DE859089C - Bladed gyroscope through which a work equipment flows - Google Patents

Description

The invention relates to centrifugal machines, such as turbines, compressors or the like, in particular on a special embodiment for the working medium duct in the stand part of such machines, whereby the nominal play between the wall of such a channel and an element, which is provided therein with play is kept at a relatively small value, and even if the parts expand and contract sharply as a result of a change in temperature are subject.

The invention is particularly applicable and has particular value for machines at where there is a large temperature difference,

t5 especially in the case of internal combustion gas turbines with work at high temperatures, for example axial flow gas turbines, such as those used for aircraft propulsion used where the task of maintaining a small game is particularly difficult Way occurs between the working medium channel and the parts moving in it. With turbines In this way, the stator has a smaller mass than the rotor and heats up faster, with the result that the stator diameter and thus the blade tip clearance increases when starting and the efficiency drops until the rotor has also been heated. In case of a Gas turbines cannot solve this problem by preheating, as is the case with steam turbines; on the contrary, it is in the nature of the machine that a rapid increase in temperature is inevitable is. Conversely, when the turbine is switched off, the stator cools, which is not just for that Cooling is stored cheaper, but also has smaller dimensions, faster than the runner, so that the stand, if not an adequate one

Game is provided from the outset on the shoveling can shrink and cause considerable damage. These difficulties are all the more important, the more the rotor diameter increases and the length or the relative length of the blades decreases, since in such a case the ratio of blade tip clearance for the blade height a particularly unfavorable value with regard to the power efficiency accepts.

According to the invention, a bladed centrifugal machine through which a working medium flows an annular through-flow channel for the working medium with one or more rotating elements each of which has the same radial clearance, both the channel walls and the Eelement experience thermal radial expansion and contraction, and is characterized by that a shell or boundary wall of this channel has one or more closed rings in a number equal to that of the rotating elements, and that the or each ring consists of individual arc-shaped elements is constructed, between which expansion openings are provided are what thermal expansion and contraction of each element in the circumferential direction allow without a corresponding change in the diameter of the ring in its entirety, these elements from the stator housing on annular seats on the upstream and downstream * lying peripheral edges are worn, which seats an even distribution ensure the wing over the circumference and keep the boundary wall in a fixed concentric radial position with respect to the housing and allow expansion of the wall elements in the circumferential direction, so that the radius of the Boundary wall regardless of its extent and contraction is determined by this housing and the temperature of the boundary wall is independent.

In a further development of the inventive concept, it is proposed that the sheath be made of an in Circumferential direction continuous, suitable for high temperatures inner wall consists of a holder suitable for low temperatures is held in the form of a rigid unit, which is shielded from the channel and within a smaller temperature range than that the casing works, the holder of the inner wall on its holder being such that that the former is free to expand in the circumferential direction, and its radius by the Working conditions of the latter is determined. It is easy to see with one of these Arrangement, the inner wall exposed to the high temperature only the same changes in the Subjected to diameter as the outer housing provided for the lower temperature, so that the diameter of the inner wall can be kept constant to an extent that that is determined by the limits of the temperature change that are permitted for the protective housing j is, and it is because for the game corresponding to the cold state only the estimated Expansion of the enclosed element is taken as a basis, nevertheless the danger is eliminated, that the exposed to the high temperature inner wall with the enclosed element at Cooling comes into contact. In some cases, however, such a game can always be still exceeds the permissible value when the machine is started from a cold state is due to the fact that the entrapped element is relatively slow warmed up. To overcome this difficulty, the element can also be cooled, so that the game when starting more the working conditions prevailing during continuous operation is adapted.

The outer housing of the stator is expediently constructed from a plurality of rings, which Undivided in scope or made up of segments that are axially connected to one another are; these rings can accommodate the stator blades in internal grooves that are used during assembly develop; the inner wall of the stator can, in the case of a multistage turbine, from a plurality be constructed from individual rings, and the inner wall and the outer housing or their Ring components suitably have mutually interlocking parts through which the inner wall is rigidly connected to the outer housing. To get the desired temperature difference between To achieve the inner wall and the outer housing, it is useful to cool the latter to be provided. For this purpose, the inner wall on the housing can be at a radial distance therefrom stored and a coolant circulation can be provided in the space thus created.

To cool the turbine rotor, openings and channels can be connected to a source of compressed air which take in this air and the same along one or more surfaces of the rotor conduct, in a preferred arrangement only a thin layer of rapidly (flowing air is passed over the surface to be cooled. This requirement can easily be met if the rotor body is enclosed on at least one side in a chamber which is held at a pressure which is higher than that of the working gas stream, and which has outlets after the latter. In the drawing, a gas turbine drive system for is as Ausfünrungsbeispiel the invention an aircraft shown, which has a two-stage axial turbine. In the drawing represents

Fig. Ι an iVxialschnitt of part of a such a system to show the position of the turbine in the same;

Fig. 2 is an axial section of this turbine in larger scale, and

Fig. 3 shows an individual part of the inner wall of the stand *.

