JP2000321189A - Wing fatigue test method and wing fatigue testing device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a wing fatigue test method and a wing fatigue tester that can reliably apply vibration to the fatigue limit level to the tip of the wing with apparently increased rigidity. SOLUTION: A fatigue test device 1 for a blade B provided with a mid-span shroud S includes a root holding portion 2 and a blade holding portion 3 for holding a root N and an intermediate portion of the blade B;
A shroud fixing portion 4 for fixing the mid-span shroud S to the blade holding portion 3 and a nozzle 5 for blowing compressed air A near the tip F of the blade B are provided. The compressed air A generates self-excited vibration (flutter) at the tip F, so that the blade B is reliably vibrated at the fatigue limit level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blade fatigue test method and a blade fatigue test apparatus for testing the blade fatigue limit by applying vibration to a blade having a mid-span shroud.

[0002]

2. Description of the Related Art Fan rotor blades (fan blades) provided in a turbofan engine or the like have a relatively long height and are large, so that vibrations are easily generated during operation. For this purpose, a mid-span shroud is provided in the middle of the wing (blade) to suppress vibration during operation. That is, the mid-span shroud is provided to increase the rigidity of the blade and to avoid resonance.
In a fatigue test of a blade having this midspan shroud, a blade is fixed by a vibrator such as an electrodynamic actuator or a piezo actuator in a state where the root, the middle portion, and the midspan shroud portion are fixed by a jig. This has been done by vibrating the tip at the resonance frequency. That is, in the actual machine, the root of the blade and the mid-span shroud are fixed, and the vibration amplitude generated is the largest near the tip of the blade, so the root of the blade and the mid-span shroud are also fixed in the fatigue test. At the same time, by vibrating the tip portion, the blade is subjected to a fatigue test under conditions close to those provided in an actual machine.

[0003]

However, in this case, since the blade has the root portion, the intermediate portion, and the midspan shroud portion fixed, the apparent rigidity in the vicinity of the tip is high. Therefore, in the conventional vibrator, since the generated force is weak, the blade is not vibrated to the fatigue limit level, and a sufficient fatigue test cannot be performed.

[0004] The present invention has been made in view of such circumstances, and it is possible to reliably apply vibration to the tip of the wing, which has apparently increased rigidity, to the fatigue limit level. It is an object of the present invention to provide a wing fatigue test method and a wing fatigue test device capable of performing a fatigue test under conditions close to a sunk state.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a blade for testing the fatigue limit of a blade having a mid-span shroud by applying vibration to the blade. The fatigue test method, characterized in that the blade is vibrated by blowing compressed air near the tip of the blade. According to the present invention, self-excited vibration (flutter) is caused at the tip of the wing by the supplied compressed air.
Occurs. Therefore, the wing is vibrated to the fatigue limit level under conditions close to those provided in the actual machine. Since a sufficient fatigue test is performed on the wing in this manner, the safety of an actual machine having the wing is also improved.

According to a second aspect of the present invention, there is provided the blade fatigue test method according to the first aspect, wherein a vibration amplitude generated in the blade is controlled by adjusting an angle of attack of the blade with respect to the compressed air. It is characterized by doing. According to the present invention,
By adjusting the angle of attack of the blade with respect to the compressed air, the amplitude of vibration generated on the blade can be adjusted, and a fatigue test can be performed at a desired vibration level.

According to a third aspect of the present invention, there is provided a blade fatigue test apparatus for testing a fatigue limit of a blade having a mid-span shroud by applying vibration to the blade, the root of the blade being held. Root holding portion, a blade holding portion for holding an intermediate portion of the blade, a shroud fixing portion for fixing the midspan shroud to the blade holding portion, and compressed air supply means for blowing compressed air near the tip of the blade Wherein the root holding unit and the blade holding unit are provided with an angle-of-attack adjusting mechanism for adjusting the angle of attack of the blade with respect to the compressed air. According to the present invention, the root portion of the blade is held by the root holding portion, the intermediate portion and the mid-span shroud portion are held by the blade holding portion and the shroud fixing portion, and the tip portion of the blade is supplied from the compressed air supply means. Since the self-excited vibration (flutter) is generated by the compressed air, the blades are subjected to a fatigue test under conditions close to those provided in an actual machine. By providing the compressed air supply means in this manner, the blades are easily vibrated to the fatigue limit level and subjected to a sufficient fatigue test, so that the safety of an actual machine having the blades is also improved. In addition, since the root holding unit and the blade holding unit can adjust the angle of attack of the blade with respect to the compressed air, and by adjusting the angle of attack, the vibration amplitude generated on the blade is controlled. A fatigue test can be performed at a desired vibration level.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a blade fatigue test method and a blade fatigue test apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing an embodiment of a blade fatigue test apparatus according to the present invention. 2 is a plan view of FIG. 1 as viewed from above, and FIG. 3 is a front view of FIG. 1 as viewed from the tip of a wing (blade). FIG. 4 is a perspective view showing a state in which a blade is attached to the fatigue test apparatus.

