Turbine with supersonic transition in the rotor

Abstract

The present invention relates to a turbine comprising a stationary part and a rotor, said stationary part being upstream of the rotor in the direction of the flow of a fluid passing through the turbine. The rotor comprises a plurality of blades (10), the minimum fluid passage cross-section between the rotor blades constituting a sonic throat. Furthermore, the cross-section of each blade is delimited by an upper surface (3) and an lower surface (4), the upper surface (3) and the lower surface (4) originating from the same leading edge (1) and converging at the same trailing edge (2'). The lower surface (4) or the upper surface (3) comprises a first curved portion (6) from the leading edge (1) to a point of intersection (A) and a second curved portion (5) from the point of intersection (A) to the trailing edge (2'). Moreover, the tangent of the first curved portion (6) forms a non-zero angle with the tangent of the second curved portion (5). Figure 2 to be published

Description

Title of the invention: Turbine with supersonic transition in the rotor technical field

[0001] The invention relates to supersonic turbines, more particularly in applications where the inlet temperature of the fluid in the turbine is relatively low, such as Rankine cycle circuits, fuel cells or internal combustion engines, especially low-rich ones.

[0002] Thus, the invention relates to the field of turbomachinery and energy recovery. Previous technique

[0003] Turbines are used in many applications to transform the energy of the fluid into rotary mechanical energy, which can itself be transformed into electricity, for example.

[0004] Generally, turbines operate with fluid flow velocities that are well below the speed of sound (i.e., below a Mach number of 1). However, at these flow velocities, it is necessary to rotate the turbine very quickly. This has the disadvantage of requiring bearings and / or bushings that operate with oil or grease to avoid significant friction and associated heating.

[0005] In the past, some supersonic turbines have been developed. Most of these turbines have a stator in which the flow becomes supersonic: this is the case, for example, in patent applications US2010 / 329856 and EP3812560. For these turbines, the transition to supersonicity occurs in the stator, and consequently, the fluid entering the rotor reaches a supersonic speed (greater than the speed of sound, i.e., greater than a Mach number equal to 1). As a result, these turbines have significant pressure losses, which leads to a loss of turbine efficiency.

[0006] US patent application 3314647A is also known, which relates to a turbine that may or may not have a stator and whose supersonic transition may be achieved in the stator or in a rotor stage. However, this patent application does not control the shock waves that may occur, which may generate vibrations detrimental to the rotor's dimensions, and which may generate a subsonic output speed.

[0007] Thus, the technical problem consists of improving the control of shock waves that can occur in the rotor in order to improve the performance of the turbine.

[0008] To address this, the invention relates to a turbine comprising a stationary part and a rotor, the stationary part being upstream of the rotor in the direction of the flow of a fluid capable of passing through the turbine (otherwise, the turbine is configured so that a fluid passing through it first passes through the stationary section and then the rotor). The rotor is capable of rotating about an axis of rotation and comprises a plurality of blades extending in a substantially radial direction with respect to the rotor's axis of rotation. The minimum fluid passage area between the rotor blades constitutes a sonic throat for given operating conditions of the turbine. Furthermore, the cross-section of each blade is delimited by an upper surface (extrados) and an lower surface (intrados), the upper and lower surfaces originating from the same leading edge and converging at the same trailing edge. The lower surface and / or the upper surface comprises a first curved portion from the leading edge to a point of intersection and a second curved portion from the point of intersection to the trailing edge.Furthermore, the tangent (to the intrados and / or extrados) of the first curved part forms a non-zero angle (between 1° and 179°) with the tangent (to the intrados and / or extrados) of the second curved part. Summary of the invention

[0009] The invention relates to a turbine comprising a stationary part and a rotor, said stationary part being upstream of the rotor in the direction of the flow of a fluid in the turbine, the rotor being capable of rotating about an axis of rotation and comprising a plurality of blades extending in a substantially radial direction with respect to the axis of rotation of the rotor, the minimum fluid passage cross-section between the rotor blades constituting a sonic throat for determined operating conditions of the turbine, the blades being configured so that the total pressure at the inlet of the blades is always greater than the static pressure at the outlet of the blades so as to generate a flow and the blades being configured so that the ratio between the total inlet pressure and the static outlet pressure is greater than or equal to the ratio between the total pressure pO at the throat and the static pressure p* at the throat,The cross-section of each blade is delimited by an upper surface (extrados) and an upper surface (intrados), the upper and lower surfaces of the cross-section of each blade extending from a leading edge to a trailing edge. Each of the upper and lower surfaces comprises a first curved portion from the leading edge to a point of intersection and a second curved portion from said point of intersection to the trailing edge. Furthermore, the tangent (to the upper or lower surface) of the first curved portion forms a non-zero angle with the tangent (to the upper or lower surface) of the second curved portion.

[0010] Preferably, the second curved part is a first straight line segment.

[0011] According to a variant of the invention, the first straight segment is inclined with respect to to the plane orthogonal to the velocity of movement of the fluid at the trailing edge of an angle of inclination between 2 and 80°, preferably between 2 and 30° and even more preferably between 5 and 15°.

[0012] Advantageously, the other of the intrados and extrados comprises a first curved portion from the leading edge to a crossing point and a second curved portion from said crossing point to the trailing edge, characterized in that the tangent of the first curved portion forms a non-zero angle with the tangent of the second curved portion.

[0013] Preferably, the second curved portion is a second straight segment.

[0014] Preferably, the second straight segment is inclined with respect to the plane orthogonal to the velocity of movement of the fluid at the trailing edge by an angle of inclination between 2 and 80°, preferably between 2 and 30° and even more preferably between 5 and 15°.

[0015] According to one configuration of the invention, the stationary part comprises a stator and / or a volute, preferably the stationary part being configured to operate exclusively in subsonic flow.

[0016] Advantageously, the determined operating conditions include the mass flow rate of the fluid at the turbine inlet, the total pressure at the turbine inlet, the total temperature at the turbine inlet, the static pressure at the turbine outlet and preferably the total temperature at the turbine inlet and / or the total temperature at the turbine outlet.

[0017] According to one embodiment of the invention, the rotor includes a ring consisting of a ring connecting the radial ends of the blades.

[0018] According to one embodiment of the invention, the blades are oriented at a deflection angle relative to the direction of said fluid at the leading edge so as to generate a change in the direction of the flow of the fluid through the blades, the deflection angle being preferably between 5° and 70° and even more preferably between 5° and 50°.

[0019] Advantageously, the rotor section at the rotor outlet is reduced compared to the rotor section just after the blades.

[0020] The invention also relates to a fuel cell comprising a turbine as described above, the turbine preferably being positioned on an output line of the fuel cell, the output line being configured to produce steam.

[0021] The invention also relates to a Rankine cycle circuit comprising a turbine as described above, preferably the circuit comprising a compressor, an evaporator, the turbine and then a condenser.

