DE102022133376A1 - METHOD FOR MEASURING A COMPONENT - Google Patents

Abstract

The present invention relates to a method for measuring a component of a turbomachine for material changes, in which the component is excited with a vibration exciter, and in order to determine eigenvalues of the component, a respective vibration deflection of the component is measured at several points on the component with a vibration sensor.

Description

Technical area

The present invention relates to a method for measuring a component of a turbomachine.

State of the art

The turbomachine can in particular be an aircraft engine, during the operation of which, in exceptional cases, e.g. due to damage or special flight situations, temperatures specified as permissible for the individual components can be exceeded. As a result of such over-temperature events, it may be necessary to inspect at least some of the components, e.g. blades or rotor blades of the engine turbine. For such an inspection, the engine is removed from the aircraft and completely dismantled in order to be able to examine the individual blades for structural changes in a metallographic examination, for example. The over-temperature events mentioned are intended to illustrate an advantageous area of application, but do not initially limit the subject in its generality.

Description of the invention

The present invention is based on the technical problem of specifying an advantageous method for measuring a component of a turbomachine.

This is achieved according to the invention with the method according to claim 1. The component is excited with a vibration exciter and a respective vibration deflection is measured at several points on the component. As explained in detail below, measurements can be taken sequentially at the individual points or simultaneously with several vibration sensors; the vibration behavior is recorded with a spatial resolution. This allows a more detailed evaluation in that the vibration form can also be identified as an alternative or in addition to the resonance frequency. If a change in the material, in particular the material structure, occurs, for example as a result of an over-temperature event described above, this can only occur locally (and still be highly relevant for component safety). Such local changes can have a negligible influence on the resonance frequency spectrum, but the geometric shape of the vibration form can change.

This can be recorded with the spatially resolved measurement of the vibration deflection, so that the change in the eigenform or modes can be used to draw conclusions about even locally limited changes. For example, "good" and "bad" components or blades can be distinguished relatively quickly from one another with regard to further operation. Due to its basic conception, the method can also be used advantageously on the blades of an aircraft engine that has not been dismantled/dismantled, which can result in time and cost savings.

Preferred embodiments can be found in the dependent claims and the entire disclosure, although the presentation of the features does not always distinguish in detail between the different claim categories.

As mentioned above, the method can be implemented in a space-saving manner, for example the vibration exciter and/or the vibration sensor(s) can be fed via an endoscope or borescope. Irrespective of this, a further advantage can be the non-destructive implementation. If the component is found to be intact after the measurement, it can then be operated without reworking or repair, for example. Although over-temperature events and the resulting changes in the material structure represent a particularly advantageous area of application, the method can also be used beyond this. Abrasive events can also occur in the gas duct of an aircraft engine, for example due to sucked-in dust or sand or soot, etc., as a result of which a protective coating on the surface of the component can degrade and be removed. This can also change the mechanical vibration behavior of the component and can therefore be detected.

In a preferred embodiment, the vibration deflection is measured simultaneously at the various points on the component, i.e. the respective vibration deflection is measured at a respective point using a respective vibration sensor. This can be advantageous, for example, in terms of the measurement time, i.e. increasing the throughput and thus reducing downtime.

In an alternative preferred embodiment, measurements are taken sequentially, i.e. the same vibration sensor is placed one after the other at the different locations and a vibration profile is created with the vibration exciter. Preferably, in each of the sequential measurements with the vibration exciter, a profile with respect to force and frequency is created. identical excitation pattern is introduced. In general, the excitation can preferably be carried out with a frequency sweep, so different frequencies can be set over time. Since fewer measuring components are used in the sequential measurement, the structural integration and thus application in confined spaces can be simplified.

The two approaches can also be combined; for example, a sensor unit with several vibration sensors can be provided, whereby this sensor unit is then placed sequentially at different locations on the component (and is measured simultaneously with the individual vibration sensors).

