Rotor assembly having a concentric arrangement of a turbine portion, a cooling channel and a reinforcement wall

The present disclosure introduces a rotor assembly having a concentric arrangement comprising a rotating turbine portion, a cooling channel and an annular reinforcement wall. The concentric arrangement is configured to rotate around a common axis. Also introduced is a rotary engine comprising the rotor assembly, in which the cooling channel further functions as a rotating compressor portion. The rotary engine also comprises a stator assembly that itself comprises a static turbine portion positioned upstream of the rotating turbine portion, a static compressor portion positioned downstream of the rotating compressor portion, and a combustion chamber positioned downstream of the static compressor portion and upstream of the static turbine portion.

TECHNICAL FIELD

The present disclosure relates to the field of gas turbines. More specifically, the present disclosure relates to a rotor assembly comprising a concentric arrangement of a turbine portion, a cooling channel, and a reinforcement wall, and to a rotary engine comprising the rotor assembly.

BACKGROUND

Ramjet engines used in aerospace applications ingest air into an engine inlet at supersonic speeds caused by the forward motion of an airplane or missile. The air is rammed into a smaller opening between a center-body and an engine side wall generating a series of shock waves. These shock waves compress and decelerate the air to subsonic speeds while, at the same time, dramatically raising working flow pressure and temperature.

The ramjet effect may also be achieved in a stationary platform by passing an accelerated flow of air over raised sections machined on the rim of a rotor disc. Combined with the high rotation rate of the rotor, this produces a supersonic flow relative to the rotor rim. Interaction between the raised sections of the rim which are rotating at supersonic speeds and the stationary engine case creates a series of shock waves that compress the air stream in a manner similar to ramjet inlets on a supersonic missile or aircraft.

The advent of carbon composite and like materials has enabled the introduction of a rotating reinforcement wall, called rim-rotor, for compensating centrifugal forces generated by rotating components of the ramjet engine. In a rim-rotor rotary ramjet engine (R4E), inlet blades compress the air and fuel mixture with shockwaves, combustion takes place to increase the flow enthalpy and finally the products are accelerated by outlet blades at a high tangential speed to generate shaft power. An example of such an engine is described in U.S. Pat. No. 7,337,606, the disclosure of which is incorporated herein in its entirety.

Increased power density from a simple and compact engine design is still a desirable goal and improvements to gas turbines are still being sought.

SUMMARY

The present disclosure introduces a rotor assembly comprising a concentric arrangement of a turbine portion, a cooling channel and an annular reinforcement wall, the concentric arrangement being configured to rotate around a common axis.

According to the present disclosure, there is also provided a rotary engine comprising a rotor assembly that, in turn, comprises a rotating turbine portion positioned for revolving around an axis of the rotary engine, a rotating compressor portion encircling the rotating turbine portion, and an annular reinforcement wall encircling the rotating compressor portion. The rotary engine also comprises a stator assembly that, in turn, comprises a static turbine portion positioned upstream of the rotating turbine portion for communication therewith, and a static compressor portion positioned downstream of the rotating compressor portion for communication therewith. The rotary engine further comprises a combustion chamber positioned downstream of the static compressor portion and upstream of the static turbine portion for communication therewith.

The present disclosure also provides a rotor assembly for a rotary engine. The rotor assembly comprises a rotating turbine portion positioned for revolving around an axis of the rotary engine, a rotating compressor portion encircling the rotating turbine portion, and an annular reinforcement wall encircling the rotating compressor portion.

The present disclosure further relates to a rotor assembly for a rotary engine. The rotor assembly comprises a rotating turbine portion positioned for revolving around an axis of the turbine stage, a cooling channel encircling the rotating turbine portion, and an annular reinforcement wall encircling the cooling channel.

The foregoing and other features will become more apparent upon reading of the following non-restrictive description of illustrative embodiments thereof, given by way of example only with reference to the accompanying drawings.

DETAILED DESCRIPTION

The present disclosure introduces a rotor assembly comprising a concentric arrangement of a turbine portion, a cooling channel and an annular reinforcement wall, the concentric arrangement being configured to rotate around a common axis.

