Turbine assembly for axial flow turbine and axial flow turbine

Abstract

The turbine assembly according to the invention further comprises passages formed in the stationary part of the second wheel of the assembly between at least some adjacent blades 1r / 1s for discharging the working medium leaking from the axial gap through the contactless seal 4r / 4s of the first wheel of the assembly in the direction of expansion of the working medium back into the primary flow path. The passage inlets according to the invention are located radially in the stationary part - between the centre of the turbine assembly axis and R8 in -An imaginary circle with a radius of 0.6*A and -the center of the turbine assembly shaft and R8 out +0.6*A radius of the imaginary circle located on the side facing the contactless seal of the first wheel, - R8 in is the inner diameter of the radial gap 8r / 8s of the last fin of the non-contact seal, and R8 out is the outside diameter, and - A is the axial distance between the last fin of the contactless seal and the side of the fixed part of the second wheel that, in operation, faces the contactless seal of the first wheel. The passage outlet according to the invention leaves into the primary flow passage between the blades at an axial distance from the main edge of the blade that is at least 1 / 5 of the total axial width Br of the blade cascade.

Description

[Technical Field]

[0001] Technical Field The invention relates to all types of axial turbines in general, both steam turbines (where the working medium is steam) and gas turbines in general (where the medium can be flue gas, gas, air, etc.), in all their variants. [Background technology]

[0002] The flowpath of an axial turbine consists of individual axial stages, which are formed by alternating successive stator and rotor wheels.

[0003] The stator wheel primarily consists of a blade cascade made up of individual airfoils arranged side by side around the circumference of the stator wheel. At the outer periphery, the airfoils are fixed to the stator with a fixation. The fixation can either be integral (a ring on an assembled stator wheel) or each blade can have its own partial fixation (as in cutting blades). At the inner diameter, the stator blade cascade is sealed against the rotor using a shroud or disk with contactless seals. The stator wheel shroud can either be integral for up to half of the cascade or (for cutting blades) it can be integral for each blade individually.

[0004] The rotor wheel primarily consists of a blade cascade of individual airfoils arranged side by side around the circumference of the rotor wheel. At the inner circumference, the airfoils are immovably fixed to the rotor or rotor disk by means of fixtures. At the outer diameter, the rotor blade cascade is sealed against the rotor using a rotor shroud with contactless seals. The rotor wheel shroud can either be common to several blades or, in the case of cutting blades, integral with each individual blade.

[0005] The stator blades are designed to accelerate and direct the flow of working medium circumferentially, and the rotor blades are designed to capture the spinning flow and transmit the forces generated by it flowing around the rotor. The blade passages of the stator and rotor blade cascades, together with the axial gaps between the blade cascades, form the primary flowpath.

[0006] The mounting arrangement of the rotor blades affects the stage design. Stages can be drum-type, where the blades forming the rotor wheel are attached directly to the rotor body, or wheel- or disk-type, where a disk is formed on the rotor and the blades are then attached to it. Drum-type stages are typically used for higher reaction stages, while wheel-type stages are typically used for lower reaction stages.

[0007] The rotor must be able to rotate relative to the stator and possibly also have some axial movement due to differential deformations, for example, caused by thermal expansion. Non-contact seals, which must have a certain gap or clearance due to long-term durability requirements, are usually used for this purpose. The gap / clearance must be as small as possible, but cannot be completely closed. Therefore, manufacturers try to reduce the flow coefficient of the non-contact seal as much as possible. Typical descriptions of such non-contact seals are various types of labyrinth-staggered labyrinth, look-through labyrinth, and fin-fin type seals. Non-contact seals also include honeycomb seals, which operate on a similar principle and therefore can also be considered labyrinth seals, only the labyrinth fins have a more complex shape. Non-contact seals, together with the axial clearances before and after them that connect them to the primary flow path, form a secondary flow path.

[0008] Therefore, a small amount of working medium, called the secondary flow, flows through the contactless seal (opposite the primary flow past the blades). The secondary flow is a source of losses. The losses are caused by the leakage itself - the medium bypassing the stator blades through the seal does not accelerate to the required speed, and the medium bypassing the rotor blades cannot exert a force on them and therefore cannot drive the rotor. Further losses occur at the point where the secondary flow of medium that has leaked through the seal rejoins the primary flow. This is because there is mixing of flows with different directions and velocities. Furthermore, there is unfavorable interaction of the two flows in the sensitive region upstream of the subsequent blade cascade. This is where secondary vortices form, which can be strengthened by this interaction.

