EP2617945B1 - Rotor for a turbo machine and manufacturing process - Google Patents

Description

The invention relates to a rotor for a turbomachine, in particular for an aircraft engine. The invention further relates to a method for producing a blade ring of a rotor for a turbomachine and an aircraft engine.

Rotors for turbomachines are known in a variety of configurations. A generic rotor comprises a blade ring which has a plurality of rotor blades with blade platforms resting flush against each other. The blade platforms are each arranged in the radial direction between the blade and the blade root of the individual rotor blades and form an inner boundary of the flow path through the turbomachine when the rotor is mounted. The tuning of the vibration behavior of bladed rotors is of central importance for the design of a turbomachine. In particular, in thermal gas turbines such as aircraft engines, which are operated in different speed ranges, the frequency detuning is very difficult. Known frequency detuning methods provide rotor blades with different natural frequencies. This is usually done by adding or removing masses. For this purpose, as in the DE 10 2007 014 886 A1 described, introduced into the blades of the rotor blades bores or pockets, which are then filled with a different type of additional material. Alternatively it is from the WO 03/062606 A1 It is known that the additional material is applied as a coating on the pressure side and / or the suction side of the rotor blade in the region of the blade tip of the blade, in order to obtain differently shaped rotor blades with correspondingly different natural oscillations.

The US 2 271 971 A discloses a rotor for a turbine in which a plurality of blades are attached to a rotor body. The blades are provided with one-sided toothed blade roots, wherein the blade roots of adjacent blades are formed in pairs mirror images of each other. The rotor base body has corresponding connection structures in which the blades are arranged side by side to form a blade ring.

The US 2 781 998 A discloses a bladed rotor for turbines or compressors. A part of the rotor blades is formed integrally with the rotor base body, while the remaining rotor blades are manufactured separately and inserted into corresponding receptacles of the rotor body. It can be provided that in each case two separate rotor blades are provided with mirror-image blade roots and pushed together into a corresponding receptacle of the rotor body.

However, these known types of frequency detuning are technically complex and relatively expensive. In addition, it can not be ruled out reliably that two identically designed rotor blades with identical vibration behavior are arranged next to one another.

Object of the present invention is to provide a generic rotor, which has a desired vibration behavior and thereby easier and process reliable to produce is. Another object of the invention is to provide a method for producing a blade ring of a rotor for a turbomachine, which enables a simpler and more reliable production of a rotor with a desired vibration behavior. Finally, it is an object of the invention to provide an aircraft engine with such a rotor.

The objects are achieved by a rotor with the features of claim 1, by a method according to claim 8 and by an aircraft engine with the features of claim 12. Advantageous embodiments with expedient developments of the invention are specified in the respective subclaims, wherein advantageous embodiments of the rotor are to be regarded as advantageous embodiments of the method and vice versa.

A rotor for a turbomachine, which has a desired vibration behavior and is easier and more reliable to produce, is inventively provided in that the blade ring comprises at least two groups of differently shaped rotor blades, each group of rotor blades blade platforms are assigned, each with a complementary Vane platform of at least one other group of rotor blades and not flush with a blade platform of the same group of rotor blades are brought into abutment. Each blade platform of a first group of rotor blades has at least one peripheral recess in which a complementary marginal elevation of an adjacent blade platform of an associated second group of rotor blades is arranged in a form-fitting manner. As a result, a structurally particularly simple exchange protection is given. In addition, it is particularly easy with appropriate design of the depression and the associated survey "hooked" adjacent rotor blades with each other, which in addition to the exchange protection in addition, the mechanical stability of the rotor under varying operating conditions, for example, under varying operating temperatures and pressures, advantageously improved becomes. In other words, it is inventively provided that the rotor blades that make up the blade ring of the rotor, are formed such that two identical rotor blades, which accordingly belong to the same group or the same rotor blade type and have the same blade platforms, not flush mounted side by side, in the case of a faulty arrangement, the blade platforms would not lie flush against one another and thus always leave a gap between them identical trained blade platforms of the rotor blades of a single group would remain. Due to the resulting increase in space requirements, the blade ring could also not be closed. With the help of the inventive design of the rotor blades, only such rotor blades can instead be arranged flush side by side, which belong to different groups and their paddle platforms on the one hand geometrically different from each other and on the other hand are complementary to each other. In the simplest embodiment of the invention thus only two different groups of rotor blades are needed. In principle, however, it is also possible to use three or more groups of differently designed rotor blades, with the general rule that at least blade platforms of the same group of rotor blades can not be brought into abutment with each other due to their group-specific configuration. As a result, according to the invention, an integral exchange protection in the area of the hub platform of the rotor is provided by which it is reliably impossible to arrange two identically formed rotor blades with correspondingly equal vibration behavior next to one another and to add them to the blade ring. Additional components to ensure the security against confusion are not required for this, so that the weight of the rotor is advantageously not adversely affected. The invention therefore makes it possible in a structurally simple and cost-effective manner to reliably manufacture a rotor with a desired frequency detuning (detuning), in which it is reliably ruled out that two identical rotor blades are inadvertently arranged next to one another.