[0022] Furthermore, the invention also relates to an internal combustion engine, in particular an internal combustion engine operating with a fuel-air ratio of less than 0.8, preferably less than 0.4, comprising a turbine as described above at the exhaust outlet of the internal combustion engine, preferably the turbine being that of a turbocharger. List of figures

[0023] Other features and advantages of the device according to the invention will become apparent from the following description of non-limiting examples of embodiments, with reference to the figures attached and described below. [Fig 1]

[0024] Fig. 1 represents a section of a rotor blade according to the prior art. [Fig 2]

[0025] Figure [Fig.2] illustrates a first embodiment of a section of a rotor blade according to the invention. [Fig 3]

[0026] Figure [Fig. 3] illustrates a second embodiment of a section of a rotor blade according to the invention. [Fig 4]

[0027] Figure 4 illustrates a third embodiment of a section of a rotor blade according to the invention. [Fig 5]

[0028] Figure 5 illustrates a turbine with a stator and a rotor according to the invention. [Fig 6]

[0029] Figure 6 illustrates the impact on the fluid flow around a first example of a rotor according to the invention. [Fig 7]

[0030] Figure 7 illustrates the impact on the fluid flow around a second example of a rotor according to the invention. [Fig 8]

[0031] Figure 8 illustrates a rotor according to the invention. [Fig 9]

[0032] Figure 9 illustrates a rotor with external rim according to the invention. [Fig 10]

[0033] Fig. 10 illustrates a comparison of the flow around the blades according to the second embodiment of the invention, of blades according to the fifth embodiment of the invention and of blades according to the first embodiment of the invention. [Fig 11]

[0034] Fig. 11 illustrates a fourth embodiment of a section of a rotor blade according to the invention. [Fig 12]

[0035] Figure 12 illustrates a fifth embodiment of a section of a rotor blade according to the invention. [Fig 13]

[0036] Fig. 13 illustrates a Rankine cycle circuit with a turbine according to the invention. [Fig 14]

[0037] Fig. 14 illustrates an internal combustion engine with a turbine according to the invention. [Fig 15]

[0038] Figure 15 illustrates a fuel cell with a turbine according to the invention. [Fig 16]

[0039] Fig. 16 illustrates the velocity vectors at the inlet and outlet of the rotor according to the invention. Description of the implementation methods

[0040] To facilitate reading the description, we recall certain definitions.

[0041] A blade (also called a vane) is a component of the rotor that allows for the transformation The energy of the fluid entering the turbine is converted into the rotational mechanical energy of the rotor. To achieve this, the blade has a cross-section with an aerodynamic profile.

[0042] The leading edge of the blade section is the point located at the front of the blade (in the blade operating position), facing the fluid; it corresponds to the stopping point.

[0043] The trailing edge of the blade section is the point located at the rear of the blade (in the blade operating position) at the level where the fluid ends its flow along the blade.

[0044] The chord is defined by the straight segment which joins the leading edge to the trailing edge on the blade section.

[0045] The upper and lower surfaces are the surfaces that delimit the blade from the leading edge to the trailing edge where they meet. On the blade cross-section, the upper and lower surfaces are represented by two lines both originating from the leading edge and meeting at the trailing edge.

[0046] The Mach number is defined as the ratio between the fluid velocity and the speed of sound. A subsonic speed is a speed lower than the speed of sound (therefore less than a Mach number of 1).

[0047] A supersonic speed is a speed greater than the speed of sound (therefore greater than a Mach number of 1).

[0048] Sonic speed is defined as a fluid velocity equal to the speed of sound (Mach number equal to 1).

[0049] A sonic throat extends as the minimum cross-sectional area of ​​fluid passage in a In this equipment (in a turbine in our case), the sonic throat is preceded and followed by sections where the fluid passage cross-section is larger than that of the sonic throat. A sonic throat is defined as the minimum cross-sectional area that allows the flow to reach sonic velocity under certain inlet conditions for the turbine. For example, for an axial flow (oriented along the longitudinal axis), the sonic throat will be the minimum passage cross-section perpendicular to the flow axis.

[0050] The sonic throat generates a sonic blockage at the throat: in other words, even by increasing the flow rate of the inlet fluid or the inlet pressure, the fluid velocity at the sonic throat will not be able to exceed a Mach number equal to 1.

[0051] The section of the sonic throat Ac can be determined from the conservation of the flow rate m entering the turbine, the speed of sound c and the density of the fluid at the throat pc.

[0052] [Math.l]

[0053] With

[0054] [Math.2] m — p • v*A

[0055] W being the mass flow rate of the fluid entering the turbine

[0056] A being the cross-sectional area of ​​the fluid passage at the turbine inlet

[0057] v: the fluid velocity at the turbine inlet

[0058] p: the density of the fluid at the turbine inlet.

[0059] The conditions determined are sufficient to allow the transition to sonic speed at the throat: for example, if the fluid inlet flow rate is insufficient, it will not be possible to reach sonic speed in the throat. Similarly, if the ratio between the fluid passage cross-section at the turbine inlet A and the sonic throat Ac is insufficient, it will not be possible to reach sonic speed at the throat.

[0060] The static pressure Ps, in a moving fluid, is the pressure measured by a sensor that moves at the same speed as the fluid.

[0061] The dynamic pressure Pdyn corresponds to a measure of the kinetic energy of a fluid per unit volume.

[0062] The total pressure Pt (also called stagnation pressure) corresponds to the sum of the static and dynamic pressures (at the location considered). It corresponds to the static pressure at a stagnation point in a fluid flow, the fluid velocity being zero at the stagnation point.

[0063] [Math.3] Pdyn = ^p- vf2

[0064] [Math.4] Pt — P s + Pdyn

[0065] With Ps: static pressure

[0066] Pt: total pressure

[0067] Pdyn: dynamic pressure

[0068] p: fluid density

[0069] vf: fluid velocity

[0070] The static temperature Ts is the temperature of the fluid, in the absence of any per turbulence related to fluid flow.

[0071] The total temperature Tt (or stagnation temperature) is the temperature at a stagnation point in a fluid flow, where the fluid velocity is zero at the stagnation point. It is expressed as follows:

[0072] [Math.5] Tt = Ts + j-^

[0073] With Tt: total temperature

[0074] Ts: static temperature

[0075] vf: fluid velocity

[0076] Cp: specific heat capacity of the fluid.

[0077] Entropy is a function expressing the principle of energy degradation: it therefore represents an irreversible phenomenon. Zero entropy represents a reversible phenomenon, while entropy strictly greater than zero represents an irreversible phenomenon such as a shock wave.

[0078] A shock wave is a very rapid and abrupt variation of pressure or temperature parameters over very short distances. It can occur in particular when the fluid velocity is supersonic.

[0079] The invention relates to a turbine comprising a stationary part and a rotor. The stationary part is positioned upstream of the rotor in the direction of fluid flow in the turbine. In other words, the turbine is configured so that a fluid passing through it first passes through the stationary part and then through the rotor.

[0080] The rotor is capable of rotating around an axis of rotation so as to transform the energy contained in the fluid into rotational mechanical energy.

[0081] The rotor comprises a plurality of blades extending in a substantially radial direction with respect to the axis of rotation of the rotor. In other words, the section of the blades that has an aerodynamic profile extends in the substantially radial direction.

[0082] Furthermore, the minimum passage area (or minimum effective passage area, it being understood that this is the section orthogonal to the direction of the flow at the location considered) of fluid between the rotor blades constitutes a sonic throat for The operating conditions of the turbine are predetermined (preferably, these conditions include the mass flow rate of the fluid entering the turbine). In other words, the turbine is configured to operate supersonically, with a supersonic transition occurring in the rotor just after the sonic throat, at the blades. The fluid passage cross-section in the stator, the fluid passage cross-section in the rotor upstream of the sonic throat, and the fluid passage cross-section downstream of the sonic throat are always strictly greater than the cross-section of the sonic throat itself, so as to generate sonic blocking at the sonic throat and allow for supersonic transition downstream.