As shown in Fig. 1, the propulsion system to which the invention is applied comprises one multi-stage i \ xial compressor with a centrifugal

Gal output stage, of which only the output stages are shown, which compressor compressed air into a promotes annular Luftgehäuae 2, which is limited by outer and inner walls 4 and 3, respectively and symmetrically surrounds a shaft 5 through which the compressor 1 is driven by a turbine 6 will. The interior of the chamber 7, which is delimited by the inner wall 3 of the air housing 2 list, is by supplying compressed air over a cooler 8 and a pipe connection 9 from the air housing 2 kept under pressure. The latter receives flame tubes 11 distributed in the circumferential sense, in which burners 10 are arranged, which flame " tubes deliver the working gases to the inlet nozzle 12 of the turbine. In this context I like mentioned that the outlets from the flame tubes are flattened in the circumferential direction., um To form segments of a ring and so a continuous annular outlet after the turbine to ensure.

The preferred application of the invention is possible with a turbine which, as shown, has a through-flow channel for the working medium which runs in the downstream direction expands. Further, the turbine inlet nozzle and the stator blades are by assembly held by ring members of suitably varying diameter which interlock with one another and support and together the inner wall and the outer housing of the stator form and which are used when assembling from the further end of the channel, each The following element secures the previous one in its position. In detail is the stator of the turbine constructed as follows (see in particular Fig. 2):

The first element of the rigid outer housing, which also forms the outer wall of the turbine nozzle ring, is a first housing ring 13, which represents the housing ring of the smallest diameter and is connected to other supporting parts of the system by means of screw bolts or the like and which is radially at its front end extending inward and outward, has a flange 14 and at its rear end an undercut groove and a radially outwardly projecting flange 15 for attachment to the second housing ring. The inlet nozzle ring 12 has individual guide vanes 16, each of which has a plate 17 of rectangular or rhomboid shape at its foot or at its root. On the side of the plate 17 facing away from the blade, a rib or a wedge 18 is provided, which lies with radial play in an axially or obliquely directed groove formed in the ring 13; and the rib has a tooth 19 at its rear end which protrudes into the undercut groove provided in the ring. Each blade is inserted from the rear until the front side of its point is adjacent to the first-mentioned flange 14 of the ring 13 and the tooth 19 is seated in the groove; their rib 18 is now in the groove of the ring 13. The second Gehäuisering 20 is now pushed against the first ring 13 until the flange 21 rests against the face 15 and its inner end against the backs of the teeth 19 of the blades 16 , whereby the same in their groove are secured. The flange 21 is extended forward in its outer part 22 and forms an angle through which the outer end of the flange 15 of the ring 13 is fixed and which also rests on the outer part of the flange 14 to which it is screwed. Together with the first ring 13, it forms an annular chamber 23, into which cooling air is passed from the cooler 8 via line 24 and the inlet 25, which is connected to the chamber 23. The latter has outlets to the spaces between the ribs 18 of the blades ιό. The second ring 20 has the shape of a double cone and on its rear side has a flange 26 which projects radially outward and has an axial annular groove.

Inside the second ring 20, the inner wall is now arranged as a boundary wall of the channel in the area of the first rotor blade ring; This is constructed as a conical ring of circumferentially subdivided parts or segments 27, which are connected to one another by strips 28 (Fig. 3), which freely enter in axially extending slots of the segments, with a clearance in the circumferential direction being provided at 29 so that these connections represent expansion connections. The front end faces (of smaller diameter) of the segments 27 are supported by means of a toothed structure 27 ″ by engaging in the rear sides of the blade plates 17, which are already mounted. The wall, which is formed by the ring segments 2, J , is spaced from the outer housing ring 20 in order to enclose an air chamber 30 with the same, which has an inlet opening 31 and, on its rear side, openings 33 in a short radial flange 32 of the wall 27 The radial flange 32 also has an axial extension which enters a correspondingly shaped groove in the second housing ring 20, whereby, together with the strip 28, the wall -2 ^ is held in a fixed position relative to the ring 20 in the radial direction.

The third housing ring 35 is also generally conical in shape and has something against no its front face set back, an outwardly directed radial flange 36, on its Perimeter a forward, axial annular flange 37 is attached, which with the flanges 36 and 26 includes an annular chamber of rectangular cross-section in which the roots 38 of the guide vanes 39 are added. The roots 38 are in the channel by bolts 40 attached, which go through axial holes of the blades and also hold the flanges 36, 26 together. The roots 38 are also held in place by cooperation with a rib projecting on the flange 36. For Cooling purposes can be provided by air spaces 41 or Cooling channels 42 may be provided.

