Method for positioning a radial clearance existing between rotary blade tips of a rotor blade and a channel wall and device for measuring a radial clearance of a turbo machine with axial flow

The invention relates to a method for adjusting existing between blade tips of the rotor blades and a channel wall radial gaps of axial throughflow turbomachine, wherein the adjustment of the radial gaps in response to at least one measured gap of the existing radial gaps occurs. Further, the invention relates to a device for measuring at least one radial gap of an axially through-flow turbomachine comprising a turbine engine having arranged on the rotor blades, whose blade tips of the annular flow path of the turbomachine radially outer limiting duct wall radial gap forming lie opposite each other, wherein at least one sensor for detecting at least one of the radial gaps is provided.

Such a method and such an apparatus are known for example from <patcit id="pcit0001" dnum="US4804905A"><text>US 4,804,905</text></patcit> known. For this purpose, in a flow path limiting casing of the turbine, a capacitive sensor is arranged which can detect the operation of the gas turbine for running past each blade the distance to the blade tip. If a is detected at a larger radial gap, the conical housing with the aid of hydraulic actuators is displaced axially to its reduction. A disadvantage, however, that each sensor, only one measuring point on the circumference of the housing can be detected, so that at least four sensors for each stage are required. Even with the use of four sensors only provide a rough indication of the gap distribution on the circumference can then be made. So z. B. the gap between the measuring points are only interpolated or estimated. Another disadvantage of the above solution is that the design for the reliable mounting of the sensors is relatively complicated and expensive, since the detection of radial gaps occurs during operation of the gas turbine and a cooling of the sensors is required, so that they can withstand the temperatures during which occur permanently ,

The object of the invention is therefore to provide a method and to provide a device by means of which extremely small means a radial gap measurement is made possible on the entire periphery of the housing, so that a comparatively small radial gap between blade tips of rotor blades and these opposing channel wall for achieving a improved efficiency of the turbo-machine can be obtained. Another object of the invention is to provide an efficient method for adjusting the radial gaps during the assembly of the turbomachine.

The object relating to the method is achieved by the rotor of the turbine engine outside the establishment with a speed below the rated speed z. B. is driven by an external rotary device and takes place during the measurement. The process is extremely advantageous for measurement and adjustment of the required column in the assembly of the turbomachinery, in which a gap measurement is required when completely assembled and no access from outside or any device for continuous radial gap adjustment is available.

According to the prior art, the radial gap setting such turbomachinery occurs during each assembly, for example by means of thin-layer sheets - as side dishes known - the relative position of the channel wall and blade tip is set prior to commissioning of the turbo engine. The process now allows the turbo engine to fit in as precise predetermined radial columns that would have been otherwise actually greater because of the manufacturing tolerances. Preferably, the method for measuring the radial gap is also used in a turbo machine, which is designed as a turbine, a gas turbine or a compressor.

Under the operation of the turbomachine is understood to mean that this is meanwhile used as intended. If the measurement of the radial gaps is performed outside the operation of the gas turbine or turbo engine, this means in detail that when the turbomachine is designed for example as a turbine or gas turbine, no hot working fluid flows through the flow path. For a compressor, this means that the temperatures occurring during operation are far below. In general, the required gap measurement is carried out at room temperature, so that the sensors used no particular resistance with respect to temperature (temperature up to 80 ° C) are required to have.

For example, amount to the rated speeds of planned power generation gas turbines 3000 min^-1 (at 50 Hz mains frequency) or 3600 rpm^-1 (at 60 Hz). According to the inventive method it is provided that the rotor rotational speed (rotor rotational speed) is much less than the rated speed of the turbomachine. Preferably, the speed can be selected via a so-called shovel-rattling speed, so that the blades reach their operating position when measuring. This can be avoided functional disorder parameter in measuring the column (such. As the clatter of at low speed rather loose-fitting blades) so that actual function column can be determined. The speed can be 120 min^-1 or less. A higher speed than 120 min-1, but not excluded.

This allows the use of particularly low-cost sensors with a comparatively low temporal resolution.

