Nickel-titanium damped porous tilting pad bearings for low viscosity fluids and their control methods

Abstract

This invention relates to the field of fluid bearing technology, specifically to a nickel-titanium damping porous tilting pad bearing and its control method for low-viscosity fluids. The bearing includes a bearing sleeve, porous tilting pads, a nickel-titanium alloy damping layer, an air supply system, a sensor unit, a central controller, and a pressure actuator. The porous tilting pads achieve uniform fluid distribution and throttling. The nickel-titanium alloy damping layer provides efficient passive damping and can be actively enhanced through phase change. The central controller uses an adaptive fuzzy-PID algorithm and an LSTM prediction model based on historical data to generate push-pull pressure regulation commands targeting the vibration direction. The pressure actuator implements anisotropic pressure control through a regulating valve, directly generating active damping force. This invention significantly improves the damping characteristics, response speed, and directional vibration suppression capability of bearings in various low-viscosity and corrosive fluids, making it suitable for extreme operating conditions such as supercritical CO₂ power generation and liquid metal-cooled reactors.

Description

Technical Field

[0001] This invention relates to the field of fluid bearing technology, specifically to a nickel-titanium damped porous tilting pad bearing for low-viscosity fluids and a control method thereof. Background Technology

[0002] In the field of high-speed rotating machinery, such as supercritical carbon dioxide (sCO2) Brayton cycle power generation turbines and coolant pumps in liquid metal-cooled reactors, bearings need to operate stably in low-viscosity, potentially corrosive fluid media. Traditional rolling bearings and oil-lubricated sliding bearings face problems such as lubrication failure, working fluid contamination, and difficulty in maintaining ultra-high speeds under these conditions.

[0003] Porous tilting pad hydrostatic gas bearings utilize externally supplied high-pressure gas to form a high-rigidity, high-load-bearing gas film through a porous medium throttling device, offering advantages such as pollution-free operation and high speed. However, existing technologies are primarily designed for conventional gases like air, exhibiting inherent limitations when applied to low-viscosity fluids. Their stability heavily relies on the damping generated by the gas film, but in low-viscosity fluids, the damping characteristics of the fluid film are poor. Especially when the rotor exceeds the critical speed or experiences disturbances, subsynchronous vibrations are easily induced, leading to system instability.

[0004] To address the problem of insufficient damping, existing improvement solutions mainly fall into two categories. One category involves structural optimization, such as using flexible damping components like corrugated stainless steel sheets to connect the support tiles and tilting tiles. The other category employs piezoelectric ceramic actuators for active control, using PVDF sensors to detect vibrations and controlling the expansion and contraction of the piezoelectric ceramics to alter the stiffness of the mechanical structure, thereby indirectly affecting the system damping. However, these solutions still have the following significant drawbacks:

[0005] Poor media adaptability: The structural design is based on gaseous media, and the materials of key components may be incompatible due to corrosion from supercritical CO2 or liquid metals, resulting in decreased reliability;

[0006] The control response is indirect and slow: the damping is indirectly affected by changing the stiffness through "mechanical adjustment". There is a transmission link, the response speed is slow, and it is difficult to track the complex vibration modes of high-speed rotors in real time.

[0007] Limited Damping Enhancement: The slight deformation of piezoelectric ceramics has a limited effect on improving the damping of the entire system. When faced with the inherent weak damping characteristics of low-viscosity fluids, the stability margin is insufficient.

[0008] Lack of anisotropic control capability: It is difficult to implement independent and precise control of the bearing blocks at different positions in the circumferential direction, and it is impossible to apply the most effective suppression force for the directionality of vibration, resulting in low control efficiency.

[0009] Therefore, there is an urgent need for a new type of intelligent bearing technology that can adapt to a variety of low-viscosity fluids and has fast response and high damping characteristics. Summary of the Invention

[0010] The purpose of this invention is to provide a nickel-titanium damped porous tilting pad bearing and a control method for low-viscosity fluids, so as to solve the technical problems of insufficient bearing damping, poor stability, weak media adaptability and lag in control response under low-viscosity fluid conditions.

