CN115081348B - A traveling wave excitation system for periodically symmetrical bladed disk structure - Google Patents

Abstract

The invention relates to the field of aeroengine test, in particular to a traveling wave excitation test system of a periodically symmetric leaf disc structure, which comprises the following components: the device comprises a pneumatic excitation device, a traveling wave excitation generating device and a non-contact measuring device which are sequentially arranged from top to bottom; the traveling wave excitation device comprises a guide cylinder and an airflow generation device arranged at the air inlet end of the guide cylinder; the traveling wave excitation generating device is positioned at the air outlet end of the guide cylinder and comprises a power driving device fixedly arranged in the air outlet end of the guide cylinder and a slotted disc which can be driven to rotate by the power driving device, the rotation center of the slotted disc is positioned on the central axis of the guide cylinder, and the number of the through slots is equal to the number of pitch diameters of pneumatic excitation applied to the leaf disc; the non-contact measuring device comprises a blade measuring sensor and a blade disc bracket. The vibration characteristics of the blisk in each order of excitation can be simulated and measured.

Description

A traveling wave excitation system for periodically symmetrical bladed disk structure

Technical Field

The invention relates to the field of aero-engine testing, and in particular to a traveling wave excitation system of a periodically symmetrical blade disk structure.

Background Art

When the aero-engine blade is in operation, the excitation form it receives is very complex, and it is necessary to obtain the dynamic response characteristics of the blade under complex excitation, especially the amplitude amplification caused by blade processing errors and other reasons. The existing blade excitation system is usually a point contact/non-contact excitation method, which cannot simulate the actual working conditions of the engine. Therefore, a reliable full-field traveling wave excitation test system is needed to simulate the actual working conditions of the engine, apply traveling wave excitation with different pitch numbers to the blade, and study the dynamic characteristics of the blade under complex working conditions.

Summary of the invention

The present invention aims to provide a traveling wave excitation system for a periodically symmetrical blade disk structure. By designing a traveling wave excitation generating device to simulate the aerodynamic excitations of different orders to which the blade disk is subjected when rotating at high speed in a laboratory environment, the vibration characteristics of the blade disk under various orders of excitation can be simulated and measured.

To achieve the purpose of the present invention, the technical solution adopted by the present invention is:

A traveling wave excitation test system for a periodically symmetrical blade disk structure comprises: a pneumatic excitation device, a traveling wave excitation generating device and a non-contact measuring device arranged in sequence from top to bottom;

The traveling wave excitation device comprises a guide cylinder and an airflow generating device installed at the air inlet end of the guide cylinder;

The airflow generating device is used to provide the aerodynamic load required to excite the blades, the guide cylinder is used to transmit the airflow, and also includes a controller for adjusting the aerodynamic excitation amplitude;

The traveling wave excitation generating device is located at the outlet end of the guide cylinder, and includes a power drive device fixedly installed in the outlet end of the guide cylinder and a slotted disc that can be driven to rotate by the power drive device, and the rotation center of the slotted disc is located on the central axis of the guide cylinder; the slotted disc is arranged with a plurality of radially opened through slots, and the number of the through slots is equal to the number of pitch diameters of the pneumatic excitation applied to the blade disk; and also includes a special controller for adjusting the rotation speed of the power drive device;

The non-contact measurement device includes a blade measurement sensor connected to a dynamic signal collector for measuring the dynamic characteristics of the blade; and also includes a blade disc bracket for placing a blade disc structure. The center of the blade disc structure placed on the blade disc bracket can be located on the central axis of the guide cylinder and is non-contactly facing the air outlet end of the guide cylinder.

Furthermore, the pneumatic excitation device also includes a support structure, including an upper support plate, a lower support plate and an optical axis;

The upper support plate and the lower support plate are both in the shape of a rectangular frame, and multiple optical axes are vertically fixed between the upper support plate and the lower support plate;

It also includes a mounting platform fixed on the outer peripheral wall of the guide cylinder;

The optical axis is provided with a locking slider that can slide up and down along the optical axis, and the locking slider is provided with a locking mechanism, which can allow the locking slider to hold or loosen the optical axis under the configuration of the user;

Each locking slider is also fixedly connected to a connecting rod, which is horizontally arranged, one end of which is fixedly connected to the locking slider, and the other end of which is fixedly connected to a connecting block, and the fixing block is fixed on the mounting platform.

