Rotor system and method for changing bearing rigidity in operation process

Abstract

According to the rotor system and the method for changing the supporting rigidity in the operation process, a device for changing the supporting rigidity in the operation process of the rotor system mainly comprises a double-rigidity elastic support and a split type fixing ring, and the working rigidity of the double-rigidity elastic support is controlled by holding and loosening the split type fixing ring; therefore, the supporting rigidity of the rotor system in the operation process is adjusted. During working, rotor vibration is reduced by actively changing the critical rotating speed, and in the speed increasing process of a rotor system, when the rotating speed is close to 15% of the critical rotating speed, the critical rotating speed is changed under the condition that the rotating speed is not changed, and the critical rotating speed is reduced to 85% of the working rotating speed at the moment. The device is matched with the method, vibration of the rotor system in the working process is reduced, the critical speed of the rotor system is more stable, the resonance problem caused by the critical rotating speed in the follow-up speed increasing process can be avoided, and the device is suitable for large-scale industrial use and popularization.

Description

Technical Field

[0001] This invention belongs to the field of rotor systems, and specifically relates to a rotor system and method for changing the support stiffness during operation. Background Technology

[0002] Vibration is a major issue in rotor systems, significantly impacting their performance in large rotating machinery such as liquid rocket engines, aero engines, and high-power gas turbines. The peak vibration of a rotor system typically occurs at its critical speed. As a crucial parameter of the rotor system, the critical speed significantly influences both the peak vibration and the operating speed during engine operation.

[0003] Existing rotor systems employ various methods to reduce vibration displacement. For example, a certain combined-power engine incorporates two squeeze film dampers in its structure to cope with the two critical speeds during the acceleration to operating speed. A certain liquid hydrogen engine designs two metal-rubber dampers to reduce the overcritical vibration peak value within the operating speed of 80,000 rpm. In the design process of high-power rotating machinery such as aero engines and marine gas turbines, it is necessary to avoid the critical speed or to design dampers specifically to pass through the critical speed to ensure the smooth and reliable operation of the equipment.

[0004] While the above settings can reduce vibration displacement to some extent, it is difficult to avoid using a damping system, which makes the rotor system less stable when passing the critical speed. Summary of the Invention

[0005] The purpose of this invention is to provide a rotor system and method that changes the support stiffness during operation, so as to solve the problem that the rotor system in the prior art is not stable enough when passing the critical speed.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A rotor system that changes its support stiffness during operation includes a bearing support, a connecting ring, and a flange arranged coaxially in sequence; the bearing support and the connecting ring are both annular and have the same outer diameter. Multiple first cage bars are evenly distributed circumferentially between the bearing support sidewall and the sidewall on one side of the connecting ring; multiple second cage bars are evenly distributed circumferentially between the sidewall on the other side of the connecting ring and the flange; the flange is connected to the external frame. The bearing support is provided with an axially penetrating bearing mounting hole, which can be used to install a bearing. The inner rings of the multiple first cage bars, the connecting ring, and the multiple second cage bars form a space that can accommodate the rotor. It also includes a fixing ring, which is coaxially sleeved on the outside of the connecting ring via a power device. The power device can drive the fixing ring to expand or contract, thereby causing the fixing ring to loosen or tighten the connecting ring.

[0007] The present invention also has the following features: Furthermore, the fixing ring comprises two half-rings; The two semi-rings are respectively connected to the power unit; The inner diameter of the inner circle of the semi-ring is the same as the outer diameter of the connecting ring. When the semi-ring is tightened around the connecting ring, there is a gap between the end faces of the two semi-rings.

[0008] Furthermore, the power unit employs two hydraulic presses; The two hydraulic press output shafts are respectively connected to the outer rings of the two semi-rings.