The rear face of the third housing ring 35 has a radial flange 43 which contains an axial groove, similar to the rear face of the second ring 20, which groove receives a forwardly directed flange 44 on the rear face of a second inner wall ring 45, similar to the design of the first inner wall ring 27, and is supported by engaging its front end face in the blade root 38. As with the first inner wall ring, a cooling space 46 is provided between the second inner wall ring 45 and the third housing ring 35, which space has an inlet opening 47 through which air enters from the recesses in the blade roots 38, and an outlet opening 48.

On the rear face of the second inner wall ring 45 is followed by a further inner wall 49, which is of a similar design as the ring 45 is in that it consists of circumferentially divided segments which are expanded by means of expansion joints are connected to each other. This inner wall 49 forms a protection for the wall 50 of the exhaust duct, which by flange and bolts connected to the flange 43 of the third housing ring.

The guide vanes 16 of the nozzle ring are with their outer ends (roots) on the first housing ring supported, and with their inner ends (tips,) they are held by an inner nozzle ring ", which is composed of two rings 51, 52 angular in cross section and with a part of the inner wall 3 of the air housing 2 is screwed and which has flanges 53, 54, which form seat surfaces on which a radial play is provided to the extent of a to enable peg-shaped member 55 provided on each blade tip, this Pins are used to secure the position of the blades and to absorb the gas pressures on them. The tips of the blades 16 are also provided with plates 56 which extend in the circumferential direction butt against each other to form a continuous guide surface for the gas flow and around too to delimit a chamber 57 for cooling air within the same, the latter through an inlet at j 58 enters, between the air housing and the plates 56 from the main stream and exits at 59 after the narrow gap between the rotor and the rear face of the nozzle ring 51.

It can be seen that the inner walls 27, 45 act as a result of them in the initial direction Expansion joints are able to maintain a constant diameter despite temperature changes maintain; that by their connection with the outer housing rings 13, 20, 35 their actual diameter is determined at any time by the diameter of these casing rings is and that finally due to the circulation of the cooling air from the chamber 23 through the Spaces between the inner wall rings and the outer housing rings the temperature change and the resulting change in diameter is reduced. So it can a smaller clearance between the blade tips and the inner walls when cold are provided.

This play can be reduced even further by cooling the rotor of the turbine, for which purpose front and rear disks 60, 61 are provided axially spaced from one another, the former having a hollow hub 62 by means of which it is directly connected to the shaft 5 which is also hollow, while the second disc is mounted on a rear extension 63 ■ of the hub 62 and has axial channels 64 in its own hub which communicate with the interior of the hollow hub extension 63 and the shaft 5 and with a gap between the two disks 60, 61 and with radial channels between the rear face of the disk 61 and a nut 65, by which this disk is held on the hub extension 63, in connection. The spaced disks 60, 61 are reinforced by an annular disk 66, which has a thickened ring 67 on its inner side, which cooperates with the inner surfaces of annular ribs 68 on the disks 60, 61, these ribs having through bores at 69. A flange 70 is provided on the circumference of the disk 66, which fills the axial space between the blade roots in the rims of the wheel disks 60, 61 in order to form a boundary edge of the flow channel of the working medium, while inward of the rim 70 the disc 66 has annular ribs 71 which have claws that engage in gaps between claws on ribs 72 of the wheel disks 60,61. Cooling air can flow between the claws to spaces 73, which are located to the side of the blade roots, and from there through the blade roots. In order to avoid internal stresses in the disk 66 as a result of uneven expansion of its ring 70, which is exposed to the hot working gases, and its body, which is relatively cool, the disk 66 is interrupted on the circumference by short radial slots (not shown in the drawing). which, for the purpose of preventing the flow of cooling air from the chambers 73 directly into the gas stream rather than through and under the root, are designed to be closed at their radially outer ends when the disc is heated. This can be achieved in that the slots are made as narrow saw cuts, the outer ends of which are closed by hammering prior to the final machining of the rim 70. The weak flanges thus formed are compressed when the rim is first expanded, so that the slots, although they are open when the window is cold, are closed at the working temperature. In order to maintain a certain flow of air through the blade roots in the disks 60, 61, it is desirable to prevent leakage flows from one chamber 73 after another. This can be done by providing sealing means, such as screws, in the radial inner

ren parts of the slots can be achieved and through! Closing the drilled holes with tenons, which holes would form the radially inner ends of the slots.

The front face of the disc 60 is shielded by a wall 74 which is on a solid Part of the bearing 75 of the shaft 5 is fixed and delimits a narrow chamber which extends over the j Most of the disk 60 extends in the radial direction j. A similar wall 76 is through a Part of the exhaust pipe carried on the rear face of the disc 61.