[0011] To achieve the above objectives, the present invention provides the following technical solution: a nickel-titanium damping porous tilting pad bearing for low-viscosity fluids, comprising:

[0012] Rotor 1 and bearing sleeve 3;

[0013] Multiple porous tilting pads 5 are arranged circumferentially within the bearing sleeve 3 and located on the surface of the rotor 1. The porous tilting pads 5 have interconnected pores inside, allowing fluid to pass through and achieving uniform throttling.

[0014] The nickel-titanium alloy damping layer 6 is a layered structure composed of multiple layers of nickel-titanium alloy mesh fixed by spot welding. It is disposed between the inner wall of the porous tiltable tile 5 and the bearing sleeve 3, and is tightly bonded to the two in a pre-pressing manner to provide passive damping.

[0015] An independent air supply system is connected to each of the porous tilting tiles 5, the independent air supply system being used to independently supply high-pressure fluid to the gap between the porous tilting tiles 5 and the rotor 1, the independent air supply system comprising:

[0016] A sensor unit is used to detect the radial vibration displacement signal of the rotor 1 relative to each of the porous tilting tiles 5 in real time.

[0017] An air supply hole 4 is provided on the surface of the bearing sleeve 3, and the air outlet end of the air supply hole 4 is connected to the gap between the porous tilting pad 5 and the rotor 1.

[0018] The central controller integrates a memory for storing historical vibration data. The central controller is configured to: receive the vibration displacement signal; use the stored historical vibration data to predict the vibration trend for a preset duration using an LSTM neural network, and simultaneously tune the PID control parameters in real time using an adaptive fuzzy-PID control algorithm; based on the predicted vibration trend and the tuned control parameters, analyze the real-time vibration direction and amplitude of rotor 1, determine the main vibration direction and its corresponding porous tilting tile 5; generate a pressure increase command for the porous tilting tile 5 corresponding to the main vibration direction, and a pressure reduction command for the porous tilting tile 5 opposite to it, thereby forming a push-pull pressure regulation command.

[0019] The pressure actuation unit includes a pressure regulating valve provided for each of the air supply ports 4. The pressure regulating valve responds to the pressure regulating command and independently regulates the fluid pressure supplied to each of the porous tilting pads 5 in a push-pull mode, thereby generating an active damping force to suppress rotor vibration.

[0020] The central controller is communicatively connected to the pressure actuation unit to send the pressure regulation command to the corresponding pressure regulating valve.

[0021] Preferably, the inner wall of the bearing sleeve 3 is provided with a plurality of mounting grooves for mounting porous tilting pads 5, wherein the porous tilting pads 5 are made of porous graphite or porous ceramic with a porosity of 10%-20%.

[0022] Preferably, the nickel-titanium alloy damping layer 6 is composed of 3 to 5 layers of nickel-titanium alloy mesh, with a single wire diameter of 0.1-0.3 mm. The mesh count of the nickel-titanium alloy damping layer 6 increases gradually from the outside to the inside along the radial direction of the bearing. The layers are fixed by spot welding. The thickness of the nickel-titanium alloy damping layer 6 is 2 mm to 5 mm.

[0023] Preferably, the sidewall of the rotor 1 is provided with rotor slots 2 that are evenly distributed around the circumference of the rotor 1. The depth of the rotor slots 2 is 0.5mm-1mm and the width is 2mm-3mm. The extension direction of the rotor slots 2 forms an angle of 15°-30° with the axis of the rotor 1.

[0024] Preferably, the air supply port 4 is threadedly connected to the air supply pipe 7 at the air inlet end, and an O-ring is provided at the connection part. The air supply pipe 7 is a flexible metal corrugated pipe, and the air supply port 4 is a multi-stage throttling orifice with the orifice diameter decreasing sequentially from the outside to the inside along the airflow direction.

[0025] A control method for the aforementioned nickel-titanium damped porous tilting pad bearing for low-viscosity fluids includes the following steps:

[0026] S1. Signal Acquisition: The radial vibration displacement signal of rotor 1 is acquired in real time through the sensor unit. The acquired signal is processed by anti-aliasing filtering, analog-to-digital conversion and bandpass digital filtering to extract the frequency band signal related to rotor vibration.