[0083] The blades are configured so that the total pressure at the inlet of the blades is always greater than the static pressure at the outlet of the blades in order to generate a flow and the blades are configured so that the ratio between the total pressure at the inlet and the static pressure at the outlet is greater than or equal to (preferably strictly greater than) the ratio between the total pressure pO at the throat and the static pressure p* at the throat with the following equation:

[0084] [Math.6] y pO __ / \ H P* ~ X 2 /

[0085] with y being the Laplace coefficient of the fluid corresponding to the ratio of the isobaric and isochoric heat capacities, this condition ensuring supersonic operation in the rotor downstream of the sonic throat. For air, the Laplace coefficient y is approximately equal to 1.4.

[0086] The section of each blade is delimited by an extrados and an intrados, the extrados and the intrados of the section of each blade starting from the same leading edge and meeting at the same trailing edge.

[0087] One of the intrados and one of the extrados, preferably the intrados, comprises a first curved portion from the leading edge to a point of intersection and a second curved portion from the point of intersection to the trailing edge. Thus, the intrados or the extrados, preferably the intrados, comprises at least two curved portions whose intersection occurs at the point of intersection.

[0088] Furthermore, at the point of intersection, the tangent (to the intrados, for example, if the intrados includes said point of intersection) of the first curved section forms a non-zero angle (and less than 180°) with the tangent (to the intrados, for example, if the intrados includes said point of intersection) of the second curved section. In other words, the tangents of the first curved section and the second curved section are not collinear. Thus, one of the intrados and the other of the extrados (preferably the intrados) presents a singularity at the point of intersection: at the point of intersection, the intrados or the extrados has a left-hand derivative (or derivative of the first curved section) different from the right-hand derivative (or derivative of the second curved section).

[0089] The first curved part may preferably be differentiable. The second curved part may preferably be differentiable. Thus, the intrados or extrados comprises a single singularity.

[0090] Each blade is thus delimited by two surfaces (the surfaces generated by the extrados and by the intrados) starting from the same leading edge to meet at the same trailing edge and at least one of these surfaces (the intrados in particular) includes a singularity zone for which the tangent to the surface on one side of the singularity zone is different from the tangent to the surface on the other side of the singularity zone, the singularity zone being close to the trailing edge so as to control the position of the shock waves near the exit of the blades.

[0091] Thanks to this singularity present on the blades, it is possible to control the position of the shock wave at the point of intersection and to control the angle of this shock wave. By controlling the position of the shock wave near the trailing edge, significant vibrations in the rotor are avoided, and the rotor's lifespan, and therefore that of the turbine, is increased. Furthermore, the pressure drop, and thus the turbine's efficiency, can also be controlled.

[0092] For ease of reading hereafter, we will consider that the intrados includes the first curved part and the second curved part as well as the point of intersection, but it is understood that these curved parts and the point of intersection could be on the extrados instead of on the intrados.

[0093] Advantageously, the second curved part can be a first straight segment. Indeed, this embodiment is simple to manufacture, while allowing good control of the shock wave position.

[0094] According to a variant of the invention, the first straight segment can be inclined with respect to the plane orthogonal to the fluid velocity at the trailing edge by an angle of inclination between 2 and 80°, preferably between 2 and 30° and even more preferably between 5 and 15°. This feature allows for more precise control of the shock absorber's position and easier control of its orientation.

[0095] According to one configuration of the invention, the other of the intrados and the extrados (the extrados preferably when the first curved part and the second curved part as well as the point of intersection are on the intrados) may comprise a first curved portion from the leading edge to a crossing point and a second curved portion from the crossing point to the trailing edge.

[0096] In other words, the extrados, for example, comprises at least two portions that intersect at the point of intersection. Moreover, at the point of intersection, the tangent (to the extrados, for example) of the first curved portion forms a non-zero angle (and less than 180°) with the tangent (to the extrados, for example) of the second portion Curve: thus, the two curved portions are not aligned at the crossing point: the extrados has a singularity point at the crossing point, as does the intrados. Consequently, the shock wave can be generated at the intersection point of the intrados and / or at the crossing point of the extrados.

[0097] The first curved part can preferably be differentiable. The second curved part can preferably be differentiable. Thus, the extrados comprises a single singularity.

[0098] Preferably, the second curved portion can be a second straight segment. This simplifies the manufacture of the blades.

[0099] Advantageously, the second straight segment can be inclined with respect to the plane orthogonal to the fluid velocity at the trailing edge by an angle of inclination between 2 and 80°, preferably between 2 and 30° and even more preferably between 5 and 15°. This feature makes it possible to control the position of the shock wave at the crossing point more precisely and to control its orientation more easily.

[0100] Preferably, the stationary part may comprise a stator and / or a volute. A volute is defined as a stationary part forming a spiral or helix so as to impart this spiral or helical direction to the flow. A stator is defined as a stationary component comprising fixed blades capable of directing the flow. The stationary part may be configured to operate exclusively in subsonic flow, with the sonic throat of the turbine located within the rotor. By preventing supersonic transition in the stationary part, pressure losses are limited, and thus the turbine's efficiency can be increased.

[0101] Advantageously, the determined operating conditions may include the mass flow rate of the fluid at the turbine inlet, the total pressure at the turbine inlet, the total temperature at the turbine inlet, and the static pressure at the turbine outlet. Indeed, depending on these characteristics and the cross-sectional ratio between the turbine inlet and the sonic throat, the transition to supersonic speed may or may not occur at the sonic throat. Thus, the dimensions of the sonic throat are determined according to the turbine design conditions, which include, in particular, the turbine inlet cross-sectional area and the mass flow rate of the fluid at the turbine inlet. Furthermore, to ensure supersonic operation at the sonic throat outlet, it is necessary to know the total inlet pressure and the static outlet pressure of the turbine.In addition, predetermined operating conditions may also include the total temperature at the turbine inlet and / or the total temperature at the turbine outlet, which can notably impact the speed of sound and the fluid density.

[0102] Advantageously, the rotor may include a ring consisting of a circular ring The ring connects the radial ends of the blades. In other words, the rotor may include an outer ring interfacing with the turbine housing. Adding this ring prevents fluid leaks between the blades and the housing that could disrupt the flow. The ring forces the fluid entering the rotor at the blades to remain within that section until it reaches the trailing edge. This results in a more consistent flow between the blades and reduces disturbances.

[0103] According to an advantageous configuration of the invention, the blades can be oriented at a deflection angle relative to the fluid direction at the leading edge so as to generate a change in the direction of the fluid flow through the blades, the deflection angle being preferably between 5° and 70° and more preferably between 5° and 50°. By generating a change in the fluid direction within the blades, the fluid velocity is further increased (see description of [Fig. 16]). Thus, the transition to sonic speed and therefore to supersonic speed is facilitated.

[0104] According to one embodiment of the invention, the rotor cross-section at the rotor outlet can be reduced compared to the rotor cross-section immediately after the blades. Consequently, the fluid passage cross-section at the rotor outlet will be increased compared to the fluid passage cross-section immediately after the blades. Indeed, by increasing this passage cross-section, the axial forces on the rotor can be limited, thus increasing the rotor's lifespan.