The present disclosure also introduces a rotor assembly for a rotary engine. The rotor assembly comprises a rotating turbine portion, a rotating compressor portion and an annular reinforcement wall. These elements are stacked one on top of the other in a concentric fashion, with the rotating turbine portion revolving around an axis of the rotary engine, the rotating compressor portion encircling the rotating turbine portion and the annular reinforcement wall encircling the rotating compressor portion.

Also introduced is a single stage, high power density rotary engine that comprises a single rotor assembly as described hereinabove. The rotary engine also comprises a stator assembly that itself comprises a static turbine portion positioned upstream of the rotating turbine portion and a static compressor portion positioned downstream of the rotating compressor portion. Gases may flow between the rotating and static compressor portions and between the static and rotating turbine portions. A combustion chamber is positioned downstream of the static compressor portion and upstream of the static turbine portion. Gases from the compressor may flow into the combustion chamber and therefrom into the turbine.

The rotating and static compressor portions may for example form a supersonic impulse compressor while the rotating and static turbine portions may form a supersonic impulse turbine, the rotary engine thus forming a supersonic gas turbine engine; other turbine configurations depend in a large part on geometries of blades within the are rotating and static compressor portions and also within the scope of the present disclosure. The rotary engine may comprise an inlet for delivering air into the rotating compressor portion, a fuel injection system for delivering fuel in the rotary engine, an ignition system for igniting an air and fuel mixture and an outlet for expelling combustion products from the rotating turbine portion. In an embodiment, air delivered through the inlet is accelerated by the rotating compressor portion. The static compressor portion then slows down the air, also increasing its pressure, before its admission into the combustion chamber. Following combustion of the air and fuel mixture in the combustion chamber, the static turbine portion converts a resulting pressure of the combustion products into kinetic energy. The rotating turbine portion then retrieves the kinetic energy from the static turbine portion. Depending on intended applications of the rotary engine, the kinetic energy may be converted into mechanical torque at an output shaft connected to the rotor assembly. For other applications, combustion products may be expelled from the rotating turbine portion, through the outlet, at a high kinetic energy level for generating thrust. In applications that generate engine thrust, the outlet may be positioned axially on the rotary engine while the inlet may be positioned radially on the rotary engine.

The annular reinforcement wall is made of resistant materials to compensate centrifugal forces generated by other components of the rotor assembly. Those of ordinary skill in the art having the benefit of the present disclosure will be able to select available materials capable of withstanding high temperatures. Combustion products flowing from the combustion chamber into the turbine are very hot. The rotating compressor portion shields the annular reinforcement wall from heat present in the rotating turbine portion.

Optionally, the combustion chamber may comprise one or more flameholders for stabilizing combustion of the air and fuel mixture. According to another option, the rotor assembly may comprise a protective layer positioned between the rotating compressor portion and the annular reinforcement wall.

As used herein, the expression “single rotor assembly” reflects the fact that the rotary engine may operate with at least one rotor. Of course, variations of the rotary engine may further comprise additional rotors used for the same or other purposes as the above described rotor assembly. As an example, the combustion chamber may optionally be made to rotate on a same axis as the rotor assembly.

The present disclosure further introduces a rotor assembly for a turbine stage of a rotary engine. This rotor assembly comprises a rotating turbine portion, a cooling channel and an annular reinforcement wall. These elements are stacked one on top of the other, in a concentric fashion, with the rotating turbine portion revolving around an axis of the rotary engine, the cooling channel encircling the rotating turbine portion and the annular reinforcement wall encircling the cooling channel.

Various embodiments of rotary engines and rotor assemblies, as disclosed herein, may be envisioned. One such embodiment is shown onFIG. 1, which is a side elevation, cutaway view of an example of rotary engine. A rotary engine100according to an embodiment comprises an air inlet102, a rotor assembly104rotating about an axis106of the rotary engine100, a stator assembly108, a combustion chamber110, an outlet112for burnt combustion products, and an output power shaft114for outputting power from the rotary engine100. The rotor assembly104, which may be mounted on a single hub120or on a pair of hubs120, comprises an outer, annular reinforcement wall122, also called a rim-rotor. The annular reinforcement wall122surrounds a rotating compressor portion118that itself surrounds a rotating turbine portion116mounted on the hubs120. The annular reinforcement wall122, the rotating compressor portion118, the rotating turbine portion116the hubs120are thus arranged in a concentric fashion and revolve about the axis106. The output power shaft114extends from the hubs120. The rotor assembly104, the hubs120and the output power shaft114all revolve about the rotation axis106. The stator assembly108comprises a static compressor portion124and a static turbine portion126. The combustion chamber110comprises a plurality of flameholders128.