In a preferred embodiment, the vibration excitation is carried out using a piezo element, which is brought into contact with the component and is itself set into vibration. This can, for example, achieve good and reproducible coupling into the component, for example in comparison to an acoustic excitation that would otherwise also be conceivable in general.

According to a preferred embodiment, the vibration sensor is a piezo sensor that is brought into contact with the component for the measurement. This can be done sequentially at several points, as described above; alternatively, at least one of the vibration sensors that measure simultaneously, or preferably all of them, can be provided as a piezo sensor and brought into contact with the component at the respective point.

According to an alternative preferred embodiment, the vibration sensor is an optical vibration meter, for example a laser vibrometer or TOF distance measuring device. In the case of simultaneous measurement, several optical vibration meters can be operated in parallel.

According to a preferred embodiment, the component that is measured is a blade of the turbomachine, i.e. a guide or rotor blade. An application in the turbine area can be particularly preferred, i.e. it can be a turbine blade, e.g. of the high, medium or low pressure turbine. Irrespective of these details, as explained at the beginning, there _is an advantage in that the component, in particular the blade, can be measured in the installed state, i.e. the measurement can be carried out on the turbomachine (in which the component is installed).

Preferably, the turbomachine is an aircraft engine. This can generally be dismantled from the aircraft for the measurement, but then cannot be dismantled any further. Particularly preferably, the measurement can even be carried out on the aircraft engine mounted on the aircraft.

The invention also relates to a method for determining a material change in the component, whereby the component is measured using a measuring method as described above and then eigenforms, i.e. eigenmodes, are determined from the vibration deflections determined at the different locations. This can be carried out in particular using a computer, for example in the course of a subsequent evaluation with an external computer unit or with a computer integrated into the borescope unit (e.g. microcontroller). To determine any material change, the eigenmodes determined can be compared, for example, with a reference measurement that can actually be from the same component (e.g. created upon delivery) or an identical reference component.

Particularly preferably, the component is checked with the method for a change in the material structure, for example the precipitation of a γ or γ phase. As explained at the beginning, such a change in the material structure can occur as a result of an over-temperature event.

The invention also relates to a borescope unit which, in addition to the borescope system which defines one or more accesses/feed channels, also has a vibration exciter and sensor. These can be delivered via the same access/feed channel, alternatively the borescope system can each define its own access. If the borescope unit is designed for simultaneous measurement (see above), it can be equipped with several vibration sensors. In general, reference is made to the above disclosure for further details (e.g. piezo exciter/sensor, etc.).

Short description of the drawings

In the following, the invention is explained in more detail using an embodiment, whereby the individual features can also be essential to the invention in other combinations within the scope of the independent claims.

• 1 ein zu vermessendes Flugtriebwerk in einem schematischen Axialschnitt;
• 2A, B die Vermessung einer Schaufel in schematischer Darstellung

In detail,

• 1 an aircraft engine to be measured in a schematic axial section;
• 2A , B the measurement of a blade in schematic representation

Preferred embodiment of the invention

1 shows a turbomachine 1, specifically a turbofan engine, in an axial section. The turbomachine 1 is functionally divided into compressor 1a, combustion chamber 1b and turbine 1c. Both the compressor 1a and the turbine 1c are each made up of several stages. Each of the stages consists of a stator 5 and a rotor 6. In the compressor gas channel, the sucked-in

Air is compressed and then burned in the downstream combustion chamber 1b with kerosene mixed in. The hot gas flows through the hot gas channel and drives the rotors 6, which rotate about the axis of rotation 2.

Schematically shown is a borescope unit 10, which on the one hand comprises a borescope system 11 and furthermore the 2A , B. The borescope system 11 can be introduced into the gas channel 7 in order to bring the vibration exciters/sensors into contact with a blade of the stator 5 or rotor 6.