[0027] S2. Vibration prediction and parameter tuning: Based on the processed frequency band signal, the historical vibration data is analyzed through the LSTM neural network to predict the rotor vibration trend within a preset time period. At the same time, the PID control parameters are tuned in real time according to the vibration error and the error change rate through the adaptive fuzzy-PID composite control algorithm.

[0028] S3, Pressure Regulation Control: Based on the adjusted control parameters and vibration prediction results, PWM control signals corresponding to each pressure regulating valve are generated. A push-pull control strategy is adopted to increase the air supply pressure of the porous tiltable tile 5 corresponding to the main vibration direction, while decreasing the air supply pressure of the porous tiltable tile 5 opposite to it, forming a damping couple to suppress vibration.

[0029] S4. Feedback Optimization: Real-time acquisition of the radial vibration displacement signal of rotor 1 after control, comparison of vibration suppression effect, storage of control process and corresponding result data into historical database, used for online optimization of LSTM neural network parameters and fuzzy rule base weights, to complete closed-loop control.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] This invention integrates porous tilting tiles with controllable porosity and a gradient mesh nickel-titanium alloy damping layer into a tilting tile structure. It can adapt to extreme operating conditions of various low-viscosity fluids such as supercritical CO2, hydrogen, and liquid metal. It has excellent media compatibility and wide-temperature-range adaptive damping adjustment capability. With the intelligent control system that independently pressurizes each tile, it realizes millisecond-level push-pull anisotropic active control. Through the synergistic effect of passive damping and active damping, it significantly improves the damping coefficient and vibration attenuation efficiency of the bearing under low-viscosity fluid conditions. It effectively solves the core problems of insufficient damping, poor stability, lag in control response, and weak media adaptability of traditional bearings. At the same time, the bearing structure has no vulnerable mechanical transmission parts, and the porous material has self-lubricating properties. It can be widely adapted to the harsh operating requirements of high-speed rotating machinery in various fields such as supercritical CO2 power generation and liquid metal cooled reactors. Attached Figure Description

[0032] Figure 1 This is an exploded view of the overall structure of the nickel-titanium damping porous tilting pad bearing for low-viscosity fluids according to the present invention.

[0033] Figure 2 This is a schematic diagram of the overall structure of the nickel-titanium damping porous tilting pad bearing for low-viscosity fluids according to the present invention.

[0034] Figure 3 This is a schematic diagram of the nickel-titanium damping porous tilting pad bearing sleeve structure for low-viscosity fluids according to the present invention.

[0035] Figure 4 This is a schematic diagram of the nickel-titanium alloy damping layer structure of the nickel-titanium damping porous tilting pad bearing for low viscosity fluids according to the present invention.

[0036] Figure 5 This is a schematic diagram of the nickel-titanium damped porous tilting pad bearing rotor structure for low-viscosity fluids according to the present invention.

[0037] Figure 6 This is a schematic diagram of the air supply pipe and air supply hole connection structure of the nickel-titanium damping porous tilting pad bearing for low viscosity fluids according to the present invention.

[0038] In the diagram: 1. Rotor; 2. Rotor slot; 3. Bearing sleeve; 4. Air supply port; 5. Porous tilting tile; 6. Nickel-titanium alloy damping layer; 7. Air supply pipe. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Please see Figure 1-6 This invention provides a technical solution: a nickel-titanium damping porous tilting pad bearing for low-viscosity fluids, comprising:

[0041] Rotor 1 has a chrome-plated surface to improve its wear resistance and corrosion resistance. The sidewall of rotor 1 has 12-24 rotor slots 2 evenly distributed around the circumference of rotor 1. The depth of rotor slots 2 is 0.5mm-1mm and the width is 2mm-3mm. The extension direction of rotor slots 2 forms an angle of 15°-30° with the axis of rotor 1, which can promote the axial flow of fluid. The structure of rotor slots 2 can effectively disrupt the continuity of fluid film and suppress oil film eddy and subsynchronous vibration.

[0042] Bearing sleeve 3 is the support structure of the bearing. Bearing sleeve 3 is a rigid support shell made of high-strength stainless steel to ensure the overall structural stability. The inner wall of bearing sleeve 3 has multiple mounting grooves for installing porous tilting pads 5.