Furthermore, one or more of the connections between the locking slider and the connecting rod, between the connecting block and the connecting rod, and between the connecting block and the mounting platform are detachable connections.

Furthermore, a plurality of shock absorbers are provided below the lower mounting plate.

Furthermore, the blade measurement sensor is fixed on a sensor bracket, and the blade disc bracket and the sensor bracket do not contact each other.

Furthermore, the blade disc support is a solid cylindrical structure, and the top end of the blade disc support is used to place the blade disc according to the specific boundary conditions of the blade disc;

The sensor bracket is divided into a sensor mounting part and a supporting part;

The support part is a hollow cylindrical structure, which is entirely sleeved outside the blade disc support, and the inner diameter of the support part is larger than the outer diameter of the blade disc support;

The sensor mounting portion is arranged at the opening of the support portion toward the blade disk, and includes a plurality of mounting positions matching the outer dimensions of the sensor for mounting various sensors.

Furthermore, each mounting position is arranged symmetrically around the central axis of the sensor bracket.

Furthermore, the sensor bracket and the blade disc bracket are installed on a vibration isolation structure.

Furthermore, the vibration isolation structure is a honeycomb vibration isolation plate.

Furthermore, the power drive device is installed in the guide cylinder through a mounting bracket, and the mounting bracket is in the shape of a disk covered with a honeycomb hollow structure and is horizontally fixed on a portion of the guide cylinder close to the air outlet.

Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

In the present invention, the order and form of excitation can be flexibly adjusted through the cooperation of the pneumatic excitation device and the traveling wave excitation generating device, so as to realize the measurement of the dynamic response of the blade under different order traveling wave excitation forms, improve the accuracy and reliability of the dynamic characteristic test of the blade disk, and reduce the dynamic test cost of the blade disk. The pneumatic excitation part and the measurement part in the present invention are divided into two parts for construction, which isolates all vibrations except the pneumatic excitation, and ensures that the sensor collects only the vibration signal of the blade disk.

The vibration reduction structure between devices designed in the present invention effectively reduces the interference between various systems and improves the signal-to-noise ratio of the blade vibration signal.

In some embodiments of the present invention, a honeycomb hollow structure is provided on a mounting bracket through which air flows, which helps to reduce interference with the airflow excitation form and plays a role in reducing the influence of other excitation orders.

In some embodiments of the present invention, the height of the guide cylinder is adjusted by using a locking slider and an optical axis connecting the bottom and top of the device, so that the height of the guide cylinder can be adjusted according to test requirements and actual conditions of the blades.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of a traveling wave excitation system in an embodiment of the present invention;

FIG2 is a schematic diagram of the structure of a pneumatic actuation device in an embodiment of the present invention;

FIG3 is a schematic structural diagram of a traveling wave excitation generating device in an embodiment of the present invention;

FIG4 is a partial cross-sectional view of a guide cylinder in an embodiment of the present invention;

FIG5 is a non-contact dynamic characteristic measuring device of the present invention;

FIG. 6 is a measurement result of the dynamic characteristics of the blade of the present invention.

The figure marks in the drawings of the specification include: pneumatic excitation device 1, upper support plate 100, lower support plate 101, airflow generating device bracket 102, airflow generating device 103, locking slider 104, optical axis 105, shock absorber 106, guide cylinder 2, mounting platform 201, connecting block 202, connecting rod 203, traveling wave excitation generating device 3, slotted disc 301, power drive device 302, honeycomb mounting bracket 303, non-contact measuring device 4, blade disk bracket 401, sensor bracket 402, sensor mounting part 402A, support part 402B, honeycomb vibration isolation platform 403.

DETAILED DESCRIPTION

The present invention is further described in detail below through specific embodiments:

As shown in FIG. 1 , the traveling wave excitation system of the periodically symmetrical blade disk structure of this embodiment includes a pneumatic excitation device 1 , a traveling wave excitation generating device 3 , and a non-contact measuring device 4 which are arranged in sequence longitudinally.

