EP0378943A1 - Compressor housing with an adaptable inner diameter for a turbo machine - Google Patents

Abstract

A compressor housing comprises an internal casing (9) in two half-shells (19, 20) assembled by flanges (21, 22). Cylindrical bellows (23) disposed between the flanges (21, 22) are deformed as a function of an internal pressure P2 supplied by a supply of withdrawn air (27) downstream of the compressor from which results in control of the diameter internal of the housing. A complementary flexible connection (24) is arranged between the two half-shells (19, 20).

Description

The present invention relates to a turbomachine compressor casing provided with a device for controlling its internal diameter in order to ensure minimum objective radial clearance between rotor and compressor stator.

Various solutions have been proposed in order to maintain in operation, between the turbomachine rotors and the associated stators and in particular, between the ends of the movable blades and the internal wall of a casing enveloping the crowns of said blades, also reduced radial clearances. as possible in order to ensure the performance of the machine and in particular a good yield and a reduced value of specific consumption, but nevertheless sufficient clearances in order to avoid, in particular in transient conditions of acceleration or deceleration and whatever the succession of these sequences, any damaging mechanical interference between the fixed part and the rotating part of the turbomachine. Adjustments of clearances in operation can thus be obtained by the use of thermal means, calling in particular on circulations of hot or cold air flows with adjustable flow rates as a function of determined parameters of operation of the turbomachine or of measurements. direct, these air flows are usually used to control the expansion / retraction of mechanical parts. Examples of these solutions are given by FR-A-2,534,982, FR-A-2,535,795 or FR-A-2,540,560.

According to other solutions, mechanical means are used to vary the diameter of the housings or fixed parts located opposite the rotors or rotating parts of the turbomachine. This principle is for example applied by FR-A-2 577 282 or FR-A-2 591 674.

These known prior solutions are however not entirely satisfactory in all applications. Air samples, often relatively large, required by the implementation of solutions using thermal means make the engine performance lose a significant part of the contribution of these provisions. Furthermore, the mechanical means envisaged have the drawbacks of causing an increase in mass, which is particularly detrimental for aeronautical applications, and of requiring complex assemblies. In particular, in the application to turbomachine compressors comprising casings in two half-shells assembled by flanges, the implementation of known solutions proves to be delicate and difficult to carry out.

Consequently, the object of the invention is to solve the problems mentioned above without incurring the drawbacks of the known prior solutions and in particular by allowing an advantageous application to the turbomachine compressor casings in two half-shells. These results are obtained by means of a turbomachine compressor casing comprising at least one radially internal envelope, composed of two half-shells carrying assembly flanges and provided with a device for controlling its internal diameter as a function of the conditions. operating mode of the turbomachine characterized in that a plurality N of deformable bellows, of variable length, are fixed between the two said casing flanges, connecting them together, a variable pressure P₂ being maintained inside each bellows by means an air intake pipe at the downstream end of the compressor and in that complementary means are arranged between the two half-shells ensuring a flexible connection between them.

Advantageously, said complementary flexible connection means consist of a number N of flexible connection elements, each flexible element being associated with a bellows, being moreover hingedly fixed at each of its ends respectively on each casing half-shell. , on either side of the assembly flanges and forming a C element spanning said bellows.

According to another advantageous embodiment, said complementary flexible connection means consist of N pairs of lever arms, each articulated at a first end on a casing half-shell in the vicinity of the assembly flange and its second end being secured to a radially outer casing by means of an elastic flange.