The object relating to the device object is achieved with such a, which is designed according to the features of claim. 5 The invention is characterized in that - based on the occurring during operation of the turbine engine in the range of the sensor operating temperature - which is at least one sensor temperature unstable. In other words, the operating temperature of the turbomachinery is higher than the maximum permissible operating temperature of the sensor.

The invention is based on the insight that a temperature stability of the sensor is not necessary, since the radial gaps of the turbomachine is not online, that are continually measured and adjusted during operation of the turbine engine, but each once, during installation of the turbo engine, for example in new buildings or after revision. For single adjustment of the radial gaps during assembly the channel walls or the housing of the flow path of the turbomachine and the tips of the blades of the rotor blades can be arranged in different positions each other, the positioning is carried out for example by means of inserts of different thicknesses or according to adjustable guide systems. Since the radial gaps of the turbomachine must be reset only during initial installation or after each performed servicing of the turbo engine, it is sufficient that the sensors used for this purpose have only one resistance for room temperature, but not a resistance to the operating turbomachinery at the measuring point temperatures occurring.

A particular advantage of the invention is that such sensors are now also available in copy forms, to dismantle the material at a temperature limit is exceeded in mainly staubteilchengroße particles. Thus may remain within the turbomachinery by measuring the radial gaps the sensors used and must not be removed by an installer. This saves installation costs and reduces the production or downtimes of the turbomachine. The decomposition in staubteilchengroße particles then occurs, for example, during the initial commissioning of the turbine engine, since the forces which then occur and temperatures above the operating conditions and temperatures of the sensor are far in this case, and this thereby destroy destructive. The particles are then carried to the medium of the turbomachine.

A further essential advantage is that the sensors do not need to be embedded in the components such as blades. Rather, the sensors can be mounted and fixed regardless of size on the surface of the blade, since during their use the turbo engine is operated to be improper.

The proposed method and device are proposed in particular for those blade rings of advantage in which not a given access to the assembler due to the axial structure of the turbomachine, or is very difficult. Consequently, at least one blade, each blade row of the turbine engine to be equipped with a sensor, which for each blade ring the gap size of the radial gaps of the entire circumference (360 °) can be determined can. It must not be reduced to a few measuring points.

Another advantage of the invention is that the sensors do not need to be wear-resistant. In principle, it is sufficient if the sensor is able to determine the gap size for a low number of revolutions only and the desired gap adjustment ensures that.

Preferably, the sensor on a blade is disposed. This allows the respective radial gap for the total current are detected, whereby a more accurate indication of the rotor position within the housing is possible. In other words, for each angular position of the sensor (on the periphery), a gap size of the radial gap can be detected. Preferably, the sensor is designed as an RFID sensor, whereby a wireless radio transmission of the sensed radial gaps of the gas turbine or the radial gaps representing measured values ​​to a stationary evaluation unit is possible.

Of course, the idea of ​​the invention can also be used outside the territory of the turbomachine, such as an electric generator, whose radial gap between stator and rotor, if possible should also be small. Regardless is also conceivable to use that method or the apparatus for Axialspaltbestimmung.

Overall, the invention provides an apparatus for recording and a method for setting between blade tips of the rotor blades and a channel wall existing radial gaps of a turbo engine in the assembly of the turbine engine, wherein the radial gaps are detected prior to commissioning of the turbine engine and the radial gap forming components so are arranged mutually determined that a predetermined allowable radial gap is set during assembly. An online radial gap-minimization in the spirit of continuous during operation of the turbine engine setting is not provided.