[0009] In these figures, the fatigue test apparatus 1 comprises:
A root holding part 2 for holding a root N of a wing (blade) B, and a blade holding part 3 for holding an intermediate part of the blade B
A shroud fixing portion 4 for fixing the mid-span shroud S to the blade holding portion 3 and a nozzle (compressed air supply means) for blowing compressed air A near the tip F of the blade B
5 is provided. The root holding part 2 and the blade holding part 3 are supported by the base part 6, and these members are formed of carbon steel such as S45C.

The blade B to be tested is, for example, a fan blade (fan blade) used in a turbofan engine or the like, and has a mid-span shroud S at an intermediate portion. This midspan shroud S
Are provided to increase the rigidity of the blade B and to suppress vibration, and are integrally connected to the abdominal side and the back side of the blade B. At this time, the length of the entire blade B is about 20 cm, and the length from the portion where the midspan shroud S of the blade B is connected to the tip F is about 5 cm.

When the blade B is provided on an actual machine,
The root N of the blade B and the disk are fixed in a state where the midspan shroud S is arranged in an annular shape on the outer periphery of the disk while being adjacent thereto. That is, the mid-span shrouds S of the adjacent blades B are fixed so as to support each other, and the blade B and the disk are connected to the root N formed in a dovetail (dove tail) shape of the blade B and the disk. A dovetail-shaped groove cut equally in the axial direction on the outer circumference is fitted, and the blade B is locked by a blade lock or a blade retainer.
Is fixed while restricting the movement in the axial direction.

The root holding portion 2 is for holding a dovetail-shaped root N portion of the blade B, and is a portion corresponding to a disk in an actual machine. The root holding section 2 includes a block section 7 and a spacer section 8, and the base section 6 and the block section 7 are fixed by bolts. The spacer section 8 has a groove 9 formed in a dovetail shape, and the root N of the blade B and the groove 9 are fitted. At this time, the spacer 8
By adjusting the mounting angle of the blade B, the mounting angle of the blade B fitted into the groove 9 can be adjusted.

The blade holding portion 3 has two support block portions 10 formed in the same shape and arranged so as to face each other, and a ring formed in a square shape in plan view and having a circular cutout portion in the center portion. It has a plate portion 11 and a disk portion 12 fitted into a circular cutout portion of the ring plate portion 11. The support block 10 is fixed to the base 6 with its flat end face facing the tip F of the blade B. The ring plate portion 11 is supported while being in contact with the end face of the support block portion 10. The disk portion 12 formed along the circular cutout portion of the ring plate portion 11 is supported by the ring plate portion 11. Can be attached to and detached from the cut-out part of.

The cutout portion of the ring plate portion 11 is formed in an L-shaped cross section as shown in FIG.
2 is provided with an engaging portion 11a for bringing the outer peripheral portion into contact. In addition, at the four corners of the ring plate 11, a disk clamp 1 that can be attached and detached with bolts.
3 are provided. The disk clamp portion 13 is provided so that the base end side is fixed to the ring plate portion 11 and the distal end side is projected to a cutout portion of the ring plate portion 11. That is, the disk portion 12 arranged in the cutout portion of the ring plate portion 11 has one surface abutting on the engagement portion 11a and the other surface abutting on the tip of the disk clamp portion 13. I have. The disk portion 12 is fixed to the ring plate portion 11 by tightening a bolt for fixing the disk clamp portion 13. On the other hand, the disk portion 12 is removed from the ring plate portion 11 by loosening the bolt and removing the disk clamp portion 13. It is designed to be removed.