[0009] A method for changing the vibration displacement of a rotor system, based on the aforementioned rotor system that changes support stiffness during operation, includes the following steps: Step 1: Connect the rotor system to the external frame and install the rotor and bearings; have the power unit drive the two semi-rings to tighten the connecting ring, and set the current support stiffness of the rotor system to the maximum support stiffness. Step 2: Under high support stiffness, gradually increase the rotor speed while simultaneously detecting the vibration displacement generated during the operation of the rotor system. Step 3: When the vibration displacement reaches its peak value, the rotational speed corresponding to that moment is defined as the critical rotational speed; Step 4: Decelerate the rotor to a standstill and then accelerate it back to 85% of the critical speed; have the power unit drive the two half-rings to expand, loosen the connecting ring, set the current support stiffness of the rotor system to the minimum support stiffness, and continue to increase the rotor speed to the required operating speed.

[0010] Furthermore, when the rotor system finishes working and the rotor needs to be stopped, the rotor is gradually decelerated to 85% of the critical speed using a small support stiffness, and then switched to a large support stiffness to decelerate to zero speed.

[0011] Compared with the prior art, the present invention has the following technical effects: The present invention relates to a rotor system and method for changing support stiffness during operation. The device for changing support stiffness during rotor system operation mainly includes a dual-stiffness elastic support and a split-type fixing ring. The working stiffness of the dual-stiffness elastic support is controlled by tightening and loosening the split-type fixing ring, thereby adjusting the support stiffness of the rotor system during operation.

[0012] During operation, rotor vibration is reduced by actively altering the critical speed. During rotor system acceleration, when the speed approaches the critical speed by 15%, the critical speed is adjusted while maintaining the original speed, reducing it to 85% of the current operating speed. This device and method, combined, reduce rotor system vibration during operation, resulting in smoother transitions past the critical speed. It also avoids resonance issues that arise when encountering the critical speed during subsequent acceleration, making it suitable for large-scale industrial use and widespread adoption. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the cross-sectional structure of a rotor system that changes the support stiffness during operation. Figure 2 This is a side view of the fixed ring under high support stiffness in one embodiment of the invention; Figure 3 This is a side view of the fixed ring under low support stiffness in one embodiment of the invention; Figure 4 This is a schematic diagram of the vibration response of the rotor under high support stiffness in one embodiment of the invention; Figure 5 This is a schematic diagram of the vibration response of the rotor under low support stiffness in one embodiment of the invention; Figure 6 This is a schematic diagram of the vibration response of a rotor using a variable stiffness method in one embodiment of the invention.

[0014] The meanings of the labels in the diagram are as follows: 1. Bearing support; 2. Connecting ring; 3. Flange; 4. First cage bar; 5. Second cage bar; 6. Fixing ring; 7. Half ring; 8. Bearing mounting hole. Detailed Implementation

[0015] It should be noted that, unless otherwise specified, all components in this invention are known in the prior art. For example, the rotor is a commonly used rotor.

[0016] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0017] like Figure 1 As shown, a rotor system that changes support stiffness during operation includes a bearing support 1, a connecting ring 2, and a flange 3 arranged coaxially in sequence; the bearing support 1 and the connecting ring 2 are both annular and have the same outer diameter. Multiple first cage bars 4 are evenly distributed circumferentially between the side wall of bearing support 1 and the side wall of one side of connecting ring 2; multiple second cage bars 5 are evenly distributed circumferentially between the side wall of the other side of connecting ring 2 and flange 3; flange 3 is connected to external frame. The bearing support 1 has an axially penetrating bearing mounting hole 8, which can be used to install the bearing; The inner rings of multiple first cage bars 4, connecting ring 2, and multiple second cage bars 5 form a space that can accommodate the rotor; It also includes a fixing ring 6, which is coaxially sleeved on the outside of the connecting ring 2 via a power device. The power device can drive the fixing ring 6 to expand or lock, thereby causing the fixing ring 6 to move away from or tighten around the connecting ring 2.

