JPS62150133A - Apparatus for testing rotation of blade - Google Patents

Abstract

PURPOSE:To facilitate a vibration test and to contrive to reduce the cost of said test, by a method wherein a magnet is arranged to the stationary structure in the vicinity of a blade and an attraction piece comprising a magnetic body is provided to the blade so as to leave a proper interval from said magnet and impulse like exciting force is applied to the blade during rotation by the attraction force between the magnet and the attraction piece. CONSTITUTION:A rotor consisting of a blade 1 to be tested, a wheel disc 2 and an axle 3 is received in a wheel disc chamber 28 held under vacuum and a magnet device 30 is fixed to the side wall of the wheel disc chamber 28 at the position corresponding to the attraction plate comprising a magnetic body arranged to the blade 1. Because a magnetic circuit is formed between the magnet 32 of the magnet device 30 and the attraction plate 31 of the blade 1 so as to provide a proper interval between both of them, cyclical impulse force is acted on one blade by magnetic attraction force when the blade 1 rotates to vibrate the blade 1. Then, by taking out the output of the strain gauge adhered to the blade 1 by a slip ring 27 while the number of rotations are changed, vibration is measured. By this method, the vibration of the blade at an arbitrary speed becomes possible and cost reduction can be contrived.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a rotation testing device for blades, and particularly to a rotation testing device for blades suitable for rotational vibration testing of turbine blades and the like.

[Background of the invention]

A blade wheel of a gas turbine or the like generally has a structure as shown in FIG. That is, several dozen blades 1 are embedded in a chassis 2 attached to a shaft 1 at equal pitches over the entire circumference of the chassis 2. A shroud (see Figure 2, 4p) is attached to the tip of each blade in the outer diameter direction to suppress blade vibration, but during operation, the shroud deforms and comes into contact with each other.
The shroud 4ai is formed as if it were an integral annular shroud.

Avoiding resonance with the natural frequency of the blade 1 due to excitation of the working fluid to the blade and preventing damage to the blade 1 is the most important consideration in the design and operation of these devices. x
A Campbell diagram as shown in FIG. 7 is used to study the avoidance of resonance of l.

Figure 7 shows that when the natural frequency of the blade is determined by changing the rotational speed of the horizontal axis and expressed as a horizontally extending curve, the higher-order excitation force ( This shows that the intersection of the straight line of higher-order harmonics (which are integral multiples of the rotational speed) and the curve of the natural frequency described above is the resonance point. In the example of FIG. 7, when the rated speed is assumed to be 500 Or pm, the broken line is between the harmonics of the harmonic order and the ninth order, and there is no resonance.

Normally, impellers such as gas turbines are designed to avoid resonance at the rated speed by calculating the natural frequency of the blades.
A rotation test is conducted for confirmation, the vibration of the blade is measured, and a measured Campbell diagram as shown in FIG. 7 is created. At this time, the vibration amplitude and vibration stress at the resonance point are often expressed by the size of a circle as shown in FIG.

In particular, the blade wheel of a gas turbine is an annular blade with the entire blade integrated with a shroud like Maehara, so the total
Because the conditions are complex and the prediction accuracy of calculations decreases, there are many opportunities for rotation tests for confirmation.

In order to obtain a Campbell diagram as shown in Figure 7 through a rotation test, it is necessary to fully excite the entire blade while rotating, in other words, excite it. As shown in Japanese Patent No. 58-214820, a method has been used in which a fluid such as air is sprayed as a jet at high pressure. However, in this method, the speed of the driven rotor blade is changed by natural deceleration caused by the frictional resistance of the air blown by the excitation VC, so it is not possible to vibrate at an arbitrary constant speed, and the driven rotor blade including the drive motor cannot be vibrated at an arbitrary constant speed. Since the entire structure is housed in a vacuum chamber, there are drawbacks such as difficulty in operation in a high-temperature atmosphere close to the actual gas temperature of the driven rotor blades.

In addition, there is, for example, Japanese Unexamined Patent Publication No. 48-60977 as a device for exciting the rotating lI& with a magnet. Although the structure is such that a vibrating tool is inserted, there is a drawback that it cannot be applied to an annular wing in which the entire wing is connected by a shroud or the like.

, [Object of the Invention] An object of the present invention is to provide a blade rotation testing device that is low cost and allows easy vibration testing.

[Summary of the invention]

The feature of the present invention is that a magnet is installed on a stationary structure near the wing,
On the other hand, a magnetic attracting piece is installed on the blade to form a magnetic circuit with an appropriate gap between the stone and the stone, and the attractive force between the magnet and the attracting piece applies an impulse-like force to the rotating blade. The reason is that it can give vibrational force.

[Embodiments of the invention]

The details of the present invention will be explained in detail below with reference to Examples.

In FIG. 1, a rotor consisting of a test blade 1, a chassis 2, and a shaft 3 is supported at both ends of the shaft 3 by bearings 21 and 22. This rotor is driven by a single drive motor 24 via a coupling 25, a speed increasing gear device 23, and a coupling 26. The impeller portion of the rotor is housed in the wheel panel chamber 28 to prevent wind damage due to rotation, and the inside of the wheel disk chamber 28 is kept in a vacuum.

The slip ring 27 is for taking out the output of a strain gauge (not shown) attached to the blade 1 to the outside and measuring the vibration of Ji1!1.

The magnet assembly [30 is a fixed stationary structure, in this case the side wall of the vehicle panel chamber 28, and is fixed thereto. The details of the magnet device 30 are shown in FIGS. 2 and 3.
The permanent magnet 32 placed on the magnet holder 33 is attached to the spacer 3
4 with bolts 35 and 36. The magnet holding stand 33 is connected to a fixed stand 41 by bolts 37 and 38, and the fixed stand 41 is fixed to the wall of the vehicle panel chamber 28 by bolts 42 and 43.

