DE1551180A1 - Guide vane ring for turbo machines, especially gas turbine engines - Google Patents

Description

The invention relates to a guide vane ring for axial turbo machines, in particular gas turbine engines, consisting of a plurality of individual guide vanes
with blade roots, several of which are combined into a group each, which are coupled to one another by means of elongated damping elements extending in the circumferential direction.

In the case of axial turbomachines, in particular axial earners for gas turbine engines in aircraft, the
non-adjustable guide vanes on two different ones

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Kinds be attached, by means of single feet or by means of supporting sectors. In the construction with Each guide vane has its own individual foot, which is individually in a holder on the compressor housing are used. In this embodiment, each blade root is mostly provided with support tabs that engage in a groove in the bracket on the compressor housing, the feet of adjacent guide vanes rest against each other. In the embodiment with support sectors, there is a common one for several guide vanes Foot present; each guide vane is rigidly attached to the vane root, which is mounted on the housing of the compressor is.

The guide vanes are in operation of the high-speed turbo machines often exposed to vibrations. The causes of these vibrations and the nature of them are in many Cases not exactly known even to a person skilled in the art. However, these vibrations are primarily due to that uneven aerodynamic forces act on the guide vanes during operation. Even one theoretically steady flow as in an axial compressor would be expected, can be very irregular and discontinuous and to forced, synchronous oscillations the guide vanes lead. If these vibrations are strong enough, they can be very strong in the guide vanes generate high stresses so that fatigue fracture eventually occurs. To prevent this from happening, one has endeavors to provide suitable means to dampen the destructive vibrations. Guide vane rings off have individual guide vanes and single foot mounting

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very good self-damping, because the individual Blade feet can move slightly in their holder and relative to each other. Be in this movement due to the friction between the individual feet and the bracket and between the adjacent surfaces of the feet destroys considerable amounts of energy. In practice, however, it has been shown that these relative movements to uneven and sometimes impermissibly strong abrasion of the support tabs on the blade roots to lead. On the other hand, with guide vane rings consisting of sectors «such as B. according to the US patents 1,366,605 and 2,090,468, generally on the common foot of each sector has very little wear because of the movement between this common The foot and its holder are relatively small and the load on the load-bearing parts of the foot is relatively even is. With this type of construction, however, there is usually only very little damping of the vibrations. Besides this type of construction is often expensive and difficult to implement, especially when using special materials such as titanium. In addition, in the case of the Breakage of only a small part of the sector, for example a single vane, the whole vane sector removed and renewed.

It is known from German patent specification 966 503 has become to dampen the vibrations of blades in that a resilient rests in blade bores slotted tube is provided, the diameter of which is greater than before being pushed into the blade bores the diameter of the blade bores is, so that

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resiliently presses the tube against the bore wall when it is introduced into the blade bores. In operation you can the vibrating blades slide on the pipe, so that the friction caused by the resilient pressure Work consumes, so the vibrations dampen · Like that shows a more detailed description of the German patent specification, the solution proposed there serves to reduce the vibrations of the blades of blade segments outside of the segments to be dampened · Admittedly, this measure reduces the damping that occurs with such on a common foot arranged blades is disadvantageous in itself, significantly increases · Here, however, is first A disadvantage of this known construction to be seen in the fact that the vibration damping element within of the propellant flow is arranged and thereby adversely affects the flow conditions will. Furthermore, despite the relatively complex construction required for damping, the others Disadvantages of the guide vane rings consisting of sectors, as shown above, have not been overcome been.

On the other hand, there are constructive measures for Control of the vibrations in the circumferential direction Shovels with fir tree feet are known, which, however, apart from the fir tree profile, which in any case requires considerable manufacturing effort, are additionally are expensive. For example, the measure proposed in German patent specification 95O 557 requires according to which the surfaces of the fir tree base bearing the centrifugal force of the blades are essentially cylindrical surfaces

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with a common axis are and after a cylindrical bolt, whose axis in the common axis of the cylinder surfaces lies in corresponding recesses of the blade root and the turbine wheel engages, considerable expenses »by these measures after the German patent specification 950 557 should be achieved that the wings on both sides of the blade absorb the centrifugal force uniformly, independently of the respective vibration position of the blade, whereby Too high stresses on individual wings of the blade root can be avoided, which is at the same time due to the better surface contact between the blade root and groove wall in the sense of a correspondingly improved vibration damping effect.