Air is forced into the rotary engine100through the inlet102and into the rotating compressor portion118. High velocity air is delivered from the rotating compressor portion118into the static compressor portion124where kinetic energy of the air is converted into pressure. Air then enters the combustion chamber110at a relatively low velocity and at a high pressure. Fuel is delivered by an injection system (not shown) either within the inlet102, within the static compressor portion124or directly into the combustion chamber110. Ignition is initiated by an ignition system (not shown). One or more flameholders128within the combustion chamber110help stabilizing combustion of a mixture formed by the air and the fuel. Gaseous burnt combustion products are expelled from the combustion chamber110at very high temperature and pressure. The static turbine portion126converts this gas pressure into kinetic energy that is then retrieved by the rotating turbine portion116. The output power shaft114being connected to the rotor assembly104via the hubs120converts the kinetic energy into mechanical torque, for turboshaft applications. A cone130guides the burnt combustion products from the rotating turbine portion116through the outlet112. As shown inFIG. 1, a majority of parts of the rotary engine100are enclosed within a casing132.

Those of ordinary skill in the art will appreciate that the rotary engine100may be adapted for turbofan applications where engine thrust is desired, for example for applications in which jet propulsion is desired. Adaptations of the geometries and sizes of the static and rotating compressor and turbine portions may be made so that the combustion products are expelled from the rotating turbine portion116, through the outlet112, at high kinetic energy level for generating thrust. In such applications, some mechanical torque may still be present on the output power shaft114, for example for purposes of driving ancillary equipment (not shown) attached to the rotary engine110. In thrust generating applications, the rotary engine110ofFIG. 1may be modified so that the air inlet102is moved away from the outlet112, for example by generally positioning the inlet102radially on the casing132while the outlet112remains positioned along the rotation axis106.

FIG. 2ais a detailed view of a compressor as in the rotary engine ofFIG. 1.FIG. 2bis a detailed view of a turbine as in the rotary engine ofFIG. 1.FIGS. 2aand 2bmay be considered at once for understanding of the way gas flows through various parts of the rotary engine100; however, scaling is approximate betweenFIGS. 2aand 2b. Also, it should be understood that the rotating turbine portion116is inserted co-axially within the rotating compressor portion118while the static turbine portion126is inserted co-axially within the static compressor portion124. Additionally, rotating and static parts of the compressor (FIG. 2a) and of the turbine (FIG. 2b) are shown as if separated by large spacings. As shown earlier inFIG. 1, these elements are in fact closely adjacent to each other.

The rotating compressor portion118comprises blades170, the static compressor portion124comprises blades172, the rotating turbine portion116comprises blades174, and the static turbine portion126comprises blades176. The various blades of the compressor and turbine portions are shaped according to their intended usage. As illustrated, the blades170and172of the rotating compressor portion118and of the static compressor portion124are shaped to provide a supersonic compressor generating chock waves in the stator assembly108. Other geometries and configurations (not shown) of the blades170and172may provide a supersonic compressor with chock in the rotor, an impulse compressor, a reaction compressor, a subsonic compressor, an impulse turbine, a reaction turbine, and the like. Yet other geometries and configurations (not shown) of the blades170and172may be such that the blades170and172channel air toward the turbine without substantially compressing the air, as will be explained in more details hereinbelow. The shapes of the blades as illustrated onFIGS. 2aand 2bas well as on other Figures are given for the purpose of example only and it is expected that those of ordinary skill in the art will be able to build other shapes of blades according to the needs of specific applications.

