FR2490721A1 - TURBOMACHINE WHOSE MOBILE AND FIXED AUBAGES ARE PROTECTED BY A CERAMIC CARAPACE - Google Patents

Abstract

THE INVENTION CONCERNS A TURBOMACHINE WHOSE MOBILE AND FIXED BLADES ARE PROTECTED BY A CERAMIC SHELL. THE SAID MACHINE INCLUDES A ROTOR 16 OF WHICH EACH OF THE FINS 20 INCLUDES A METAL CORE 24 SURROUNDED BY A CERAMIC CARAPACE 22 INTENDED TO PROTECT IT FROM THE HARMFUL EFFECTS OF A FLUID PASSING THROUGH THE MACHINE. A CAP 26 RETAINS THE CARAPACE 22 IN POSITION AROUND THE CORE 24 SO THAT IT IS SUBJECT ONLY TO COMPRESSION EFFORTS. APPLICATION TO TURBOMACHINES, ESPECIALLY PUMPS OR TURBINES.

Description

The present invention relates to turbomachines

  and more particularly a turbomachine whose bladed blades

  bile and fixed are thermally protected by shells in

  ceramic to operate at high temperatures.

  In order to improve the efficiency and to reduce the fuel consumption of turbomachines, such as

  pumps or turbines, it has been proposed to turn the turbines

  at high input temperatures. Temperatures

  Input above 1 3160C is theoretically desirable.

  However, these temperatures are much higher than those that even high-strength metals can withstand.

  perfected without the need for cooling techniques

  complex and expensive. High temperature ceramics

  are the most able to satisfy the conditions of the

  application of high inlet temperatures without the need for a complex cooling technique. Unfortunately,

  ceramics are of a fragile nature. In addition, the costs of

  of ceramic turbine elements are high, since the previous process of producing elements

  profiles of precise dimensions and high resistance to

  ceases hot pressing and grinding. As a result,

  years of research and huge sums of money have been

  thoughts to define and minimize tension stresses

  in ceramics and to develop

  Factories for manufacturing ceramic turbine elements.

  It has also been proposed ceramic elements for over-

  mount abrasion and erosion by substances such as

  coal suspensions. Rotors and bladders

  have been made and tried; however, they are

  throws at tensile stresses under the effect of cen-

  trifuges and are therefore very prone to failure.

  The present invention makes it possible to overcome the disadvantages of the prior art and proposes improved methods and apparatus in which shells or heat-insulating sleeves are made of ceramic materials,

  while metals are used to confer resistance

  necessary mechanical resistance against the resulting stress

  both centrifugal forces, the ceramic shells being fixed to the insulated metal structures in such a way that

  ceramic shells are only subject to

  pressure by centrifugal forces. In addition, injection molding techniques have been developed which allow ceramics to be manufactured inexpensively and

  large quantities with great uniformity and

  remarkable characteristics of mechanical strength, density and surface finish.

complex.

  Accordingly, the present invention is

  object of advanced turbine elements that can sup-

  have inlet temperatures in excess of approximately 1 316 ° C, as well as methods and apparatus for

  ceramic materials for producing turbo components.

machine. -

  The present invention is particularly

  object of the components of a turbomachine having

  heat-insulating shells or sleeves made of ceramic materials which are subject only to compressive forces and which surround

  metal elements that confer the necessary resistance

  re to centrifugal and tension forces.

  The invention will be described in more detail in

  drawings annexed as examples which are in no way

and on which:

  FIG. 1 schematically represents

  ceramic poses of a turbomachine of the prior art; Figure 2 is a section of a portion of the impeller of a turbine whose fins are protected according to the present invention;

  FIG. 3 is a cross-section of a

  section of the impeller of the turbine of FIG. 2; Figure 4 is a horizontal section of one of the blades of the turbine of Figure 2: Figure 5 is a horizontal section of a variant of the blade of the turbine of Figure 2; and Figure 6 is an exploded view of the dawn of the

249072 '

turbine of Figure 2.

  In order to satisfy the conditions of high temperature and erosion of modern turbomachines, the prior art has proposed to make ceramic elements, such as the impeller of a turbine which is generally designated by 2 on the Figure 1. The ceramic impeller 2 of a prior art turbine comprises in particular several fins 4 which form part of the hub 6 of the turbine, as indicated at 8 or which may be removable inserts with roots 10 which are housed in appropriate notches 12 formed in the hub 6. However, when the moving wheel 2 is rotated, it is obvious that the centrifugal force imposes a tension on the fins 4 as indicated by the arrow 14. Since the Ceramic materials are fragile and are particularly prone to failure under the effect of a voltage, these ceramic components of a turbomachine

  of the prior art have not given satisfaction.