Another way to dampen vibrations Shovels with fir tree feet is proposed in German Auslegeschrift 1 039 535 by in one Shank, which is provided between a cover plate on the blade and the blade root, damping wires are arranged. This facility is also iat not only structurally complex, in that a separate shaft is required between the blade root and cover plate is, but it leads to a complicated assembly process · According to the German interpretation 1 039 535 it is necessary here to first remove the blades provided with the fir tree base at a mutual distance sufficient to permit the insertion of the wires that one then brings the blades in a special assembly device in the position that they will later be inside

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of the blade ring «The carrier disk is then pushed on from the side, and necessarily at the same time on the foot sections of all blades, which requires considerable prior adjustment and precise guidance of the rotor disc requires

The object of the invention is to provide a guide vane ring create, with which the above-mentioned design disadvantages of the known guide vane rings avoided and which is still characterized by both high resistance to abrasion and good vibration damping excels.

This object is achieved in that, according to the invention, a guide vane ring of the type mentioned at the beginning is formed that several blades of a blade sector by means of an elongated, arc-shaped, arched leaf spring, which is clamped in grooves or the like arranged in the blade roots, against each other are aligned and centered. In this way, a constructively simpler and, as is based on below a preferred embodiment is explained in more detail, very good vibration-damping guide vane ring created, which can also be put together in the simplest possible way *

In order to be able to connect several guide vanes to the leaf spring in a particularly simple manner in terms of construction, is the guide vane ring is designed so that the leaf spring is in a continuous, mutually corresponding

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grooves formed in the individual blade roots, engages arcuate groove parallel to the annular groove.

A particularly secure and at the same time easily detachable connection is achieved when dismantling, when the grooves or the like, in which the leaf spring engages, are designed as dovetail grooves.

The frictional force and cohesion is improved, in that the leaf spring is pretensioned and elastically engages in the arcuate grooves.

A simple construction and assembly results overall if, according to a preferred embodiment of the invention Guide vane ring each blade root in the axial direction with a front and a rear Flap is provided, which correspond to each other and together each a front and a rear multi-part Form a flange and a bracket is provided on the housing, which is attached to the two multi-part flanges engages and holds the guide vane ring in the predetermined position. In this case, the holder expediently has two axially spaced apart annular grooves in which the multi-part flanges of the sectors engage. It is also advantageous that the holder for the guide vane ring with the substantially cylindrical Housing consists of one piece.

Around the blades, which are made up of several blades arranged on a leaf spring, as a unit without any particular further deformation

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To be able to slide into the holder is according to a Further development of the invention provided that the pretensioned leaf spring in the unstressed state in its Length corresponds essentially to the arc length of the groove and has a greater width than the groove, so that when Insertion of the leaf spring into the groove this assumes a shape in which it is around both in its longitudinal direction the axis of the turbomachine as well as in cross section is curved in an arc shape and in the longitudinal direction the same has arcuate curvature, like the arcuate groove.

A special reinforced interaction with the housing is achieved in that the leaf spring rests on the inner wall of the housing under tension.

In Figures 1 to 7 of the drawing, the subject the invention based on a preferred embodiment, which is shown below in detail is explained in more detail. Show it:

1 shows a gas turbine engine, partially in longitudinal section;

2 shows a plan view of a compressor guide vane ring in the direction of arrows 2-2 in FIG

FIG. 3 shows a sector of the guide vane ring according to FIG. 2 in perspective view;

FIG. K shows a view of a guide vane with its base part seen in the direction of the arrows kk in FIG. 2;

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Fig. 5 the element pretensioned in the stator before installation, in the unloaded state)

6 shows the base part of the guide vane on a larger scale according to FIG. 4 to illustrate the frictional engagement of the foot part on the pretensioned one Element and

FIG. 7 shows a representation similar to FIG. 6 slightly modified arrangement.

1 shows the structure of a gas turbine jet engine. The engine 10 has a generally cylindrical housing 11, within which the annular air inlet duct 12, the compressor 13, the combustion chamber 14, the drive turbine 15 for the compressor 13 and the annular outlet nozzle 16 are arranged. The radial struts 17 in the air inlet duct 12 carry the front bearing 18 of the engine rotor. Several rings of radial compressor guide vanes, e.g. B. 21, 22, 23 etc., the combustion chamber 14, the nozzles or guide vanes Zh and 25 of the turbine 15 and the radial struts 26 in the area of the outlet nozzle 16 sit on the engine housing 11 the rear bearing 27 for the runner. The engine rotor comprises the drum rotor 30 of the compressor 13 with several compressor rotor blade rings 31, 32, 33 etc., the turbine rotor disks 34 and 35 with the turbine rotor blade rings 36 and 37, and the hollow shaft 38, which the drum 30 and the rotor disks 3k and 35 connects with each other.