The rotating compressor portion118revolves at a high speed. Air from the inlet102enters in a direction indicated by arrow200at low speed and at atmospheric pressure. The blades170induce the air to exit the rotating compressor portion118at high speed, for example at 1000 meters per second, in the direction of arrow202. The air then flows through the static compressor portion124where the blades172force the air to adopt a high pressure and a low speed, exiting in the direction of arrow204, to then enter the combustion chamber110. Combustion products from the combustion chamber110enter the static turbine portion126, in a direction indicated by arrow206, at high pressure and low speed. This pressure in converted into kinetic energy by the blades176within the static turbine portion126. The combustion products follow the direction of arrow208into the rotating turbine portion116where the kinetic energy is retrieved by the blades174. The combustion products then exit the rotating turbine portion126in the direction of arrow210toward the outlet112. The combustion products may exit the rotating turbine portion116. The combustion products are expelled at a relatively low speed for applications where mechanical torque is transferred by the turbine onto the output power shaft114. Alternatively, for thrust generating applications, the rotary engine100may be considered a gas generator and the combustion products may be expelled while still having significant energy in terms of pressure or in terms of velocity. In other embodiments, kinetic energy left in the flow exiting the rotating turbine portion116may be retrieved using a second stage turbine (not shown) revolving at a different speed from that of the rotor assembly104, the second stage turbine transferring the leftover kinetic energy to the output power shaft114or to another output shaft.

FIG. 3ais a rear perspective, partial cutaway view of the rotary engine ofFIG. 1.FIG. 3bis another rear perspective, partial cutaway view of the rotary engine ofFIG. 1, showing details of a stator assembly. BothFIGS. 3aand 3bshow details of the annular reinforcement wall122.FIG. 3aprovides a perspective of the rotating turbine portion116and of the rotating compressor portion118whileFIG. 3bhighlights details of the static compressor portion124and of the static turbine portion126.

FIG. 4ais a front perspective, partial cutaway view of the rotary engine ofFIG. 1.FIG. 4bis a front elevation, partial cutaway view of the rotary engine ofFIG. 1. BothFIGS. 4aand 4bshow a support136for the cone130, as well as some more details of the rotor assembly104.

FIG. 5is an exploded view of an example of rotor assembly. In addition to the annular reinforcement wall122, the rotating compressor portion118and the rotating turbine portion116, the rotor assembly may comprise a protective layer140inserted between the rotating compressor portion118and the annular reinforcement wall122. The annular reinforcement wall122supports the rotating turbine and compressor portions in compression, unlike traditional turbine engines in which rotating components are primarily supported in tension from their rotational axis. At high angular velocity, compressive stress in blades170of the rotating compressor portion118may damage the annular reinforcement wall122. To avoid this problem, the protective layer140formed of a thin layer of metal, or any other suitable material, may in an embodiment be added between the rotating compressor portion118and the annular reinforcement wall122to distribute local high stresses from the blades170over a broader area of the annular reinforcement wall122. Alternatively, the protective layer140may be machined or integrated directly on top of the blades170, as a part of the rotating compressor portion118.

At high angular velocity, the rotating compressor portion118, the rotating turbine portion116and the annular reinforcement wall122may not expand equally. Additionally, due to the difference in material properties, a high difference in temperature between these components might be detrimental to the integrity of the rotor assembly104.FIG. 5further shows an optional manner of building the rotating compressor portion118, the rotating turbine portion116and the protective layer140. Any or all of these components of the rotor assembly104may be formed of complementary sections such as sections141of the protective layer140, sections119of the rotating compressor portion118and sections117of the rotating turbine portion116. The various sections117,119and141may thus independently expand as the rotational speed of the rotor assembly104increases.FIG. 5also shows that the hubs120may comprise studs121adapted to slide into grooves123of the rotor assembly104, allowing some deformation of the ensemble.

FIG. 6is a partial perspective view of a rotor assembly according to an embodiment. All elements shown onFIG. 6have been introduced hereinabove.FIG. 7shows temperature gradients on a part of the rotor assembly ofFIG. 6. Temperatures shown are in degrees Celcius (° C.). Indicia a-i reflect temperature values present on various parts of the rotor assembly104, from a minimum of 50° C. to a maximum of nearly 700° C. The protective layer140is not distinguishable from the annular reinforcement layer122onFIG. 7because these two elements are substantially at a same temperature level. Thermal analysis of the rotary engine100in operation shows that central parts of the rotating turbine portion116are hottest, nearing 700° C. (indicia i). This temperature level could be quite damageable to the annular reinforcement layer122, especially if it is constructed from a composite material such as for example unidirectional carbon fibers, monofilament carbon fibers, high strength fiber windings without a linking matrix, and the like. The construction of the rotor assembly104prevents overheating of the annular reinforcement layer122owing to the placement of the rotating compressor portion118between the annular reinforcement layer122and the hot rotating turbine portion116. Due to the flow of air from the inlet102being accelerated therethrough, the rotating compressor portion118acts as a heat insulator, or shield, between the rotating turbine portion116and the annular reinforcement layer122, the latter showing a temperature of about 50° C. (indicia a). It may be observed from the thermal analysis illustrated onFIG. 7that, in addition to compressing the flow of air from the inlet102, the rotating compressor portion118further acts as a cooling channel, shielding the annular reinforcement layer122from the high temperatures of the rotating turbine portion116.