• - la figure 1 représente, selon une demi-vue partielle schématique, en coupe par un plan longitudinal passant par l'axe de rotation de la turbomachine, un compresseur dont le carter est muni d'un dispositif de pilotage de son diamètre interne, suivant un premier mode de réalisation de l'invention :
• - la figure 2 représente un détail agrandi du carter de compresseur représenté sur la figure 1, selon une vue partielle schématique en coupe par un plan passant par la ligne II-II de la figure 3 ;
• - La figure 3 représente, dans une vue suivant F1 de la figure 2, un détail de réalisation du dispositif de pilotage du diamètre interne du carter de compresseur représenté sur la figure 1 ;
• - la figure 4 représente un détail agrandi d'un élément du dispositif de pilotage du diamètre interne du carter de compresseur, représenté sur la figure 2 ;
• - la figure 5 représente un détail de réalisation d'un dispositif de sécurité entrant dans le dispositif d'assemblage des deux demi-coquilles de l'enveloppe interne du carter de compresseur représenté sur la figure 1;
• - la figure 6 représente, selon une demi-vue partielle schématique, en coupe par un plan longitudinal passant par l'axe de rotation de la turbomachine, analogue à celle de la figure 1, un compresseur dont le carter est muni d'un dispositif de pilotage de son diamètre interne, suivant un deuxième mode de réalisation de l'invention ;
• - la figure 7 représente un détail agrandi du carter de compresseur représenté sur la figure 6, selon une vue analogue à celle de la figure 2 ;
• - la figure 8 représente, dans une vue suivant F2 de la figure 7, analogue à celle de la figure 3, un détail de réalisation du dispositif de pilotage du diamètre interne du carter de compresseur représenté sur la figure 6 ,
• - la figure 9 représente un détail de réalisation d'un dispositif de sécurité, analogue à celui qui est représenté sur la figure 5 dans le premier mode de réalisation de l'invention et entrant dans le dispositif d'assemblage des deux demi-coquilles de l'enveloppe interne du carter de compresseur représenté sur la figure 6 ;
• - la figure 10 représente un détail d'un dispositif utilisé pour le montage du dispositif de pilotage du diamètre interne de carter de compresseur représenté sur la figure 7.

Other characteristics and advantages of the invention will be better understood on reading the following description of two embodiments of the invention, with reference to the accompanying drawings in which

• - Figure 1 shows, in a partial schematic half-view, in section through a longitudinal plane passing through the axis of rotation of the turbomachine, a compressor whose casing is provided with a device for controlling its internal diameter, according to a first embodiment of the invention:
• - Figure 2 shows an enlarged detail of the compressor housing shown in Figure 1, in a schematic partial view in section through a plane passing through the line II-II of Figure 3;
• - Figure 3 shows, in a view along F1 of Figure 2, a detail of the device for controlling the internal diameter of the compressor housing shown in Figure 1;
• - Figure 4 shows an enlarged detail of an element of the device for controlling the internal diameter of the compressor housing, shown in Figure 2;
• - Figure 5 shows a detail of a safety device entering the assembly device of the two half-shells of the inner casing of the compressor housing shown in Figure 1;
• - Figure 6 shows, in a partial schematic half-view, in section through a longitudinal plane passing through the axis of rotation of the turbomachine, similar to that of Figure 1, a compressor whose housing is provided with a device piloting its internal diameter, according to a second embodiment of the invention;
• - Figure 7 shows an enlarged detail of the compressor housing shown in Figure 6, in a view similar to that of Figure 2;
• FIG. 8 represents, in a view along F2 of FIG. 7, similar to that of FIG. 3, a detail of embodiment of the device for controlling the internal diameter of the compressor casing shown in FIG. 6,
• - Figure 9 shows a detail of an embodiment of a safety device, similar to that which is shown in Figure 5 in the first embodiment of the invention and entering the device for assembling the two half-shells of the inner casing of the compressor housing shown in Figure 6;
• FIG. 10 represents a detail of a device used for mounting the device for controlling the internal diameter of the compressor casing shown in FIG. 7.

A turbomachine compressor casing 1, schematically represented in FIG. 1, according to a first embodiment of the invention, comprises, on the one hand, a radially external casing 2 comprising at each end of the radial flanges, respectively 3 and 4 , oriented towards the outside and assembled by any known means, such as bolts 5 and 6, with the flanges 7 and 8 of an adjacent casing and, on the other hand, an internal envelope 9, radially spaced from the previous one and which supports, according to a method of construction known per se in the production of axial compressors, a number of circular rows of fixed blades forming stator stages 10, 11, 12 which are three in number in the example shown in the Figure 1 and between which are interposed stages of movable blades 13, 14, 15 of the compressor rotor. The external 2 and internal 9 envelopes are connected together, in a manner also known, by telescopic devices 16 with pins and grooves, at the level of radial lugs such as 17 and 18. These connecting devices 16 are regularly distributed and six in number , for example in the embodiment shown in Figure 1, are arranged in two longitudinally spaced series.