[0009] All these losses depend on the amount of medium flowing through the secondary flow. Therefore, one way to reduce these losses is to reduce the flow velocity through contactless seals. However, this reduction is limited by the need for reliable operation throughout the entire operating range of the machine.

[0010] prior art In a standard design of a stage, the non-contacting seal typically enters the axial gap ("cavity") between the shroud or disk and the blade stationary part in the direction of the primary flow of the next wheel. The secondary flow leaves the non-contacting seal at a relatively high velocity, overcomes the axial gap by inertia, strikes the face of the stationary part of the next wheel, and bends against it, changing the axial component of the velocity to a radial one, while the circumferential component of the flow is only slightly reduced by friction. The secondary flow therefore enters the primary flow with a high radial component, and also with a high circumferential component in the coordinate system associated with the blade cascade of the next wheel. Both of these components differ significantly from the primary velocity component and therefore result in high losses.

[0011] Various solutions are applied to reduce the losses resulting from the interaction between the secondary flow returning from the seal to the primary flow. For example, US Patent No. 9,476,315 B2 describes a solution that cancels the circumferential component of the secondary flow velocity. This reduces the difference between the circumferential component of the primary flow, which is very small, and the circumferential component of the secondary flow velocity. This reduces the losses caused by the mixing of the two flows and also the losses due to increased secondary losses further downstream in the blade cascade. The drawback is that some of the kinetic energy of the secondary flow that could be used is lost.

[0012] Another way to reduce these losses is to use passages in the stator or rotor stationary part that bypass the next blade cascade and allow the seal of the next downstream blade cascade to be refilled (for example, DE 4331779 A1, US 8147180 B2, US 5328326 or US 10041368 B2). The secondary flow does not actually return to the primary flow, does not affect it and does not increase the losses in the blade cascade. The disadvantage is that the kinetic energy contained in the secondary flow is not used in this case.

[0013] Thus, none of the solutions mentioned above address the utilization of the kinetic energy of the secondary flow. Nevertheless, the kinetic energy of the secondary flow in the flow to the next blade cascade is greater than the kinetic energy of the primary flow. The kinetic energy resulting from packing is addressed, for example, in U.S. Pat. No. 5,328,326 (see FIG. 5 therein), where the rotor blade stationary sections are inclined, so that the medium flowing from the stator wheel seal can flow between the rotor blades, at least partially utilizing its kinetic energy. However, a major drawback is that, in the relative coordinate system, the secondary flow has a large circumferential component in the direction opposite to the rotor blade rotation, impinging on the suction (rear) side of the rotor blades, which, on the one hand, causes them to brake, and, on the other hand, is in the same direction as the secondary vortices rotate. The secondary flow thus accentuates the secondary vortices and increases secondary losses.

[0014] This problem is addressed by the document DE 2140720 A1, which describes a similarly shaped fixing at the rotor blade hub as the previous one, but with the addition of a protrusion from the stator wheel disk that overlaps this shape. The protrusion guides the secondary flow axially. Grooves are then formed inside it, through which the secondary flow flows, to guide it in the correct circumferential direction. However, the efficiency of this guidance is very low, and this solution is associated with a large loss of the kinetic energy of the secondary flow. Furthermore, this disk protrusion protrudes the axial length of the stage, which results in a smaller number of stages for a given bearing distance and poorer turbine efficiency. Summary of the Invention [Means for solving the problem]

[0015] Summary of the Invention The above mentioned drawbacks of the state of the art are eliminated by the turbine assembly according to the invention as defined in claims 1 and 9 respectively, and by the axial turbine as defined in claim 20.

[0016] These devices reduce losses in axial turbines that occur when secondary flow through a leak returns to the primary flow.

[0017] In the case of a turbine assembly consisting of a rotor wheel in the direction of working medium flow and a stator wheel following it in the direction of working medium flow, such a turbine assembly is called a turbine stage. For the purposes of describing the present invention, the generic term turbine assembly includes both a stator wheel-rotor wheel pair and a rotor wheel-stator wheel pair following it in the direction of primary working medium flow.

