EP1462617A2 - Blading for an axial-flow turbomachine - Google Patents

Abstract

An axial streaming turbine engine with a metal rotor (1) in which rotor blades (3) made from an intermetallic material are mounted in a peripheral slot forming a rotor blade series, where at least two rotor blades (3') made from a ductile material are located in the rotor blade series between the intermetallic rotor blades (3), where rotor blades (3') are either longer than blades (3) or of equal length but have different blade tips.

Description

Technical field

The invention relates to the field of power plant technology. It affects an axially flowed thermal turbomachine according to the preamble of claim 1, which compared to the known state of the Technology has a reduced rotor weight.

State of the art

Thermal turbomachinery, e.g. B. high pressure compressor for gas turbines or Turbines consist essentially of a rotor equipped with blades Rotor and a stator, in which guide vanes are suspended. The Blades and the guide blades each have a blade and a blade root. Around the blades on the rotor or in the stator to be able to fasten are grooves in the stator and on the rotor shaft stabbed. The feet of the guide and rotor blades are in these grooves inserted and locked there.

The fixed guide vanes are responsible for the flow of the compressing or to relax the gaseous medium so on the rotating barrel blading to direct that energy conversion with best possible efficiency.

It is known to make blades in one piece from a single material, e.g. B. from stainless steel for gas turbine compressors or made of a nickel-based superalloy for gas turbines, to manufacture and with these Shovels to fill a row of shovels. Such blades are hereinafter referred to as conventional blades.

For certain applications, the average mass is one Bucket row limited by the load capacity of the rotor.

This is why solutions have become known, blades in hybrid design manufacture. In the hybrid design, a blade is used to manufacture different materials with different physical properties combined with each other in order to optimize the design of a bucket receive. So z. B. a hybrid rotor blade for an engine from DE 101 10 102 A1 known, in which the rear edge of the airfoil, the only has an aerodynamic function, made of a lightweight material, preferably a fiber composite, e.g. B. carbon fiber composite, is made. With such a (light) trailing edge, this can be advantageous Reduce the weight of the bucket. The connection of the two Blade parts (heavy metallic leading edge and slight trailing edge made of fiber composite material) by gluing or riveting.

A similar solution is described in WO 99/27234. There is a rotor with integral blading, in particular for an engine, disclosed on the circumferentially rotor blades are arranged, the rotor blade for Reduction of vibrations of a metallic blade root, one metallic airfoil section, the at least part of the Blade front edge and the adjacent area of the Blade surface forms, and an airfoil made of fiber-reinforced plastic exhibit. Here, too, the blade is attached Plastic on the metallic airfoil section by gluing / riveting or by clamping.

This known prior art has those listed below Disadvantage. On the one hand, the mentioned types of fastening hold one long period of time, there are no major burdens fiber-reinforced plastics only in certain temperature ranges can be used, so that these known technical solutions in particular only are suitable for engine technology. In addition, the characteristic of the airfoil (mechanical properties, oxidation resistance, Friction properties) compared to that of a single material existing blades changed, which adversely affects Operating behavior of the machine.

Furthermore, EP 0 513 407 B1 describes a turbine blade made of an alloy known on the basis of a dopant-containing gamma titanium aluminide, which are made of airfoil, blade root and if necessary Bucket shroud consists. In the manufacture of this blade, the Castings are partially heat-treated and thermoformed so that the The airfoil subsequently has a coarse-grained structure that is too high Tensile and creep rupture strength leads, and that the blade root and / or that Bucket shroud has a fine grain structure that opposes one leads to increased ductility of the airfoil.

With the use of gamma titanium aluminide Compared to conventional blades, blades advantageously have the mass the rotor lowered, but a disadvantage of this prior art is that the tips of the blades burst due to their brittleness when they are in use during operation come into contact with the stator. That friction is usually not preventing.

Experience with steel blades in high pressure compressors has shown that even with so-called abrasion layers on the stator Blades are ground during the operation of the compressor can. This is associated with a considerable amount of friction, too causes a blade brittle fracture if the blade is not ductile.

Presentation of the invention

The aim of the invention is to overcome the disadvantages of the prior art avoid. The invention is based on the object of a thermal Turbomachine to develop, which on the one hand by a reduced Total weight of the rotor, and on the other hand Blade brittle fracture is prevented, so that the life of the machine is increased.

According to the invention, this object is achieved in a thermal turbomachine according to the preamble of claim 1 solved in that at least two equally spaced blades made from a more ductile one Material in a row of blades between the intermetallic blades are arranged, the blades of the more ductile material either are significantly longer than the intermetallic blades or the same Length of a different blade tip shape than the intermetallic blades exhibit.