The invention is illustrated by the following figures. Show it:<dl id="dl0001"><dt>FIG 1, FIG 2</dt><dd>a longitudinal and cross section of the flow path of a compressor and</dd><dt>FIG 3, FIG 4</dt><dd>the longitudinal and cross-section of the flow path of a turbine.</dd></dl>

<figref idrefs="f0001">1 shows</figref> shows the longitudinal section through a section of a compressor 10. The compressor 10 is one of the axial throughflow Turbomachinery and instructs a rotor not shown radiating pattern on to a wreath arranged blades 12th The rotor blades 12 are detached formed with a blade tip 14, which is opposite to a channel wall 16 radially gap forming. The channel wall 16 is concentric to the machine axis 18 and delimited radially outwardly a flow path 20 of the compressor 10, in which the medium to be compressed is conveyed through the compressor 10th The channel wall 16 is substantially formed thereby convergent. On the blade of the blade 12, a sensor 22 is provided tip side. The sensor 22 here comprises a transmission and reception unit 24 which is arranged for example on a slide 26th Further, an electrically conductive conductor track 28 is formed on the film 26 is applied, which is electrically connected to the transmitting / receiving unit 24th The sensor 22 protrudes beyond the tip 14 of the blade 12 and rests against the channel wall 16th As in the cross-section according to<figref idrefs="f0001">FIG 2</figref> illustrated, the sensor 22 and in particular its electrical conductor 28 is bent in the tangential direction, whereby the bending of the conductor 28 depends on the distance between the blade tip 14 and the channel wall sixteenth The degree of bending of the electrical conductor 28 leads to a change in its electrical properties. This electrical property or one of the dependent value is detected from the transmitting and receiving unit 24th Their size is then used as a measure of the radial gap R. The detected by the sensor 22 bend of the electrical conductor 28 is thus converted into an electric variable, which is not shown, the sensor 22 with the aid of the transmitting / receiving unit 24 to a stationary arranged evaluation -and- receiving unit transmits. The power supply of the sensor 22 can also take place via the transmitting / receiving unit 24, as is common for RFID sensors. Using the thus-detected gap size, the relative position of the channel wall to blade tip using the enclosures mentioned or adjusting system are then adjusted to provide a desired gap distribution over the entire circumference (360 °) can be adjusted.

An alternative embodiment of the invention is in <figref idrefs="f0002">Figures 3 and 4</figref> shown, wherein <figref idrefs="f0002">FIG 3</figref> the longitudinal section through a formed as a turbine 30 turbomachine shows and <figref idrefs="f0002">FIG 4</figref> the corresponding cross section to. Corresponding components of the compressor 10 and the turbine 30 are provided with identical reference numerals today. According to the in<figref idrefs="f0001">Figures 1 and 2</figref> -described first embodiment, the sensor 22 according to the second embodiment, shown in <figref idrefs="f0002">Figures 3 and 4</figref>, A vapor-deposited on a plastic film conductor track 28. According to the second embodiment, however, the plastic film is also formed as a loop 38, wherein the electrical resistance of it, the vapor-deposited conductor track 28 due to its compression / bending changes. The change in resistance is again a measure of the distance R between the blade tip 14 and its opposite channel wall 16 that stores the 22 gaps or the gaps representing electrical voltage values ​​using a built in sensor 22 antenna 24 on a not shown, external, statically arranged receiving, processing and displaying means be emitted.

The energy supply of the sensor 22 can be generated via a built-in micro-battery or by the deformation of the sensor 22 itself. Also is possible in this embodiment, the use of RFID technology known feed possibility of electrical energy.

The antenna 24 of the sensor 22 is either adhered to the suction side or on the pressure side of the blades 12 in order to ensure the best possible direct radiation of the antenna 24th

With both of the aforementioned embodiments, it is possible a continuous recording and reporting of the measurement results, ie, the gap size of the radial gap R representing physical quantity to the external evaluation and display device to transmit. Consequently, it is possible, during the assembly or final inspection of the turbomachine 10, 30 - that is, only in the cold condition and with very little effect of centrifugal force - the gap size of the radial gap R between the tips 14 of the blades 12 and the outer wall 16 of the flow path with the help of the proposed in situ sensors to detect the 22nd Since the turbomachine 10, 30 in any case has no device for continuous radial gap adjustment, the sensors used must 22 therefore can not withstand those temperatures, the appropriate locations where they are installed, usually occur during operation of the turbine engine at 10, 30th