[0018] In the turbine assembly according to the invention, passages are formed at least in the stationary part (in the working medium flow direction) of the second wheel of the assembly (i.e. the rotor or stator wheel) between some adjacent blades for discharging the working medium leaking through the labyrinth seal (in the working medium flow direction) of the first wheel of the assembly (i.e. the stator or rotor wheel) and returning it to the primary flow path.

[0019] The passage inlet of the present invention is radially aligned with the center of the turbine assembly axis and R8 in -0.6*A, and a virtual circle with a radius of R8 out +0.6*A and an imaginary circle having a radius of R8, which is located on the side of the fixed part facing the labyrinth seal of the leading wheel. in is the inner diameter of the radial gap of the last fin of the labyrinth seal (commonly called the radial clearance), and R8 out is the outer diameter and A is the axial distance between the last fin of the labyrinth seal and the side of the stationary part of the next wheel that faces towards the labyrinth seal of the preceding wheel during operation (the axial distance between the radial gap of the last fin and the blade stationary part can be different for some types of packing during operation and in the non-operating state of the turbine).

[0020] The passage outlet according to the invention enters the primary flow passage between the blades at an axial distance from the major edge of the blade that is at least 1 / 5 of the total axial width of the blade cascade.

[0021] The solution according to the present invention reduces losses of the secondary flow through mixing and interaction with the primary flow, increasing the overall efficiency of the turbine assembly and therefore the turbine as a whole. This solution is based on creating passages that properly discharge the secondary flow from the non-contacting seal into the blade cascade downstream of a given non-contacting seal. The passages guide the secondary flow so that it does not disturb the primary flow and its kinetic energy is used to reduce losses and increase the work done by the stage. The passages are located in the stationary part of the wheel downstream of a given packing and therefore do not increase the axial length of the stage. There is enough space for the secondary flow to be properly guided, and only after such guidance is the secondary flow introduced into the primary blade passage. The passages can be formed in the stationary part of the rotor blades and in the stationary part of the stator blades for both drum and wheel (disk) type stages.

[0022] Advantageous embodiments are the subject of the dependent claims. Preferably, in the turbine assembly according to the invention, - Passages are formed between all the blades of the wheel, the passage inlet is located radially on the side of the stationary part facing the labyrinth seal of the preceding wheel, at the level of the gap of the last fin of the labyrinth seal, i.e. at the same radial distance from the axis of the turbine assembly as the radial gap, so that the working medium can flow directly from the radial gap of the last fin of the labyrinth seal into the passage inlet; the passage inlet extends circumferentially between adjacent blades over substantially the full width of the blade passage, i.e. over substantially the full spacing between the blades; - The radial height of the passage at the inlet is determined by the radial gap size of the last fin of the labyrinth seal (R8 out -R8 in ), preferably greater than or equal to (R8out -R8 in ) and 4*(R8 out -R8 in ) between the passage outlet exits into the primary flow passage between the blades at an angle of less than 45° (measured in the meridian plane from the end wall of the blade passage at the point of passage exit), preferably less than 26°; - at least one additional labyrinth seal fin is formed on the first wheel shroud of the assembly, and a cylindrical surface is formed on the stationary part of the second wheel in front of the passage inlet (or directly on the rotor or stator), this additional fin forming the last radial gap of the labyrinth seal and connecting this last radial gap of the labyrinth seal with the passage inlet.For turbine assemblies consisting of a stator wheel and a rotor wheel arranged downstream thereof in the direction of working medium flow (i.e. for passages formed in the rotor), the additional fin can be formed directly on the stator disk, and a cylindrical surface is formed directly on the rotor wheel, in particular on the rotor disk (in particular in the case of wheel (disk) type turbine stages). The passage exit cross section has a size of 20% to 120%, preferably 85%, of the gap size of the last labyrinth seal fin per blade of the second wheel of the assembly. The last stator labyrinth seal fin clearance Fs per rotor blade for the case of conventional circular last stator labyrinth seal fin clearance seal Regarding the area of

number

number

[0023] In the case of a turbine assembly consisting of a rotor wheel and a stator wheel arranged in a downstream direction of the working medium flow (i.e. with respect to the passages formed in the stator), it is further preferred that: - the passage outlet extends circumferentially between adjacent stator wheel blades across substantially the full width of the blade passage; the radial height of the passage at the outlet to the primary blade passage is 0.25 to 1.1 times its radial height at the inlet, preferably 70% of its radial height at the inlet; - The passage outlet enters the primary flow passage between the blades of the stator wheel at an axial distance of at least 1 / 2*Bs, preferably 0.64*Bs to 0.86*Bs from the main edge of the blade, where Bs is the total axial width of the stator blade cascade at its point of connection to the stationary part.