As shown in Figure 2, the supporting structure of the pneumatic excitation device 1 includes an upper support plate 100, a lower support plate 101, an optical axis 105 and a shock absorber 106; the upper support plate 100 and the lower support plate 101 are both in the shape of a rectangular frame, and four optical axes 105 are vertically established between the upper support plate 100 and the lower support plate 101, and each optical axis 105 is fixed between a corner of the upper support plate 100 and the midpoint of a frame of the lower support plate 101, and a shock absorber 106 is installed on the downward side of each of the four corners of the lower support plate 101.

The pneumatic excitation function of the pneumatic excitation device 1 is mainly completed by the guide cylinder 2 and the airflow generating device 103 fixed on the top of the guide cylinder 2 through the airflow generating device bracket 102. The guide cylinder 2 in this embodiment is a hollow cylindrical tube. As shown in the figure, an annular mounting platform 201 is formed on the outer peripheral wall of the guide cylinder 2, and each optical axis 105 is sleeved with two locking sliders 104 that can slide up and down along the optical axis 105. The locking slider 104 is provided with a locking mechanism, and the locking mechanism can allow the locking slider 104 to hold or loosen the optical axis 105 under the configuration of the user; on the other hand, each locking slider 104 is also fixedly connected to a connecting rod 203, which is horizontally arranged, one end of which is fixedly connected to the locking slider 104, and the other end is fixedly connected to a connecting block 202, and the fixing block is fixed on the mounting platform 201. In some embodiments, one or more of the connections between the locking slider 104 and the connecting rod 203, between the connecting block 202 and the connecting rod 203, and between the connecting block 202 and the mounting platform are all detachably connected, and the specific connection method includes but is not limited to screw connection, direct threaded connection or snap connection. Therefore, when the locking slider 104 releases the optical axis 105, the position of the guide cylinder 2 on the pneumatic excitation device 1 can be adjusted up and down along the optical axis 105. After it is in place, the guide cylinder 2 can be fixed by simply locking the locking slider 104.

The airflow generating device 103 in this embodiment adopts a fan, and its air outlet direction is toward the inside of the guide cylinder 2, which is used to provide aerodynamic load for exciting blades; the airflow generating device bracket is disc-shaped, and its diameter is basically the same as the diameter of the guide cylinder 2, and the diameter of the airflow generating device 103 is smaller than the airflow generating device bracket. The airflow generating device bracket is provided with a mounting structure that cooperates with the airflow generating device, so that the airflow generating device can be coaxially mounted on the airflow generating device bracket 102, and the airflow generating device bracket 102 between the airflow generating device and the edge of the airflow generating device bracket is hollowed out to facilitate air intake, and the airflow generating device 103 and the airflow generating device bracket 102 are fixed to each other by bolts; on the other hand, the edge of the airflow generating device bracket 102 is connected to the edge of the top of the guide cylinder 2 by snap connection or thread connection, so that the airflow generating device 103, the airflow generating device bracket 102 and the guide cylinder 2 are coaxial. The airflow generating device 103 is also connected to a controller (not shown in the figure) for adjusting the aerodynamic excitation amplitude, and is connected to a voltage-stabilized power supply.

The traveling wave excitation generating device 3 shown in FIG3 includes a honeycomb mounting bracket 303, a power driving device 302, and a slotted disc 301 with multiple through slots;

The center of the slotted disk 301 is fixed to the output shaft of the power drive device 302 by bolts. The speed of the power drive device 302 is adjusted by a dedicated controller (not shown in the figure) and connected to a DC regulated power supply. The rotation speed of the power drive device can be obtained in real time by a speed monitor. The slotted disk 301 is used to control the frequency and pitch diameter of the aerodynamic excitation. The number of slots on the disk is equal to the number of pitch diameters of the aerodynamic excitation applied to the blade disk, so the number of slots is equal to the order of the traveling wave excitation required to be applied.