[0043] Multiple porous tilting pads 5 are arranged circumferentially inside the bearing sleeve 3 and located on the surface of the rotor 1. The porous tilting pads 5 are made of porous graphite or porous ceramic with a porosity of 10%-20%. They have interconnected pores inside, allowing fluid to pass through and achieving uniform throttling, adapting to the variable viscosity characteristics of low viscosity media such as supercritical CO2 and hydrogen.

[0044] The nickel-titanium alloy damping layer 6 is a layered structure composed of multiple layers of nickel-titanium alloy mesh fixed by spot welding. It is placed between the porous tilting pad 5 and the inner wall of the bearing sleeve 3 and is tightly bonded to both of them by pre-compression to provide passive damping. The nickel-titanium alloy damping layer 6 is composed of 3 to 5 layers of nickel-titanium alloy mesh, with a single wire diameter of 0.1-0.3 mm. The mesh count of the nickel-titanium alloy damping layer 6 varies from the outside to the inside along the radial direction of the bearing, with the outer layer being 100 mesh and the inner layer being 200 mesh. The layers are fixed by spot welding. The thickness of the nickel-titanium alloy damping layer 6 is 2 mm-5 mm.

[0045] An independent air supply system is connected to each porous tilting tile 5. This independent air supply system independently supplies high-pressure fluid to the gap between the porous tilting tile 5 and the rotor 1, achieving anisotropic pressure control. The independent air supply system includes:

[0046] The sensor unit is used to detect the radial vibration displacement signal of the rotor 1 relative to each porous tiltable tile 5 in real time.

[0047] An air supply hole 4 is provided on the surface of the bearing sleeve 3, and the air outlet end of the air supply hole 4 is connected to the gap between the porous tilting pad 5 and the rotor 1. The air inlet end of the air supply hole 4 is threadedly connected to the air supply pipe 7, and an O-ring is provided at the connection. The air supply pipe 7 is a flexible metal bellows that allows a certain radial displacement. The air supply hole 4 is a multi-stage throttling hole with the diameter decreasing from the outside to the inside along the airflow direction.

[0048] The central controller integrates a memory for storing historical vibration data. It is configured to: receive vibration displacement signals; use the stored historical vibration data to predict future vibration trends for a preset duration via an LSTM neural network, while simultaneously tuning PID control parameters in real time using an adaptive fuzzy-PID control algorithm; analyze the real-time vibration direction and amplitude of rotor 1 based on the predicted vibration trend and the tuned control parameters, determining the main vibration direction and its corresponding porous tilting pad 5; and generate a pressure increase command for the porous tilting pad 5 corresponding to the main vibration direction, and a pressure reduction command for the opposite porous tilting pad 5, thus forming a push-pull pressure regulation command.

[0049] The pressure actuator includes a pressure regulating valve provided for each air supply port 4. The pressure regulating valve responds to the pressure regulating command and independently regulates the fluid pressure supplied to each porous tiltable tile 5 in a push-pull mode, thereby generating an active damping force to suppress rotor vibration.

[0050] The central controller is connected in communication with the pressure actuator to send pressure regulation commands to the corresponding pressure regulating valve.

[0051] The assembly process is as follows:

[0052] Step 1: Prepare parts: Clean all parts to ensure they are free of contamination. The rotor 1 is chrome-plated. The porous tilting pads 5 in the bearing sleeve 3 are made of graphite or ceramic.

[0053] Step 2: Install the nickel-titanium alloy damping layer 6: After spot welding the nickel-titanium alloy damping layer 6, pre-press it into the inner wall of the bearing sleeve to ensure a tight fit without gaps. The thickness of the nickel-titanium alloy damping layer 6 is adjusted by shims and controlled within the range of 2-5mm.

[0054] Step 3: Install the porous tilting pad 5: Embed the porous tilting pad 5 into the circumferential mounting groove of the bearing sleeve 3. The porous tilting pad 5 is connected to the mounting groove by adhesive. The air supply hole 4 is aligned with the channel on the porous tilting pad 5.

[0055] Step 4: Connect the air supply system: The air supply pipe 7 is connected to the air supply hole 4 of the bearing sleeve 3 through a threaded seal. A flexible bellows is used to accommodate thermal expansion. Each air supply pipe 7 is independently controlled, and O-rings are used to seal the interface.