FIG. 8is a partial cutaway view of a stator assembly and of a combustion chamber according to an embodiment. A bleeding system (not shown) may be installed in the static compressor portion124to allow proper inlet starting at supersonic flow speeds, as is well-known in the art. This bleeding system may comprise a passive system of perforated inlets located radially on the stator assembly108or an active system using manually activated holes also located radially on the stator assembly108. A flow of air or a premixed flow of air and fuel exits the static compressor portion124at an angle of approximately 45 degrees, with a speed of several meters per second. As the flow turns about 180 degrees from the static compressor portion124, through the combustion chamber110and toward the static turbine portion126, a high centrifugal force gravity field (g-field) is created. The combustion chamber110takes advantage of this high g-field to increase its combustion efficiency and combustion speed. Reactants enter the combustion chamber110at high pressure and turn toward the static turbine portion126, generating the g-field. Positive flameholders128are located on an outer part of the combustion chamber128and oriented in a direction of the flow in order to fully take advantage of the g-field. The flameholders128stabilize the flame during the turn.

The combustion chamber110may operate with premixed air and fuel or in a non-premix configuration. In a premix configuration, fuel may be added to the flow of air in the static compressor portion124or upstream thereof. In the non-premix configuration, a fuel injection system (not shown) is proximate to the flameholders128within the combustion chamber110, in its curved part, taking advantage of the g-field to increase combustion speed.

Internal functions of the combustion chamber110are further shown inFIG. 9, which is a schematic illustration showing a flame front in a combustion chamber comprising a flameholding system. Reactants140comprising a mix of air and fuel enter the combustion chamber. Reactants140ignite at an ignition point142downstream from a given flameholder128and are pushed in a downward direction, toward the rotation axis106, by the flameholder128. A flame front generally follows a direction144and is driven toward the rotation axis106, reaching a flame front end146substantially near an internal radius of the combustion chamber110. Combustion products148are expelled toward the static turbine portion126. An arrow labeled “g” indicates a general direction of the g-field forces.

The combustion chamber110may be static, for example by being fixedly connected to the stator assembly108. In some embodiments, the combustion chamber110may rotate within the casing132. Returning toFIG. 1, as an example of a system for allowing the combustion chamber110to rotate, a gear set134may connect the output shaft114to the combustion chamber110in order to drive the combustion chamber110to rotate in a direction opposite to that of the rotor assembly104, at the same or at a different speed of rotation. Those of ordinary skill in the art will appreciate that the combustion chamber110may be driven to rotate by other means and that the mention the gear set134is for the purpose of illustration only with no intent to restrict the scope of the present disclosure. This rotation of the combustion chamber110may be used to increase the g-field in the combustion chamber110, in order to increase combustion speed. A pressure ratio of the combined rotating and static compressor portions is increased as the speed of air getting into the static compressor portion124increases due to the counter-rotation of the combustion chamber110. Rotation of the combustion chamber110may thus allow reducing a rotational speed of the rotor assembly104. Alternatively, rotation of the combustion chamber110may be used to increase the pressure ratio of the combined rotating and static compressor portions.