[0105] The invention also relates to a fuel cell comprising a turbine as described above. The turbine is preferably positioned on an outlet line of the fuel cell, the outlet line being configured to produce steam. Indeed, on this outlet line, the steam generally has a temperature between 20°C and 200°C. By using the turbine according to the invention, the loss of thermal energy can be compensated by an increase in kinetic energy, thus increasing the turbine's efficiency. Furthermore, this eliminates the need for grease- or oil-lubricated bearings and bushings.

[0106] The invention also relates to a Rankine cycle circuit comprising a turbine as described above. The Rankine cycle circuit may, in particular, comprise a closed-loop circuit with a compressor, an evaporator, the turbine, and then a condenser. For example, the temperature of the fluid entering the turbine may be on the order of 90°C, which is quite low; using the turbine with supersonic speeds in the rotor makes it possible to compensate for the loss of thermal energy by increasing the kinetic energy and thus the efficiency of the turbine.

[0107] Furthermore, the invention also relates to an internal combustion engine comprising a turbine as described above at the exhaust gas outlet In the internal combustion engine, the turbine can be, for example, that of a turbocharger. Supersonic speeds in the rotor increase kinetic energy while limiting pressure losses in the stator (compared to supersonic speeds in the stationary section). Furthermore, because the rotor is supersonic, the turbine can rotate at a lower speed. This eliminates the need for grease- or oil-lubricated bearings and bushings.

[0108] More specifically, the engine can be configured to operate at a fuel-air ratio below 0.8, preferably close to 0.4. The fuel-air ratio is the ratio between the amount of fuel actually injected into the engine and the stoichiometric ratio. Thus, for an engine operating at stoichiometric speed, the fuel-air ratio is equal to 1. When operating at a lean fuel-air ratio (below 0.8 and preferably close to 0.4), it is referred to as a "lean" engine. For this type of engine, the exhaust gases are cooler than in internal combustion engines with a richer fuel-air ratio. Thus, the use of the turbine according to the invention is particularly well-suited to this type of "lean" engine since the increase in kinetic energy partially compensates for the loss of thermal energy.

[0109] Fig. 1 illustrates, schematically and not in a limiting way, the section of a blade in a usual manner.

[0110] The blade 10 has a cross-section shown in the figure forming an aerodynamic profile. The fluid F (air for example) arrives in the direction of the black arrow towards the blade 10, at the level of the leading edge 1.

[0111] The section of the wing 10 is delimited by an extrados 3 and an intrados 4. The extrados 3 and the intrados 4 both start from the leading edge 1 and meet at the trailing edge 2.

[0112] The straight line segment shown in dashed lines corresponds to the chord 20 which joins the leading edge 1 to the trailing edge 2. As can be seen in the figure, the chord 20 is not aligned with the direction of the fluid F arriving at the blade. However, aligning the chord 20 with the direction of the fluid F is possible without departing from the scope of the invention.

[0113] In this figure, the intrados 4 and the extrados 3 form two continuous and differentiable curves from the leading edge to the trailing edge: there is no singularity on these curves of the extrados 3 and the intrados 4.

[0114] Fig. 2 illustrates, schematically and not in a limiting manner, a first example of a turbine blade according to the invention.

[0115] In this figure, the profile corresponding to that of [Fig.l] is represented by the dotted lines near the trailing edge 2 corresponding to the profile of [Fig.l].

[0116] The section of the turbine blade 10 according to the invention is truncated (or cut) compared to the usual profile of [Fig. 1]. Indeed, the trailing edge of the blade 10 is the edge 2' escape.

[0117] The wing 10 is thus delimited by an extrados 3 and an intrados 4 both starting from the same leading edge 1 and meeting towards the same trailing edge 2'.

[0118] However, the intrados 4 does not form a differentiable curve from the leading edge 1 to the trailing edge 2'. On the contrary, the intrados 4 has a singularity point at the point of intersection A. The intrados 4 comprises two curved parts 5 and 6 which meet at the point of intersection A. A first curved part 6 of the intrados runs from the leading edge 1 to the point of intersection A and a second curved part 5 of the intrados runs from the point of intersection A to the trailing edge 2'.

[0119] The second curved part 5 is here a straight segment joining the point of intersection A to the trailing edge 2'.

[0120] The point of intersection A forms a singularity of the intrados 4: the intrados 4 has a tangent T1 at the level of the first curved part 6 at the point of intersection A which is different from the tangent T2 of the second curved part 5 at the point of intersection A. In other words, the intrados 4 has two distinct and different derivatives on each side at the point of intersection A. Thus, the intrados 4 is not differentiable at the point of intersection A.

[0121] This singularity generated at the point of intersection A makes it possible to control the position of the shock waves generated in the rotor during supersonic operation.

[0122] The fluid (air for example) arrives in the direction of arrow F on blade 10.

[0123] Because the blade 10 is truncated compared to that of [Fig. 1], the outlet fluid of dawn 10 has a direction Fl parallel to that of F but a non-parallel direction Fl would be possible without going out of the scope of the invention.

[0124] The second curved section 5, formed by the straight segment joining the intersection point A at the trailing edge 2', forms a non-zero angle with the direction of the fluid Fl at the blade outlet 10 (at the rotor outlet). The angle of inclination between the straight segment of the second curved section 5 and the direction of the fluid Fl at the blade outlet 10 is between 1 and 89°. This angle of inclination allows control of the direction of the shock wave generated at the intersection point A.

[0125] Fig. 3 illustrates, schematically and not in a limiting manner, a second example of a turbine blade according to the invention.

[0126] In this figure, the profile corresponding to that of [Fig. 1] is represented by the dotted lines near the trailing edge 2 corresponding to the profile of [Fig. 1].

[0127] The section of the turbine blade 10 according to the invention is truncated (or cut) compared to the usual profile of [Fig. 1]. Indeed, the trailing edge of the blade 10 is the trailing edge 2'.

[0128] The wing is thus delimited by an extrados 3 and an intrados 4 both starting from the same leading edge 1 and meeting towards the same trailing edge 2'.

[0129] However, the intrados 4 does not form a differentiable curve from the leading edge 1 to the trailing edge 2'. On the contrary, the intrados 4 has a singularity point at the point of intersection A. The intrados comprises two curved parts 5b and 6 which meet at the point of intersection A. A first curved part 6 of the intrados runs from the leading edge 1 to the point of intersection A and a second curved part 5b of the intrados runs from the point of intersection A to the trailing edge 2'.

[0130] The second curved part 5b is here a straight segment joining the point of intersection A to the trailing edge 2'.

[0131] The point of intersection A forms a singularity of the intrados 4: the intrados 4 has a tangent T1 at the first curved part 6 at the point of intersection A which is different from the tangent T2 of the second curved part 5b at the point of intersection A. In other words, the intrados 4 has two distinct and different derivatives on each side at the point of intersection A. Thus, the intrados 4 is not differentiable at the point A.

[0132] This singularity generated at the point of intersection A makes it possible to control the position of the shock waves generated in the rotor during supersonic operation.

[0133] The fluid (air for example) arrives in the direction of arrow F on blade 10.