The inner casing 9 of the casing consists of two half-shells 19 and 20 assembled together by remarkable means in accordance with the invention, constituting a device for controlling the internal diameter of the casing 1 of the compressor and shown in detail in the figures. 2 to 5. Each half-shell 19 and 20 comprises, at each end, a longitudinal flange, respectively 21 and 22, located in the compressor assembled in a horizontal plane. According to the invention, instead of being rigidly and directly connected to each other, the flanges 21 and 22 of the half-shells are slightly spaced and in the space thus provided, a bellows 23 is arranged, as shown in the detail. enlarged in Figure 4. The bellows 23 is secured at each end, respectively to one of the flanges 21 and 22 of the half-shells 19 and 20 of the housing. Spanning the bellows 23 and the flanges 21 and 22, a flexible connecting element 24, having the general shape of a C is further articulated at each of its ends 25 and 26, directly on a half-shell, respectively 19 and 20 The bellows 23 and the flexible elements 24 in the same number are, for example, four in number, in the embodiment shown in FIGS. 1 to 5. An air supply duct, symbolized at 27, supplies each bellows 23 in air taken downstream of the compressor. As shown in Figure 4, the air inlet into the bellows 23 can be through an orifice 28 drilled in the flange 21 and through a chamber 29 formed at the inlet. The seal between the two half-shells 19 and 20 is ensured by longitudinal tongues 30 arranged in the grooves provided in the thickness of the half-shells at their connection. Furthermore, safety devices each comprising a rod 31 forming a spacer between the flanges 21 and 22, and visible in FIGS. 4 and 5 are arranged so as to ensure a minimum internal diameter of the compressor housing.

The operating mode of the device for controlling the internal diameter of the casing according to the invention, which has just been described, is as follows. Between the outer 2 and inner 9 casing casings, an air sampling carried out, for example, upstream of the casing 1 ensures a pressure P1. In each bellows 23, the supply 25 brings an air pressure P2. Each increase in flow pressure at the outlet of the compressor activates the control device and increases the internal diameter of the casing 1. The deformation and the elongation of the bellows 23 in fact exert moments on each flange 21 or 22 of the internal casing 9 of housing. The half-shells 19 and 20 are deformed only in bending and an increase in diameter is obtained without ovalization, the half-shells 19 and 20 being separated by the bellows 23 while the flexible elements 24 retain them. Furthermore, in the telescopic connections 16 between the inner casing 9 and the outer casing 2 of the casing, a clearance is provided between the pins and the grooves, to allow non-radial movement of the pins in the grooves.

Similarly, a drop in flow pressure at the outlet of the compressor brings the internal diameter of the casing back to its initial value. The control of the internal diameter of the housing ensuring the objective clearance between the ends of the movable blades of the rotor and the corresponding diameter of the housing is thus carried out without energy consumption.

Various variant embodiments can be made to the first embodiment of the invention which has been described above with reference to Figures 1 to 5. In particular, Figures 6 to 10 show a second embodiment of the invention for which , references increased by a hundred compared to those which were used in the description of the first mode will be given to designate parts or elements identical or of function analogous to those of the first mode. Thus and in a similar manner, the casing 101 of the turbomachine compressor is composed of an external casing 102, between two flanges 103 and 104, connected to the flanges 107 and 108 by bolts 105 and 106 and an internal casing 109 in two half-shells 119 and 120, carrying stator stages of fixed blades 110, 111, 112 and 112a between rotor stages of movable blades 113, 114, 115, 115a and 115b. The two half-shells 119 and 120 also include the longitudinal flanges 121 and 122 slightly spaced and connected by bellows 123, supplied with air taken downstream from the compressor by a pipe 127. There are also the sealing tongues 130 as well as the safety devices with rods 131 visible in FIGS. 8 and 9. The variant applied in this second embodiment relates to the complementary flexible connection means between the two flanges 121 and 122 of the two half-shells 119 and 120 of the internal envelope 109 of the compressor housing according to the invention. As shown more particularly in Figures 7 and 8, said flexible connection means are constituted at each bellows 123, two lever arms 124a and 124b. Each lever-arm 124a or 124b has one of its ends, respectively 125 and 126, articulated directly on a half-shell, respectively 119 and 120 and their other end 125a or 126a is secured to the outer casing 102 of the casing by a flange elastic 32. In the second embodiment shown in FIGS. 6 to 10, the bellows 123 and the pairs associated with the same number of lever arms 124a and 124b are six in number.

