WO2020029716A1

WO2020029716A1 - Load reduction apparatus for fan blade-out event of aero-engine

Info

Publication number: WO2020029716A1
Application number: PCT/CN2019/094197
Authority: WO
Inventors: 赵芝梅; 郑李鹏; 宋会英; 王少辉; 唐振南
Original assignee: 中国航发商用航空发动机有限责任公司
Priority date: 2018-08-06
Filing date: 2019-07-01
Publication date: 2020-02-13
Also published as: CN110805496A; CN110805496B

Abstract

A load reduction apparatus and method for a fan blade-out (FBO) event of an aero-engine, capable of bidirectionally adjusting the critical speed of a low pressure rotor even after the fuse part of the low pressure rotor fails under the action of an FBO load. The load reduction apparatus comprises a fuse part, a fan shaft, at least two sensors, and a controller. The fuse part is provided on a bearing block or a supporting cone wall of a first bearing. The fan shaft comprises an intelligent extendable structure. The at least two sensors are used for monitoring dynamic responses of the first bearing and a second bearing. The controller is disposed in association with the sensors and the intelligent extendable structure separately. The sensors detect abnormal dynamic responses of the first bearing and the second bearing, and transmit the detected dynamic responses to the controller. The controller sends a signal to the intelligent extendable structure so that said structure extends or retracts within a predetermined range, so as to change the length of the fan shaft.

Description

Load reduction device for aero engine fan blade fall-off event

Technical field

The invention relates to an aero engine, in particular to a load shedding device for an aero engine fan blade falling event.

Background technique

According to the requirements of airworthiness regulations (FAR33.74, FAR33.94), commercial aviation engines must ensure that the occurrence of the FBO event (fan blade off event) will not lead to catastrophic consequences. The FBO event will generate a huge unbalanced load, which may cause damage to key components such as engine mounting joints and bearings, causing catastrophic accidents such as engine shedding, broken blades and breakdown of the nacelle. Immediately after the FBO event, the damaged engine should be stopped to slow down the engine from a higher working speed to the speed of the windmill, and continue for a period of time (sometimes up to 180 minutes) during the rotation of the windmill until the landing conditions are met Slow down and land safely.

In order to ensure that the engine can land safely after the FBO event, a load reduction design is generally used to reduce the FBO limit load on the engine components (mainly installation systems, low-pressure shafts and other components) to ensure the safety of the engine. The commonly used load reduction design is also known as the fuse design, which refers to providing a weak mechanical component on the bearing support structure, such as a thinned section (see patent US6447248), a diameter reduction bolt (see patent US7318685), etc. Failure under the action of load (threshold value), on the one hand, changes the FBO load transmission path, and on the other hand, reduces the critical speed of the rotor, which is far lower than the current operating speed of the engine and higher than the speed of the windmill. In a critical state, it is in a subcritical state during the rotation of the windmill to reduce unbalanced loads and protect the safety of the engine.

Therefore, adjusting the critical speed of a low-voltage rotor through the failure of a fuse component needs to meet two requirements. On the one hand, it is necessary to reduce the critical speed below the operating speed of the engine at the time of the FBO event, so that the rotor is in a supercritical state at the time of the failure of the fuse component, and exerts a self-centering effect to reduce the FBO load. On the other hand, it is necessary to ensure that the critical speed is higher than the speed of the windmill, to avoid continuous resonance of the rotor during the rotation of the windmill, resulting in damage to key components. In summary, on the basis of reducing the critical speed with a traditional fuse device, if the critical speed of the engine is lowered during the stopping and deceleration phase, and the critical speed is appropriately increased during the windmill rotation phase, it will help to further reduce the dynamic response of the engine. . Therefore, there is a need for an FBO load shedding device with an adaptive function, which can reduce the critical speed during the parking phase, increase the critical speed during the rotation phase of the windmill, and implement a two-way adjustment function of the critical speed under different operating states, thereby better reducing the engine's FBO Dynamic response after the event.

Summary of the invention

The purpose of the present invention is to provide a load reduction device and a load reduction method for an aero engine fan blade fall-off event, which can bidirectionally adjust the critical speed of the low-pressure rotor after the fuse component of the low-pressure rotor fails under the action of FBO load.

An aircraft engine fan blade load shedding device for a low-pressure rotor, the low-pressure rotor is supported by at least a first bearing and a second bearing, and a bearing seat of the first bearing is connected to an intermediate casing by a supporting cone wall, Wherein, the load shedding device includes a fusible part, a fan shaft, at least two sensors, and a controller. The fusible part is disposed on the bearing seat of the first bearing or the supporting cone wall; the fan shaft includes an intelligent retractable structure; at least two sensors To monitor the dynamic response of the first bearing and the second bearing; a controller, the sensor, and the intelligent retractable structure are respectively associated with each other; wherein the sensor detects the first bearing and the The abnormal dynamic response of the second bearing, and transmits the detected dynamic response to the controller, which sends a signal to the intelligent retractable structure to make it expand and contract along a predetermined range, thereby changing the length of the fan shaft .