2A shows a component 20 located in the gas channel 7 in a schematic representation, which is a blade 21 with a blade 21.1 and a blade root 21.2. Using the borescope system (not shown here), a vibration exciter 25 is brought into contact with the blade 21.1, which in this case is provided as a piezo element 26. Furthermore, a vibration sensor 35, which in this example is provided in the form of a piezo sensor 36, is brought into contact with the blade 21.1. Vibration excitation is introduced using the vibration exciter 25, and the resulting vibration deflection 37 is measured using the vibration sensor 35.

The latter takes place one after the other at different points 40.1-40.3 of the component 20 or blade 21.1. After an initial measurement at the first point 40.1, the vibration sensor 35 is moved to the second point 40.2 and an excitation pattern identical in terms of frequency and force is introduced using the vibration exciter 25. As a result, a respective vibration deflection is then present at a large number of points 40.1-40.3, and the eigenmodes of the vibration deflection can be determined on the basis of this. As explained in the introduction to the description, these can react sensitively to even local deviations in the material properties, so that local changes in the material structure can be inferred from the measurement.

2 B illustrates a comparable structure with regard to the vibration exciter 25, but in this case a respective vibration sensor 35.1-35.3 is arranged at each point 40.1-40.3. Accordingly, the respective vibration deflections 37.1-37.3 are measured simultaneously.

LIST OF REFERENCE SYMBOLS

1

Turbomachine

1a

compressor

1b

Combustion chamber

1c

turbine

2

Rotation axis

5

stator

6

rotor

7

Gas channel

10

Borescope unit

11

Borescope system

20

Component

21

shovel

21.1

Shovel blade

21.2

Shovel foot

25

Vibration exciter

26

Piezo element

35

Vibration sensor

35.1-35.3

several vibration sensors

37

Vibration deflection

37.1-37.3

respective vibration deflection

40.1-40.3

Place

Claims (13)

Method for measuring a component (20) of a turbomachine (1), in which - the component (20) is excited with a vibration exciter (25), and - to determine eigenmodes of the component (20) at several points (40.1-40.3) of the component (20) a respective vibration deflection (37.1-37.3) of the component (20) is measured with a vibration sensor (35). Procedure according to Claim 1 , in which measurements are taken simultaneously with several vibration sensors (35.1-35.3), i.e. the respective vibration deflection (37.1-37.3) is measured at several points (40.1-40.3) of the component (20) with a respective vibration sensor (35.1-35.3). Procedure according to Claim 1 , in which measurements are taken sequentially at several locations (40.1-40.3) of the component (20) using the same vibration sensor (35). Method according to one of the preceding claims, in which the vibration exciter (25) is a piezo element (26) which is brought into contact with the component (20) and caused to vibrate for the vibration excitation. Method according to one of the preceding claims, in which the vibration sensor (35) or at least one of the vibration sensors (35.1-35.3) is a piezo sensor (36) which is brought into contact with the component (20) for the measurement. Method according to one of the Claims 1 until 4 , in which the vibration sensor (35) or at least one of the vibration sensors (35.1-35.3) is an optical vibration meter. Method according to one of the preceding claims, in which the component (20) is a blade (21) of the turbomachine (1). Method according to one of the preceding claims, in which the component (20) is measured in the installed state, i.e. the measurement is carried out on the turbomachine (1). Method according to one of the preceding claims, in which the turbomachine (1) is an aircraft engine. Procedure according to the Claims 8 and 9 , in which the measurement is carried out on the aircraft engine in a state mounted on the aircraft. Method for determining a material change of a component (20), in which - the component (20) is measured in a method according to one of the preceding claims, and - eigenmodes are determined from the respective vibration deflection (37.1-37.3) measured at the multiple locations (40.1-40.3). Procedure according to Claim 11 , in which the material change is a material structure change, in particular the precipitation of a phase Borescope unit (10) for a method according to one of the Claims 1 until 10 , with a borescope system (11), a vibration exciter (25) and a vibration sensor (35), wherein the vibration exciter (25) and the vibration sensor (35) can be delivered via the same or different accesses of the borescope system (11).

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