It may be remembered that the chamber 7, which is from the inner wall 3 of the air

* 5 housing is enclosed, is kept under pressure. The stationary parts of the shaft bearing ^ 75 have air seals TI against the shaft 5, so that leakage air into the bearing housing, not only through the bearing itself, but also through a channel 78 to a chamber 79 which surrounds the hub of the disk 60, got. There is thus a constant outward flow of compressed air between the end face of the disk 60 and the wall 74, the pressure being kept higher than that of the working medium in the flow channel of the turbine, so that the air between the inner nozzle ring 59 and the first disk 60 flows into the turbine duct. In addition, the shaft 5> has openings for receiving compressed air from the chamber 7, and this passes through outlet openings 80 to the channels 64 in the hub of the disk 61 and from there along the inner end faces of the two disks and the rear end face of 61 and also gets into the working medium flow. By means of these means, the expansion and contraction of the turbine rotor as a whole can be significantly reduced, which makes it possible to also reduce the clearance at the blade tips, in comparison with an uncooled rotor; and in connection with the rotor construction described, a very high efficiency results from the point of view of the losses at the blade tips.

Claims (1)

PATENT CLAIMS: i. Bladed centrifugal machine through which a working medium flows, which has a has an annular through-flow channel for the working medium, which has one or more rotating elements contains, each of which has the same radial clearance, the channel walls and the element is subject to thermal radial expansion and contraction, characterized in that a shell or boundary wall of this channel one or more closed rings in a number which is the same as that of the rotating elements, and that the or each ring consists of Thus, individual arcuate members is constructed, between which the expansion apertures provided which thermal expansion and contraction of the individual elements in the L ^T mfangsrichtung without a corresponding change in the diameter of the ring in its entirety allow w ^r obei these elements from the stator housing annular seats at the upstream and downstream peripheral edges are supported, which seats ensure an even distribution of the support surface over the circumference and hold the boundary wall in a fixed concentric radial position with respect to the housing and allow an expansion of the wall elements in the circumferential direction, so that the radius of the boundary wall is independent of their expansion and contraction is determined by this housing and is independent of the temperature of the boundary wall. 2. Machine according to claim 1, characterized in that that the element in the working medium channel is designed as a rotor provided with blades and that 'the inner wall, the forms the boundary wall of the channel, consists of a rotor blade shell. 3. Machine according to claim 1 and 2, which has guide vanes and rotor blades, characterized in that the inner wall extends axially from the downstream go Side of the guide vanes until not significantly above the exit point from the rotor blades extends addition and at these points rests with their edges on the stator housing, the Guide vanes are attached to the stator housing regardless of "the inner wall. 4. Machine according to claim r and 2, characterized in that the elements of the inner wall, which forms the boundary wall, connected to one another by expansion joints which make the ring a whole in the circumferential direction, and an extension of the individual Allow parts. 5. Machine according to claim 1 to 4, characterized in that the expansion connections are formed by strip-shaped elements which enter in the circumferential direction in slots that in the circumferential direction successive sides of adjacent parts of the ring are provided. 6. Machine according to claim 1 and 2, characterized in that the inner wall on the Outer housing of the stator is fixed at a radial distance therefrom and that precaution is taken for the circulation of a coolant in the space thus formed. 7. Machine according to claim 1 and 2, characterized in that the guide vanes on the stator housing are attached and that means for cooling the guide vane roots by a coolant are provided. 8. Machine according to claim 1 to 7, characterized in that the stator blades on the case holder and extend through the case, with their holding tion supply means to. Supplying a coolant to their foot or root ends having. G. Machine according to claims 1 and 2, characterized in that the stator housing has an inlet nozzle ring at the inlet, the guide vanes of which are mounted in fixed parts at their inner and outer ends so that they can expand radially. ι o. Machine according to claim ι and 2, with a plurality of stator and rotor stages, characterized in that the outer housing of the stator from ^ a plurality of ring units is constructed, which are fastened in an interlocking manner in the axial direction, wherein each extends in the axial direction over a stator and a rotor stage. ii. Machine according to claim 1, 2 and 10, characterized characterized in that the axially interlocking ring units of the outer housing additional Have recesses that form inner seat grooves in which the feet of the guide vanes are stored. 12. Machine according to claim 1 and 2, with several stator and several rotor stages, characterized in that the boundary wall of the channel forming the inner wall of the stator housing from a plurality of ring units is constructed, which lie between the successive stator stages, wherein each ring unit corresponds to a stator stage. 13. Machine according to claim 1, 2, 10 and 12, characterized in that the rings forming the inner wall and the outer housing are mutually exclusive have interlocking parts, through which the inner wall at a radial distance from the outer housing is held, but there is freedom to expand in the circumferential direction. 1 sheet of drawings © 5551 12.52