The advantages of the invention are that by using the Paddles made of intermetallic compounds on the one hand the weight of the Rotors is reduced, increasing the life of the rotor Rotor / blade connection leads and on the other hand the brittleness of the Intermetallic blades do not pose an increased risk to the operation of the machine means that the blades arranged in the same blade row are made of absorb the friction / wear forces of the more ductile material.

It is advisable if there is an additional one between the blades Bucket row spacers made of a lighter material than that Rotor material, preferably an intermetallic compound or Titanium alloy, are arranged in the rotor. This way the weight of the rotor additionally reduced.

It is also advantageous if the intermetallic blades and the Intermediate pieces made of an intermetallic γ-TiAl compound or intermetallic orthorhombic TiAl compound exist because of this Material use according to the invention for a considerable weight reduction of the rotor. The specific density of the intermetallic titanium aluminide compounds is z. B. only about 50% of the density of stainless Cr-Ni-W steel.

Finally, it is advantageous if the blade tips are hard Phase coated or a laser welding Wear protection layer is applied to grind off the To prevent blade tips or to reduce the frictional force.

Brief description of the drawings

Fig. 1

einen Querschnitt durch eine Laufschaufelreihe eines schematisch dargestellten erfindungsgemässen Hochdruckverdichters in einer ersten Ausführungsvariante;

Fig. 2

ein Detail einer zweiten Ausführungsvariante der Erfindung, bei welcher zwischen den Laufschaufeln Zwischenstücke aus intermetallischen Verbindungen im Rotor angeordnet sind und

Fig. 3

eine TiAl-Schaufel mit einer beschichteten Schaufelspitze als dritte Ausführungsvariante der Erfindung.

Several exemplary embodiments of the invention are shown in the drawing. Show it:

Fig. 1

a cross section through a rotor blade row of a schematically illustrated high-pressure compressor according to the invention in a first embodiment;

Fig. 2

a detail of a second embodiment of the invention, in which intermediate pieces of intermetallic compounds are arranged in the rotor between the blades and

Fig. 3

a TiAl blade with a coated blade tip as a third embodiment of the invention.

In the figures, the same positions are the same Provide reference numerals.

Ways of Carrying Out the Invention

The invention is illustrated below by exemplary embodiments and by FIGS to 3 explained in more detail.

Fig. 1 shows a cross section through a schematically shown Blade row of a rotor 1 for a high pressure compressor Gas turbine. The rotor 1 is surrounded by a stator 2. In the rotor 1 are blades 3, 3 'are mounted in a circumferential groove therein, while guide vanes (not shown here) are suspended in the stator 2. The Blades 3, 3 'are, for example, at a pressure of approximately 32 bar a temperature of around 600 ° C for several thousand hours exposed.

According to the invention, the row of blades shown has two different ones Types of blades 3, 3 'equipped. For the purpose of weight loss Most of the blades, namely the blades 3, from one intermetallic compound, preferably a γ-titanium aluminide compound manufactured. The blades 3 ', however, are made of one more ductile material, such as a stainless Cr-Ni steel, than that Material for the blades 3 made. At least two evenly spaced such ductile blades 3 (According to FIG. 1, these are in present embodiment four pieces) are in the row of blades the intermetallic blades 3 arranged. The blades 3 'from the more ductile material in this embodiment are significantly longer than the intermetallic blades 3, d. H. if you accidentally touch the Blading with the stator during operation can make it more ductile Buckets absorb the frictional forces without causing a brittle fracture comes. In another embodiment variant can be achieved same effect both blade types 3, 3 'also the same length, for that but have different shapes of the blade tip 5, z. B. have the more ductile blades 3 'advantageously blunted blade tips 5.

In the present exemplary embodiment, the rotor blades 3 ′ consist of a stainless steel with the following chemical composition (in% by weight): 0.12 C, <0.8 Si, <1.0 Mn, 17 Cr, 14.5 Ni, <0.5 Mo, 3.3 W, <1 Ti, <0.045 P, <0.03 S, balance Fe. The shaft of the rotor 1 is also made of steel. As is known, the density of steel is approximately 7.9 g / cm ³ . The intermetallic compound from which the rotor blades 3 are made has the following chemical composition (in% by weight): Ti (30.5-31.5) Al- (8.9-9.5) W- (0.3-0.4) Si. The density of this alloy is advantageously only 4 g / cm ³ , so that the rotor 1 according to the invention is considerably lighter than a rotor with exclusively conventional steel blades.

Fig. 2 shows a further embodiment of the invention in a Detailed display. The weight of the rotor 1 can also be reduced if - as shown in Fig. 2 - between two neighboring Blades of a row of blades of the rotor 1 each intermediate pieces 4 an intermetallic compound, here a γ-titanium aluminide compound, are mounted in the circumferential groove of the rotor 1.

The intermetallic used for the manufacture of the intermediate pieces 4 Compound has the same chemical composition as that for the Paddles 3 used and described connection.