The honeycomb mounting bracket is in the shape of a disc covered with a honeycomb hollow structure, as shown in FIG4 , the honeycomb mounting bracket is horizontally fixed on the part of the guide cylinder 2 near the air outlet, and the power drive device 302 is connected to the center of the honeycomb bracket by four bolts, so that the slotted disc 301, the power drive device 302, the honeycomb mounting bracket and the guide cylinder 2 are coaxially arranged, and the installation height of the honeycomb mounting bracket and the size of the power drive device 302 are matched so that the slotted disc 301 is located in the guide cylinder 2, and the outer edge of the slotted disc 301 is intermittently or slidingly matched with the inner circumferential wall of the guide cylinder 2, so that the guide cylinder 2 can rotate freely in the guide cylinder 2. The bracket structure itself will affect the passing airflow, and the honeycomb structure helps to reduce the interference with the airflow excitation form, and plays a role in reducing the influence of other excitation orders.

As shown in FIG5 , the non-contact measuring device 4 includes a blade disk support 401 , a sensor support 402 and a honeycomb vibration isolation platform 403 .

The blade disk support 401 is a solid cylindrical structure, and the top end of the blade disk support 401 is used to place the blade disk according to the specific boundary conditions of the blade disk;

The sensor bracket 402 is divided into a sensor mounting portion 402A and a supporting portion 402B;

The support portion 402B is a hollow cylindrical structure, which is entirely sleeved outside the blade disc bracket 401, and the inner diameter of the support portion 402B is larger than the outer diameter of the blade disc bracket 401, so that the sensor bracket 402 and the blade disc bracket 401 are separated by a gap, and there is no contact between the blade disc bracket 401 and the sensor bracket 402, and both are fixed to the honeycomb vibration isolation platform 403 by bottom bolts respectively, and the honeycomb vibration isolation platform 403 also plays the role of isolating the vibration transmission between the sensor bracket 402, the blade disc bracket 401 and the ground; the sensor mounting portion 402A is formed at the opening of the support portion 402B facing the blade disc, and includes a plurality of mounting positions that match the outer dimensions of the sensor, which are used to install various sensors, such as eddy current sensors, and each mounting position is symmetrically arranged around the central axis of the sensor bracket 402.

In this embodiment, the outer diameter and length of the guide cylinder 2 and the outer diameter of the slotted disk 301 need to be selected according to the diameter of the tested blade disk; accordingly, different outer diameter selections require replacement of different connecting rods for fixed installation.

During the test, we first analyze the speed of the blade disk in the working state by making a Campbell diagram to calculate the excitation order of the blade disk to reach the resonance area, and then conduct a dynamic response test on the blade disk under the excitation order of these working states to obtain the blade vibration signal.

The operating steps of performing an exemplary blade disk dynamic response test under an exemplary free boundary condition using the exemplary traveling wave excitation system in this embodiment are as follows:

First, place the whole blade disk on the measuring table, and position the bottom of the blade disk with a soft material mold to simulate the free boundary conditions of the blade disk, and fine-tune the position of the test bench to ensure that the center of the whole blade disk corresponds to the center of the slotted disk. Then select and install the slotted disk with the corresponding excitation order, install and adjust the eddy current sensor on the sensor mounting part, and ensure that different sensors measure the same position of each blade.

During the test phase, the size of the airflow output by the airflow generating device 103 is first adjusted and kept stable, and then the speed of the rotating disk below is adjusted so that the excitation frequency is close to the resonance area of the blade corresponding to the modal family, and the speed value N1 at this location is recorded. The speed is continued to increase so that the excitation frequency gradually moves away from the blade resonance area, and the speed value N2 at this location is recorded. Within the speed range of N1-N2, the displacement (Offset Y values) of each blade at different speeds is measured 10 times or more, and when the displacement response is stable, the time point when it begins to stabilize is recorded. Figure 6 shows the displacement measurement data of a single blade 1, blade 2, and blade 3. It can be seen from Figure 6 that the measurement data is divided into three parts: the initial stage, applying aerodynamic excitation loads, and adjusting the speed of the rotating disk so that the excitation frequency reaches a resonant or near-resonant state. Finally, Fourier transform is used to extract the vibration amplitude of the blade in the resonance\near-resonance state in each test and other parameters for evaluating the dynamic characteristics of the blade.