The magnetic attracting piece is bonded to the permanent magnet 31 on the radially inner side of the shroud 4p of all the blades 1 with an adhesive so as to have a gap g. The gap g between the permanent magnet 32 and the attraction piece 31 can be adjusted using bolts 37 and 38. That is, with nuts 39 and 40 loosened, bolt 37
and 38fjr: The nuts 39 and 40 are tightened into the screw holes of the fixed base 41, and when a predetermined gap g is reached, the nuts 39 and 40 are tightened and fixed to the magnet holding base 33 and the fixed base 41.

Next, the functions of the blade rotation testing apparatus of the present invention will be explained. Are the permanent magnet 32 and the attraction piece 31 at the positions shown in FIG. 2 or 3? If there is an i\ relationship, a magnetic circuit is formed by these, so an attraction piece 31 is placed between the gap 2 and the magnet 3.
A magnetic attraction force is generated that tries to attract the two sides. wing 1
When the blade rotates, this attractive force creates a magnetic force F (
t) acts.

Where, fo is the static attraction force of the permanent magnet 32, to is the magnet passage time of the attraction piece 31, T is the rotation period of the rotor, b is the circumferential length of the permanent magnet 320, and D is the attachment of the attraction piece 31. It is the position diameter. As is clear from the second term on the right side of equation (1), when the rotor rotates, the higher harmonic component power 2
It will be excited by foto/T.

As long as the rotor is rotating, the blade 1 is vibrated, so a strain gauge (not shown) is attached to the blade 1 while changing the rotation speed.
When the vibration is measured by extracting the output from the slip ring 27, a measured Campbell diagram as shown in FIG. 7 can be obtained.

FIG. 4 shows another embodiment. The suction piece 31 is adhered to the outer side surface of the lip 5 of the reduced shroud 4p. The same effect can be obtained by adhering the adsorption piece 31 to the outside of the other lip 6 and placing the electromagnet 32 facing it. However, this embodiment is effective only when the rotation speed of the rotor is low and there is no problem with adhesion of the suction pieces 31 due to centrifugal force.

In this embodiment, the degree of vacuum in the vehicle panel chamber 28 is increased to 1 (10
Since it was possible to perform a rotational excitation test of % (torr) and gl, the power loss due to air was reduced, and the power required for rotation could be reduced by at least several minutes compared to the conventional technology. did it.

Moreover, once the magnet device 30 was installed, it was easy to carry out the test, especially since there was no need to touch the magnet device.

FIG. 5 shows the tendency of temperature rise in the vehicle panel chamber in this embodiment. As mentioned above, even though it was in a high vacuum state, the temperature in the wheel panel chamber 28 rose due to the slight frictional resistance of the residual air, reaching several hundred degrees Celsius at the maximum rotation speed. For this reason, a heat-resistant permanent magnet is used as the magnet. As described above, according to the blade rotation testing device of the present invention, rotation testing at high temperatures is possible by appropriately selecting the heat resistance of the magnet. Furthermore, if the temperature of the rotating field is low due to cooling of the vehicle panel chamber 28, the magnet device 30 can be constructed using another magnet, for example, a DC' electromagnet. In this case, a current will be passed through the electromagnetic coil, so the structure of the magnet device 30 will be somewhat complicated, but by increasing the current, the excitation force to the magnet 1 can be selected to be large.

〔Effect of the invention〕

According to the present invention, it is possible to vibrate the blade at any speed at high temperatures, and furthermore, it is possible to reduce the driving horsepower of the blade, thereby reducing costs.

[Brief explanation of drawings]

Fig. 1 is an elevational view of one embodiment of the present invention, Fig. 2 is a plan view showing details of the magnet device, Fig. 3 is an elevational view showing details of the magnet device, and Fig. 4 is another embodiment. FIG. 5 is an explanatory diagram of the temperature rise in the vehicle panel chamber, FIG. 6 is an explanatory diagram showing the configuration of the blade wheel, and FIG. 7 is a diagram showing the vibration characteristics of the blade. 1... Wing, 2... Vehicle board, 3... Shaft, 4p... Shroud, 21.22... Bearing, 23... Speed increaser,
24... Drive motor 1.27... Slip ring, 2
8... Car chassis complete, 30... Magnet device, 31... Adsorption piece, 32... Permanent magnet, 33... Magnet holding stand, 37
．． 38...Bolt, 40...Fixing base.
'Representative Patent Attorney Katsuo Ogawa −' Figure 4 Figure 50 Lagoon Figure 7 Exit Significant Number [P/IYL]

Claims (1)

[Scope of Claims] 1. A rotor having a shaft with test blades embedded in the vehicle chassis, bearings that support this rotor at both ends of the shaft, and a rotor that is connected to one end of the shaft via a shaft coupling. A magnet is installed on a stationary structure near the test blade, and a magnetic material is attached to the rotor blade with an appropriate gap to form a magnetic circuit. A wing rotation testing device characterized by being equipped with a piece. 2. A vehicle board chamber is provided to rotatably house a vehicle board including the test blade of the rotor, the vehicle board chamber is evacuated, and the wall of the vehicle board chamber is used as the stationary structure in which magnets are installed. The blade rotation testing device according to claim 1, wherein the blade rotation testing device is used. 3. The blade rotation testing device according to claim 1 or 2, characterized in that a permanent magnet is used as the magnet. 4. The blade rotation test according to claim 1, 2, or 3, wherein the adsorption piece of the magnetic material is attached to the shroud portion of the test blade with an adhesive. Device.