WO2010083805A1

WO2010083805A1 - Turbomachine

Info

Publication number: WO2010083805A1
Application number: PCT/DE2010/000040
Authority: WO
Inventors: Frank Stiehler
Original assignee: Mtu Aero Engines Gmbh
Priority date: 2009-01-24
Filing date: 2010-01-18
Publication date: 2010-07-29
Also published as: DE102009006029A1

Abstract

The invention relates to a turbomachine, in particular a gas turbine, comprising a device for actively changing the gap (28) between the rotating blade tips (26) and a shroud (46). Piezoelectric actuators (48) are disposed radially outside of a circumferential wall (32) of the housing (20) and displace the shroud (46).

Description

turbomachinery

The invention relates to a turbomachine, in particular gas turbine, with a stator and a rotor, wherein the rotor blades and the stator has a housing and vanes, wherein the rotor-side blades with radially outer tips adjacent to the housing and define a gap therewith, and wherein to minimize the gap between the tips of the blades and the housing, a shroud is provided which is radially moved over a plurality of circumferentially distributed piezoelectric actuators.

Turbomachines, for example gas turbines such as aircraft engines, have at least one rotor and at least one stator, both in the compressor and in the turbine area. The rotor blades associated with the rotor rotate with respect to the stationary housing and the likewise stationary vanes.

There are gaps between the radially outer blade tips and the housing. These must be as small as possible to optimize the efficiency of the turbomachine, which is especially true for the radially outer gap between the blade tip and the housing. The housing as well as the blades are subject to considerable changes during operation of the gas turbine, since on the one hand the housing and the blades vary in extent due to their different thermal behavior and on the other hand cause the rotating blades due to the centrifugal forces acting during operation of the turbomachine gap changes. In addition, it can also come to a so-called rotor pendulum, which is of course even more problematic with respect to the gap seal.

In the past, so-called ACC (Active Clearance Control) systems have already been used. In this case, the gap between the blade tips and so-called shrouds, which lie between the housing and the blade tips, directly changed by the shrouds are moved. This overflow losses are kept very small. In addition, the rubbing of the blades is reduced to the inlet lining at unbalanced loads or even prevented.

Spreader designs, hydraulic adjustments and thermally controlled designs such as case cooling are expensive and in part expensive Also large-scale, heavy solutions with high power requirements and, above all, relatively high inertia in the adjustment of the shrouds. In addition, these systems can only produce symmetrical shifts.

From the generic WO 96/17156 an ACC system is known, in which between the shroud and the housing a circumferentially continuous, sinusoidal piezoelectric element extends, which is alternately secured to the shroud and to the housing. A voltage is applied between the individual attachment points, so that the section between these attachment points leads to the activation of the piezoelectric section when the voltage is applied. The shrouds are subdivided into segments, and the individual segments have a gap between them.

The object of the invention is to provide a turbomachine with an improved ACC system.

This is achieved in a turbomachine of the type mentioned above in that the housing has a peripheral wall adjacent to the shroud and the actuators are arranged radially on the opposite with respect to the blade tips side of the peripheral wall.

By the actuators are arranged so to speak outside of the housing wall, they can be separated gas and thermal from the interior, which has advantages especially in the turbine area due to the hot gas. The housing can be made integral as before and does not have to be divided axially. The suspension of the stator components is not affected by the invention.

The ACC system, which is used in the turbomachine according to the invention, builds very light and small, consumes only small power supply and has a high reliability. The piezoelectric actuators have high actuating forces and are extremely responsive, so that the required small shifts can be implemented quickly enough. Due to the numerous distributed around the circumference actuators, the shroud can also deform asymmetrically, for example, to adjust the gap, so to speak, the tumbling motion when Rotortaumeln. According to the preferred embodiment, the shroud is circumferentially closed, that is in one piece, so that the movement of actuators on one side also have an influence on the portions of the shroud on another, for example, opposite side.

Of course, the shroud can also be slotted or composed of several segments. The slots can optionally be closed on all sides, i. be limited by a wall.

The peripheral wall should have openings through which pressing or pulling elements extend, which couple the actuators with the shroud.

Here, according to the preferred embodiment, a so-called sheet-metal assembly is conceivable in which the pressure or tension elements are integrally connected to the shroud (for example, by soldering or welding). This results in a high stability of the ACC system.

Of course, the elements can also be connected to one another from a plurality of parts in a positive and / or non-positive manner, e.g. over rivets.

The openings are preferably slots, in particular narrow slots in the housing, through which the pressing or pulling elements extend.

Preferably, the pressing or pulling elements are narrow webs.

The structure is designed so that it is geometrically optimally aligned to resistance characteristics.

The pressing or pulling elements extend according to an embodiment radially up to a bar, which lies on the inside of the associated actuators.

The strip is in particular part of a frame in which an actuator is received.

The actuator can pull the bar outward or press radially on the bar, then the bar is actually on him. The actuator can also act in the axial or circumferential direction, so that on the change in thickness in the axial or circumferential direction and a kind Umlenkkinematik can take place an adjusting movement in the radial direction. Preferably, at least one separate strip and at least one own pressing or pulling element is provided for each actuator. Alternatively or additionally, a bar can accommodate a package of actuators.