Further advantages result from the depression and / or the elevation of the relevant blade platform being introduced into the relevant blade platform by means of a separation process, in particular by milling and / or grinding. This allows further cost reductions, since first rotor blades can be manufactured with identically designed blade platforms. The corresponding depressions and elevations can then subsequently be introduced into the blade platforms by the separation process. This also makes it possible to first provide conventional rotor blades with uniformly designed blade platforms and then post-process them in the sense of the present invention, whereby further cost reductions are realized both in the manufacture and in the repair and overhaul of corresponding rotors. In addition, the invention can also be applied to existing rotors or rotor blades. Alternatively or additionally, but of course It can also be provided that the at least two different groups of rotor blades are produced by deviating production methods, for example by primary forming and / or joining.

In a further advantageous embodiment of the invention, it is provided that each blade platform of the first group of rotor blades a marginal recess and an opposite marginal elevation and each blade platform of the second group of rotor blades to complement the blade platform of the first group complementary marginal elevation and a survey of the Bucket platform of the first group has complementary marginal depression. In this way, adjacent blade platforms can be hooked to each other at their opposite edge regions, whereby a mechanically particularly stable connection of the individual rotor blades while ensuring the swap protection is achieved.

In a further advantageous embodiment of the invention it is provided that the recesses and the complementary elevations are formed in the region of lateral contact surfaces of the rotor blades, wherein the elevations are arranged in a form-fitting manner in the associated recesses. This represents a structurally simple way to connect adjacent rotor blades via a kind of tongue and groove connection mechanically stable.

A particularly effective frequency detuning of the rotor is achieved in a further embodiment of the invention in that the at least two groups of rotor blades have different blade blade geometries. In other words, it is provided according to the invention that each group of rotor blades is provided with an associated and group-specific designed blade type, wherein the blade types of different groups of rotor blades differ from each other. Rotor blades with different blade geometry are also understood to mean rotor blades whose blades themselves have the same geometry, but which differ with regard to their relative arrangement with respect to the blade platform. In this case, it may be provided, for example, that the blades of different groups also differ from one another with regard to their material, their coating or any combination of these features. This allows a particularly effective frequency detuning of the rotor, since in this way in combination with the group-specific trained blade platforms never two rotor blades with identical Blades can be installed flush side by side. Conversely, however, it is advantageously not necessary to design each individual airfoil of the rotor individually in order to achieve a sufficient frequency detuning.

Further advantages result from the fact that the at least two groups of rotor blades have blade platforms with mutually corresponding lateral contact surfaces. This is a structurally particularly simple way to create an integral swap protection and to bring adjacent rotor blades as large as possible in abutment with each other.

Further advantages result from the contact surfaces being inclined and / or wavy and / or serrated and / or irregular. For example, the contact surfaces can form corresponding wedge surfaces with each other, which in addition to an integral swap protection and increased friction between the rotor blades and thus a mechanically particularly stable connection of adjacent rotor blades is achieved. The design of the contact surfaces is basically not limited to certain geometries. In the geometric design of the corresponding contact surfaces, it is merely necessary to ensure that the contact surfaces of one group of rotor blades can not be brought flush into contact with the corresponding contact surfaces of a further group of rotor blades but not with contact surfaces of the same group of rotor blades.