Specific examples are used in this application to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is to help understand the core idea of the present invention. It should be pointed out that it is obvious that those familiar with the art can easily make various modifications to these embodiments, or replace some or all of the technical features therein, and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims (10)

1. A traveling wave excitation system of a periodically symmetric leaf disc structure, comprising: the device comprises a pneumatic excitation device, a traveling wave excitation generating device and a non-contact measuring device which are sequentially arranged from top to bottom;

The traveling wave excitation generating device comprises a guide cylinder and an airflow generating device arranged at the air inlet end of the guide cylinder;

The air flow generating device is used for providing pneumatic load required by exciting the blades, the guide cylinder is used for transmitting air flow, and the air flow generating device further comprises a controller used for adjusting the pneumatic excitation amplitude;

The traveling wave excitation generating device is positioned at the air outlet end of the guide cylinder and comprises a power driving device fixedly arranged in the air outlet end of the guide cylinder and a slotted disc which can be driven to rotate by the power driving device, and the rotation center of the slotted disc is positioned on the central axis of the guide cylinder; the slotted disc is provided with a plurality of through slots which are arranged along the radial direction, and the number of the through slots is equal to the number of pitch diameters of pneumatic excitation applied to the leaf disc; the device also comprises a special controller for adjusting the rotating speed of the power driving device;

the non-contact measuring device comprises a blade measuring sensor connected to the dynamic signal acquisition instrument and used for measuring the dynamic characteristics of the blade; the device also comprises a leaf disc support for placing the leaf disc knot member, wherein the center of the leaf disc knot member placed on the leaf disc support is positioned on the central axis of the flow guiding cylinder and is not contacted with the air outlet end which is opposite to the flow guiding cylinder.

2. The system of claim 1, wherein the pneumatic actuation device further comprises a support structure comprising an upper support plate, a lower support plate, and an optical axis;

The upper support plate and the lower support plate are rectangular frame-shaped, and a plurality of optical axes are vertically fixed between the upper support plate and the lower support plate;

The device also comprises an installation table fixedly arranged on the peripheral wall of the guide cylinder;

the optical axis is sleeved with locking slide blocks which can slide up and down along the optical axis, the locking slide blocks are provided with locking mechanisms, and the locking mechanisms can enable the locking slide blocks to clamp or release the optical axis under the configuration of a user;

Each locking slide block is also fixedly connected with a connecting rod, one end of the connecting rod is horizontally arranged and fixedly connected with the tightening slide block, the other end of the connecting rod is fixedly connected with a connecting block, and the connecting block is fixed on the mounting table.

3. The system of claim 2, wherein one or more of the connection between the locking slide and the connecting rod, the connection between the connecting block and the connecting rod, and the connection between the connecting block and the mounting table is a detachable connection.

4. The system of claim 2, wherein a plurality of shock absorbers are provided below the lower support plate.

5. The system of claim 1, wherein the blade measurement sensor is mounted on a sensor mount, the blisk mount and the sensor mount being out of contact with each other.

6. The system of claim 5, wherein the blisk support is a solid cylindrical structure, the tip of the blisk support being configured to position the blisk according to blisk specific boundary conditions;

The sensor bracket is divided into a sensor mounting part and a supporting part;

The supporting part is of a hollow cylinder structure and is entirely sleeved outside the leaf disc support, and the inner diameter of the supporting part is larger than the outer diameter of the leaf disc support;

The sensor installation department is located the supporting part and is faced the opening part of leaf disc, has included a plurality of and sensor's external dimension complex installation position for install all kinds of sensors.

7. The system of claim 6, wherein each mounting location is disposed circumferentially symmetrically about a central axis of the sensor mount.

8. The system of claim 5, wherein the sensor mount and the blisk mount are mounted on a vibration isolation structure.

9. The system of claim 8, wherein the vibration isolation structure is a cellular vibration isolation plate.

10. The system of claim 1, wherein the power driving device is mounted in the guide cylinder by a mounting bracket, and the mounting bracket is in a shape of a plate covered with a honeycomb hollow structure and is horizontally fixed on a portion of the guide cylinder near the air outlet.