[0056] Step 5: Assembly and Testing: Install rotor 1 into bearing sleeve 3, install end cover to form a sealed cavity, and conduct airtightness test and low-speed operation test to confirm that there is no leakage and the lubricating film is uniform.

[0057] The work process is as follows:

[0058] Start-up phase: First, high-pressure fluid (approximately 5-6 atmospheres) is introduced. The hydrostatic lubrication film supports rotor 1, preventing dry friction. The fluid is uniformly throttled through porous tilting pads 5, forming a stable gas film.

[0059] During operation: As the rotational speed increases, the rotor slots 2 promote axial fluid flow, and the hydrodynamic effect enhances the lubrication film pressure. The nickel-titanium alloy damping layer 6 absorbs vibration energy. As the operating conditions change and the temperature rises, the nickel-titanium alloy damping layer 6 undergoes phase transformation and shrinkage, actively increasing the preload and further improving the damping coefficient.

[0060] The control process employs a closed-loop adaptive adjustment mechanism, which achieves real-time suppression of rotor vibration and maintenance of system stability through the cyclical execution of four stages: signal acquisition, algorithm processing, pressure regulation, and feedback optimization. The specific process is as follows:

[0061] Signal acquisition: Multiple high-precision eddy current displacement sensors or PVDF piezoelectric film sensors are evenly distributed around the bearing sleeve 3 to monitor the radial vibration displacement of rotor 1 relative to each porous tilting tile 5 in real time. The acquired analog signals are converted into digital signals through anti-aliasing filtering and a 24-bit high-precision analog-to-digital converter. Subsequently, they are passed through a bandpass digital filter with a cutoff frequency of 0.1-1.5 times the rotor's rated speed to filter out high-frequency electrical noise and low-frequency drift, extracting the frequency band signals directly related to rotor vibration.

[0062] S2. Vibration Prediction and Parameter Tuning: Adaptive fuzzy-PID composite control is adopted, introducing a fuzzy logic layer on the basis of the traditional PID algorithm to achieve parameter self-tuning. The control output is determined by the following formula:

[0063]

[0064] The initial parameter tuning range for the PID is: K p =20-35, K i =0.4-0.8, K d =1.5-3.0 (tuned based on the Ziegler-Nichols method); based on LSTM network analysis of vibration data from the past 1000 cycles (sampling frequency 10kHz, corresponding to 100ms of historical data), predict the vibration trend within the next 10ms; if a critical speed (e.g., the rotor's first-order critical speed ±5%) is detected to be approaching, K is adjusted in advance according to fuzzy rules. p K i K d The initial value is adjusted with a step size of ±10%; the fuzzy logic layer uses a 7×7 rule base, with the input variables being the vibration error e (universe of discourse [-1.5, 1.5]) and the error change rate ec (universe of discourse [-0.5, 0.5]), and the output being ΔK. p ΔK i ΔK d (Universe of discourse [-1,1]); The controller maps pressure commands to the corresponding porous tiltable tile 5 according to the vibration direction. The amplitude of the pressure command ranges from 0.2 to 0.8 MPa. Historical data is used to optimize the mapping weights using the least squares method. The weight iteration step size is 0.05, and the mapping accuracy is improved to ±0.02 MPa.

[0065] S3. Pressure Regulation Control: Each porous tilting pad 5 is connected to a pressure regulating valve through an independent air supply system. The controller outputs a PWM signal to drive the valve, using push-pull control for pressure regulation. If the vibration mainly occurs in the radial direction corresponding to a certain porous tilting pad 5, the air supply pressure of that porous tilting pad 5 is increased, while the pressure on the opposite porous tilting pad 5 is decreased, forming a damping couple to suppress vibration. The mapped pressure command is sent to the high-speed pressure regulating valve of the corresponding porous tilting pad 5 in the form of a PWM signal, with a response speed of less than 1ms and a pressure regulation range of 0.2-0.8MPa. Pressure regulation directly changes the flow rate of the high-pressure fluid flowing into the back chamber of the porous tilting pad 5, thereby dynamically and independently adjusting the fluid film pressure and stiffness between the porous tilting pad 5 and the rotor 1 to generate the required active damping force.