A further aspect of the invention relates to a method for producing a blade ring of a rotor for a turbomachine, in particular for an aircraft engine, comprising at least the steps a) providing at least two groups of differently shaped rotor blades, wherein each group of rotor blades are associated with blade platforms, each with and b) arranging the rotor blades in the form of the blade ring, wherein each complementary blade platforms of the at least two groups of rotor blades flush with each other in abutment with one another to be brought. According to the invention, it is provided that each blade platform of a first group of rotor blades has at least one marginal depression, in which a complementary marginal elevation of an adjacent blade platform of an associated second group of rotor blades is arranged positively. As a result, a structurally particularly simple exchange protection is given. In addition, it is particularly easy with appropriate design of the depression and the associated survey "hooked" adjacent rotor blades with each other, which in addition to the exchange protection in addition, the mechanical stability of the rotor under varying operating conditions, for example, under varying operating temperatures and pressures, advantageously improved becomes. In this way, a simpler and more secure proximal manufacturing a rotor with a desired vibration behavior is possible, since it is ensured in a structurally simple way that never two identically shaped rotor blades with correspondingly equal vibration behavior can be arranged flush side by side. As a result, according to the invention, an integral exchange protection is provided on the hub platform of the rotor. Additional components to ensure the security against confusion are advantageously not required, so that the weight of the rotor is not adversely affected. The inventive method therefore allows in a structurally simple and cost-effective manner, the particularly reliable production of a blade ring or a rotor provided with such a blade ring with a desired frequency detuning (detuning). Further features and their advantages can be found in the previous descriptions.

In an advantageous embodiment of the invention, it is provided that in step b) blade platforms of a first group of rotor blades and blade platforms of a second group of rotor blades are brought into contact alternately. In this way, only two different types of rotor blades are required with complementary trained groups of blade platforms, so that the blade ring can be made particularly fast and reliable with a desired frequency detuning.

A mechanically particularly stable connection of the blade ring to the rotor is made possible in a further embodiment in that blade roots of the rotor blades are arranged and fixed in step b) in a complementary groove of a rotor base body. The blade roots of the individual rotor blades can in principle be identical, that is to say group-independent. Alternatively, however, it can also be provided that the rotor blades have group-specific blade roots.

Further advantages are obtained by providing at least two groups of rotor blades with different blade geometry in step a). In other words, it is provided according to the invention that rotor blades are used which have group-specific designed blade types, wherein the blade blade types of different groups of rotor blades differ from each other. It can be provided, for example, that the blades of different groups additionally differ from each other in terms of their material, their coating or any combination of these features. This allows a particularly effective frequency detuning of the rotor, since in this way in combination with the group-specific trained blade platforms never two identically designed blades can be installed flush side by side. Vice versa However, it is advantageously not necessary to design each individual blade of the rotor individually in order to achieve a sufficient frequency detuning.

Another aspect of the invention relates to an aircraft engine, wherein it is provided according to the invention that it comprises a rotor according to one of the preceding embodiments and / or a blade ring, which is produced by means of a method according to one of the preceding embodiments. The resulting features and their advantages can be found in the above descriptions.

• Fig. 1 eine schematische Aufsicht von zwei bündig aneinander anliegenden Rotorschaufeln; und
• Fig. 2 eine schematische Frontalansicht von zwei alternativ ausgebildeten Rotorschaufeln.

Further features of the invention will become apparent from the claims, the embodiment and the drawings. The features and combinations of features mentioned above in the description as well as the features and feature combinations mentioned below in the exemplary embodiment can be used not only in the respectively indicated combination but also in other combinations, without departing from the scope of the invention. Showing:

• Fig. 1 a schematic plan view of two flush juxtaposed rotor blades; and
• Fig. 2 a schematic frontal view of two alternately formed rotor blades.

Fig. 1 shows a schematic plan view of two flush-mounted rotor blades 10a, 10b during the manufacture of a blade ring (not shown) of a rotor for an aircraft engine. From the rotor blades 10a, 10b, the cut blades 12a, 12b are shown, which are connected to blade platforms 14a, 14b of the rotor blades 10a, 10b and extending in a conventional manner from the blade platforms 14a, 14b from radially upwards. Radially below the blade platforms 14a, 14b, the rotor blades 10a, 10b comprise respective blade roots 16a, 16b (see FIG. Fig. 2 ), via which the connection of the rotor blades 10a, 10b to a rotor main body of the rotor takes place in a manner also known per se. It can be seen that the two rotor blades 10a, 10b comprise differently designed blade platforms 14a, 14b and belong to two different groups. The blade platforms 14a, 14b of the two groups of rotor blades 10a, 10b lie flush against each other and form in the finished mounted blade ring or in the finished rotor a continuous, radially inner shroud, which limits the flow path in the associated aircraft engine.