[0024] All directions (radial, circumferential, axial, longitudinal) are named throughout the text in relation to the turbine's major axis. The plane containing the turbine's major axis is identified as the "meridian" plane.

[0025] DESCRIPTION OF THE DRAWINGS The present invention will now be described in detail using specific embodiments shown in the drawings. [Brief explanation of the drawings]

[0026] [Figure 1] Longitudinal section of flow passage with drum type axial stage with cylindrical end walls at hub and tip and staggered labyrinth type stator and rotor wheel contactless seals. Standard state of the art design. [Figure 2] Longitudinal section of a flow passage with a drum-type axial stage with cylindrical end walls at the hub and tip and staggered labyrinth-type stator and rotor wheel contactless seals, showing the passages in the stationary portions of the rotor and stator blades. [Figure 3] 3 is a cross section UU of FIG. 2 showing a radially inward view of the rotor blade stationary portion with the passage shape and outlet. [Figure 4a] 3 is a cross section YY of FIG. 2 showing a view axially away from the center of the fixed part of the stator blade with a passage shape. FIG. 4 is an embodiment with separate deflectors 9s for the design of the assembled stator wheel with an airfoil profile. [Figure 4b] 3 is a YY cross section of FIG. 2 showing a view axially away from the center of the stationary portion of the stator blade with a passage shape.

[0023] FIG. 3 is a cross section of FIG. 2 showing a view axially away from the center of the stationary portion of the stator blade with a passage shape.

[0024] FIG. 3 is a cross section of FIG. 3 showing a view axially away from the center of the stationary portion of the stator blade with a passage shape for a stator wheel design with airfoils milled as one piece with the stationary portion. [Figure 5] 4a , cross section ZZ, showing a portion of the passage formed between the separate deflectors 9s and the fixed part 2s for the assembled stator wheel design with the airfoil profile depicted. [Figure 6] Detail of a front V-view of the rotor wheel of FIG. 2 showing the passage entrance at the rotor blade stationary portion. [Figure 7] XX section of the rotor wheel of FIG. 2 showing a cross section of the passages in the fixed part of the rotor blades. [Figure 8] Longitudinal section of a flow passage with a drum-type axial stage with conical end walls at the hub and tip and staggered labyrinth-type stator and rotor wheel contactless seals, showing the passages in the stationary portions of the rotor and stator blades. [Figure 9] Longitudinal section of a flow passage with a drum-type axial stage with cylindrical end walls at the hub and tip and contactless seals at the Louk-Lu labyrinth-type stator and rotor wheels, showing the passages in the stationary parts of the rotor and stator blades. [Figure 10] Longitudinal section of a flow passage with a drum-type axial stage with conical end walls at the hub and tip and non-contact seals at the fin-fin type stator and rotor wheels, showing the passages in the stationary parts of the rotor and stator blades. [Figure 11]Longitudinal section of a flow passage with a drum-type axial stage with cylindrical end walls at the hub and tip and contactless seals at the honeycomb-type stator and rotor wheels, showing the passages in the stationary parts of the rotor and stator blades. [Figure 12] Longitudinal section of a flow passage with a drum-type axial stage with staggered labyrinth-type stator and rotor wheel contactless seals with conical end walls at the hub and tip and additional fins 10s and 10r at the seal outlet. Shown are the passages in the stationary part of the rotor and stator blades and the cylindrical surfaces 11r and 11s that seal against the additional fins and guide the working medium into the passage inlet. [Figure 13] Longitudinal section of a flow passage with a wheel (disk) type axial stage with a staggered labyrinth type stator and rotor wheel contactless seal with conical end walls of the hub and tip and additional fins 10s and 10r at the seal outlet. Shown are the passages in the stationary part of the rotor and stator blades and the cylindrical surfaces 11r and 11s that seal against the additional fins and guide the working medium into the passage inlet. DETAILED DESCRIPTION OF THE INVENTION