[0066] S4. Feedback Optimization: The radial vibration displacement signal of rotor 1 after control is collected in real time, the vibration suppression effect is compared, and the control process and corresponding result data are stored in the historical database. If the vibration is not effectively suppressed, the historical data learning module will record the control-result pair and use it to fine-tune the weights of the fuzzy rule base or the LSTM network parameters to achieve online adaptive optimization of the control strategy and complete closed-loop control. The LSTM neural network parameters and the weights of the fuzzy rule base are updated every 100-1000 control cycles.

[0067] Example

[0068] To verify the damping performance of the nickel-titanium damped porous tilting pad bearing of the present invention, comparative tests were conducted.

[0069] The bearing of the present invention (experimental group): The nickel-titanium alloy damping layer 6 is composed of 5 layers of nickel-titanium alloy mesh, with a single wire diameter of 0.2 mm. The mesh count of the nickel-titanium alloy damping layer 6 changes gradually from the outside to the inside along the radial direction of the bearing, with the outer layer being 100 mesh, the middle layer being 150 mesh, and the inner layer being 200 mesh. The layers are fixed by spot welding.

[0070] Traditional control bearing: Except for the damping layer being replaced with a nitrile rubber damping layer of the same thickness, the rest of the structure (bearing sleeve, porous tilting pad, air supply system, etc.) is the same as the experimental group.

[0071] Test equipment and methods:

[0072] Test bench: A high-speed rotating mechanical dynamic performance test bench is used, and the test fluid medium is helium (viscosity approximately 2×10⁻). 5 Pa·s (simulating low viscosity conditions), with the gas supply pressure stabilized at 0.5 MPa.

[0073] Damping test: A radial harmonic excitation force was applied to the non-drive end of the rotor using an electromagnetic exciter, and the radial vibration response of the rotor was measured using a laser displacement sensor. The equivalent damping coefficients of the two sets of bearings were tested using the half-power bandwidth method under the conditions of an excitation frequency of 200 Hz and a temperature of 120 ℃.

[0074] Transient response test: The rotor is driven at 10,000 rpm, and a transient eccentricity disturbance of 0.05 mm is artificially created by the control system. The time required for the rotor vibration amplitude to decay to 5% of the initial value after the disturbance is recorded to evaluate the vibration decay efficiency.

[0075] Test results:

[0076] Passive damping coefficient: At room temperature (25℃), the passive damping coefficient of the experimental group bearing was measured to be 8100 N·s / m, while that of the control group bearing was 3200 N·s / m.

[0077] Overall damping coefficient: Under 120℃ operating conditions, the nickel-titanium alloy damping layer undergoes a phase transition, increasing the overall damping coefficient of the experimental bearings to 1.25 × 10⁻⁶. 4 N / (m·s), while the performance of the rubber damping layer in the control group decreased, with the damping coefficient dropping to approximately 2800 N·s / m.

[0078] Vibration damping efficiency: In transient response testing, the vibration damping time of the experimental bearing was 8 ms, while that of the control bearing was 21 ms. Calculations show that the vibration damping efficiency of the bearing of this invention (evaluated as the reciprocal of the damping time) is approximately 162% higher than that of traditional rubber damping layer bearings. If calculated based on the vibration energy dissipated per unit time, the efficiency improvement exceeds 60%.

[0079] The experimental results show that the present invention significantly improves the damping effect of the extrusion membrane of the system. The present invention provides high passive damping of ≥8000 N·s / m through the extrusion membrane effect. The shape changes by 0.5%-2% depending on the operating temperature (-20℃~150℃), further improving the damping coefficient to 1.2×104 N / (m·s). Compared with the traditional rubber damping layer, the vibration attenuation efficiency is improved by more than 60%.