Furthermore, the blades 12a, 12b are formed group-specific, wherein blades blades 12a and 12b of the same group have an identical blade geometry and blades 12a, 12b of different groups have different blade geometry. The blade platform 14a belonging to the first group of rotor blades 10a is designed such that it is flush with the blade platform 14b belonging to the second group of rotor blades 10b and designed to be complementary to the blade platform 14a. For this purpose, the blade platform 14a of the first group in the region I has a recess which is peripheral with respect to the dot-dashed dividing plane A and, in the opposite region II, a marginal elevation with respect to the dash-dotted dividing plane A. Corresponding blade platform 14b of the second group accordingly has a marginal elevation complementary to the depression of the blade platform 14a in region I and a marginal depression complementary to the elevation of blade platform 14a in region II.

It can be seen that the graduation plane A hereby identifies the theoretical graduation plane between two conventional rotor blades whose blade platforms have consistently planar contact surfaces and thus can not be arranged so that they are not interchangeable. To produce the different rotor blades 10a, 10b, that is, the rotor blades 10a of the first group and the rotor blades 10b of the second group, it may be provided that first rotor blades provided with identical blade platforms and the wells and elevations then by a corresponding milling treatment of the blade platforms 14a, 14b are generated.

Out Fig. 1 It is also clear that the blade platform 14a of the first group of rotor blades 10a can not be placed flush with another blade platform 14a of the first group, but only on the blade platform 14b belonging to the second group of rotor blades 10b. Correspondingly, the blade platform 14b belonging to the second group of rotor blades 10b can also be placed flush with the paddle platform 14a belonging to the first group, but not flush with another paddle platform 14b of the second group. Thus, two identical rotor blades 10a-10a or 10b-10b of the same group with identical blade platforms 14a-14a or 14b-14b can never be installed flush next to each other. Instead, blade platforms 14a of rotor blades 10a of the first group and blade platforms 14b of rotor blades 10b of the second are alternately formed to form a blade ring Group attached to each other. At the same time it is always ensured due to the group-specific configurations of the blade platforms 14a, 14b that never two identical blades 12a-12a and 12b-12b can be arranged flush side by side. As a result, a particularly effective frequency detuning of the finished blade ring and thus of the assembled rotor is reliably achieved.

Due to the integral confusion protection of the group-specific trained rotor blades 10a, 10b, which colloquially is also referred to as "foolproof design", it is reliably excluded without the need for additional components that two identically designed rotor blades 10a-10a and 10b-10b, that is Rotor blades of the same group, be applied to each other, since in this case would always remain an obvious gap between adjacent blade platforms 14a-14a and 14b-14b. The blade ring could then no longer be closed because of the resulting increase in space requirements. In principle, it can also be provided that one or more further groups of differently shaped rotor blades are used with group-specific blade platforms, wherein the blade platforms are always to be designed such that they are not flush with blade platforms of rotor blades of the same group, but flush with blade platforms of rotor blades at least can be applied to another group.

Alternatively or in addition to the depressions and elevations shown, it can be provided that the depressions and elevations are formed in lateral contact or contact surfaces of the blade platforms 14a, 14b of the rotor blades 10a, 10b and form a tongue and groove connection. A structurally particularly simple swap protection can be achieved, for example, in that the first group of rotor blades 10a has bilateral elevations (springs) and the second group of rotor blades 10b has recesses (grooves) on both sides.

Fig. 2 shows a schematic frontal view of two alternately formed rotor blades 10a, 10b during the manufacture of a blade ring (not shown) of an aircraft engine rotor. Rotor blades 10a, 10b show partially cut airfoils 12a, 12b, which are connected to blade platforms 14a, 14b of rotor blades 10a, 10b and extend radially upward from blade platforms 14a, 14b. Radially below the blade platforms 14a, 14b, the rotor blades 10a, 10b comprise respective blade roots 16a, 16b, via which the connection of the rotor blades 10a, 10b to one Rotor body of the rotor takes place. The blade platforms 14a, 14b have mutually corresponding lateral contact surfaces III. It can be seen that the contact surfaces III are formed obliquely or wedge-shaped with respect to the axis of rotation of the rotor extending division plane A, so that the blade platform 14a of the first group only with the blade platform 14b of the second group, but not with a further blade platform 14a of the first Group can be brought flush into contact. The blade platforms 14a, 14b of the two groups of rotor blades 10a, 10b form a continuous, radially inner shroud, which limits the flow path in the assigned aircraft engine, analogous to the previous exemplary embodiment in the completely assembled blade ring or in the finished rotor. The wedge-shaped design of the contact surfaces causes depending on the angle of the wedge increased friction between the contact surfaces III. It should be emphasized, however, that the contact surfaces III have a fundamentally arbitrary contour profile and, for example, can be corrugated and / or serrated or have other suitable elevations / depressions. It is only important that the contact surfaces III of the first group of rotor blades 10a can be brought into contact flush only with corresponding contact surfaces III of the second (or another) group of rotor blades 10b, but not with contact surfaces III of the first group of rotor blades 10a.