[0134] Because the blade 10 is truncated compared to that of [Fig. 1], the outlet fluid of dawn 10 has a direction Fl parallel to that of F but a non-parallel direction Fl would be possible without going out of the scope of the invention.

[0135] The second curved section 5b, formed by the straight segment joining the point of intersection A at the trailing edge 2', forms a perpendicular angle with the direction of the fluid Fl at the blade outlet 10 (at the rotor outlet). The angle of inclination between the straight segment of the second curved section 5 and the direction of the fluid Fl at the blade outlet 10 is therefore approximately equal to 90°.

[0136] Here too, we could consider that the trailing edge is formed at the point of intersection A and that it is the extrados 3 which would then comprise two curved portions (including the curved portion 5b, here consisting of a straight segment) connected at the level of a crossing point which would then be the point 2'.

[0137] [Fig.3] differs from [Fig.2] in that the straight segment 5b is orthogonal to the direction of the fluid Fl at the blade outlet.

[0138] Fig. 4 illustrates, schematically and not in a limiting manner, a third example of a turbine blade according to the invention.

[0139] This blade comprises a leading edge 1 onto which the fluid arrives in direction F and a trailing edge 2'. The lower surface comprises two curved parts connected at the point of intersection A, which forms a singularity (the lower surface is not differentiable at the point of intersection A but includes a derivative T1 that each curved part at the point of intersection A has, distinct from the derivative T2 of the other curved part at the point of intersection A). intersection point A).

[0140] The blade of [Fig. 4] is configured to give the fluid exiting the blade a direction Fl inclined relative to the direction F of the fluid entering the blade. The inclination angle 0 between the fluid exit direction Fl and the fluid inlet direction F is between 5 and 70°, preferably between 5 and 50°. This fluid inclination facilitates the supersonic flow of the fluid through the rotor.

[0141] Figure 11 illustrates, schematically and without limitation, a fourth example turbine blade according to the invention.

[0142] In this figure, the profile corresponding to that of [Fig. 1] is represented by the dotted lines near the trailing edge 2 corresponding to the profile of [Fig. 1].

[0143] The section of the turbine blade 10 according to the invention is truncated (or cut) compared to the usual profile of [Fig. 1]. Indeed, the trailing edge of the blade 10 is the trailing edge 2”.

[0144] The wing is thus delimited by an extrados 3 and an intrados 4 both originating from the same leading edge 1 and meeting at the same trailing edge 2”.

[0145] However, the upper surface 3 does not form a differentiable curve from the leading edge 1 to the trailing edge 2”. On the contrary, the upper surface 3 has a singularity point at the crossing point 25. The upper surface comprises two curved portions 26 and 27 which meet at the crossing point 25. A first curved portion 26 of the upper surface extends from the leading edge 1 to the crossing point 25 and a second curved portion 27 of the upper surface extends from the crossing point 25 to the trailing edge 2”.

[0146] The second curved portion 27 is here a straight segment joining the crossing point 25 to the trailing edge 2”.

[0147] The crossing point 25 forms a singularity of the extrados 3: the extrados 3 has a tangent T3 at the first curved portion 26 at the crossing point 25 which is different from the tangent T4 of the second curved portion 27 at the crossing point 25. In other words, the extrados 3 has two distinct and different derivatives on each side at the crossing point 25. Thus, the extrados 3 is not differentiable at the crossing point 25.

[0148] This singularity generated at the crossing point 25 allows control of the position of the shock waves generated in the rotor during supersonic operation.

[0149] The fluid (air for example) arrives in the direction of arrow F on blade 10.

[0150] Because the blade 10 is truncated compared to that of [Fig. 1], the outlet fluid of dawn 10 has a direction Fl parallel to that of F but a non-parallel direction Fl would be possible without going out of the scope of the invention.

[0151] The second curved portion 27 formed by the straight segment joining the crossing point 25 to the trailing edge 2” forms a non-zero angle with the direction of the fluid Fl at the blade exit 10 (at the rotor exit). The angle of inclination between the straight segment of the second curved section 27 and the fluid direction Fl at the blade exit 10 is between 1 and 89°. This angle of inclination allows control of the direction of the shock wave generated at the crossing point 25.

[0152] Fig. 12 illustrates, schematically and not in a limiting manner, a fifth example of a turbine blade according to the invention.

[0153] In this figure, the profile corresponding to that of [Fig. 1] is represented by the dotted lines near the trailing edge 2 corresponding to the profile of [Fig. 1].

[0154] The section of the turbine blade 10 according to the invention is truncated (or cut) compared to the usual profile of [Fig. 1]. Indeed, the trailing edge of the blade 10 is the trailing edge 2'”.

[0155] The wing is thus delimited by an extrados 3 and an intrados 4 both starting from the same leading edge 1 and meeting towards the same trailing edge 2”.

[0156] However, the lower surface 4 does not form a differentiable curve from the leading edge 1 to the trailing edge 2'”. On the contrary, the lower surface 4 has a singularity point at the intersection point A. The lower surface comprises two curved parts 5 and 6 which meet at the intersection point A. A first curved part 6 of the lower surface extends from the leading edge 1 to the intersection point A, and a second curved part 5 of the lower surface extends from the intersection point A to the trailing edge 2'”.

[0157] The second curved part 5 is here a straight segment joining the point of intersection A to the trailing edge 2'”.

[0158] The point of intersection A forms a singularity of the intrados 4: the intrados 4 has a tangent T1 at the level of the first curved part 6 at the point of intersection A which is different from the tangent T2 of the second curved part 5 at the point of intersection A. In other words, the intrados 4 has two distinct and different derivatives on each side at the point of intersection A. Thus, the intrados 4 is not differentiable at the point A.

[0159] Furthermore, the upper surface 3 does not form a differentiable curve from the leading edge 1 to the trailing edge 2''. Indeed, the upper surface 3 has a singularity point at the crossing point 25. The upper surface comprises two curved portions 26 and 27 which meet at the crossing point 25. A first curved portion 26 of the upper surface runs from the leading edge 1 to the crossing point 25 and a second curved portion 5 of the upper surface runs from the crossing point 25 to the trailing edge 2''.

[0160] The second curved portion 27 is here a straight segment joining the crossing point 25 to the trailing edge 2” '.

[0161] The crossing point 25 forms a singularity of the extrados 3: the extrados 3 has a tangent T3 at the level of the first curved portion 26 at the crossing point 25 which is different from the tangent T4 of the second curved portion 27 at the point of crossing 25. In other words, the extrados 3 has two distinct and different derivatives on each side at the crossing point 25. Thus, the extrados 3 is not differentiable at the crossing point 25.

[0162] These singularities around the crossing point 25 and the intersection point A respectively on the extrados and on the intrados allow control of the position of the shock waves generated in the rotor during supersonic operation.

[0163] The fluid (air for example) arrives in the direction of arrow F on blade 10.

[0164] Because the blade 10 is truncated compared to that of [Fig. 1], the outlet fluid of dawn 10 has a direction Fl not parallel to that of F but a direction Fl parallel to the direction would be possible without going out of the scope of the invention.

[0165] The second curved portion 27, formed by the straight segment joining the crossing point 25 to the trailing edge 2", forms a non-zero angle with the direction of the fluid Fl at the blade outlet 10 (at the rotor outlet). The angle of inclination between the straight segment of the second curved portion 27 and the direction of the fluid Fl at the blade outlet 10 is between 1 and 89°. This angle of inclination allows control of the direction of the shock wave generated on the upper surface at the crossing point 25.

