GB2596307A

GB2596307A - Rub depth measuring tool

Info

Publication number: GB2596307A
Application number: GB2009573.3A
Authority: GB
Inventors: Feuillard Bernard; Prou Florent; Przybyl Robert
Original assignee: Ansaldo Energia Switzerland AG
Current assignee: Ansaldo Energia Switzerland AG
Priority date: 2020-06-23
Filing date: 2020-06-23
Publication date: 2021-12-29
Also published as: GB202009573D0

Abstract

The rub depth measuring tool 1 comprises a base 2, sliding beams 4 are connected to the sides of the base, supports 15, 16 are respectively connected to the base 2 and to the beams 4 and an instrument tool 7 is disposed in sliding manner on the base 2 and/or the beams 4. The measuring tool is used for measuring the depth of rubbing marks of static components of gas turbine engines, such as heat shields, caused by rotating blades.

Description

RUB DEPTH MEASURING TOOL

The present invention relates to a rub depth measuring tool. In particular, the tool is adapted to be used for measuring the depth of rubbing marks of static components of gas turbines, such as heat shields, caused by rotating components of gas turbines, such as blades.

The required amount of clearances among rotating and static components (typically between blades and stator) is an important parameter for gas turbine design, as it is a compromise between integrity risk and gas turbine efficiency. Indeed, the smaller the clearances, the higher the efficiency, but if the clearances are too small then the blades will rub into the casing, due to the thermo-mechanical behavior of the gas turbine during the different operating cycles. If the rubbing amount is too high, there is the risk of blade loss, gas turbine damage and forced outage.

Due to the complexity of the thermo-mechanical 20 behavior of the gas turbine during operation, clearances are typically not optimized based on simulations only, but also based on field experience.

For a given gas turbine model, it is possible to assess an optimized cold build clearance (CBC) based on the 25 initial cold build clearance and the amount of rub measured in the fleet after operation. The simplified optimization rule is: optimized CBC = initial CBC -rubbing depth + maximum acceptable rubbing depth.

An aspect of the invention includes providing a rub depth measuring tool, which enables the measurement of the 5 rubbing depth of the rubbing marks caused by the rotating blades in the static components during operation.

These and further aspects are attained by providing a rub depth measuring tool in accordance with the accompanying claims.

Further characteristics and advantages will be more apparent from the description of a preferred but nonexclusive embodiment of the tool, illustrated by way of non-limiting example in the accompanying drawings, in which: Figure 1 shows an example of the tool; Figure 2 shows a different view of the tool of figure 1, with an axial plate in a different operating position. With reference to the figures, these show a rub depth measuring tool 1. The tool 1 has a base 2 defined e.g. by 20 an U-shaped element with an axial plate 3 provided at one end of the U-shaped element; sliding beams 4 are provided at the sides of the base 2 and are connected to it by screws or wing nuts 5 screwed in threaded holes of the base 2. The beams 4 can slide and be repositioned in order to 25 adjust the length of the tool 1. A looking plate 6 is provided at the ends of the beams 4 and connects them forming a U-shaped structure.

The base 2 and the beams 4 carry a measurement instrument 7. The measurement instrument 7 has a body 9 with T-shaped feet 10; the protrusions of the T-shaped feet 5 are slidingly inserted in undercuts 11 of the base 2 and undercuts 12 of the beams 4. The body 9 can move along the base 2 and beams 4 thanks to the sliding connection of the T-shaped feet in the undercuts 11 and 12 and with the body 9 supported either by the undercuts 11 of the base 2 or by 10 the undercuts 12 of the beams 4 or by both the undercuts 11 and 12 together with the T-shaped feet 10.

The measurement instrument 7 also has a gouge 13 that protrudes from the body base 2 and beams 4 in order to carry out measurements; in the embodiment shown, the gauge 13 is housed between the legs of the U-shaped base 2 and beams 4.

The tool 1 further has two supports 15 fixed to the base 2 and two supports 16 fixed to the beams 4; these supports 15 and 16 allow an accurate positioning of the tool 1 on the static component, outside of the rubbed area. Advantageously, four supports 15 and 16 allow measurements independent from the curvature of the component.

The operation of the tool 1 is apparent from what described and illustrated and is substantially the 25 following.

The rubbed static component is removed from the gas turbine; then the length of the tool 1 is adjusted in accordance with the size of the static component and rubbing marks, whose depth has to be measured, by loosening the wing nuts 5, sliding the beams 4 with respect to the base 2 and then retightening the wing nuts 5.

Thus, the tool 1 is positioned on the component, with the supports 15 and 16 resting on non-rubbed parts thereof and the base 2 and beams 4 crossing the rubbed part of the component.

Then, the measurement instrument 7 can be used in order to precisely measure the depth of the rubbed area; e.g. the measurement instrument 7 can be moved over the rubbed area of the component by sliding the feet 10 along the undercuts 11 and 12. During measurement a reference point may be taken at the middle of the two supports 15 of the base 2 or at the middle of the two supports 16 of the beams.

In addition, the axial plate 3 may serve as an axial reference, if required, e.g. in case of curved or anyway not planar components, when measurements at different circumferential positions using different axial reference would result in different values. This axial plate 3 is fixed to the base 2 by a screw, which can be loosen for the axial plate 3 to be rotated by 180 degrees. The axial plate will thus offer an axial surface extending to a level lower than the supports 15; this surface can come in contact with of border of the component to enable a repeatable axial position.

Advantageously, the tool is economical, accurate, easily transportable, usable by one person only and 5 adaptable to a wide range of row widths.

Naturally the features described may be independently provided from one another.

In practice the materials used and the dimensions can be chosen at will according to requirements and to the 10 state of the art.

Claims

CLAIMS1. A rub depth measuring tool comprising a base, beams connected to the base, supports connected to the base and to the beams and an instrument tool slidindly supported by the base and/or the beams.
2. The tool of claim 1, wherein the measurement instrument has a body with T-shaped feet; protrusions of the T-shaped feet being slidingly inserted in undercuts of the base and undercuts of the beams 4.
3. The tool of any the previous claims, further comprising two supports fixed to the base and two supports fixed to the beams.
4. The tool of any the previous claims, further comprising an axial plate connected to the base, wherein the axial plate is fixed to the base by a screw, which can be loosen for the axial plate to be rotated by 180 degrees.