  Figures 2 to 4 show a moving wheel

  turbine, generally designated 16, which is

  according to the invention and has a metal hub 18 sup-

  carrying a plurality of composite fins generally designated 20. Each of the fins 20 comprises a shell

  22 ceramic which has an external air configuration

  appropriate dynamic, as seen in particular in Figure 4, surrounding a metal core 24 which is attached to the

  hub 18 as shown in FIG. 3. The shell 22 is

  The core 24 may be integral with the hub 18, as shown at 28 in FIGS. 2 and 3, or it may be fixed to the hub 18 by means of a hub 24.

  appropriate means as a root 30 represented on the

  Figure 2. Also, the cap 26 may be integral with the core 24, as indicated at 32 in Figure 2, or it may be attached to the core 24 by a suitable retaining means such as a link or With this structure, when the mobile wheel 16 is rotated, the ceramic shells 22 are biased against the cap 26 by a force F and the tension forces are supported by the metal cores 24 and the caps 26. Thus , the ceramic shells 22 are subjected only to compressive forces, which

that they support perfectly.

  It is understood that the hot gases that

  S drag the impeller 16 of the turbine pass one way

  conventional input and output ducts (not shown).

  smoked), so that the hot gases come into contact with

  the fin 20 in the region indicated by 36 in FIG.

  Thus, the ceramic shells 22 heat insulate or isolate

thermally the nuclei 24.

  - Possibly, it can be provided shoulder-

  ments 38 on the shells 22 so as to also protect

  the caps 26 of the heat. This allows you to leave

  pace 40 which compensates for the radial expansion of the shells 22 under the effect of heat. Moreover, if it proves necessary

  or desirable, cooling ducts may be provided

  42 in the hub 18 to deliver a cooling fluid

  between the ceramic shells 22 and the cores

  24 metal. As shown in Figures 3 and 4, the cara-

  Ceramic tiles may be made in such a way as to

  suitable recesses 44 to allow the cooling fluid to circulate in the space 44 thus formed between the shell 22 and the core 24 and exit through passages 46 between the cap 26 and said shell 22. Alternatively, as it is see in Figure 5, recesses 48 for

  to the circulation of the cooling fluid, which are

  to the recesses 44 of FIG. 4 may be provided in the outer surface of the cores 24. Moreover, since the stators are not subjected to centrifugal force and

  are less critical than the rotating elements, the

  burps or caps of the stator elements (not shown) may be made of ceramic and can be

with the carapaces.

  FIG. 6 is an exploded view of a variant of the blade of the turbine of FIG. 2 having a metal core 50 integral with a mobile wheel 52. However, it

  It should be noted that nucleus 50 could constitute a

  It is separate and attached to the moving wheel 52 by any suitable means. A ceramic shell 54 has an outer surface 56 that is contoured to provide a desired aerodynamic configuration and has a central opening 58 configured to allow it to slide easily.

  on the core 50 of the fin leaving a gap between them.

  A sheet 60 of corrugated metal is interposed between the core and the shell 54 (in the space designated by 44 on the

  figure 3) to form a flexible layer that compensates for the difference

  thermal expansion of the core 50 and the shell 54, which dampens the aerodynamic forces between the shell 54

  and the nucleus 50 which also delimits several

  circulating coolant fluid which can be introduced between the core 50 and the shell 54 by suitable inlet and outlet conduits formed in the

  movable wheel 52, as indicated by dots 62 and 64.

  A cap 66 is intended to close the outer end of

  opening 58. Said cap 66 has on its underside

  a plurality of ribs, designated 68, which allow the coolant to pass across the outer end of the core 50. Finally, a suitable connecting material (not shown) serves to secure the cap 66 and the

  carapace 54 at nucleus 50, as described with reference to

Figure 3.

  It goes without saying that many modifications can be made to the machine described and shown

  without departing from the scope of the invention.

Claims (7)

  1. Turbomachine having a rotor (163 pre-   a rotating hub (18) and a plurality of fins (20)   protruding beyond the periphery of the rotor, each of the fins (20) comprising a metal core (24) fixed to rotate with the hub (18), turbomachine characterized in that it comprises a carapace (22) ceramic which surrounds   the core (24) and is positioned so as to protect this   deny the harmful effects of a fluid passing through the   machine; and a metal cap (26) which holds the cara-   pace (22) in position around the core (24).   2. Turbomachine according to claim 1, characterized   characterized in that the cap (26) is in contact with the cara-   pace (22) so as to submit the latter to the compro-   during rotation of the rotor (16).   3. Turbomachine according to claim 1, characterized   characterized in that the outer surface of the shell (22) has a aerodynamic configuration.   4. Turbomachine according to claim 1, characterized   characterized in that the shell (22-) is constructed to delimit a gap (44) between it and the core (24) and that a means provided in the hub (18) is operative to deliver a   cooling fluid in said space ú44).   5. Turbomachine according to claim 1, characterized   characterized in that it comprises a plurality of stator vanes mounted near the rotor vanes (201, each of the stator vanes comprising a metal core and a ceramic shell which surrounds said core to protect it   harmful effects of a fluid passing through the machine.   6. Turbomachine according to claim 4, characterized   characterized in that it comprises a flexible element placed in said space (44) for resiliently supporting the shell (54).   7. Turbomachine according to claim 6, characterized   the flexible element consists of a sheet the corrugated (60).   B. Turbomachine according to claim 7, characterized   characterized in that the corrugations of the sheet (60) are oriented substantially in the radial direction relative to the hub or wheel (52) and are intended to delimit several channels for   circulating the fluid in said space (44).