In this second embodiment, the operating mode of the device for controlling the internal diameter of the casing is the same as that which was previously described for the first embodiment, with reference to FIGS. 1 to 5. Another particularity of the second embodiment concerning the assembly of the assembly. As shown in the detail in FIG. 10, elements 33 are used to hold the lever arms 124a or 124b in the docking position during the positioning of the elastic flange 32, these elements 33 then being eliminated.

In the first, as in the second embodiment, the device for controlling the internal diameter of the compressor casing according to the invention can be combined with additional arrangements. As shown in FIG. 1 for the first mode and in FIG. 6 for the second mode, watertight walls, respectively 34 and 35 or 134 and 135, are arranged at each end of the casing, between the internal envelopes 9 or 109 and the external 2 or 102, thus forming a sealed enclosure between the two envelopes. The air pressure P1 prevailing in this enclosure can then also be controlled by adding a valve to the air sample taken upstream of the casing and which supplies the enclosure, the control device for this valve, not shown in drawing, which can, for example, be controlled by an operating parameter of the turbomachine or a measurement of the real clearance in operation between the rotor and the compressor stator.

Claims (7)

1. Turbomachine compressor housing comprising at least one radially internal casing (9; 109) composed of two half-shells (19,20; 119,120) carrying assembly flanges (21,22; 121,122) and provided with a device for controlling its internal diameter as a function of the operating conditions of the turbomachine, characterized in that a plurality N of deformable cylindrical bellows (23; 123), of variable length, are fixed between the two said assembly flanges (21 , 22; 121,122) of the casing, connecting them together, a variable pressure P2 being maintained inside each bellows (23; 123), by means of a pipe (27; 127) for taking air from the 'downstream end of the compressor and in that complementary means (24; 124a, 124b) are arranged between the two half-shells (19,20; 119,120), ensuring a flexible connection between them. 2. A turbomachine compressor casing according to claim 1 wherein said complementary connection means consist of a number N of flexible connection elements (24), each flexible element (24) being associated with a bellows (23), being further fixed to each of its ends (25,26) respectively on each half-shell (19,20) of the casing, on either side of the assembly flanges (21,22) and forming an element in C spanning said bellows (23). 3. turbomachine compressor housing according to one of claims 1 or 2 wherein the bellows (23) and the flexible elements (24) are respectively four in number. 4. turbomachine compressor housing according to claim 1 wherein said complementary connection means are constituted by a number N of pairs of lever arms (124a, 124b), each articulated at a first end (125,126) on a half-shell (119,120) of the housing, in the vicinity of the assembly flange (121, 122) and its second end (125a, 126a) being secured to a radially outer casing (102) of the compressor housing, by means of an elastic flange (32). 5. A turbomachine compressor casing according to claim 1, in which the bellows (123) and the pairs of lever-arms (124a, 124b) are six in number, respectively. 6. turbomachine compressor housing according to any one of claims 1 to 5 characterized in that a safety device comprising at least two rods (31, 131) forming spacers between the two half-shells (19,20 ; 119,120) of the housing maintains a minimum internal diameter of the housing. 7. turbomachine compressor casing according to any one of the preceding claims, characterized in that a sealed enclosure is formed between the radially internal casing (9, 109) of the casing and an radially spaced outer casing (2; 102), at means of sealed walls (34,35; 134,135) disposed respectively at each end of the casing, an air pressure, controlled by means of a valve, being established in said enclosure.

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