[0166] .

[0167] The second curved section 5, formed by the straight segment joining the intersection point A at the trailing edge 2", forms a non-zero angle with the direction of the fluid Fl at the blade outlet 10 (at the rotor outlet). The angle of inclination between the straight segment of the second curved section 5 and the direction of the fluid Fl at the blade outlet 10 is between 1 and 89°. This angle of inclination allows control of the direction of the shock wave generated on the lower surface at the intersection point A.

[0168] Figure 5 illustrates, schematically and not in a limiting manner, an example of a turbine according to the invention.

[0169] The turbine comprises a stationary part 14, such as a stator or volute, and a rotor 13 in a casing (not shown), the casing allowing the fluid to be guided into the turbine.

[0170] The fluid arrives in the turbine in the direction of F. It therefore first passes through the stationary part 14, then enters the rotor 13.

[0171] The stationary part 14 is fixed while the rotor 13 is able to rotate around its axis of rotation materialized by the dashed line.

[0172] The rotor 13 includes blades 12 (also called vanes) which enable the transformation of the fluid's energy into the rotational mechanical energy of the rotor.

[0173] The rotor 13 also includes a portion 11 located after the blades 12 (downstream of the blades in the direction of fluid flow in the turbine). This portion 11 has a reduced cross-section: the diameter of the frustoconical portion 11 at the outlet is smaller than the diameter of this portion 11 immediately after the blades. This reduction of the The rotor cross-section increases the fluid passage area and therefore the static pressure at the outlet. This reduces axial forces on the blades, ensuring mechanical strength and extending the rotor's lifespan.

[0174] Fig. 16 illustrates, schematically and not in a limiting way, the operation of the rotor and the impact of the velocity vector on the rotational speed and on the sonic throat passage section.

[0175] The figure shows the rotor here with three blades in cross-section. The thick black arrows represent the direction of rotation of the rotor. The rotation of the rotor induces a rotor speed represented by the vector U.

[0176] Furthermore, the fluid arrives at the blades according to a velocity vector VI, which is called incident velocity, which makes an angle al with the axis of rotation of the rotor.

[0177] Thus, the relative velocity of the fluid at the inlet W1 with respect to the rotating blades is the sum of the velocity vectors U and VL

[0178] At the outlet, the fluid exits at an incident velocity V2 which makes an angle α2 with the axis of rotation of the rotor. The angle α2 is generated by the deflection of the blade to change the direction of the fluid exiting the blade.

[0179] Thus, the relative velocity of the fluid at the outlet W2 with respect to the rotating blades is the sum of the velocity vectors U and V2.

[0180] Thus, by rotating the rotor, the relative speed of the fluid at the outlet can be increased compared to the relative speed of the fluid at the inlet, and thus the passage of the supersonic through the rotor can be facilitated.

[0181] Furthermore, the throat section Ac is in a plane orthogonal to the fluid velocity at the throat. As this velocity at the throat is not parallel to the rotor axis (due to the blade deflection angle), the throat section Ac is in a plane inclined at a non-zero angle (less than 180°) to the vertical in the figure, which facilitates the transition to supersonic speed.

[0182] Fig. 8 illustrates, schematically and not in a limiting way, more precisely the rotor of Fig. 5.

[0183] The rotor 13 is placed in a housing 15. The rotor includes blades 12. The clearance between the blades 12 and the housing 15 is reduced to a minimum to avoid clearance flows between the radial end of the blades 12 and the housing 15, which could generate flow disturbances and reduce the efficiency of the turbine.

[0184] At the rotor outlet, just after the blades 12 in the direction of flow, the rotor 13 may include a reduced cross-sectional portion 11. Here, portion 11 is frustoconical in shape with a diameter at the intersection with the blade outlet greater than the diameter of portion 11 of the rotor at the outlet. Of course, other non-fruconical shapes exist for obtaining a reduced cross-sectional area of ​​the rotor after the blades. possible without going outside the scope of the invention.

[0185] Thus, the static pressure Psi of the fluid entering the rotor is greater than the static pressure Ps2 just after the blades 12, and the static pressure Ps3 at the outlet of the rotor 13 can correspond substantially to the inlet pressure Psi. The increase in the static pressure at the outlet is related to the reduction in the cross-section of the rotor section 11 after the blades 12 (thanks to the frustoconical profile here). Therefore, the axial forces on the rotor shaft can be reduced.

[0186] Figure 9 illustrates, schematically and not in a limiting manner, a variant of the rotor according to the invention.

[0187] In this figure, the rotor comprises blades 12 which extend radially, the longitudinal axis corresponding to the axis of rotation which is orthogonal to the plane of section of the figure.

[0188] The rotor is placed in a housing 15, substantially cylindrical so as to adapt to the rotor capable of rotating around the longitudinal axis.

[0189] The rotor also includes a band 17 which may include a cylindrical ring. This band 17 is fixed to the radial ends of the blades 12. This band 17 is therefore opposite the housing 15. As a result, the fluid passing over the blades 12 cannot pass through the gap between the blades 12 and the housing 15, the band acting as a barrier to the flow. Thus, flow disturbances are limited.

[0190] In addition, the clearance (voluntarily amplified in the figure to facilitate understanding) between the ring 17 and the housing 15 is reduced to the maximum so as to avoid fluid leaks in this space, before the fluid enters the blades 12.

[0191] It is also possible to consider adding a seal in the gap between the rim 17 and the housing 15. The seal can be a labyrinth seal, for example.

[0192] The band 17 therefore extends in the longitudinal direction over at least the entire longitudinal length of the blades 12.

[0193] Fig. 13 illustrates, schematically and not in a limiting manner, a Rankine cycle circuit with a turbine according to the invention.

[0194] The Rankine cycle circuit includes a pump 110 for circulating a working fluid, for example, water. Downstream of the pump 110, in the direction of fluid flow, a pipe 120 connects to an evaporator 130, which heats the working fluid and vaporizes it. Thus, at the outlet 140 of the evaporator 130, the working fluid is in gaseous form and is conveyed via the pipe 150 to an expansion device 160, such as a turbine, which can be coupled to an electric generator 170.

[0195] The fluid exiting the expansion means 160 is conveyed by a pipe 185 to a condenser 190 where it is cooled and liquefied. It then exits the condenser through outlet 191 in liquid form and is conveyed via pipe 196 to pump 110. Thus, the the circuit operates in a closed loop.

[0196] The circuit may also include a filter (195) upstream of the pump 110 to prevent solid particles that could damage the pump 110. It may also include a reservoir (not shown) of the working fluid.

[0197] The evaporator 130 and the condenser 190 can be heat exchangers capable of exchanging heat with the working fluid, via a fluid hotter than the working fluid in the evaporator 130 and via a fluid colder than the working fluid in the condenser 190.

[0198] The expansion means 160 is here a supersonic rotor turbine according to the invention. Indeed, by allowing supersonic operation in the rotor, the low enthalpy associated with the relatively cold temperature (generally below 100°C, close to 90°C) of the working fluid can be compensated for by an increase in the fluid's kinetic energy. Furthermore, when operating at supersonic speed, the turbine's rotational speed is reduced (compared to subsonic operation in the rotor). Consequently, oil- and grease-free bearings can be used, which simplifies and facilitates the system.