[0018] In the working state, when the fixed ring 6 tightens the connecting ring 2, the rotor support stiffness is provided by multiple first cage bars 4, and the support stiffness of the rotor system at this time is defined as the maximum support stiffness. When the fixed ring 6 loosens the connecting ring 2, the rotor support stiffness is provided by multiple first cage bars 4 and multiple second cage bars 5. The support stiffness of the rotor system at this time is defined as the small support stiffness. It should be noted that the terms "large support stiffness" and "small support stiffness" are relative terms. The support stiffness of the rotor system not using this embodiment is defined here as the large support stiffness, to distinguish it from the small support stiffness after the use of variable support stiffness.

[0019] As a preferred embodiment, the fixing ring 6 comprises two half-rings 7; The two semi-rings 7 are respectively connected to the power unit; The inner diameter of the inner circle of the semi-ring 7 is the same as the outer diameter of the connecting ring 2. When the semi-ring 7 is tightened around the connecting ring 2, there is a gap between the end faces of the two semi-rings 7.

[0020] During rotor speed increase, when the rotational speed reaches its target value, the two semi-rings 7 are actively separated. At this point, there is a certain gap 16 between the split-ring fixed section and the intermediate connecting section 18 of the double-stiffness elastic support. This gap value is determined based on the rotor vibration and is generally not less than 1mm. After the variable stiffness mechanism is in operation, the rotor support stiffness is provided by the cage bars at both ends of the double-stiffness elastic support. At this time, the stiffness decreases, and the rotor system is in a low support stiffness state, thus realizing variable stiffness vibration reduction of the rotor system.

[0021] Specifically, the power unit uses two hydraulic presses; The output shafts of the two hydraulic presses are respectively connected to the outer rings of the two semi-rings 7.

[0022] It should be noted that hydraulic drive is only one optional implementation method. This embodiment can also use electromagnetic drive or other forms of drive.

[0023] A method for changing the vibration displacement of a rotor system, based on the aforementioned rotor system that changes support stiffness during operation, includes the following steps: Step 1: Connect the rotor system to the external test bench and install the rotor and bearings; set the current support stiffness of the rotor system to the maximum support stiffness, at which point the state is as follows. Figure 2 As shown; Step 2: Under high support stiffness, gradually increase the rotor speed while simultaneously detecting the vibration displacement generated during the operation of the rotor system. Step 3: When the vibration displacement reaches its peak value, the rotational speed corresponding to that moment is defined as the critical rotational speed; Step 4: Decelerate the rotor to a standstill, then accelerate it back to 85% of the critical speed; have the power unit drive the two semi-rings 7 to tighten the connecting ring 2, setting the current support stiffness of the rotor system to the minimum support stiffness. The state at this point is as follows: Figure 3 As shown; continue increasing the rotor speed to the required operating speed.

[0024] Furthermore, when the rotor system finishes working and the rotor needs to be stopped, the rotor is gradually decelerated to 85% of the critical speed using a small support stiffness, and then switched to a large support stiffness to decelerate to zero speed.

[0025] To verify the effectiveness of the device in this embodiment, specific experimental verification is given below: Figure 4 This is a schematic diagram of the vibration response of a rotor under high support stiffness in this embodiment.

[0026] Under high support stiffness, the vibration displacement increases with the rotational speed, forming the vibration response of the rotor under high support stiffness. When the vibration displacement increases to the vibration peak value with the rotational speed 1, the corresponding rotational speed is the critical rotational speed of the rotor under high support stiffness. Taking this embodiment as an example, the rotational speed is 2186 r / min, and the vibration peak value is 77 μm. Figure 5 This is a schematic diagram of the vibration response of a rotor under low support stiffness according to this embodiment. Under low support stiffness, the vibration displacement increases with the increase of rotational speed, forming the vibration response of the rotor under low support stiffness. When the vibration displacement increases with the increase of rotational speed to the vibration peak value, the corresponding rotational speed value is the critical rotational speed of the rotor under high support stiffness. Taking this embodiment as an example, the rotational speed is 1704 r / min, and the vibration peak value is 72 μm. Figure 6This is a schematic diagram of the rotor's vibration response using the variable stiffness method in this embodiment. Under high support stiffness, the vibration displacement 2 increases with the rotational speed 1. When the rotational speed reaches 85% of the rotational speed 5, the support stiffness is changed to a lower support stiffness, resulting in the rotor's vibration response using the variable stiffness method. It can be seen that the peak vibration value of the rotor using the variable stiffness method is significantly smaller than the peak vibration value. Taking this embodiment as an example, with a rotational speed of 1858 r / min, the peak vibration value is 4.7 μm. The peak vibration value of the rotor system throughout the entire rotational speed cycle is reduced by 93.9%, demonstrating a significant vibration reduction effect of this invention.