FIG. 10shows details of an example of gas sealing system between static and dynamic parts of the rotary engine ofFIG. 1. Seals may be used to ensure that the air or the mixture of air and fuel and that resulting combustion products remain in a flow path of the rotary engine100, from the inlet102through the rotor assembly104to the stator assembly108and from the stator assembly108through the rotor assembly104and to the outlet112. An embodiment of the rotary engine100may thus comprise a sealing system for reducing gas leaks from the rotating compressor portion118toward the annular reinforcement wall122or toward the rotating turbine portion116. In the same or other embodiment, the rotary engine100may further comprise a sealing system for reducing gas leaks from the rotating turbine portion116toward the rotating compressor portion118or toward the hubs120. Two types of seals may be used in some embodiments of the rotary engine100: a labyrinth seal150and a viscous pump152. The structure of the labyrinth seal150maximizes a length of the flow path therethrough and minimizes the height of the path as shown onFIG. 10. The viscous pump152has blades that build a pressure gradient to equilibrate a difference in pressure and centrifugal forces. Viscous pumps152may be used to reduce pressure in parts of the rotary engine100, for example in the area of the hubs120, in order to reduce drag.

Some embodiments of the sealing system may comprise one or more viscous pumps152. In other embodiments, one or more labyrinth seals150may form the sealing system. In yet other embodiments, combinations of the viscous pump152and of the labyrinth seals150may be present in the sealing system. Placement of the labyrinth seals150and of the viscous pump152may be interchanged. Therefore, placement of the labyrinth seals150and of the viscous pump152as shown onFIGS. 10 and 11is for illustration purposes and is not intended to limit the present disclosure.

FIG. 12is a detailed view of a drag and wall temperature reduction system according to an embodiment. Drag opposing rotation of the rotor assembly104is reduced, in the embodiment ofFIG. 12, by the injection of a light gas in a cavity160between the annular reinforcement wall122and the casing132. The light gas, which may for instance be hydrogen or similar gas also re-used as a gaseous fuel for the rotary engine100, is injected in the cavity160via injection holes162. Convergent-divergent conduits (not shown) may lead to the injection holes162in order to accelerate a speed of the gas entering the cavity160. The gas may enter the cavity160at a high tangential speed in order to align at least in part with a direction of rotation of the rotor assembly104. This use of the light gas injected in the cavity160tends to reduce supersonic drag around the rotor assembly104, reducing shear stress on the annular reinforcement wall122while also providing some level of cooling of the annular reinforcement wall122. This effect, which is a characteristic of a reduced gas density and of a reduced Mach number of the flow, further provides a reduction in total temperature of the flow. Drain holes (not shown) on a wall of the casing132opposite from the injection holes162collect the gas from the cavity160and, if this gas is to be used as a fuel, channel the gas toward the fuel injection system introduced hereinabove. If a liquid fuel, for example kerosene, is used in the rotary engine100, air may be delivered to the cavity160via the injection holes162instead of a gaseous fuel.

The manner presented hereinabove of using the rotating compressor portion118to shield the annular reinforcement wall122from heat generated by the rotating turbine portion116underneath may also be used for reducing a required bleed in a first stage turbine of regular gas turbine. To this end, the blades170and172of the rotating and static compressor portions118and124may be modified, when compared to those shown onFIGS. 2aand 2b, to form a thinner, bladed and substantially non-compressing channel, in which the rotating compressor portion118becomes a non-compressing cooling channel118. The resulting rotor assembly may then become a turbine stage for a gas turbine. In such a case, the turbine stage and the cooling channel are supported in compression by the annular reinforcement wall. Therefore, it may be possible to use low-tensile resistant materials, such as for example ceramics, to build the blades of the cooling channel, owing to the compression support in the annular reinforcement wall.

Those of ordinary skill in the art will realize that the description of the rotary engine and rotor assembly are illustrative only and are not intended to be in any way limiting. Other embodiments will readily suggest themselves to such persons with ordinary skill in the art having the benefit of the present disclosure. Furthermore, the disclosed rotary engine and rotor assembly may be customized to offer valuable solutions to existing needs and problems of gas turbine design.

In the interest of clarity, not all of the routine features of the design and implementation of the rotary engine and rotor assembly are shown and described. It will, of course, be appreciated that in the development of any such actual implementation of the rotary engine and rotor assembly, numerous implementation-specific decisions may need to be made in order to achieve the developer's specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the field of gas turbines having the benefit of the present disclosure.

Although the present disclosure has been described hereinabove by way of non-restrictive, illustrative embodiments thereof, these embodiments may be modified at will within the scope of the appended claims without departing from the spirit and nature of the present disclosure.