingly delivering the cooling fluid to said first plurality of spaces, said last-named means including hollow spacers each sealingly connected to opposite blades defining each of said second plurality of spaces and orifices defined in each of said blades adjacent said spacers for placing cooling fluid in communication with each of said first plurality of spaces but excluding the cooling fluid from said second plurality of spaces, and means on said casing for collecting the cooling fluid, whereby each blade receiving the working fluid across one side thereof correspondingly receives the cooling fluid across an opposite side thereof.