[0027] Description of the embodiment Embodiment 1 The bottom of Figure 2 shows a turbine assembly, or in this case a drum-type turbine stage, for an axial turbine, consisting of a stator wheel and a rotor wheel arranged downstream of the working medium flow. The blades forming the rotor wheel are fixed directly to the rotor body. The stator wheel consists of a pair of blade airfoils 1s arranged side by side around the circumference of the stator wheel to form a stator blade cascade, and a stationary part 2s that secures the blades 1s to the stator and seals the blade cascade at its outer periphery. The blade cascade is sealed against the rotor at its inner periphery by a shroud 3s with a non-contact labyrinth seal 4s. The rotor wheel consists of a pair of blade airfoils 1r arranged side by side around the circumference of the rotor wheel to form a rotor blade cascade, and a stationary part 2r that secures the blades 1r to the rotor and seals the blade cascade at its inner periphery. The blade cascade is sealed against the stator at its outer periphery by a shroud 3r with a non-contact labyrinth seal 4r. In this embodiment, this is a so-called staggered labyrinth.

[0028] In the stationary part 2r of the rotor wheel, between at least some adjacent blades 1r, passages 7r are formed to discharge the working medium that has leaked from the axial gap ("cavity") 6s through the labyrinth seal and return it to the primary flow path. The inlets of the passages 7r are located on the side of the stationary part 2r facing the labyrinth seal 4s of the preceding stator wheel.

[0029] The secondary flow leaving the stator contactless seal 4s enters passage 7r, firstly because the passage is opposite the outlet of the contactless seal and the flow goes there by inertia, and secondly because the passage exits into the rear of the main rotor passage where the pressure is lower at the passage inlet, and the secondary flow is therefore sucked into the passage outlet. Thus, as in the standard stage design according to Figure 1, little or no secondary flow enters the main passage through the axial gap. Flow disruption and secondary vortex buildup are therefore minimized.

[0030] It is advantageous if the passage inlet is located directly opposite the outlet of the contactless seal, but it has been found to work well if the passage is located over a relatively wide range of angles (-α, +α), reliably from 0° to about 30° or more, measured in the meridian plane.

[0031] The passage shape is such that it has an acute angle β r In the meridional plane, the secondary flow is guided into the primary flow so that its radial component is small. In the circumferential direction, the passages are formed so that the secondary flow is discharged on the suction (rear) side of the blade with as few losses as possible. Now, due to its higher relative kinetic energy, the secondary flow after entering the main passage accelerates the boundary layer that would normally form around the surface of the stator 2r, further reducing rotor blade losses.

[0032] The passage can be formed, for example by milling, so that its wall defining it in the circumferential direction is formed in the fixing part of the adjacent blade, its wall limiting it in the radial direction closer to the main passage is formed in one blade, and its wall limiting it in the radial direction further away from the main passage is formed in the other blade. The passage is thus formed by attaching the blades together, as shown in Figures 6 and 7. However, this is only one option for creating the passage. Another option is to close the passage to the main passage, for example by drilling or fixing other components to the fixing part 2r or to the airfoil.

[0033] Embodiment 2 Another possible application of the claimed principle comprises passages formed in the fixed part 2s of the stator blades shown in the upper part of Figure 2. Here, use is limited to stages having another stage immediately upstream with a contactless seal 4r in the rotor shroud 3r. There is no benefit to using passages in the first stage of the flow path or in stages downstream of the working medium extraction from the flow path.

[0034] The passage design can be described as follows: in the fixed part 2s of the stator wheel, passages 7s are formed between at least some adjacent blades 1s to discharge the working medium leaking from the axial gap ("cavity") 6r through the labyrinth seal 4r into the primary flow path. The inlets of the passages 7s are located on the side of the fixed part 2s facing towards the labyrinth seal 4r of the preceding rotor wheel.

[0035] The passages can be formed by milling in a similar manner as described above for the passages in the rotor stator, and their function is therefore similar to that described. This technique is suitable for blades manufactured by milling, where the airfoil and its stator are made in one piece. The passages can then be aerodynamically shaped in the best case, as shown in Figure 4b. The passages should have as little resistance as possible and a sufficient flow area at the outlet for the medium to be discharged.