In an embodiment of the load shedding device, the load shedding device further includes a secondary bearing provided on a bearing block of the second bearing or a wall body connecting the second bearing block to the intermediate casing. Fuse parts.

In one embodiment of the load shedding device, the intelligent scalable structure is a rare earth giant magnetostrictive structure.

In an embodiment of the load shedding device, the sensor is a strain gauge, a vibration sensor, or an acceleration sensor.

Method for reducing load of aero engine fan blade falling event, used for low-pressure rotor, the fan shaft of the low-pressure rotor is supported by at least a first bearing and a second bearing, and the bearing seat of the first bearing is connected to the intermediary by a supporting cone On the box, a smart retractable structure is arranged on the fan shaft. Under normal operating conditions, the fan shaft is supported by the first bearing and the second bearing together, and the smart retractable structure maintains the initial length; the fan blade falls off event occurs. Then, the dynamic response of the first bearing and the second bearing is detected by a sensor, and the collected dynamic response is transmitted to the controller, and the controller sends a signal to the intelligent scalable structure, so that the intelligent The telescopic structure extends along a predetermined range, thereby increasing the length of the fan shaft.

In one embodiment of the load shedding method, after the fan blade shedding event occurs, during the process of reducing the engine speed from the operating speed to the windmill speed, the engine will pass the critical speed and use the controller to determine from the signals monitored by the sensors that the engine has Over the critical speed, then send a signal to the intelligent retractable structure to make it shrink within a predetermined range, reducing the length of the fan shaft.

During the stopping and decelerating phase after the FBO event, the engine is in a supercritical state. Through the extension of the intelligent retractable structure, the cantilever length of the fan shaft is increased to further reduce the critical speed and reduce the dynamic response during the stopping and decelerating phase. During the rotation of the windmill, the engine is in a subcritical state. Through the contraction of the intelligent retractable structure, the cantilever length of the fan shaft is reduced to increase the critical speed and to better reduce the engine's dynamic response. Therefore, by controlling the length of the intelligent retractable structure to adjust the critical speed of the rotor in both directions, the design load of the engine component system is reduced, which helps to reduce the design difficulty of the engine.

Overview of the drawings

The above and other features, properties, and advantages of the present invention will become more apparent through the following description with reference to the accompanying drawings and embodiments, in which:

FIG. 1 is a schematic diagram of an embodiment of a front end of a large bypass turbofan engine.

FIG. 2 is a schematic diagram of an embodiment of a load shedding device for a fan blade fall-off event of an aero-engine.

Figure 3 is a schematic diagram of the equivalent distance between the first bearing and the second bearing before the FBO event.

FIG. 4 is a schematic diagram of the equivalent distance between the first bearing and the second bearing during the period of the speed reduction after the FBO event.

Best Mode of the Invention

The following discloses various implementations or examples for implementing the subject technical solution. To simplify the disclosure, specific examples of each element and arrangement are described below. Of course, these are merely examples, and are not intended to limit the protection scope of the present invention. For example, the first feature described later in the specification is formed above or above the second feature, and may include an embodiment in which the first and second features are formed by direct contact, or may be formed between the first and second features. Implementation of additional features so that the first and second features may not be directly linked. In addition, these disclosures may repeat reference numerals and / or letters in different examples. This repetition is for the sake of brevity and clarity, and does not in itself represent the relationship between the embodiments and / or structures to be discussed. Further, when the first element is described in a manner of being connected or combined with the second element, the description includes the embodiment in which the first and second elements are directly connected or combined with each other, and also includes the use of one or more other intervening elements to join The first and second elements are indirectly connected or combined with each other.

In the embodiment described later, the aero-engine configuration is a high- and low-pressure dual-rotor system, where the first bearing is a 1 # bearing commonly known in the industry, and the second bearing is a 2 # bearing commonly known in the industry. The typical rotor support scheme is that the low-pressure rotor is supported by 1 #, 2 #, and 5 # bearings, of which 1 # and 5 # are roller bearings, and 2 # are ball bearings. As shown in FIG. 1, the front end portion of the turbofan engine is symmetrical along the axial centerline 1. The controller includes a signal acquisition device 18 and a signal processing device 19, and the signal processing device 19 adjusts the current or voltage input to the intelligent scalable structure 15 to implement functions such as the expansion and contraction of the intelligent structure, which can be implemented using existing technologies, and will not be repeated here. Detailed description.