The disk portion 12 has a blade insertion hole 14 at the center. As shown in FIG. 3, the blade insertion hole 14 is a through hole formed along the cross-sectional shape of the blade B having the mid-span shroud S, and allows the blade B to be inserted. And root holding part 2
The blade holding portion 3 is fixed to the base 6 so that the blade insertion hole 14 and the groove 9 are located at substantially the same height position, so that the blade B can be held. In addition, disk part 1
2 is provided with a shroud fixing part 4. The shroud fixing portion 4 is constituted by a clamp provided so as to sandwich the midspan shroud S, and is formed on the ventral side and the back side of the blade B, respectively.
Two mid-span shrouds S are provided at two locations. The mid-span shroud S is fixed to the disk portion 12 by arranging the mid-span shroud S at an intermediate portion of each clamp and tightening bolts provided on both sides.

The nozzle 5 is for blowing the compressed air A to the vicinity of the front end F of the mid-span shroud S of the blade B held by the root holding part 2 and the blade holding part 3, and a compressed air supply part (not shown) The supplied air is blown to the vicinity of the front end F at a strength of about 4 kg / cm ² . The tip F of the blade B is vibrated by the compressed air A supplied from the nozzle 5. At this time, the vibration generated in the blade B is self-excited vibration (flutter), and the vibration at the fatigue limit level of the blade B is generated.

The angle of attack of the blade B with respect to the compressed air A supplied from the nozzle 5 can be adjusted by adjusting the mounting angle between the spacer portion 8 of the root holding portion 2 and the disk portion 12 of the blade holding portion 3. It has become. That is, the angle at which the root holding portion 2 holds the root N portion of the blade B and the angle at which the blade holding portion 3 holds the intermediate portion of the blade B can be matched.
By adjusting the angle of attack of the blade B with respect to the compressed air A, the amplitude of the vibration generated at the tip F of the blade B is controlled.

A method for performing a fatigue test of the blade B by the above-described fatigue test apparatus 1 will be described. First, a case where the blade B to be tested is attached to the fatigue test apparatus 1 will be described. First, the disk clamp 13 is removed from the ring plate 11 and the disk 12 is removed from the ring plate 11. Then, the blade B is inserted from the front side (tip F side) toward the root holding part 2 into the cutout hole of the ring plate part 11 that appears when the disk part 12 is removed, and the root N is formed in the spacer part 8. Into the groove 9. Since the groove 9 is formed along the shape of the root N, the root N of the blade B and the groove 9 are stably fitted.

Next, the blade B is inserted into the blade insertion hole 14 of the disk portion 12 from the front end F side. Then, the disk portion 12 with the blade B inserted therein is fixed to the ring plate 11 by the disk clamp portion 13, and the midspan shroud S is fixed to the disk portion 12 by the shroud fixing portion 4. At this time, since the groove 9 and the blade insertion hole 14 are provided at substantially the same height, the blade B is held substantially horizontally. Then, the mounting angle of the disk portion 12 and the mounting angle of the spacer portion 8 are both adjusted, and the blade B is fixed at a desired mounting angle.

After the blade B is held by the root holding unit 2 and the blade holding unit 3, the nozzle 5 is brought close to the vicinity of the tip F of the blade B, and the compressed air A is supplied toward the vicinity of the tip F of the blade B. Then, vibration (flutter) occurs at the tip F of the blade B. Then, the fatigue test is performed at a desired vibration amplitude while monitoring the vibration state using a vibration sensor such as a laser Doppler meter.

At this time, if the vibration amplitude generated at the blade B is not at a desired level, the angle of attack of the blade B with respect to the compressed air A is adjusted to control the vibration amplitude generated at the blade B. That is, the spacer portion 8
The angle of attack of the blade B is adjusted by adjusting the mounting angle of the disk portion 12. This spacer portion 8
The adjustment of the mounting angle of the disk unit 12 is performed manually. For example, the spacer unit 8 and the disk unit 12 are supported by a support unit connected to a hydraulic actuator, and the mounting angle is adjusted by driving the hydraulic actuator. Can be performed automatically.

The amplitude of the vibration caused by the flutter is
Although it is theoretically infinite, it is actually a finite value due to the attenuation by the material constituting the blade B and the condition of holding by each holding portion. Therefore, the blade B for the compressed air A
By adjusting the angle of attack of the blade B, the amplitude of the vibration generated in the blade B can be adjusted.

