JP2003214399A - Characteristic frequency variable mechanism for stationary blade of compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a characteristic frequency variable mechanism for a stationary blade of a compressor capable of preventing the resonance caused by the agreement of a rotating speed of a rotor and the characteristic frequency of a stationary blade without giving the influence on aerodynamic performance of the stationary blade itself, and remarkably shortening the resonance time. <P>SOLUTION: This characteristic frequency variable mechanism comprises the stationary blade 12 having a hollow hole 12a extended in the radial direction, an inner weight 13 closely fitted to the hollow hole and movable in the radial direction, and a weight moving device 16 for moving the inner weight in the radial direction. By radially moving the inner weight 14 by the weight moving device 16, the characteristic frequency of the stationary blade 12 is changed on the basis of a position of the weight. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a natural frequency varying mechanism for changing the natural frequency of an axial flow compressor vane.

[0002]

2. Description of the Related Art FIG. 4 shows a variable vane mechanism in an axial compressor such as a jet engine. As shown in this figure, in a jet engine for an aircraft, for example, not only the circumferential velocity of the rotor blade row but also the axial velocity of the inflow air fluctuate greatly depending on the flight condition. Therefore, in order to prevent flow separation due to an increase in the attack angle α and surging resulting from this, as shown in this figure, the variable inlet stator vane (Variable Inlet Guide Vane) is provided in the first stage.
e: VIGV) and variable stator vanes (Va
In some cases, the angle of attack α of the airflow with respect to the moving blade row is adjusted to an appropriate range by attaching a riable static vane (VSV).

That is, in the variable inlet vane and the variable vane,
Each vane 1 that constitutes the vane row and a ring 2 that surrounds the engine
Are connected by an arm 3 having a fixed length (variable mounting angle arm), and the ring 2 is moved in the circumferential direction to swing each stationary blade 1 via the arm 3. Incidentally, such a variable vane device is disclosed in US Pat. No. 5,308,226,
No. 5,593,275 is proposed.

[0004]

FIG. 5 is a diagram schematically showing a part of a blade row of an axial flow compressor. In this figure,
Reference numeral 1 is a stationary blade, and 4a and 4b are moving blades. In an actual compressor, one set of stationary blades and moving blades performs one-stage compression, and multiple sets of stationary blades and moving blades perform multiple-stage compression. The compressed air flows from the left to the right in the figure, the airflow that rotationally drives the moving blades 4a is deflected by the stationary blades 1, and the air flows into the moving blades 4b on the downstream side at an angle of attack within an appropriate range. The side moving blade 4b is rotationally driven. Moving blade 4
The rotational force of a and 4b drives the turbine located on the downstream side or is taken out to the outside to rotationally drive the generator or the like.

The stationary vane 1 described above has an outer casing 5a.
It is cantilevered or is supported at both ends by both the outer casing 5a and the inner liner 5b. In this case, the stationary blade 1 receives a periodic fluid force determined by the number of blades and the number of rotations of the moving blade 4a on the upstream side, and the stationary blade of the compressor vibrates.

The natural frequency of the stationary blades 1 of the compressor is governed by the blade shape, material, support structure, etc. determined at the time of design and is determined at the design stage. Therefore, the natural frequency is changed during the operation of the compressor. I can't do that. On the other hand, the periodic fluid force (exciting force) acting on the stationary blade 1 changes depending on the operating condition, such as the number of moving blades in the front and rear, the rotation speed of the rotor, etc. It may coincide with the natural frequency of the stationary blade 1 during operation. In this case, it may take a long time to accelerate the rotor, especially during high-speed rotation (for example, 10 to 20 seconds)
During that time, the rotational speed of the rotor was in agreement with the natural frequency of the stationary blade 1 to cause resonance, which could violently vibrate and damage the equipment. Also, in order to avoid this resonance point,
If the natural frequency of the stationary blade is set to be sufficiently high, there is a problem that the aerodynamic performance of the stationary blade itself deteriorates.

The present invention was devised to solve such problems. That is, the object of the present invention is to avoid resonance due to the matching of the rotor rotational speed and the natural frequency of the stationary blade without affecting the aerodynamic performance of the stationary blade itself,
Another object is to provide a mechanism for varying the natural frequency of a compressor vane, which can significantly reduce the resonance time.