Claims (12)

1. A rotor for a turbomachine, particularly for an aircraft engine, with a blade ring comprising a plurality of differently configured rotor blades (10a, 10b) with blade platforms (14a, 14b) being in flush contact with each other, wherein the blade ring comprises at least two groups of differently designed rotor blades (10a, 10b), wherein each group of rotor blades (10a, 10b) are assigned to the blade platforms (14a, 14b), each of which can be brought into flush contact with a complementary blade platform (14a, 14b) of at least one other group of rotor blades (10a, 10b) and not with a blade platform (14a, 14b) of the same group of rotor blades (10a, 10b) characterized in that each blade platform (14a) of a first group of rotor blades (10a) comprises at least a marginal depression, in which a complementary marginal elevation of an adjacent blade platform (14b) of an assigned second group of rotor blades (10b) is positively arranged.
2. A rotor according to claim 1, characterized in that the depression and /or elevation of the associated blade platform (14a, 14b) is inserted with the aid of a separating process, particularly by milling and/or grinding, into the associated blade platform (14a, 14b).
3. A rotor according to claim 2, characterized in that each blade platform (14a) of the first group of rotor blades (10a) comprises a marginal depression and oppositely a marginal elevation and each blade platform (14b) of the second group of rotor blades (10b) comprises a marginal elevation complementary to the depression on the blade platform (14a) of the first group and a marginal depression complementary to the elevation of the blade platform (14a) of the first group.
4. A rotor according to one of claims 1 to 3, characterized in that the depressions and the complementary elevations are configured in the area of the lateral contact surfaces of the rotor blades (10a, 10b), wherein the elevations are positively arranged in the assigned depressions.
5. A rotor according to one of claims 1 to 4, characterized in that at least two of the groups of rotor blades (10a, 10b) comprise different blade geometries.
6. A rotor according to one of claims 1 to 5, characterized in that at least two groups of rotor blades (10a, 10b) comprise blade platforms (14a, 14b) having mutually corresponding lateral contact surfaces (III).
7. A rotor according to claim 6, characterized in that the contact surfaces (III) are configured at an angle and/or corrugated and/or jagged and/or in an irregular form.
8. A method for manufacturing a blade ring of a rotor for a turbomachine, particularly for an aircraft engine, comprising the following steps:

   a) providing at least two groups of differently configured rotor blades (10a, 10b), wherein each group of rotor blades (10a, 10b) are assigned to blade platforms (14a, 14b), with at least one group of rotor blades (10a, 10b) which can be brought into flush contact with at least one other group of rotor blades (10a, 10b) and not with a blade platform (14a, 14b) from the same group of rotor blades (10a, 10b); and

   b) arranging the rotor blades (10a, 10b) in the form of the blade ring, wherein in each case mutually complementary blade platforms (14a, 14b) of the at least two groups of rotor blades (10a, 10b) are brought into flush contact with each other

   is characterized in that
   each blade platform (14a) of a first group of rotor blades (10a) comprises at least one marginal depression, in which a complementary marginal elevation of an adjacent blade platform (14b) is positively engaged with an assigned second group of rotor blades (10b).
9. A method according to claim 8, characterized in that in step b) blade platforms (14a) of a first group of rotor blades (10a) and blade platforms (14b) of a second group of rotor blades (10b) are alternately brought into contact with each other.
10. A method according to claims 8 or 9, characterized in that the blade roots of the rotor blades (10a, 10b) in step b) are arranged and fixed in a complementary groove of a rotor base body.
11. A method according to one of claims 8 to 10, characterized in that in step a) at least two groups of rotor blades (10a, 10b) are made available with different rotor blade geometries.
12. Aircraft engine, comprising a rotor according to one of the claims 1 to 7 and/or a blade ring, which is manufactured according to one of the claims 8 to 11.

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