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From Figure "1 and the above description before manufacturing ^v that the engine casing and the rotor of the engine, an annular flow channel kO for the sucked and compressed air or" form for the gas, which extends over the entire length of the engine 10. " In a gas turbine engine, the working medium, which initially consists of air and then of combustion products, ie hot gases, is subjected to several processes as it flows through the channel kO Burned at constant pressure, hot exhaust gases are generated, which drive the turbine 15, in which both the temperature and the pressure of the gases are reduced often viewed as a continuous flow machine driven by the working fluid vol The flow is uniform or uniform. In practice, however, the flow is by no means uniform and steady, in particular as a result of disturbances which are introduced into the flow by the guide vanes and rotor blades and the struts, etc., and which extend over the annular flow channel kO As a result of these discontinuities and Disturbances, the various components of the engine are exposed to fluctuating aerodynamic forces that cause these components to vibrate. The guide vanes 21, 22, 23 etc. of the compressor are particularly sensitive to these vibrations. Of course, aerodynamic forces are not the only cause of the un-

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desired and possibly destructive vibrations} that occur in a turbo machine · Even if the rotor is very well balanced, it can during operation with several thousand revolutions per second «even in generate vibrations in the stator as well as in the rotor. When generating such vibrations with specific resonance frequencies, the vibration amplitudes and stresses caused thereby in the stator, especially in the guide vanes of the compressor grow up. According to the invention, a novel device for damping such vibrations is now created. been fenced.

In Fig. 2, the ring of the non-adjustable guide vanes 21 is shown seen from the inflow side, which is composed of several sectors 45 which adjoin one another. The rim of the guide vanes 21, which extends over 360 ° of the circumference, consists, for example, of twelve sectors 45, which each extend over an angle of 30 °. Any number of sectors can be selected.} For example, only six sectors of 60 each can be provided. According to the invention, each sector should have so many guide vanes that sufficient resistance to abrasion is achieved. This requirement can be understood from the description below.

As described, the individual guide vanes 21 form multiple sectors 45. These sectors 45 differ fundamentally different from the sectors of known guide devices, because each guide vane 21 is integral with one Blade 46 is formed and in the circumferential direction spaced guide vanes 21 of

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their blade roots 46 protrude radially inward into the annular flow channel 40. The adjacent Blade roots 46 of the blades 21 of each sector 45 together form a multi-part Foot 47 »which has the shape of an arcuate section which is central to the longitudinal axis of the engine 10, such as from Figs. 2 and 3 emerges. The longitudinal axis of the engine 10 is therefore the center of curvature of the multi-part Foot 47.

Each blade root 46 has a front tab 50 and a rear tab 51 in the axial direction.The front tabs 50 of the blade roots 46 of each sector 45 correspond to one another and form a multi-part, arcuate flange 50 ' multi-part flanges 50 'and 51' engages a bracket 52 which is made in one piece with the compressor housing 11 and in particular has a front and a rear flange 53 and 55, in which the annular grooves 54 and 56 are located. The annular grooves 54 and ^, 6 are axially aligned with one another, and are moreover dimensioned so that they can accommodate the multi-part flanges 50 'and 51' of the guide vane sectors 45 with sufficient play, so that they sit slidably in the channels of the annular grooves 54 and 56 . So that the flanges 50 ¹ and 51 'can be inserted or pushed into the annular grooves 54 and 56, the housing is divided in a longitudinal or axial plane and designed to be removable. Furthermore, according to FIG. 4, there is a smaller one between the outer surfaces 58 of the blade roots 46 and the inner surface 59 of the housing 11

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Radial distance 57 available.

Since several blade roots 46 together form a multi-part, Form arcuate foot 47, means must be provided which hold the individual blade roots 46 together. According to the invention a device is provided the frictionally engaged at the blade roots 46 of each root 47 attacks in order to hold them together in such a way that vibration damping is achieved.

As can be seen from FIGS. 3 and 4, in each blade root 46 there is a dovetail groove 65 in the circumferential direction in the radially outer surface 58.The individual grooves 65 in the adjacent blade roots 46 correspond to one another and form a continuous groove 66 over the entire circumferential length of the multi-part foot 47. As FIG. 5 shows, the device engaging frictionally on the blade roots 46 consists of a spring element 70 which is inserted into the arcuate groove 66 according to FIGS. Since the spring member 70 extends over the entire length of the groove 66, it has substantially the same arc length L as the groove 66, in the unstressed state of the spring element 70 is the curvature of the above-referred basic something has stronger than that of the groove 66 further the spring element 70 in the unstressed state has an arcuate cross-section over its entire length, so that the spring element 70 is doubly curved.

When assembling a guide vane ring sector 45, the spring element 70, the width of which V. is greater than the width of the groove 66 at the widest point,

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in cross-section the shape of an arc au, which is then more curved than in the untensioned state. Here, the spring element 70 also extends in its longitudinal direction until it has the same curvature as the groove 66 in this direction. The spring element 70 is therefore doubly curved both in the installed and in the unstressed state, but the curvatures are different in the two states. Within the scope of the invention, the spring element 70 can consist of various highly elastic materials.