[0199] Fig. 14 schematically and non-limitingly illustrates an internal combustion engine with a turbine according to the invention.

[0200] In this figure, the system comprises an internal combustion engine 201 and a turbocharger with a turbine 210 and a compressor 208, the turbine 210 and the compressor 208 being fixed on the same rotating shaft.

[0201] The compressor 208 compresses air 211 entering the compressor. The compressed air exiting the compressor 208 is sent through a pipe 204 into a distribution network 203 which splits the airflow into several pipes 202, each pipe 202 supplying air to the intake of one cylinder of the internal combustion engine 201. Here, the internal combustion engine consists of four cylinders 212b, 2122, 2123 and 2124, each pipe 202 supplying air to one cylinder 212b, 2122, 2123 and 2124. Of course, the internal combustion engine could use a different number of cylinders than four without departing from the scope of the invention.

[0202] In each cylinder, combustion occurs between the incoming air and a fuel. The exhaust gases exiting each piston are collected in a manifold 205 and then directed via a pipe 206 to the turbine 210 of the turbocharger, and the gases are then released at the outlet 209 of the turbine 210.

[0203] By using a turbine with a rotor capable of generating a sonic throat and supersonic operation at the sonic throat outlet, the kinetic energy of the fluid can be increased, thereby increasing the efficiency of the turbine and consequently the turbocharger. Furthermore, the supersonic operation of the rotor allows for a reduction in rotational speed (compared to normal operation). subsonic), which eliminates the need for grease or oil-filled bearings and / or bushings.

[0204] Furthermore, if the internal combustion engine operates at a lean mixture (air-fuel ratio less than 0.8 and preferably less than 0.4), the exhaust gas temperature is lower (on the order of 400 to 500°C) than for an engine operating at an air-fuel ratio of 1 (i.e., under stoichiometric conditions). The use of the turbine according to the invention thus makes it possible to partially compensate for the loss of thermal energy in the exhaust gases with kinetic energy. The lean mixture helps to limit unburned hydrocarbons.

[0205] Figure 15 illustrates, schematically and not in a limiting manner, a fuel cell with a turbine according to the invention.

[0206] The fuel cell is a cell in which an electrical voltage (and therefore electricity) is produced by an oxidation reaction on one electrode and by a reduction reaction on the other electrode.

[0207] In this fuel cell, hydrogen 301 is introduced and comes into contact with the anode 302, and air 305 is introduced and first compressed in a compression device such as the compressor 312 before coming into contact with the cathode 304. The anode 302 and the cathode 304 are separated by an electrolyte 303 (for example, a proton exchange membrane that allows protons to pass through and blocks electrons). Catalysts such as platinum can also be used to accelerate the oxidation and / or reduction reactions.

[0208] When hydrogen 301 comes into contact with the anode 302, it dissociates into electrons and protons. The protons pass through the electrolyte 303 and reach the cathode 304, while the electrons are forced to use the external circuit 310. The movement of electrons in the external circuit 310 generates an electric current: thus, electricity is generated.

[0209] At the cathode 304, the air exiting the compressor 312 (more precisely, the oxygen in the air) reacts with the electrons arriving via the external circuit 310 and with the protons passing through the electrolyte 303 to generate water. Furthermore, this reaction generates heat. Thus, the water exiting the fuel cell 307 can be in the form of low-temperature steam (generally below 50°C). Therefore, a turbine 308, according to the invention, can be used to recover some of the energy from the steam produced by the fuel cell.

[0210] At the outlet of the turbine 308, the water vapor 309 can be released into the environment.

[0211] The electrolyte can be, for example, potassium hydroxide or a Naflon / PBI polymer membrane.

[0212] On the external circuit 310, an electric motor M can, for example, be positioned which will be able to be powered by the generated electricity. A battery can be positioned in place of motor M.

[0213] At outlet 301, the excess hydrogen is recovered. This outlet 301 is optional.

[0214] The example presented here is a hydrogen / air fuel cell, but it is understood that other fuel cells could be used, with the fuels / oxidants / electrolytes being adapted accordingly to each other.

[0215] Moreover, since the temperature of the water vapor produced is quite low (on the order of 20 to 50°C), the use of a supersonic rotor turbine according to the invention is particularly advantageous since it increases the kinetic energy and therefore partially compensates for the low thermal energy of the water vapor.

[0216] The invention can be applied to axial turbines (inlet and outlet in the axis), radial turbines (radial inlet and axial outlet), mixed flow turbines (inlet forming a non-zero angle with the axial direction and with the radial direction) as well as centrifugal turbines (axial inlet and radial outlet).

[0217] Of course, the different variants of the invention can be combined with each other without going out of the scope of the invention. Examples

[0218] [Fig.6] illustrates an example of a first variant of supersonic acceleration rotor according to the invention.

[0219] The rotor blades 12 have a chord parallel to the direction of the fluid F arriving on the blades. Thus, the direction of the fluid arriving on the blades 12 is parallel to that of the fluid exiting the blades 12, which is also parallel to the axis of rotation of the rotor (in other words, the angle of incidence of the incoming fluid and the angle of deflection of the blade are nu).

[0220] Moreover, each of these blades 12 has a symmetrical profile: the upper and lower surfaces are symmetrical with respect to the chord. In addition, the second curved part 5b of the lower surface forms a straight line segment orthogonal to the fluid flow exiting the blades 12.

[0221] In this figure, the gradient of grey shows a variation in Mach number around the blades 12. The lighter the colour and the higher the speed in Mach number, the scale corresponds to the Mach number.

[0222] The Smin section is the minimum fluid passage cross-section between the blades 12. This Smin section constitutes a sonic throat under certain conditions where the sonic velocity (Mach number equal to 1) is reached. Downstream of this passage cross-section, the fluid has a supersonic velocity (Mach number > 1).

[0223] At the exit of the blades 12, at the singularity points formed by the trailing edge and the point of intersection of the two curved sections on the intrados, oblique shock waves Cl and C2 are observed to occur. Thus, by cutting the blades by Compared to a typical profile like the one in [Fig. 1] (i.e., an intrados with at least one singularity point), the position of the shock waves on the blade can be controlled. Furthermore, since the second curved section 5b is orthogonal to the fluid direction exiting the blades, the shock waves C1 and C2 are essentially symmetrical with respect to the fluid direction (and with respect to the rotor's axis of rotation, which is parallel to it).

[0224] It can be observed that, thanks to the invention, the Cl and C2 shock waves occur at the exit of the blade and thus make it possible to improve the lifespan of the blades.

[0225] [Fig.7] illustrates another example of a second rotor variant according to the invention.

[0226] The rotor blades 12 have a chord with a non-zero deflection angle (between 5 and 70°, preferably between 5 and 50°) to the direction of the fluid F arriving on the blades, the direction of the fluid arriving on the blades 12 can be parallel to the axis of rotation of the rotor (in other words, the angle of incidence at the inlet of the inlet fluid is close to zero).

[0227] Furthermore, these blades 12 have an asymmetrical profile: the upper and lower surfaces are not symmetrical with respect to the chord. In addition, the second curved part 5 of the lower surface forms a straight line segment inclined at an angle between 2 and 80° to the fluid flow exiting the blades 12.

