FR2560929A1 - IMPROVEMENTS TO TURBO-MACHINE ROTOR FINS - Google Patents

Abstract

TURBINE ROTOR FIN WITHOUT ENCLOSURE ESPECIALLY FOR GAS TURBINE ENGINES HAVING A PLANE BEARING WITH A RECESS 36 AT ITS OUTER RADIAL END. THE RECESS 36 IS DEFINED BY A PERIPHERAL WALL 46. SEVERAL CROSS-SECTIONAL WALLS 56, 58, 60 CROSS IT, CUT THE MAIN MEMBER OF THE PLAN BEARING 32 AND DIVIDE IT INTO SEVERAL CHAMBERS 48, 50, 52, 54. THE PERIPHERAL WALL 46, THE CROSS-SECTIONAL WALLS 56, 58, 60, THE CHAMBERS 48, 50, 52, 54 AS WELL AS A FIXED ENVELOPE 38 COOPERATING WITH THEM FORM A CHICANE TO CONTROL THE LEAKAGE CURRENT OF HOT GAS FLOWING BETWEEN THE OUTSIDE RADIAL END OF THE BEARING PLAN 32 AND THE ENVELOPE 38. THE OPTIMAL REDUCTION OF THE LEAKAGE CURRENT OF THE HOT GASES BETWEEN THE OUTER RADIAL END AND THE ENVELOPE IS OBTAINED WHEN THE CROSS-SECTIONAL WALLS ARE PROVIDED SUBSTANTIALLY TO THE PERPENDICULAR OF THE DIRECTION OF THE LEAKAGE CURRENT.

Description

1o The present invention relates to a turbomachine rotor fin

and in particular of the recesses

  in the top of the turbo rotor fins

  machine for a gas turbine engine.

  The efficiency of each rotor stage in a gas turbine engine depends on the amount of energy

  transmitted to each of the stages, which is limited, par-

  especially with fins without an envelope, by

  leakage currents from the working fluid, air or gas

  flowing at the end of the rotor fins.

  The present invention relates to a turbomachine fin which will reduce the air leakage current or

  of gas at the end of the fins without envelopi.

  To this end, the present invention provides a turbine rotor fin without an envelope comprising a bearing plane, the outer radial end of the plane

  bearing having a recess circumscribed by a peri-wall

  spherical; at least one transverse wall passing through the recess, cutting the main member and delimiting at least two chambers, the peripheral wall, the wall 2. passing through the recess, the chambers and a fixed casing cooperating with them forming a baffle

  a leakage current of hot gases between the outer end

  radial of the bearing plane and the envelope.

  The wall (s) crossing the recess and intersecting the main member is (are) substantially perpendicular (s) to the direction of the leakage current of hot gases circulating between the outer radial end

of the bearing plan and the envelope.

  The bearing plan can include two or three parts.

  kings crossing the recess at its outer radial end

better.

  The lift plan may include a cir-

  internal duct bake for the cooling air flow

management.

  The bearing surface may be hollow and include a

  outer wall by defining the shape and an inner wall

  dividing its cavity into a united interior chamber and an exterior chamber; the inner wall is held

  separated from the outer wall by a plurality of eminents

  these projecting from the outer wall; the inner wall

  has a plurality of orifices allowing

  the cooling air contained in the internal chamber

  to enter the exterior room and to

  to come into contact with the inner surface of the outer wall

  better. The outer wall of the bearing plane comprises

  a plurality of orifices, allowing the air to cool

  contained in the outer chamber to circulate

  on the outer surface of the outer wall.

  Possibly the bearing plane can be massive.

  The invention will be described in more detail.

  cut in relation to the attached drawings in which:

  Figure 1 is a schematic view of a mo-

  gas turbine generator comprising a partial cutaway revealing 3. a section view of the turbine stage; Figure 2 is a partial enlargement of the sectional view of the turbine stage of Figure 1; Figure 3 is an enlarged view of an embodiment of the top of the turbine rotor fin shown in Figure 2; Figure 4 is a sectional view along line A-A of Figure 3; Figure 5 shows on an enlarged scale the direction of the leakage current at the top of the fin of the turbine rotor of Figure 2; Figure 6 is an enlarged view of another embodiment of the top of the turbine rotor fin of Figure 2; Figure 7 is a sectional view along line B-B of Figure 6; and Figure 8 is a sectional view along the line

C-C in Figure 7.

  A 10 motor & gas turbine, like the one that

  is shown in Figure 1, has aligned in the following

  each other a fan 12, a compressor 14, a combustion device 16, a turbine stage 18 and

  a nozzle 20. The turbine stage 18 comprises several rotors

  tors 22 and several stator vanes 26. Each rotor 22 carries a plurality of turbine fins 24 arranged

in axial directions.