When the fatigue test of the blade B is completed at the desired vibration amplitude level, the fixing of the shroud fixing portion 4 is released, the holding of the disk clamp portion 13 is released, and the blade B is removed from the fatigue test device 1.

As described above, since the fatigue test for the blade B provided with the mid-span shroud S is performed under the condition close to the state provided in the actual machine, it is necessary to fix the root N portion and the mid-span shroud S portion. There is
In this case, the apparent rigidity near the tip F, which is the vibrating portion, becomes high, and the conventional vibrator could not vibrate to the fatigue limit level. However, by applying high-speed compressed air A to the tip F of the blade B to cause flutter, vibration at the fatigue limit level can be easily generated. Therefore, the fatigue test of the blade B with the mid-span shroud S, which has been difficult in the past, can be easily and reliably performed. Therefore, since the blade is subjected to a sufficient fatigue test in advance, the safety of an actual machine equipped with the blade is also improved.

In the flutter vibration using the compressed air A, the vibration amplitude of the flutter becomes theoretically infinite,
Actually, the value becomes a finite value due to the damping due to the material of the blade B and the fixing condition of each holding portion. Therefore, by adjusting the angle of attack of the blade B with respect to the compressed air A, the vibration amplitude generated in the blade B can be controlled. . Therefore, a fatigue test at a desired vibration amplitude level is easily performed.

[0026]

The wing fatigue test method and wing fatigue test apparatus of the present invention have the following effects. (1) According to the first aspect of the present invention, self-excited vibration (flutter) is generated at the tip of the blade by the supplied compressed air. Therefore, the wing is vibrated to the fatigue limit level under conditions close to those provided in the actual machine. Since a sufficient fatigue test is performed on the wing in this manner, the safety of an actual machine having the wing is also improved. (2) According to the second aspect of the present invention, by adjusting the angle of attack of the blade with respect to the compressed air, it is possible to adjust the vibration amplitude generated in the blade, and to perform a fatigue test at a desired vibration level. Can be. (3) According to the third aspect of the present invention, the root portion of the blade is held by the root holding portion, the intermediate portion and the mid-span shroud portion are held by the blade holding portion and the shroud fixing portion, and the tip portion of the blade. Self-excited vibration (flutter) by compressed air from compressed air supply means
Therefore, the wing is subjected to a fatigue test under conditions close to those provided in an actual machine. By providing the compressed air supply means in this manner, the blades are easily vibrated to the fatigue limit level and subjected to a sufficient fatigue test, so that the safety of an actual machine having the blades is also improved. In addition, since the root holding unit and the blade holding unit can adjust the angle of attack of the blade with respect to the compressed air, and by adjusting the angle of attack, the vibration amplitude generated on the blade is controlled. A fatigue test can be performed at a desired vibration level.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment of a blade fatigue test apparatus according to the present invention.

FIG. 2 is a plan view seen from above in FIG. 1;

FIG. 3 is a front view as viewed from the tip end side of FIG.

FIG. 4 is a perspective view showing a state in which the wing is attached to the wing fatigue test apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fatigue test apparatus 2 Root holding part 3 Blade holding part 4 Shroud fixing part 5 Nozzle (compressed air supply means) 6 Base 7 Block part 8 Spacer part 9 Groove 10 Support block part 11 Ring plate part 12 Disk part 13 Disk clamp part 14 Blade insertion hole A Compressed air B Blade (wing) F (Blade) tip N (Blade) root S Mid span shroud

Claims (3)

[Claims] 1. A blade fatigue test method for testing the fatigue limit of a blade having a mid-span shroud by applying vibration to the blade, the method comprising applying compressed air to a vicinity of a tip of the blade. A wing fatigue test method characterized by vibrating a wing. 2. The blade fatigue test method according to claim 1, wherein a vibration amplitude generated in the blade is controlled by adjusting an angle of attack of the blade with respect to the compressed air. Fatigue test method. 3. A blade fatigue test apparatus for testing a fatigue limit of a blade provided with a mid-span shroud by applying vibration to the blade, the root holding unit holding a root of the blade, A blade holding portion for holding an intermediate portion of the blade, a shroud fixing portion for fixing the midspan shroud to the blade holding portion, and a compressed air supply means for blowing compressed air near a tip of the blade, the root holding A blade fatigue testing device, wherein the unit and the blade holding unit are provided with an attack angle adjusting mechanism for adjusting an angle of attack of the blade with respect to the compressed air.