[0036] Embodiment 3 A different technique is suitable for the airfoils of the stator blades 1s, which are made according to the depicted profile and then assembled with the ring forming the stationary part 2s. The ring of the stationary part 2s is formed to have the shape of the outer end wall of the passage, while the inner end wall is then formed by the deflector 9s, a separate component with cutouts for the blades 1s inserted between them. The passages 7s then take the form of slots between the deflector 9s and the stationary part 2s (see FIG. 5). The airfoil of the blade 1s passes through the slots 7s and defines the shape of the passages 7s in the circumferential direction. The passage outlets 7s then take the form of slots spanning the full width of the primary blade passages (see FIG. 4a). The secondary flow passing through the slots separates from the profile surface as it flows around the profile, which is related to losses, but what is important is that the deflector 9s prevents it from flowing radially along the airfoil and amplifying secondary vortices. Despite these losses, most of the secondary flow maintains its high kinetic energy and accelerates the boundary layer again at the passage exit, reducing losses in the stator blade cascade 1s. Another beneficial effect is that the secondary flow, which has a medium with higher energy than the primary flow, is guided obliquely towards the center under the shroud of the following rotor wheel and therefore does not leak into the rotor seal 4r. The work done thereby is greater than that done with the same flow velocity of the primary flow.

[0037] Embodiment 4 FIG. 8 shows a similar solution to the preceding examples 1 to 3, but the stages shown differ in the end walls of the fixed parts 2s and 2r and the conical surfaces of the shrouds 3s and 3r.

[0038] Embodiment 5 FIG. 9 shows a similar solution to the preceding examples 1 to 3, but differs in the look-through labyrinth type contactless seal.

[0039] Embodiment 6 FIG. 10 shows a similar solution to the preceding Examples 1 to 3, but differs in the fin-fin type contactless seal.

[0040] Embodiment 7 FIG. 11 shows a solution similar to the preceding examples 1 to 3, but differs in the non-contact seals of honeycomb types 12s and 12r.

[0041] Embodiment 8 12, this is similar to the preceding examples 1-3, but differs in the additional fins 10s and 10r at the outlets of the contactless seals 4s and 4r, which improve sealing and, together with the opposing cylindrical surfaces 11r and 11s, better guide the flow into the passages 7r and 7s.

[0042] Embodiment 9 According to FIG. 13, the arrangement is for a wheel (disk) type stage. Unlike the drum type stage (preceding examples 1-8), the stator blade cascade in this embodiment is not sealed at its inner diameter with a shroud, but rather with a disk 13s carrying a contactless seal 4s at its inner diameter. The disk 13r is formed on the rotor, to which the stationary part 2r of the rotor blades 1r is attached. Because the radial distance between the stator wheel seal 4s and the passage 7r of the stationary part 2r is too large, the kinetic energy of the secondary flow exiting 4s is lost along this path. Therefore, at least one additional fin 10s is formed on the outer diameter of the stator disk 13s, which, together with the cylindrical surface 11r formed on the rotor disk 13r or on the stationary part 2r, accelerates the secondary flow again and guides it into the passage 7r. In this embodiment, this additional fin then represents the last fin of the labyrinth seal defined in the claims.

[0043] A note about signs The addition of a lower case "r" or "s" to the reference numbers and individual dimension symbols refers to the respective element / dimension relating to the rotor ("r") or the stator ("s"), although some reference numbers do not have these "indexes" if it is not distinguished whether the respective element / dimension relates to the rotor or the stator. This should make the analogy of solutions for passages in the rotor wheel or stator wheel clearer.