  There is shown in Figure 2 one of the rotors 22, one of the turbine fins 24 which is subject thereto

  as the adjacent stator vanes 26. The fin 24 of tur-

  bin has a base 28, a platform 30 and a plane

  both 32, the base 28 and the plane bearing 32 being subject to

  woven on either side of the platform 30. The plane carrying 32 has a vertex 34 at its end remote from the

  platform 30, which has a recess 36. An envelope

  loppe 38 surrounds it circumferentially, which is separated from the rotor 22 and the radial turbine fins 24 by a 4.

gap 40.

  In Figures 3 and 4 is shown the recess-

  ment 36 located at the top 34 of the bearing plane 32. The bearing plane 32 has a leading edge 42 and a trailing edge 44; a peripheral wall 46 located at the radial end

  outside of the bearing plan delimits the recess 36. The recess

  dement 36 is divided into several chambers 48, 50, 52, 54 by several walls 56, 58, 60 respectively crossing the recess 36 and cutting the main merbrage of the plane

o10 bearing.

  FIG. 5 shows the direction of the leakage current at the top 34 of a turbine fin 24. In turbines with fins

  rotor without casing a small fraction of the fluid

  tor circulating through the turbine tends to pass from the pressure surface 100 to the suction surface 102 of the bearing plane through the gap 40 located between the top of the bearing plane and the fixed casing. This leakage current occurs due to the pressure difference between the pressure surface and the suction surface of the bearing plane. The leakage current, due to the fact that it is created over a large part of the height of the bearing plane, causes current disturbances, which reduces the efficiency

of the turbine.

  In Figures 6, 7 and 8, the evi-

  dement 36 located at the top 34 of the bearing plane 32, which

  has several walls which pass through the recess.

  The internal structure of the bearing plane 32 has also been shown. The bearing plane has a leading edge 62 and a trailing edge 64. A peripheral wall 66 located at the outer radial end of the bearing plane defines the recess 36. L recess 36 is divided into several

  chambers 68, 70, 72 by several walls 74, 76 respectively

  which cross the recess 36 and cut the mem-

  main burn of the bearing plane. In this particular embodiment 5. the internal structure of the bearing plane

  has an interior chamber 80 and an exterior chamber

  78 which are separated from each other by a

  inner king 82. The inner wall 82 has several

  several openings 84 which put the internal chamber 80 and the external chamber 78 in communication so that

  the cooling air contained in the chamber 80 can-

  go through the holes 84, and come into contact with the

  inner surface of the outer wall 86 of the plane

  so much, thus helping to cool it down. Other cooling modes can be envisaged, and it is possible,

  for example, make holes 88 in the wall ex-

  of the bearing plane so as to create a layer of

  cooling on the external surface of the wall ex-

later.

  A turbine fin 24, like the one shown, is generally manufactured as follows:

  base, platform and outer wall of the plane

  both are molded, and the inner wall 82 is brazed on several projections projecting from the wall

  exterior 86. The top 34 of the bearing plane is then

  subject to the outer radial end of the bearing plane

  by brazing or any other metallurgical or mechanical means

picnics.

  During the operation of the turbocharged engine 10

  no gas the air enters the engine, crosses it and is compressed by the blower 12 and the compressor 14. The

  fuel mixed with compressed air is burned in the dispo-

  combustion sitive. The hot gases produced by the com-

  fuel mixed with air cross the turbine 18, the nozzle 20 and then enter the atmosphere. The hot gases move the turbines, which drive, by means of shafts, the fan 12 and the

compressor 14.

  The turbine stage 18 comprises stator vanes

  tor 26 and rotor fins 24 arranged alternately.

  6. each stator blade 26 directing the hot gases onto the plane carrying 32 of the rotor fin 24 with an optimum angle of incidence. Each fin 24 of the rotor borrows kinetic energy from the hot gases. flowing through the turbine stage 18 to move the blower 12

and compressor 14.

  The efficiency with which the fins 24 of the ro-

  tor borrows kinetic energy from hot deter-

  undermines the efficiency of the turbine, which in part depends

  tie of the hot gas leakage current passing between the

  vertex 34 of the plane carrying 32 and the circumferential envelope

  tielle 32. It is by controlling the leakage current passing

  between the top of the plane carrying 34 and the circular envelope

  conference 38 that we can improve the efficiency of

the turbine.