[0228] In this figure, the gradient of grey shows a variation in Mach number around the blades 12. The lighter the colour and the higher the speed in Mach number, the scale corresponds to the Mach number.

[0229] The Smin section is the minimum fluid passage cross-section between the blades 12 perpendicular to the fluid direction. This Smin section constitutes a sonic throat where the sonic velocity (Mach number equal to 1) is reached. Downstream of this passage cross-section, the fluid has a supersonic velocity (Mach number > 1).

[0230] At the exit of the blades 12, at the singularity points formed by the trailing edge and the point of intersection of the two curved sections on the intrados, oblique shock waves Cl and C2 are observed to occur. Thus, by cutting the blades relative to a conventional profile as in [Fig. 1] (i.e., by an intrados with at least one singularity point), the position of the shock waves on the blade can be controlled.

[0231] It can be observed that, thanks to the invention, the Cl and C2 shock waves occur at the exit of the blade and thus make it possible to improve the lifespan of the blades.

[0232] [Fig. 10] illustrates comparisons of three examples of rotor according to the invention in this which concerns the shock waves produced (diagrams a), b) and c)) and with regard to the entropy produced (diagrams d), e) and f)).

[0233] In diagrams a), b), and c), the grey levels depend on the speed in number of Mach, with darker values ​​corresponding to high (supersonic) speed.

[0234] Schemes a) and d) correspond to a blade with a singularity point on the intrados where the second curved part is a straight line segment orthogonal to the fluid flow at the blade outlet.

[0235] Diagrams c) and f) correspond to a blade with a singularity point on the intrados where the second curved part is a straight line segment inclined at an angle of 15° to the fluid flow at the blade outlet.

[0236] Diagrams b) and e) correspond to a blade with a singularity point on the lower surface (intrados) and a singularity point on the upper surface (extrados), where the second curved portion is a straight line segment inclined at an angle of 15° to the fluid flow at the blade outlet, and where the second curved portion of the upper surface is a straight line segment inclined at an angle of 15° to the fluid flow at the blade outlet. Thus, the second curved portion of the lower surface and the second curved portion of the upper surface are symmetrical with respect to the direction of the fluid flow at the blade outlet.

[0237] In diagram a), we observe that several shock waves are generated at the exit of the dawn (dark grey parts) and that the corresponding entropy (diagram d)) is relatively important (light grey parts).

[0238] In diagram b), we observe that the shock waves are much more spaced out than in diagram a) and that the entropy (diagram e)) is also much lower than in diagram d). Thus, the second variant corresponding to diagrams b) and d) is more advantageous because it allows for increased efficiency by reducing irreversible energy losses.

[0239] Furthermore, in diagram c), the shock waves are much more widely spaced than in diagram a), and they occur only on one side, unlike in diagram b), due to the asymmetry near the trailing edge. In addition, the entropy (diagram f)) is also much lower than in diagram d) and diagram f). Thus, the third variant, corresponding to diagrams c) and f), is more advantageous than the first and second variants of diagrams a) / d) and b) / e), respectively, because it increases efficiency by reducing irreversible energy losses.

Claims

Demands

1. Turbine comprising a stationary portion (14) and a rotor (13), said stationary portion (14) being upstream of the rotor (13) in the direction of fluid flow in the turbine, the rotor (13) being capable of rotating about an axis of rotation and comprising a plurality of blades (12) extending in a substantially radial direction with respect to the axis of rotation of the rotor (13), the minimum fluid passage area (Smin) between the rotor blades constituting a sonic throat for specified operating conditions of the turbine, the blades (12) being configured such that the total pressure at the inlet of the blades is always greater than the static pressure at the outlet of the blades so as to generate flow, and the blades being configured such that the ratio between the total inlet pressure and the static outlet pressure is greater than or equal to the ratio between the total throat pressure and the static throat pressure,the section of each blade (12) being delimited by an extrados (3) and an intrados (4), the extrados (3) and the intrados (4) of the section of each blade (12) extending from a leading edge (1) to a trailing edge (2',2”,2'”), one of the intrados (4) and the extrados comprising a first curved portion (6) from the leading edge (1) to a point of intersection (A) and a second curved portion (5) from said point of intersection (A) to the trailing edge (2',2”,2'”), characterized in that, at the point of intersection (A), the tangent of the first curved portion (6) forms a non-zero angle with the tangent of the second curved portion (5), the point of intersection forming a singularity near the trailing edge, in that the other of the intrados and the extrados comprises a first curved portion (26) of the leading edge (1) at a crossing point (25) and a second curved portion (27) from said crossing point (25) to the trailing edge (2', 2”,2”'), and in that, at said crossing point,the tangent of the first curved portion (26) forms a non-zero angle with the tangent of the second curved portion (27), said point of intersection forming a singularity, said singularity being near the trailing edge (2', 2”, 2' ”).

2. Turbine according to claim 1, wherein the second curved part (5) is a first straight segment.

3. Turbine according to claim 2, wherein the first straight segment is inclined with respect to the plane orthogonal to the fluid velocity at the trailing edge (2',2”,2'”) at an angle with an inclination between 2 and 80°, preferably between 2 and 30° and even more preferably between 5 and 15°.

4. Turbine according to any one of the preceding claims, wherein the second curved portion (27) is a second straight segment.

5. Turbine according to claim 5, wherein the second straight segment is inclined with respect to the plane orthogonal to the fluid displacement velocity at the trailing edge (2',2”,2'”) by an angle of inclination between 2 and 80°, preferably between 2 and 30° and even more preferably between 5 and 15°.

6. Turbine according to any one of the preceding claims, wherein the stationary part (14) comprises a stator and / or a volute, preferably the stationary part (14) being configured to operate exclusively in subsonic flow.

7. Turbine according to any one of the preceding claims, wherein the determined operating conditions include the mass flow rate of the fluid at the turbine inlet, the total pressure at the turbine inlet, the total temperature at the turbine inlet, the static pressure at the turbine outlet and preferably the total temperature at the turbine inlet and / or the total temperature at the turbine outlet.

8. Turbine according to any one of the preceding claims, wherein the rotor (13) comprises a ring (17) consisting of a ring connecting the radial ends of the blades (12).

9. Turbine according to any one of the preceding claims, wherein the blades (12) are oriented at an angle of deflection with respect to the direction of said fluid at the leading edge (1) so as to generate a change in the direction of the flow of the fluid through the blades, the angle of deflection being preferably between 5° and 70° and even more preferably between 5° and 50°.

10. Turbine according to any one of the preceding claims, wherein the rotor section at the rotor outlet (13) is reduced compared to the rotor section (13) just after the blades (12).

11. Fuel cell comprising a turbine according to any one of the preceding claims, the turbine preferably being positioned on an output line of the fuel cell, the output line being configured to produce steam.

12. Rankine cycle circuit comprising a turbine according to any one of claims 1 to 10, preferably the circuit comprising a compressor, an evaporator, the turbine and then a condenser.

13. Internal combustion engine, in particular an internal combustion engine operating with a richness of less than 0.8, preferably less than 0.4, comprising a turbine according to any one of claims 1 to 10 at the exhaust outlet of the internal combustion engine, preferably the turbine (210) being that of a turbocharger.