[0008]

According to the present invention, a vane (12) having a hollow hole (12a) extending in a radial direction,
A compressor vane comprising an inner weight (14) fitted in the hollow hole and movable in the radial direction, and a weight moving device (16) for moving the inner weight in the radial direction. A variable natural frequency mechanism is provided.

According to the above configuration of the present invention, the natural frequency of the vane (12) is changed according to the position of the weight by moving the internal weight (14) in the radial direction by the weight moving device (16). You can Therefore, when the rotation speed of the rotor during constant speed operation and the natural frequency of the stationary blade match, the natural frequency of the stationary blade (12) is changed by changing the position of the weight to change the natural frequency during constant speed operation. The resonance of can be avoided. In addition, even if the rotor rotation speed during constant-speed operation is higher than the natural frequency of the stationary blade and passing through the resonance point is unavoidable, the passing time at the resonance point can be shortened by changing the position of the weight when passing through the resonance point. can do.

According to a preferred embodiment of the present invention, the weight moving device (16) comprises an elongated threaded rod (16a) which is screwed into a penetrating internal thread of the inner weight (14), and the threaded rod having its axis line. Drive motor (16b) that drives to rotate in the center
Consists of.

With this configuration, the internal weight (14) is moved in the radial direction only by rotating the screw rod (16a) about its axis by the drive motor (16b), and the natural vibration of the stationary blade (12) is generated. You can change the number.

According to another preferred embodiment, the weight moving device (16) is composed of a linear cylinder (16c) that linearly moves the internal weight (14) in the radial direction.

With this structure, the direct acting cylinder (16c)
The inner weight (14) is moved linearly in the radial direction by the
The natural frequency of 2) can be easily changed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. In each drawing, common portions are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 is a first embodiment of a natural frequency varying mechanism of a compressor vane of the present invention. As shown in this figure, the natural frequency varying mechanism 10 of the present invention comprises a vane 12, an internal weight 14, and a weight moving device 16.

In this example, the stationary vanes 12 are supported at both ends by both the outer casing 5a and the inner liner 5b, but may be cantilevered by the outer casing 5a. The stationary blade 12 may be the variable stationary blade illustrated in FIG. 4 or a fixed stationary blade.

In the present invention, the vane 12 has a hollow hole 12a extending in the radial direction. This hollow hole 12a
Have the same cross-sectional shape in the radial direction. The hollow hole 12a preferably extends through the vane 12 from the end to the tip, but the hollow hole 12a is not limited to this and may extend partially. The internal weight (14) is closely fitted in the hollow hole 12a with a slight clearance and smoothly moves in the radial direction so that the internal weight moves integrally with the vane 12 and contributes to the addition of rigidity. It is inserted as possible.

In the first embodiment shown in FIG. 1, the weight moving device 16 includes an elongated screw rod 16a screwed into a female screw that penetrates the inner weight 14 in the radial direction, and the screw rod 16a.
And a drive motor 16b for driving the motor to rotate about its axis. The drive motor 16b is, for example, a hydraulic motor, an electric motor, or the like. Further, in this embodiment, a rotation preventing mechanism may be provided between the hollow hole 12a and the internal weight 14 so that the internal weight 14 does not rotate together with the screw rod 16a. As the rotation preventing mechanism, for example, the hollow hole 12a and the internal weight 14 may be formed into an ellipse or a polygon other than a perfect circle, or the unevenness extending in the radial direction may be provided.

With the above-mentioned structure, the drive motor 16b simply drives the screw rod 16a to rotate about its axis.
The natural weight of the stationary blade 12 can be changed by moving the inner weight 14 in the radial direction.

FIG. 2 is a second embodiment of the natural frequency varying mechanism of the compressor vane of the present invention. In this figure, the weight moving device 16 is composed of a linear cylinder 16c that linearly moves the internal weight 14 in the radial direction. In addition, in this embodiment, the above-described detent mechanism is not necessary, and the inner weight 14 moves integrally with the stationary vanes 12 and contributes to the addition of rigidity, so that the hollow holes 12a are closely packed with a slight gap. It suffices that they are fitted and inserted so that they can be smoothly moved in the radial direction. Other configurations are similar to those of the first embodiment.

With this structure, the internal weight 14 is formed by the direct acting cylinder 16c (eg, hydraulic cylinder, pneumatic cylinder).
The natural frequency of the stationary blade 12 can be easily changed only by directly moving in the radial direction.