Through an aero-engine fan blade fall event load reduction device with adaptive function shown in Figs. 1-4, the critical speed can be adjusted bidirectionally after a # 1 bearing support or a fused component on the support cone wall fails. After the FBO event, the fuse component on the 1 # bearing support or supporting cone wall fails, and the critical speed of the low-voltage rotor is reduced. The load reduction device can further reduce the critical speed of the rotor during the deceleration phase of the stop and increase the critical speed of the rotor during the rotation of the windmill. To better reduce the dynamic response of the engine under different operating conditions after the fan blade shedding event.

The structure of the fan rotor support system is shown in Figure 2. The fan shaft 8 is supported by 1 # bearing 7 and 2 # bearing 9, among which 1 # bearing 7 is a roller bearing, which provides radial restraint to the

fan shaft

8, and 2 # bearing 9 is a ball bearing, and provides a shaft to the fan shaft 8 at the same time Directional and radial constraints. The supporting cone wall 5 connects the 1 # bearing 7 to the intermediate casing 4, which is an important path for the fan rotor load to be transmitted to the intermediate casing 4. In order to protect the safety of the engine after the FBO event, a fuse member 6 is provided on the support cone wall 5. For some engines, a secondary fuse component is also provided near the 2 # bearing.

An intelligent retractable structure 15 is provided on the fan shaft 8, and the axial length of the structure 15 can be controlled according to operating conditions. Under normal working conditions, the fan shaft 8 is supported by 1 # bearings and 2 # bearings together, and the intelligent retractable structure maintains the initial length.

At the 1 # bearing and the 2 # bearing (including the vicinity of the bearing), sensors 12 and 11 are respectively set to monitor the dynamic response of the 1 # bearing and the 2 # bearing and are transmitted to the signal acquisition device through the

signal transmission lines

14 and 13 18, transmitted from the signal acquisition device 18 to the signal processing device 19. The signal processing device 19 can determine the running state of the engine according to the input signal.

An intelligent retractable structure 15 is provided on the fan shaft 8, and its length can be controlled by the signal processing device 19 according to operating conditions. The choice of the intelligent retractable structure 15 can be diversified. In one embodiment, a rare earth super magnetostrictive structure is used as an example. The length of the rare earth super magnetostrictive structure can be repeatedly extended and shortened with an external magnetic field. After removing the external magnetic field, , And restored to the original state, and has the advantages of good reversibility, fast response speed, strong carrying capacity and so on.

Under normal working conditions, the fan shaft 8 is supported by the 1 # bearing 7 and the 2 # bearing 9, the intelligent retractable structure 15 maintains the initial length S ₀ , and the axial distance between the 1 # bearing and the 2 # bearing is L ₀ , as shown 3 shown.

After the FBO incident, 1 # bearing 7 will bear a huge FBO load, its bearing seat or supporting cone wall 5 fusing part 6 fails, and the fan shaft 8 loses the constraint at 1 # bearing 7, and will be mainly subject to 2 # bearing 9 Constrained, the fan shaft 8 is similar to a cantilever structure. At this time, the engine is in a supercritical state due to the failure of the fuse member 6.

After the FBO event, the sensors 12 and 11 near the 1 # bearing 7 and the 2 # bearing 9 will test a significant dynamic response, and pass the collected dynamic response to the signal processing device 19 through the signal acquisition device 18. The signal processing device 19 sends a signal to the intelligent retractable structure 15 so as to extend along the predetermined range, thereby increasing the length of the fan shaft 8. At this time, the fan shaft 8 is similar to a cantilever beam structure. Increasing the length of the fan shaft 8 helps to further reduce the critical speed. During the stopping and decelerating phase after the FBO event, the engine is in a supercritical state due to the failure of the fuse component. Further reducing the critical speed can increase the interval between the critical and working speed, thereby significantly reducing the power of the engine during the stopping and decelerating process. Learn to respond.

As shown in FIG. 4, during the parking deceleration phase, the signal processing device 19 sends a signal to the intelligent retractable structure 15 to extend the length from S ₀ to S ₁ , and the length of the fan shaft 8 also increases accordingly. Increasing the axial equivalent distance between 2 # bearings 9 from L ₀ to L _{1 is} equivalent to increasing the length of the cantilever beam and further reducing the critical speed. This helps to increase the interval between the critical speed and the working speed, and significantly reduces the dynamic response of the engine during the process of stopping and decelerating.