  We can reduce the leakage current by conserving

  a recess 36 in the sonmmet 34 of the bearing plane. This hollow

  ment 36 has several walls 56, 58 and 60 passing through the recess 36 and cutting the main frame of the bearing plane, which delimit several chambers 48, 50

  and 52 as it appears in FIGS. 3 and 4. The pa-

  kings 56, 58 and 60 are arranged substantially at the per-

  pendulum of the leakage current so as to produce a

  optimal reduction of leakage current.

  Walls 56, 58 and 60 as well as the peri-wall

  spherical 46 form a baffle with the envelope 38 cir-

  conference. It is accepted that vortices are

  trapped in chambers 48, 50, 52 and 54 and that these trapped vortices reduce the leakage current between

  the top 34 of the turbine rotor fin 24 and the

veloppe 38.

  The leakage current must pass below several walls 56, 58 and 60, which are oriented directly across the current path and the leakage current is reduced in each of the chambers 48, 50, 52 and 54 by the trapped vortices in each of these 7. bedrooms. Similarly, in Figures 6 and 7, the

  walls 74 and 76., as well as the peripheral wall 66, for-

  a baffle with the casing 38 and the vortices trapped in the chambers 68, 70 and 72 reduce the leakage current between the top 34 of the fin 24 of

turbine rotor and casing 38.

  The rooms delimited in the recess located

  at the top of the bearing plane may be sufficiently

  yours to trap one or more vortices each.

  If, for example, a top of the cell type with a large number of chambers is used, the reduction of the leakage current flowing between the top of the bearing plane and the envelope will not occur, because it will not occur

  no vortices in the chambers of the honeycomb material.

  A recess located at the top of the bearing plane as well as the walls passing through it can be arranged on fins of a solid turbine or on fins

  of a turbine comprising a circuit of cooling conduits

internally.

  The present invention is not limited to the exemplary embodiments which have just been described, it

  is on the contrary subject to modifications and

  laughing who will appear to those skilled in the art.

8.

Claims (8)

  1 - Turbine rotor fin without casing   comprising a bearing plane, the outer radial end   re of the bearing plane comprising a recess circumscribed by a peripheral wall, at least one wall passing through the recess and delimiting at least two chambers,   the peripheral wall, the wall (s) crossing the evi-   the two or more chambers and the fixed envelope cooperate   rant with them and forming a baffle to control the   leakage current of hot gases flowing between the   external radial mite of the bearing plane and the casing, characterized in that at least one wall (56, 58, 60) crosses the recess (36) transversely and cuts the   main frame of the bearing plane.   2 - Turbine rotor fin without envelope according to claim 1, characterized in that the or   the wall (s) (56, 58, 60) which cross (s) transverse-   ment the recess (36) and cut (s) the main member is (are) substantially perpendicular (s) to the direction   the leakage current of hot gases flowing between the former   outer radial end (34) of the bearing plane (32) and the envelope (38).   3 - Turbine rotor fin according to one   claims 1 or 2, characterized in that the plane   bearing (32) has two through walls (74, 76)   the recess (36) at its outer radial end (34).   4 - Turbine rotor fin according to one of the   claims 1 or 2, characterized in that the plane   bearing (32) has three walls (56, 58, 60) crossing   sant the recess (36) at its end (34) radial outer   better. - Turbine rotor fin according to one of the   claims 1 to 4, characterized in that the plane   while (32) has a circuit of conduits (78, 80, 84)   internal for cooling air circulation. 9.   6 - Turbine rotor fin according to the re-   vendication 5, characterized in that the bearing plane (32) is hollow and has an outer wall (86)   which defines the shape of the bearing plane, an interior wall   upper (82) which divides the hollow bearing plane (32) into an inner chamber (80) and an outer chamber (78), the inner wall (82) being spaced from the outer wall (86) by a plurality of eminences which do   protrusion on the outer wall (86), the inner wall   re (82) comprising a plurality of orifices (84) which allow   put the cooling air to pass from the cham-   inner bre (80) in the outer chamber (78) and coming into contact with the inner surface of the wall   outside (86) during operation.   7 - Turbine rotor fin according to the resale   dication 6, characterized in that the outer wall   (86) of the bearing plane (32) comprises a plurality of ori   sockets (88) which allow the cooling air to be   held in the outer chamber (78) to circulate on the outer surface of the outer wall (86) during operation.   8 - Turbine rotor fin according to the resale   dication 6, characterized in that the bearing plane (32) is massive.   9 - Turbine rotor comprising a plurality   turbine rotor fins according to one of the claims previous tions.   - Gas turbine engine comprising at least   a turbine rotor according to claim 9.