RU2461717C1 - Vibration damping device of wide-chord moving blades of fans with high conicity of sleeve, and gas turbine engine fan - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: vibration damping device of wide-chord moving blades of fan with high sleeve conicity is located between impeller and booster of add stages of fan. Device includes ring-shaped metal plate attached on the outside to disc of fan and/or to booster and bent shaped elements. Elements protrude respectively to each moving blade above ring-shaped plate along its outer diameter. Each of the elements includes elastic part and friction part unbent from elastic part and bent in direction of inner diameter of ring-shaped metal plate. Elements are made so that friction part can be pressed to mating end surface of blade root with centrifugal force of fan without performing any joint vibrations for creation of friction force damping the blade vibrations. Rigidity of element attachment to fan disc and/or to booster allows no joint vibrations of the device and blade root.

EFFECT: higher vibration damping reliability of wide-chord fan blades with high conicity of sleeve due to creation of friction force at movements of friction element of the device and external surface of blade root face.

11 cl, 10 dwg

Description

The invention relates to a damper for damping the vibrations of the working blades of aircraft gas turbine engines, and in particular to devices for damping the vibrations of wide-chord working fan blades with a large taper (high rise) of the sleeve.

When creating modern aviation gas turbine engines, the urgent task is to increase reliability by preventing fatigue damage to rotor blades. Their occurrence is largely determined by the level of vibrational stresses in the blades in the entire range of engine operating modes. The most important factor limiting the level of vibration is the damping ability of the blades, which depends on the dispersion of energy in the flowing gas stream (air damping) and in the material, the castle connection, and for steps with retaining or anti-vibration shelves, in the contact node of the shelves (structural damping). Fans of modern gas turbine engines are made with wide-chord titanium working blades without anti-vibration shelves, often have a hollow blade design of the blade and a significant taper of the sleeve. In such blades, structural damping is small, and aerodynamic damping sharply in off-design conditions. Under these conditions, to prevent dangerous resonant vibrations of the blades, it becomes important to introduce special damping devices that provide increased energy dissipation by dry friction between contacting surfaces with their relative displacement during oscillations (B.F. Shorr, G.V. Melnikova, N.N. Serebryakov “Development of technologies for damping the vibrations of the working blades of turbines of turboprop engines”, TO No. 13496, 2009).

In the practice of aviation gas turbine construction for damping turbine (rarely compressor) blades, built-in friction dampers in the form of inserts that are installed under the path shelves of adjacent blades and are pressed to them under the action of their own centrifugal forces have been used (US patent No. 5205713, April 27, 1993).

However, in wide-chordate blades (especially with hollow blades manufactured using special technologies), path shelves are absent, which makes it impossible to use this type of damping device.

To damp vibrations of working blades, it is known to use friction-type devices, the action of which is based on the dispersion of vibration energy due to the work of dry (coulomb) friction forces that occur when a sedentary element of a damping device contacts a body part of an oscillating blade located inside its legs or in the area of the lock joint . To ensure contact pressure, springs or other elastic elements are used (US Pat. No. 5,205,714, April 27, 1993).

Oscillation damping devices are also known that use the centrifugal inertia force of structural elements from impeller rotation through elastic elements to create contact pressure (US Pat. No. 6,283,707, 09.09.2001)

In these technical solutions, damping is carried out by creating special devices placed inside the pen or padlock of the blade, creating frictional forces between the device and the body inside the pen or padlock of the blade. However, in modern fans with hollow wide-chordate blades, it is impossible to use a damping device of this type due to the absence of the body of the feather blade.

When the inner surface of the blade is used as the oscillating element of the damper, the contact points have insignificant relative displacements in the plane of the lateral vibrations of the blade, due to which such devices do not provide reliable damping and, therefore, prevent fatigue damage.

The basis of the invention is the task of improving the reliability of damping and preventing fatigue damage of broad-chordate blades with a large taper of the sleeve, including their hollow execution, and increasing the reliability of the fan of a gas turbine engine.

The technical result is the creation of an oscillation damping device for wide-chord fan blades with a large taper of the sleeve, which is also applicable for hollow blades, which increases reliability by creating friction damping oscillations of the blades during relative movements of the friction element of the device and the outer surface of the end face of the blade legs.