Claims

1. A turbine assembly or turbine stage of an axial flow turbine, comprising a stator wheel and a rotor wheel arranged in a downstream direction of the working medium flow, - said stator wheel comprises airfoils of blades (1s) arranged side by side around the circumference of said stator wheel so as to form a stator blade cascade, and fixing parts (2s) which fix said blades (1s) to the stator and also seal said blade cascade at its outer periphery, said blade cascade being sealed at its inner periphery to the rotor by a shroud (3s) or to the stator disk (13s) by a contactless seal (4s); - a turbine assembly in which the rotor wheel comprises airfoils of blades (1r) arranged side by side around the circumference of the rotor wheel so as to form a rotor blade cascade, and a fixing part (2r) fixing the blades (1r) to the rotor or rotor disk (13r) and also sealing the blade cascade at its inner periphery, the outer periphery of which is sealed against the stator by a shroud (3r) with a contactless seal (4r), Passages (7r) are formed in the stationary part (2r) of the rotor wheel between at least some adjacent blades (1r) for discharging the working medium leaking through the contactless seal (4s) from the axial gap (6s) into the primary flow path, the entrance of said passage (7r) is radially - centred on the axis of said turbine assembly and having a radius of R8s ｉｎ -0.6*Ar and a virtual circle where - a radius centered on the axis of the turbine assembly R8s ｏｕｔ +0.6*Ar A virtual circle between the stator wheel and the stationary part (2r) on the side facing the non-contact seal (4s) of the preceding stator wheel, R8s ｉｎ is the inner diameter of the radial gap (8s) at the last fin of said contactless seal (4s), R8s ｏｕｔ is the outer diameter of the radial gap (8s) at the last fin of the contactless seal (4s), Ar is the axial distance between the last fin of the contactless seal (4s) and the side of the stationary part (2r) of the next rotor wheel which, in operation, faces the contactless seal (4s) of the preceding stator wheel; the outlets of said passages (7r) emerge into the primary flow passages between said blades (1r) at an axial distance of at least 1 / 5*Br from the main edges of said blades (1r), Br being the total axial width of said rotor blade cascade at its point of connection to said fixed part (2r); 1. A turbine assembly comprising:

2. A turbine assembly according to claim 1, characterized in that said passages (7r) are formed between every two adjacent blades (1r) of said rotor wheel.

3. 2. A turbine assembly according to claim 1, characterized in that the inlet of the passage (7r) is located radially on the side of the stationary part (2r) facing towards the contactless seal (4s) of the preceding stator wheel, at the level of the gap (8s) at the last fin of the contactless seal (4s).

4. 2. A turbine assembly according to claim 1, characterized in that the inlets of the passages (7r) extend in the circumferential direction across the entire width of the blade passage between adjacent blades (1r) of the rotor wheel.

5. The radial height of the passage (7r) at the inlet is equal to the radial size (R8s) of the gap (8s) at the last fin of the contactless seal (4s). ｏｕｔ -R8s ｉｎ ), preferably greater than or equal to (R8s ｏｕｔ -R8s ｉｎ ) ~ 4 * (R8s ｏｕｔ -R8s ｉｎ 2. The turbine assembly of claim 1, wherein:

6. The passage exit cross section (7r) is the area Fs of the gap (8s) at the last fin of the non-contact seal (4s) due to one rotor blade. ｓｅａｌ 2. A turbine assembly according to claim 1, characterized in that it has an area of between 20% and 120%, preferably 85% of the area of the first and second fins.

7. 2. A turbine assembly according to claim 1, characterized in that the outlets of the passages (7r) exit into the primary flow passage between the blades (1r) at an angle βr of less than 45°, measured in a meridional plane from the blade passage endwall at the outlet of the passage (7r), and preferably the angle βr has a magnitude of less than 26°.

8. 2. The turbine assembly according to claim 1, characterized in that at least another additional fin (10s) of the contactless seal (4s) is formed on the shroud (3s) of the stator wheel or on the stator disk (13s) and at least one cylindrical surface (11r) is formed on the stationary part (2r) or directly on the rotor or on the rotor disk (13r), which together with said additional fin forms the last radial gap (8s) of the contactless seal (4s) and connects the inside of this last radial gap (8s) of the contactless seal (4s) with the radially inside of the inlet of the passage (7r).