FIG. 3 is an example of a Campbell diagram of an axial compressor. The operation of the present invention will be described based on this figure. In this figure, the horizontal axis represents the rotor speed (rpm), and the vertical axis represents the frequency (Hz). The four substantially horizontal curves in the figure are primary bending, primary twisting, secondary bending, and secondary bending in order from the bottom. This is the natural frequency of the next twist. As shown in this figure, each natural frequency is less affected by the rotor speed, is governed by the blade shape, material, support structure, etc., and is determined at the design stage. Further, in this figure, the periodic fluid force (exciting force) acting on the stationary blade increases almost in proportion to the rotor speed as shown by the straight line rising to the right in the figure.

Further, the two substantially horizontal curves in the figure are the natural frequencies of the primary bending and the primary torsion which are changed by the natural frequency varying mechanism of the present invention. As shown in this figure, according to the configuration of the present invention described above, by moving the inner weight 14 in the radial direction by the weight moving device 16,
The natural frequency of the stationary blade 12 can be changed depending on the position of the weight.

Thus, in this example, the axial flow compressor is approximately 1380
When the rotor rotation speed during constant speed operation and the natural frequency of the stationary blade (in this case, primary bending) match as in the case of operating at 0 rpm (230 Hz), the position of the weight is changed and the stationary blade is rotated. Resonance during constant speed operation can be avoided by changing the natural frequency of No. 12 as shown by the broken line.

Further, even when the rotational speed of the rotor during constant speed operation (for example, about 20000 rpm) is higher than the natural frequency of the stationary blade and passage of the resonance point is unavoidable, when passing through the resonance point (about 13800 rpm and about 17,000 rpm). ), By changing the position of the weight from the broken line to the solid line in a short time by the device of the present invention, the passage time of the resonance point can be shortened even when the changing speed of the rotation speed of the rotor is slow (accelerating ability is insufficient). You can

The present invention is not limited to the above-described embodiments and examples, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0027]

As described above, according to the present invention, by moving the weight in the passage provided inside the blade, the natural frequency of the blade is changed, and it is easy to avoid the resonance point which was difficult to avoid when the frequency is not changed. To do. In the present invention, the outer shape of the stationary blade 12 is the same as the conventional one and does not affect the aerodynamic performance, so that the avoidance method with a high degree of freedom is possible. Further, when used together with the conventional change of the blade shape, the influence on the aerodynamic performance is reduced as compared with the case where it is not used together.

That is, the mechanism for varying the natural frequency of the compressor vane of the present invention avoids resonance due to the matching of the rotor rotation speed and the natural frequency of the vane without affecting the aerodynamic performance of the vane itself. Or has an excellent effect that the resonance time can be significantly shortened.

[Brief description of drawings]

FIG. 1 is a first embodiment diagram of a natural frequency varying mechanism of a compressor vane of the present invention.

FIG. 2 is a second embodiment diagram of a natural frequency varying mechanism of a compressor vane of the present invention.

FIG. 3 is an example of a Campbell diagram of an axial compressor.

FIG. 4 is a schematic perspective view of a conventional variable vane device for an axial compressor.

FIG. 5 is a relationship diagram between a stationary blade and a moving blade of a conventional axial flow compressor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 stationary blade, 2 rings, 3 arms, 4a, 4b moving blades, 5a casing, 5b linearr, 10 natural frequency variable mechanism, 12 stationary blades, 12a hollow hole, 14 internal weight, 16 weight moving device, 16a screw rod, 1
6b drive motor, 16c direct acting cylinder

Claims (3)

[Claims] 1. A vane (12) having a hollow hole (12a) extending in the radial direction, an inner weight (14) fitted in the hollow hole and movable in the radial direction, and the inner weight in the radial direction. And a weight moving device (16) for moving to
A mechanism for varying the natural frequency of a compressor vane, which is characterized in that 2. The weight moving device (16) comprises an elongated threaded rod (1) that is screwed into a penetrating internal thread of the internal weight (14).
The natural frequency varying mechanism of the compressor vane according to claim 1, characterized in that it comprises 6a) and a drive motor (16b) for rotationally driving the screw rod about its axis. 3. The weight moving device (16) comprises a linear cylinder (16) for linearly moving the internal weight (14) in a radial direction.
The natural frequency varying mechanism of the compressor vane according to claim 1, characterized in that the variable frequency mechanism comprises c).