The present invention is based on the fact that with the most excited forms of oscillation of the blade with a large taper of the sleeve, there are sufficiently large relative displacements in the circumferential direction between the end of the blade legs at the sleeve on the output edge side and the inactive parts of the rim of the disk of the fan impeller or booster directly connected with the impeller fan wheel.

The problem is solved in that the vibration damping device of the broad-chord fan blades with a large taper of the sleeve, located between the impeller and the booster of the retaining stages of the fan (damping device), contains a ring-shaped metal plate for external mounting to the fan disk and / or to the booster and curved profiled elements protruding respectively to each working blade above the annular plate along its outer diameter, each of which includes an elastic the part and the friction part, bent from the elastic and bent in the direction of the inner diameter of the annular metal plate, made with the possibility of pressing the friction part to the mating end surface of the blade legs by the centrifugal force of the fan without performing joint vibrations to create a friction force that dampens the vibrations of the blade.

The elastic and friction parts of the profiled elements can be made as a whole.

The elastic element can be bent from the annular metal plate at a small angle in the direction of the booster.

An annular metal plate, friction and elastic elements can be made as one unit.

The annular metal plate can be made in the form of an arched structure, for which it has a rise in the radial direction and a bend towards the booster at a small angle.

The annular metal plate is provided with holes for bolted connections for mounting to a fan disk and / or booster.

The damping device can be made with the possibility of a radial stroke relative to the feather of the blade, for which the profiled elements can be equipped with devices for radial movements, made, for example, in the form of skids.

The problem is also solved by the fact that the fan of a gas turbine engine with wide-chord blades with a large taper of the sleeve contains the specified vibration damping device, the rigidity of which is attached to the fan disk and / or to the booster is designed to prevent joint damping of the damping device and the blade legs.

A wear resistant coating may be applied to the contacting surfaces of the end face of the blade legs and / or friction elements of the vibration damping device.

The elastic part of the damping device can be made rectilinear, the free end of the friction part is located at a smaller radius r than the upper radius R of the blade legs, the end surface of the legs has a conical surface with a slight taper angle with respect to the plane of rotation, and the attachment plane is biased towards the booster.

The invention is further illustrated by the drawings, which show:

Figure 1 (a, b) - the position of the damping device according to the invention, relative to the blade and the booster of the fan impeller with a cut along the blade leg (1, a) and a cut along the profile insert (1, b);

Figure 2 - sector damping device (view from the side of the fan);

Figure 3 (a, b, c) - options for attaching the damping device to the fan parts: a) to the booster, b) to the profile insert, c) to the profile insert and booster at the same time;

Figure 4 is a damping device (embodiment) in the form of a shaped plate in which the friction part of the protrusion is integral with the elastic part;

5 is a damping device (embodiment), in which the elastic part is flat, the friction part has a limb towards the fan, and at the end of the blade legs there is a section of a conical surface;

6 is a sector of a damping device of an arched type (embodiment);

7 - the position of the friction surfaces on the end surface of the legs of the blades and the friction part of the damping device (sector shown);

Fig - position of the end surface of the legs of the blades relative to the sector of the damping device with the possibility of radial stroke;

Fig.9 - the position of the damping device relative to the pen blades, view in the Assembly;

Figure 10 - position of the damping device with fastening with the possibility of a radial stroke relative to the end of the blade, view in the assembly.

The invention is further illustrated by the example of a gas turbine engine fan containing wide-chord fan blades with a large taper of the sleeve.

The impeller 19 of the fan consists of impellers, a disk and interscapular inserts. 1, a and 1, b show the impeller 19 of the fan and the booster 7, which are interconnected by a pin 10. Also shown is one of the working blades 1, the interscapular insert 22 (figure 1, b) located between the legs of adjacent blades and a part of the rim of the disk 6. The working blade has a profile part 2, a leg 4 and a shank 5. The flow part is limited by the lower contour 3 on the impeller formed by the outer surface of the interscapular insert 22 and the booster 7. The booster 7 contains the blades of the retaining stages 8.

A device 11 for damping oscillations of wide-chord fan blades with a large taper of the sleeve located between the impeller and the booster of the retaining stages of the fan (damping device 11) according to the invention is located between the impeller of the fan 19 and the booster 7 and includes an annular metal plate 16 and shaped curved elements (protrusions) containing the elastic part 15 and the friction part 12.