When the guide vane sector 45 is assembled and inserted into the support device or holder 52, the spring element 70 is in the pretensioned state and, due to its elasticity, therefore tries to return to the shape it had in the unstressed state. As best as those shown in Figs. Embodiments are apparent, the element 70 therefore exerts considerable forces F on the walls S of the groove 66 , which forces hold the blade roots 46 together. During operation of the engine, the friction between the pretensioned spring element 70 and the blade roots 46 can destroy a considerable amount of energy. Furthermore, the element 70 allows a limited relative movement and friction between the tabs 50 and 51 and the walls of the annular grooves 54 and between the abutting surfaces of the blade roots 46. This can cause considerable vibration damping. At the same time the prestressed element 70 gives the multi-part foot 47 of the sector 45 such rigidity that the wear along the

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Support flanges 50 ^! and 51 * is substantially uniform. The pretensioned element 70 therefore allows a limited relative movement, but transfers moments and shear forces between adjacent blade feet 46, so that it prevents the large relative movements which normally lead to severe abrasion.

It can thus be seen that the arrangement or design according to the invention is suitable for the designer of turbomachinery allows the values of the vibration damping and the abrasion resistance within considerable To choose limits. If, for example, a relatively thin spring element 70 * is used, as is shown, for example, in FIG. 6 as shown, a fairly compliant, anti-vibration arrangement is obtained. However, according to FIG. 7 a spring element 70 "is provided which is much thicker than the spring element 70 'according to FIG. 6, so one obtains a stiffer guide vane sector 45 »the one along it Support flanges 50 'and 51' are generally smaller Shows abrasion.

The rigidity can be increased still further if the element 70 ″ in the manner shown in FIG the inner surface 59 of the housing 11 rests and the flanges 50 'and 51' inwards onto the bearing surfaces of the Annular grooves 54 and 56 are printed.

In the embodiment described above, there is the facility for frictional attack on the Blade feet 46 from a spring element 70 in a

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Dovetail groove 66, It is obvious to those skilled in the art that other prestressed elements which have the same effect can also be used for this purpose. The device according to the invention can also be used not only with compressor guide vanes, but also with other, non-adjustable guide vanes and rotor blades of turbo machines.

The guide vane ring designed according to the invention with non-adjustable guide vanes thus has multi-part sectors that are highly resistant to abrasion the blade roots thanks to good vibration-damping properties distinguish. Since each guide vane is manufactured individually with its vane root, the inventive Arrangement in terms of manufacture, assembly and maintenance the advantages of single blades

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Claims (9)

155118U Claims 1 ·! Guide vane ring for turbo machines, in particular gas turbine engines, consisting of a plurality of individual guide vanes with blade roots, several of which are combined into a group, which are coupled to one another by means of elongated damping elements extending in the circumferential direction, characterized in that several blades (21) of a blade sector (45) by means of an elongated, arched, arched leaf spring (70), which is clamped in grooves (66) or the like arranged in the blade roots (46), aligned and centered against one another. 2. Guide vane ring according to claim 1, characterized in that the leaf spring (7O) ₁ engages in a continuous, arcuate groove (66) formed by mutually corresponding grooves in the individual blade roots (46) and parallel to the annular groove (54, 56). 3. Guide vane ring according to claim 2, characterized in that the grooves (66) or the like, in which the leaf spring (70) engages, are designed as dovetail grooves (65). 4. Guide vane ring according to claim 1, 2 or 3, characterized in that the leaf spring (70) is prestressed and engages elastically in the arcuate grooves (66) 909 82S / 0909 5. Guide vane ring according to one of claims 1 to 4, characterized in that each blade root (46) is provided in the axial direction with a front and a rear tab (50 and 51) which correspond to each other and together each have a front and a rear multipart flange (50 · and 51 ') form and that a holder (52) is provided on the housing (11) attached to the two multi-piece flanges (5O ¹ or "51' engages) and holding the vane ring in the predetermined position. 6. Guide vane ring according to claim 5 »characterized in that the holder (52) has two axially spaced apart annular grooves (54,56) in which the multi-part flanges (50 ¹ or 51 ') of the sectors (47) engage. 7. guide vane ring according to claim 5 or 6, characterized in that that the holder (52) for the guide vane ring (20) with the substantially cylindrical housing (11) consists of one piece. 8. guide vane ring according to one of claims 4 to 7 »characterized in that the pretensioned leaf spring (70) in the unstressed state corresponds in length substantially to the arc length of the groove (66) and has a greater width than the groove (66), so that when the leaf spring (70) is inserted into the groove (66) it assumes a shape in which it is arcuately curved both in its longitudinal direction around the axis (c) of the turbo-machine and in cross-section and the same arcuate in the longitudinal direction 909825/0909 Has curvature, like the arcuate groove. 9. guide vane ring according to one of claims 1 to 8, characterized in that the leaf spring (70) rests under tension on the inner wall of the housing (11). 909826/0909