[0027] During rotor operation, the rotor support stiffness is changed by the main control mechanism. The support stiffness before the change is the large support stiffness, and the support stiffness after the change is the small support stiffness. The rotor support stiffness before and after the change should make the corresponding rotor system critical speeds differ by more than 30%.

Claims

1. A rotor system that changes support stiffness during operation, characterized in that, It includes a bearing support (1), a connecting ring (2) and a flange (3) arranged coaxially in sequence; the bearing support (1) and the connecting ring (2) are both annular and have the same outer diameter; Multiple first cage bars (4) are evenly distributed circumferentially between the side wall of the bearing support (1) and the side wall of the connecting ring (2); multiple second cage bars (5) are evenly distributed circumferentially between the side wall of the other side of the connecting ring (2) and the flange (3); the flange (3) is connected to the external frame. The bearing support (1) is provided with an axially penetrating bearing mounting hole (8), and a bearing can be installed in the bearing mounting hole (8). The inner rings of the multiple first cage bars (4), the connecting ring (2), and the multiple second cage bars (5) form a space that can accommodate the rotor; It also includes a fixing ring (6), which is coaxially sleeved on the outside of the connecting ring (2) via a power device. The power device can drive the fixing ring (6) to expand or lock, thereby causing the fixing ring (6) to loosen or tighten the connecting ring (2).

2. The rotor system for changing support stiffness during operation as described in claim 1, characterized in that, The fixing ring (6) includes two half-rings (7); The two semi-rings (7) are respectively connected to the power unit; The inner diameter of the inner circle of the semi-ring (7) is the same as the outer diameter of the connecting ring (2). When the semi-ring (7) tightens the connecting ring (2), there is a gap between the end faces of the two semi-rings (7).

3. The rotor system for changing support stiffness during operation as described in claim 2, characterized in that, The power unit consists of two hydraulic presses; The two hydraulic press output shafts are respectively connected to the outer rings of the two semi-rings (7).

4. A method for changing the vibration displacement of a rotor system, the method being based on the rotor system described in claim 3 that changes the support stiffness during operation, characterized in that... Includes the following steps: Step 1: Connect the rotor system to the external frame and install the rotor and bearings; have the power unit drive the two half-rings (7) to tighten the connecting ring (2), and set the current support stiffness of the rotor system to the maximum support stiffness; Step 2: Under high support stiffness, gradually increase the rotor speed and simultaneously detect the vibration displacement generated during the operation of the rotor system. Step 3: When the vibration displacement reaches its peak value, the rotational speed corresponding to that moment is defined as the critical rotational speed; Step 4: Decelerate the rotor to a standstill and then accelerate it back to 85% of the critical speed; cause the power unit to expand the two half-rings (7), loosen the connecting ring (2), set the current support stiffness of the rotor system to the small support stiffness, and continue to increase the speed of the rotor to the required working speed.

5. The method for changing the vibration displacement of a rotor system as described in claim 4, characterized in that, When the rotor system finishes working and the rotor needs to be stopped, the rotor is gradually decelerated to 85% of the critical speed using a small support stiffness, and then switched to a large support stiffness to decelerate to zero speed.

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