The plate 16 is attached to the rim of the disk of the impeller of the fan 19 from the exit from the stage or to the part of the booster 7 adjacent to the impeller or simultaneously to both parts in the areas between adjacent working blades (Fig. 3 (a, b, c), respectively) bolted connections 17. The plate 16, as will be shown below, can have various structural forms of execution.

Profiled elements protrude above the plate 16 along its outer diameter, respectively, of each working blade 1 and their number is equal to the number of fan blades.

The elastic 15 and friction 12 parts can have various options for structural execution, as will be shown below.

The elastic portion 15 of the protrusion can be bent from the plane of the annular plate 16 towards the booster 7 or be straightforward.

The friction part 12 is bent to the opposite side with respect to the elastic part, has a flat or curved surface.

Figure 2 presents a view of the sector of the damping device 11 from the side of the fan. On the ring-shaped plate 16 there are holes 18 through which the damping device 11 is mounted to the fan.

Figure 3 presents the options for attaching the damping device 11: a) to the booster 7, b) to the interscapular insert 22, c) to the interscapular insert 22 and the booster 7 at the same time. The damping device is fixed to the indicated parts of the fan through the holes 18 by means of a bolted connection 17.

Figure 4 represents the damping device 11, in which the friction part of the protrusion 12 is integral with the elastic part 15.

Figure 5 represents the damping device 11, in which the friction part of the protrusion 12 is integral with the elastic part 15, while the elastic part 15 is straight.

In this case, the execution of the elastic part for pressing under the action of centrifugal forces, the attachment plane should be shifted towards the booster 7, and the free end of the friction part 12 is bent towards the blades 1 so that its free end is located at a smaller radius r than the upper radius R legs. The end surface 9 of the legs 4 should be modified so as to create a conical surface with a small angle of taper with respect to the plane of rotation.

Figure 6 shows such a structure in which the plate 16, which is an arched structure, performs the function of the elastic part of the protrusion, for which there is a rise in the radial direction and a limb from the fastening plane towards the booster 7 by a small angle. The bent portion of the plate, on which additional mass can be placed, creates a bending moment. The friction part 12 can be made integral with the annular part 16, or mechanically connected to it. The manufacture and assembly of the fan impeller 19 provides for the axial position of the blades 2 on the disk 6 within production tolerances. Uniform pressing of the friction part 12 to the end surface 9 of the blades 2 should be ensured by tightening tolerances or using special washers inserted into the bolt connection 17 of the annular part with the disk 6 and / or booster 7.

Figure 7 shows the implementation of the damping device 11 from individual sectors, the number of which is equal to the number of blades 1 of the impeller 19, with holes 18 for bolted connections for fastening to the fan disk and / or booster. Sectors have profiled elements, like a full-ring device.

7 also shows the position of the friction surfaces 13 and 14 on the end surface 9 of the legs of the blades 4 and the friction part 12 of the sector of the damping device 11, respectively.

When the blades vibrate between the friction surface 14 of the friction portion 12 of the protrusion and the adjacent friction surface 13 of the end surface 9 of the leg 4 of the working blade of the fan 1, a variable relative displacement occurs, forming a friction pair and dissipating energy during vibrations of the blade.

On Fig shows such a design of the damping device 11, in which the radial stroke of the device relative to the end surface 9 of the blade legs is ensured, which ensures that the device is pressed against the conical surface of the blade legs regardless of wear.

The radial stroke is provided either by the oval-shaped opening of the holes 18, or by using a special device in the form of runners 20 mounted on the plate 16, while the fixing of the device 11 occurs using the curved part 21 of the device 11, which provides a spring clip. This design of the damping device 11 involves the installation and adjustment relative to the end surface of the blade legs of each sector individually.

In Fig.9 shows a General view of the damping device and its mounting, respectively, the blade to the rear end surface of the interscapular protrusions of the fan disk 6, and Fig.10 shows a General view and mounting of the damping device 11 with the possibility of a radial stroke. In both figures, the image is given at the same scale with the scapula.

To increase the durability of the device in all cases of design performance, wear-resistant coatings can be applied to the friction surface 13 of the end surface 9 and the friction surface 14 of the friction part 12.

The rigidity of mounting the damping device to the fan disk and / or to the booster is designed to prevent joint vibrations of the damping device and the blade legs.