After the FBO event, the engine will go through the process of stopping and decelerating until it reaches the windmill speed, and it lasts for a long time during the windmill speed phase. In the process of reducing the engine speed from the operating speed to the windmill speed, it will pass the critical speed. When the critical speed is exceeded, the dynamic response of the engine will increase significantly. When the signal processing device 19 determines from the signals monitored by the sensors 12 and 11 that the engine has passed a critical speed, it sends a signal to the intelligent retractable structure 15 to shrink it within a predetermined range and reduce the length of the fan shaft 8, thereby Increase the critical speed. When the engine reaches the rotation stage of the windmill, increasing the critical speed so that it is much higher than the speed of the windmill will help reduce the dynamic response of the engine.

In the foregoing embodiments, the types of sensors are not limited, as long as they can quickly capture signals generated by abnormal events of the engine, such as strain gauges, vibration sensors, or acceleration sensors. The monitoring position of the sensor is generally set in the area where the monitoring amount is not sensitive during the normal operation of the engine. After the FBO event, the monitoring amount becomes significantly larger, such as near the 1 # bearing and the 2 # bearing.

In the foregoing embodiments, the intelligent scalable structure has a variety, for example, controlling the expansion and contraction of the mechanical structure by controlling the magnitude of the current, or using a controllable intelligent material to change the length of the structure.

In the foregoing embodiment, the controller may be a microprogram controller, and the signal processing device and the signal acquisition device may be integrated by the same physical device, or one of them may be implemented by a program. In addition, the position of the signal processing device may be various, as long as There is a power supply that does not affect the normal operation of the engine. The signal transmitted by the sensor can be used for signal amplification and anti-interference.

The beneficial effects of the foregoing embodiments are reflected in:

1. During the stopping and decelerating phase after the FBO event, the engine is in a supercritical state. Through the extension of the intelligent retractable structure, the cantilever length of the fan shaft is increased to further reduce the critical speed and reduce the dynamic response during the stopping and decelerating phase.

2. During the rotation of the windmill, the engine is in a subcritical state. Through the contraction of the intelligent retractable structure, the cantilever length of the fan shaft is reduced to increase the critical speed, and the dynamic response of the engine is better reduced.

3. By controlling the length of the intelligent retractable structure, the critical speed of the rotor is adjusted in both directions, which reduces the design load of the engine component system and helps reduce the difficulty of designing the engine.

Although the present invention is disclosed as above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, all modifications, equivalent changes, and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention fall within the protection scope defined by the claims of the present invention.

Claims

Load reduction device for aero engine fan blade fall-off event, used for low-pressure rotor, the low-pressure rotor is supported by at least a first bearing and a second bearing, and the bearing seat of the first bearing is connected to the intermediate casing by a supporting cone wall. The load shedding device includes:

A fusible component, which is arranged in a bearing housing of the first bearing or the support cone wall;

Fan shaft, including intelligent retractable structure;

At least two sensors for monitoring the dynamic response of the first bearing and the second bearing;

A controller, which is respectively associated with the sensor and the intelligent scalable structure;

Wherein, the sensor detects the abnormal dynamic response of the first bearing and the second bearing, and transmits the detected dynamic response to a controller, and the controller sends a signal to the intelligent scalable structure, so that It expands and contracts along a predetermined range, thereby changing the length of the fan shaft.
The load reduction device for an aero-engine fan blade fall-off event according to claim 1, wherein the load reduction device further comprises a bearing block of the second bearing or the second bearing block is connected to an intermediate casing The secondary fuse parts are set on the wall of.
The load reduction device for an aero-engine fan blade fall-off event according to claim 1, wherein the intelligent telescopic structure is a rare earth giant magnetostrictive structure.
The load reduction device for an aero-engine fan blade fall event according to claim 1, wherein the sensor is a strain gauge, a vibration sensor, or an acceleration sensor.
Method for reducing load of aero engine fan blade falling event, used for low-pressure rotor, the fan shaft of the low-pressure rotor is supported by at least a first bearing and a second bearing, and the bearing seat of the first bearing is connected to the intermediary by a supporting cone wall The box is characterized by,

An intelligent retractable structure is set on the fan shaft. Under normal operating conditions, the fan shaft is supported by the first bearing and the second bearing together, and the intelligent retractable structure maintains the initial length;

After the fan blade fall-off event occurs, a sensor detects the dynamic response of the first bearing and the second bearing, and transmits the collected dynamic response to the controller, which sends a signal to the intelligent scalable structure. The intelligent telescopic structure is extended along a predetermined range, thereby increasing the length of the fan shaft.
The method for reducing load of an aero engine fan blade falling event according to claim 5, wherein after the fan blade falling event occurs, during the process of reducing the engine speed from the operating speed to the windmill speed, a critical speed is passed through the controller. The signal monitored by the sensor determines that the engine has passed a critical speed, and then sends a signal to the intelligent retractable structure to shrink it within a predetermined range and reduce the length of the fan shaft.