Intermetallic compounds of titanium with aluminum have some interesting properties which they as construction materials in make the middle and higher temperature range appear attractive. This includes theirs compared to superalloys and stainless Steels lower density. Their technical usability is in the this form often counteracts their brittleness.

The intermetallic γ-titanium aluminide compound described above is distinguished is about 50% less dense than this Embodiment for the rotor 1 and the blades 3 'steel used. It also has a modulus of elasticity of 171 GPa and at room temperature a thermal conductivity λ of 24 W / mK.

The physical properties of the two alloys are compared in Table 1. Physical properties of the different materials Density in g / cm ³ Coefficient of thermal expansion in K ^-1 γ-Ti-Al 4 10 x 10 ^-6 Stainless steel 7.9 18.6 x 10 ^-6

Since the rotating components of the high pressure compressor are one Gas turbine plant subject to heavy loads at temperatures up to approx. 600 ° C the weight reduction of the rotor 1 according to the invention has an effect advantageous to increase the life of the machine. It will the stresses in the blade root fixation in the rotor 1 are reduced.

The manufacture of the intermetallic blades 3 and the intermediate pieces 4 takes place in a known manner by casting, hot isostatic pressing and Heat treatment with minimal post-processing.

A further preferred embodiment variant is shown in FIG. 3. It will a rotor blade 3 is shown, the blade tip 5 of which is coated. The The blade tip can be coated with a hard phase or a wear protection layer can be created by means of laser welding be applied. In both cases, the grinding of the Avoid blade tips or reduce the frictional force.

Of course, the invention is not limited to that described Embodiments limited.

For example, an orthorhombic titanium-aluminide alloy with a density of 4.55 g / cm ³ can also be used as the material for the intermetallic blades 3 or the intermediate pieces 4. Orthorhombic titanium aluminide alloys are based on the ordered compound Ti ₂ AlNb and have the following chemical composition in (% by weight): Ti- (22-27) Al- (21-27) Nb.

The intermediate pieces 4 can also be made of a cheaper titanium alloy instead of an intermetallic γ-titanium aluminide compound, in which case the weight reduction is not quite as great.

It is also conceivable that the invention not only for High pressure compressor rotors is used, but also for Turbine rotors with turbine blades made of known turbine steel, heat-resistant steel or from a super alloy, for example a nickel-based super alloy, where the intermediate pieces between the Blades made of an intermetallic γ-titanium aluminide alloy or an intermetallic orthorhombic titanium aluminide alloy. Weight reductions and an increase can also be advantageous with this reach the life of the machine.

For the use according to the invention of the intermetallic Ti-Al alloys their brittleness does not play a negative role, since they Use as intermediate pieces no sliding contact or none Frictional wear are exposed and when used as a shovel corresponding ductile blades have the friction / wear forces take up.

LIST OF REFERENCE NUMBERS

1

rotor

2

stator

3, 3 '

blade

4

connecting piece

5

blade tip

Claims (8)

Axial flow-through thermal turbomachine with a metallic rotor (1), in which rotor blades (3) made of an intermetallic connection to a row of blades are mounted in a circumferential groove, characterized in that at least two evenly spaced rotor blades (3 ') made of a more ductile material in of the said row of blades are arranged between the intermetallic blades (3), the blades (3 ') made of the more ductile material either being significantly longer than the intermetallic blades (3) or having a different blade tip shape than the intermetallic blades (3) , Turbomachine according to claim 1, characterized in that intermediate pieces (4) made of a lighter material than the material of the rotor (1), preferably made of an intermetallic compound or a titanium alloy, are additionally arranged between adjacent rotor blades (3, 3 ') of a row of blades. Turbomachine according to claim 1 or 2, characterized in that the intermetallic connection for the blades (3) and the intermediate pieces (4) is a γ-titanium aluminide alloy or an orthorhombic titanium aluminide alloy. Turbo machine according to claim 3, characterized in that the γ-titanium aluminide alloy has the following chemical composition (in% by weight): Ti- (30.5-31.5) Al- (8.9-9.5) W- (0.3-0.4) Si. Turbomachine according to one of claims 1 to 4, characterized in that the blade tips (5) of the moving blades (3) can be coated with a hard phase. Turbomachine according to claim 5, characterized in that a wear protection layer can be applied to the blade tips by means of laser welding. Turbomachine according to one of claims 1 to 6, characterized in that the turbomachine is a high-pressure compressor of a gas turbine with a rotor (1) which consists essentially of a stainless Cr-Ni steel. Turbomachine according to one of Claims 1 to 7, characterized in that the blades (3 '), which are more ductile than the intermetallic blades (3), consist of a stainless Cr-Ni steel or a heat-resistant turbine blade steel or a superalloy.

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