The operation of the damping device of the vibrations of the fan blades, according to the invention, occurs as follows:

During assembly, the damping device 11 is positioned relative to the end surfaces of the legs 9 of the blades 1 of the fan 19 with a small initial clearance. The initial clearance is selected for the specific design of the fan impeller based on the considerations of creating a contact force during operation that provides the necessary friction force. In this case, possible deviations of the end surfaces of the legs of individual blades from the nominal position are also taken into account.

When the impeller rotates under the action of centrifugal force, the end of the elastic part 15 of the device 11, together with the associated friction part 12, receives movement in the direction of the fan, selects the initial clearance and presses the friction part 12 against the end surface 9 of the blade legs 4. In this case, out of resonance modes of oscillation, no static contact occurs between the friction surface 14 of the friction part 12 and the friction surface 13 of the end surface 9. In the arch type design, the gap under the action of centrifugal forces is selected due to the elastic deformation of the plate 16.

Own centrifugal forces of the protrusion create a bending moment during rotation, which presses the friction part 12 against the end surface 9, located against the protrusion of the legs 4 of the blades 1 from the side of the output edge.

In the event of vibrations of the blade, variable displacements of the friction surface 13 of the end surface 9 of the blade legs 4 relative to the friction surface 14 of the friction part 12 of the damping device 11 occur. High rigidity of all parts of the device 11 in the circumferential direction does not allow the friction part 12 to oscillate with the end surface 9 of the legs the blades 4 during its oscillations, providing their relative movement. The force of dry friction arising upon contact does the work aimed at dissipating the vibration energy. The outer surface of the bent portion of the friction element 12 is adjacent to the mating end surface of the blade legs and pressed against it by the centrifugal force of the fan, creating a friction force that dampens the vibrations of the blades.

When the impeller stops the fan, the centrifugal force disappears, the gap is restored and the damping device 11 due to the elastic forces returns to its original position.

The device 11 can be used in fans of a gas turbine engine with wide-chord working blades with a large lift of the sleeve to protect the blades from damage due to multi-cycle fatigue.

The location of the damping device outside the working blade does not require changes in the design and manufacturing technology of the blade itself, simplifies the assembly and replacement of the entire device when necessary.

Claims (11)

1. A device for damping oscillations of wide-chord fan blades with a large taper of the sleeve, located between the impeller and the booster of the retaining stages of the fan and containing an annular metal plate attached externally to the fan disk and / or to the booster, and curved profiled elements that protrude respectively from each working blade above the annular plate by its outer diameter, each of which includes an elastic part and a friction part, bent from the elastic and bent into the board of the inner diameter of the annular metal plate, made with the possibility of pressing the friction part to the mating end surface of the blade legs by centrifugal fan force without performing joint vibrations to create a friction force that dampens the blade vibrations. 2. The vibration damping device according to claim 1, characterized in that the elastic and friction parts of the profiled elements are made integrally. 3. The vibration damping device according to claim 2, characterized in that the elastic element is bent from the annular metal plate by a small angle in the direction of the booster. 4. The vibration damping device according to claim 1, characterized in that the annular metal plate, friction and elastic elements are made as a whole. 5. The vibration damping device according to claim 4, characterized in that the annular metal plate is made in the form of an arched structure, for which it has a rise in the radial direction and a bend towards the booster at a small angle. 6. The vibration damping device according to claim 2, characterized in that the profiled elements are equipped with devices for radial movements, made, for example, in the form of skids. 7. A gas turbine engine fan containing wide-chord rotor blades with a large taper of the sleeve, characterized in that it contains the vibration damping device according to claim 1, the rigidity of which is attached to the fan disk and / or to the booster does not allow joint vibrations of the damping device and the blade legs. 8. The fan of a gas turbine engine according to claim 7, characterized in that the damping device according to claim 1 is configured to radially move relative to the blade blade. 9. The gas turbine engine fan according to claim 7, characterized in that the annular metal plate of the vibration damping device according to claim 1 is made in the form of separate sectors with bolt holes for fastening to the fan disk and / or booster, while the number of sectors is equal to the number working blades. 10. The gas turbine engine fan according to claim 7, characterized in that a wear-resistant coating is applied to the contacting surfaces of the end face of the blade legs and / or friction elements of the vibration damping device. 11. The gas turbine engine fan according to claim 7, characterized in that the elastic part of the damping device is rectilinear, the free end of the friction part is located at a smaller radius r than the upper radius R of the blade legs, while the end surface of the legs has a conical surface with a small taper angle in relation to the plane of rotation, and the plane of attachment is biased towards the booster.

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