Strip, frame and / or pressing or pulling element can be integrally connected to each other, so that there is a kind of solid joint ..

The strips should be fixed in the housing or in the frame, which may also be done by welding or soldering if necessary.

The housing has according to the preferred embodiment radially outside the peripheral wall chambers for accommodating the actuators and possibly also the aforementioned frame.

The invention is particularly advantageous in connection with a cooling of the actuators. Since the actuators are outside the peripheral wall, they can be kept at a temperature of their own via a separate coolant flow. The coolant flow can be diverted from the Bypaßstrom and be introduced back into this, so that the cost of cooling is very low.

The actuators can be arranged in the housing so that the coolant flow in the axial direction of the turbomachine flows through the housing in the region of the actuators for their cooling, which is particularly advantageous when using the bypass flow.

The advantages of the invention include the fact that no scratching of the blades takes place even under dynamic loads more and that a low power consumption and a very good energy balance can be achieved, because in the switched state, the actuators are virtually de-energized. In addition, a back storage of auxiliary energy can take place. The inertial behavior of the ACC system is very low and the stability of the storage of the shroud is very high. A very accurate and fast control behavior at high forces as well as a high reliability in many switching cycles are further advantages to be highlighted. Further features of the invention will become apparent from the following description and the drawings, to which reference is made. In the drawings show:

1 shows a longitudinal sectional view through a turbomachine according to the invention in the form of a gas turbine,

FIG. 2 is a perspective view of an ACC system used in the invention;

FIG. 3 shows a front view of the ACC system according to FIG. 2,

FIG. 4 shows an enlarged front view of a section of the ACC system according to FIGS. 2 and 3,

FIG. 5 is a perspective view of the portion shown in FIG. 4;

FIG. 6 shows a slightly modified embodiment of the ACC system in radial section,

Figure 7 is an enlarged view of the outer edge of the ACC system of Figure 6, and

FIG. 8 shows an enlarged sectional view of a section of the ACC system along the line VIII - VIII in FIG. 7.

FIG. 1 shows a turbomachine with an inlet diffuser 10, a compressor 12, a combustion chamber 14, a turbine 16 and a thrust nozzle 18, all of which are located in a housing 20. By way of example only, some of the numerous blades 22 as part of the rotor and vanes 24 are shown as part of the stator in the compressor or turbine section. Between the blade tips 26 and the housing 20 results in a circumferential gap 28, which is shown exaggerated only for clarity in Figure 1. Another gap arises between the vanes and the hub 30th

In the area of each vane ring, an ACC system shown in FIGS. 2 and 3 is provided, which consists of several components and is integrated in the housing 20. The housing 20 itself has several sections, namely (see FIGS. 4 and 5) inner circumferential wall 32 and an outer circumferential wall 34 which are connected to each other via radial ribs 36. Numerous chambers 38 result between the ribs. The chambers 38 are separated radially inwards from a flexible strip 40 in each case. The chamber walls outside the peripheral wall may also be made separately from the peripheral wall 32. The strip 40 may abut or be connected to the ribs 36, but it must have some flexibility in the radial direction.

Radially on the inside, each strip 40 in particular integrally merges into a pressing or pulling element (web 42), wherein preferably each strip 40 is associated with a web 42. The very thin webs 42 extend through elongate, in particular slot-shaped, only axially sections extending openings 44 in the inner peripheral wall 32 and split into a Y-shape, that is to two webs, then in particular integrally with an inner shroud 46 connected. The shroud 46 preferably runs closed circumferentially. Immediately adjacent to the shroud 46, the blade tips 26 abut. The gap 28 between the blade tips and the shroud 46 is almost negligible.

Seated in each chamber 38, a piezoelectric actuator in the form of an actuator 48 is fitted, which should also abut the webs 40, at least in this embodiment. Preferably, the position of the actuators 48 is individually or in groups adjustable in the radial direction, e.g. by training individually or in groups radially adjustable and adjustable chamber walls or by within the chambers 38 radially adjustable actuators 48. It is important in the assembly of the turbomachine that the gap 28 is uniform in the ground state. Thus, over the position of the chambers 38 and / or the actuators 48, the shroud 46 is preferably positioned uniformly close to the blade ring. This calibration must be very accurate.

As can be seen in Figures 4 and 5, there is a kind of solid state kinematics with solid joints through the ribs 36, strips 40 and webs 44, wherein all parts would not merge integrally with each other, but could for example also be connected to each other via joints. As can be seen in Figures 2 and 3, there is a kind of ring with circumferentially numerous adjacent chambers 38 and associated actuators 48th

The piezoelectric actuators 48 are, in particular, packages of individual, thin piezoelectric elements, whereby of course a single piezoelectric element can also be used. If necessary, higher adjustment paths can be realized via piezo element packages.

Each actuator 48 can be controlled individually. By changing the thickness of the actuator 48, the strips 40 are pressed or pulled radially more or less radially inward or outward, acting as pressing or tension elements webs 44 transmit the force as in a solid state kinematics on the shroud 46. Thus, the shroud 46 can expand or contract more or less or even deform to a non-circular, which rotates.