9. A turbine assembly for an axial flow turbine, comprising a rotor wheel and a stator wheel arranged in a downstream direction of a working medium flow, - said rotor wheel comprises airfoils of blades (1r) arranged side by side around the circumference of said rotor wheel so as to form a rotor blade cascade, and a fixing part (2r) fixing said blades (1r) to the rotor disk (13r) and sealing said blade cascade at its inner circumference, said blade cascade being sealed at its outer circumference against the stator by a shroud (3r) equipped with a contactless seal (4r); a turbine assembly in which the stator wheel comprises airfoils of the blades (1r) arranged side by side around the circumference of the stator wheel so as to form a stator blade cascade, and a fixing part (2s) fixing the blades (1s) to the stator and also sealing the blade cascade at its outer periphery, the inner periphery of which is sealed against the rotor by a shroud (3s) or against a stator disk (13s) by a contactless seal (4s), Between at least some adjacent blades (1s), passages (7s) are formed in the stationary portion (2s) of the stator wheel for discharging working medium leaking from the contactless seal (4r) through the axial gap (6r) into the primary flow path; - the inlet of the passage (7s) is radially - centred on the axis of said turbine assembly and having a radius of R8r ｉｎ -0.6*As and a virtual circle where - a radius centered on the axis of the turbine assembly R8r ｏｕｔ +0.6*As and a virtual circle between the fixed part (2s) and the non-contact seal (4r) of the preceding rotor wheel. R8r ｉｎ is the inner diameter of the radial gap (8r) at the last fin (4r) of the contactless seal, R8r ｏｕｔ is the outer diameter of the radial gap (8r) at the last fin (4r) of the contactless seal, As is the axial distance between the last fin (4r) of the contactless seal and the side of the stationary part (2s) of the trailing stator wheel that faces the contactless seal (4r) of the leading rotor wheel during operation; - a turbine assembly characterized in that said outlets of said passages (7s) emerge into said primary flow passages between said blades (1s) at an axial distance of at least 1 / 5*Bs from said main edges of said blades (1s), Bs being the overall axial width of said stator blade cascade at its point of connection to said fixed part (2s).

10. A turbine assembly according to claim 9, characterized in that a passage (7s) is formed between every two adjacent blades (1s) of said stator wheel.

11. 10. A turbine assembly according to claim 9, characterized in that the inlet of the passage (7s) is located radially at the level of the gap (8r) of the last fin of the contactless seal (4r), on the side of the stationary part (2s) facing towards the contactless seal (4r) of the preceding rotor wheel.

12. 10. A turbine assembly according to claim 9, characterized in that the inlets of the passages (7s) extend circumferentially between adjacent blades (1s) of the stator wheel across the entire width of the blade passage.

13. The radial height of the passage (7s) at the inlet is equal to the radial size (R8r) of the gap (8r) at the last fin of the contactless seal (4r). ｏｕｔ -R8r ｉｎ ), preferably greater than or equal to (Rr ｏｕｔ -R8r ｉｎ ) ~ 4 * (R8r ｏｕｔ -R8r ｉｎ 10. The turbine assembly of claim 9, wherein:

14. 10. A turbine assembly according to claim 9, characterized in that the outlets of the passages (7s) extend in the circumferential direction between adjacent blades (1s) of the stator wheel across the entire width of the blade passage.

15. A turbine assembly according to claim 14, characterized in that the radial height of the passage (7s) at the outlet to the primary blade passage is between 0.25 and 1.1 times its radial height at the inlet, preferably 70% of its radial height at the inlet.

16. 10. A turbine assembly according to claim 9, characterized in that the outlets of the passages (7s) emerge into the primary flow passages between the blades (1s) at an axial distance of at least 1 / 2*Bs from the main edges of the blades (1s), preferably between 0.64*Bs and 0.86*Bs from the main edges of the blades (1s), Bs being the overall axial width of the stator blade cascade at its point of connection to the fixed part (2s).

17. The exit cross section of the passage (7s) is the area Fr of the gap (8r) at the last fin of the contactless seal (4r) due to one stator blade. ｓｅａｌ 10. A turbine assembly according to claim 9, characterized in that it has an area of between 20% and 120%, preferably 85% of the area of the first and second fins.

18. 10. A turbine assembly according to claim 9, characterized in that the outlets of the passages (7s) exit into the primary flow passage between the blades (1s) at an angle βs of less than 45°, measured in a meridional plane from a blade passage end wall at the outlet of the passages (7s), preferably said angle βs having a magnitude of less than 26°.

19. 10. A turbine assembly according to claim 9, characterized in that at least another additional fin (10r) of the contactless seal (4r) is formed on the shroud (3r) of the rotor wheel and a cylindrical surface (11s) is formed on the fixed part (2s) or directly on the stator, which together with said additional fin forms the last radial gap (8r) of the contactless seal (4r) and radially connects the outside of this last radial gap (8r) of the contactless seal (4r) with the radially outside of the inlet of the passage (7s).

20. An axial flow turbine, characterized in that it comprises at least one turbine assembly according to claim 1 and / or at least one turbine assembly according to claim 9.

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