It can hereby, tailored to the particular condition, produce a minimum gap 28.

As can be seen in Figure 4, the peripheral wall 32 forms a kind of thermal barrier, which serves as a first shield of the actuators 48. As a second shield then act the strips 40, which are part of a frame, which is formed by the ribs 36 and the outer peripheral wall 34, to each actuator 48th

While in the embodiment according to FIGS. 2 to 5 the actuators extend radially, in the embodiment according to FIGS. 6 to 8 they expand axially. The web 42 does not have to be integrated into the strip 40 in one piece, but instead the strip 40 can be made e.g. be coupled via inclined intermediate strips 50 with end walls 52 to form a kind of frame for receiving the actuator 48.

Functionally identical parts are provided with the already introduced reference numerals.

The housing with the peripheral walls 32 and 34 has been omitted for simplicity in Figures 6 and 7, but it is carried out according to the embodiment of Figure 2, so that the webs 42 pass through corresponding openings in the peripheral wall 32 therethrough. For each actuator 48, so to speak, a separate chamber 38 is formed with a frame 54, so that numerous frames border each other circumferentially. When the actuator 48 is actuated and the piezoelectric element elongates in the axial direction, the end walls 42 are pressed farther away from each other, so that the intermediate strips 50 are less angled outwards or inwards, ie parallel to the actuator 58. Thus, the bar 40 is moved upward, so that the web 42 and thus the shroud 46 are pulled radially outward. Conversely, when shortening the piezoelectric element in the axial direction, the shroud 46 is pressed radially inward at this point. In this embodiment results from the Umlenkkinematik a translation of the axial extent in the finally radially acting movement of the bar.

It should be emphasized for all embodiments that by section-wise pressing or pulling the shroud 46 this makes in intermediate sections and a circumferential movement. Hereby, the gap can be adapted very well and quickly to the requirements in operation.

In the embodiment according to FIGS. 2 to 5, preferably the end faces of the ACC system are closed as well as according to FIG. 6 or 7, ie the actuators 48 do not protrude out of the housing walls as shown in FIG. 5, but are accommodated in a kind of chamber, such as FIG shown in Figure 6 or 7.

A branched off from the bypass flow of coolant flow F can flow radially outside of the peripheral wall 32 through the individual chambers 38 in the axial direction and cool the actuators 40. This is also possible in the embodiment according to FIGS. 2 to 5. Incidentally, the coolant flow is also reintroduced into the bypass flow. A cooling air consumption from the gas stream, that is from the compressor area, is not provided.

The thermal separation of actuators and internal gas flow, it is possible to keep the actuators to temperatures below 400 ° C, especially below 250 ° C.

The illustrated ACC system can be used both in the compressor and in the turbine area.

Claims

claims

A turbomachine, in particular a gas turbine, with a stator and a rotor, wherein the rotor rotor blades (22) and the stator has a housing (20) and guide vanes (24), the rotor-side rotor blades (22) having radially outer tips (26). adjoin the housing (20) and define with this a gap (28), and wherein for minimizing the gap (28) between the tips (26) and the housing (20) a shroud (46) is provided which over several on Circumferentially distributed piezoelectric actuators (48) is moved radially, characterized in that the housing (20) has a to the shroud (46) adjacent peripheral wall (32) and the actuators (48) radially on the relative to the blade tip (26) opposite side the peripheral wall (32) are arranged.

2. Turbomachine according to claim 1, characterized in that the shroud (46) is circumferentially closed.

3. Turbomachine according to claim 1 or 2, characterized in that the peripheral wall (32) has openings (44) through which pressing or tension elements extend, the actuators (48) with the shroud (46) couple.

4. Turbomachine according to claim 3, characterized in that the openings (44) slots, in particular closed slots on all sides, are.

5. Turbomachine according to claim 3 or 4, characterized in that the pressure or tension elements webs (42).

6. Turbomachine according to one of claims 3 to 5, characterized in that the pressure or tension elements are integrally connected to the shroud (46).

7. Turbomachine according to one of the preceding claims, characterized in that extending the pressing or pulling elements radially to a bar (40) which lies on the inside of the associated actuator (48).

8. Turbomachine according to claim 7, characterized in that the strip (40) is part of a frame (54) in which an actuator (48) is accommodated.

9. turbomachine according to claim 7 or 8, characterized in that for each actuator (48) at least one own bar (40) and at least one own pressing element is provided.

10. Turbomachine according to one of claims 7 to 9, characterized in that the strips are fastened to the housing (20).

11. Turbomachine according to one of the preceding claims, characterized in that the housing (20) has radially outside the peripheral wall (32) chambers (38) for accommodating the actuators (48).

12. Turbomachine according to one of the preceding claims, characterized in that a separated from the gas stream coolant flow (F) is guided to the actuators.

13. Turbomachine according to claim 12, characterized in that the actuators (48) are arranged in the housing (20), that the coolant flow (F) in the axial direction of the turbomachine, the housing (20) in the region of the actuator (48) to its Cooling flows through.