[0080] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0081] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A nickel-titanium damping porous tilting pad bearing for low-viscosity fluids, characterized in that: include: Rotor (1) and bearing sleeve (3); Multiple porous tilting pads (5) are arranged circumferentially inside the bearing sleeve (3) and located on the surface of the rotor (1). The porous tilting pads (5) have interconnected pores inside, allowing fluid to pass through and achieving uniform throttling. The nickel-titanium alloy damping layer (6) is a layered structure made up of multiple layers of nickel-titanium alloy mesh fixed by spot welding. It is set between the inner walls of the porous tiltable tile (5) and the bearing sleeve (3) and is tightly bonded to the two in a pre-pressing manner to provide passive damping. An independent air supply system corresponding to each of the porous tilting tiles (5), the independent air supply system being used to independently supply high-pressure fluid to the gap between the porous tilting tiles (5) and the rotor (1), the independent air supply system comprising: A sensor unit is used to detect the radial vibration displacement signal of the rotor (1) relative to each of the porous tilting tiles (5) in real time; An air supply hole (4) is opened on the surface of the bearing sleeve (3), and the air outlet end of the air supply hole (4) is connected to the gap between the porous tilting pad (5) and the rotor (1). The central controller integrates a memory for storing historical vibration data. The central controller is configured to: receive the vibration displacement signal; use the stored historical vibration data to predict the vibration trend for a preset duration in the future through an LSTM neural network, and simultaneously tune the PID control parameters in real time through an adaptive fuzzy-PID control algorithm; based on the predicted vibration trend and the tuned control parameters, analyze the real-time vibration direction and amplitude of the rotor (1), determine the main vibration direction and its corresponding porous tilting tile (5); generate a pressure increase command for the porous tilting tile (5) corresponding to the main vibration direction, and a pressure reduction command for the porous tilting tile (5) opposite to it, thereby forming a push-pull pressure regulation command; The pressure actuation unit includes a pressure regulating valve provided for each of the air supply ports (4), which, in response to the pressure regulating command, independently regulates the fluid pressure supplied to each of the porous tiltable tiles (5) in a push-pull mode, thereby generating an active damping force to suppress rotor vibration.

2. The nickel-titanium damping porous tilting pad bearing for low-viscosity fluids according to claim 1, characterized in that: The inner wall of the bearing sleeve (3) is provided with multiple mounting grooves for installing porous tilting tiles (5), which are made of porous graphite or porous ceramic with a porosity of 10%-20%.

3. The nickel-titanium damping porous tilting pad bearing for low-viscosity fluids according to claim 1, characterized in that: The nickel-titanium alloy damping layer (6) is composed of 3 to 5 layers of nickel-titanium alloy mesh, with a single wire diameter of 0.1-0.3 mm. The mesh count of the nickel-titanium alloy damping layer (6) increases gradually from the outside to the inside along the radial direction of the bearing. The layers are fixed by spot welding. The thickness of the nickel-titanium alloy damping layer (6) is 2 mm-5 mm.

4. The nickel-titanium damping porous tilting pad bearing for low-viscosity fluids according to claim 1, characterized in that: The sidewall of the rotor (1) is provided with rotor slots (2) that are evenly distributed along the circumference of the rotor (1). The depth of the rotor slots (2) is 0.5mm-1mm and the width is 2mm-3mm. The extension direction of the rotor slots (2) forms an angle of 15°-30° with the axis of the rotor (1).

5. The nickel-titanium damping porous tilting pad bearing for low-viscosity fluids according to claim 1, characterized in that: The air supply port (4) is threadedly connected to an air supply pipe (7), and an O-ring is provided at the connection. The air supply pipe (7) is a flexible metal corrugated pipe, and the air supply port (4) is a multi-stage throttling orifice with the orifice diameter decreasing sequentially from the outside to the inside along the airflow direction.

6. A control method for a nickel-titanium damped porous tilting pad bearing for low-viscosity fluids as described in any one of claims 1-5, characterized in that: Includes the following steps: S1, Signal Acquisition: The radial vibration displacement signal of the rotor (1) is acquired in real time through the sensor unit. The acquired signal is processed by anti-aliasing filtering, analog-to-digital conversion and bandpass digital filtering to extract the frequency band signal related to rotor vibration. S2. Vibration prediction and parameter tuning: Based on the processed frequency band signal, the historical vibration data is analyzed through the LSTM neural network to predict the rotor vibration trend within a preset time period. At the same time, the PID control parameters are tuned in real time according to the vibration error and the error change rate through the adaptive fuzzy-PID composite control algorithm. S3, Pressure Regulation Control: Based on the adjusted control parameters and vibration prediction results, generate PWM control signals corresponding to each pressure regulating valve, adopt push-pull control strategy, increase the air supply pressure of the porous tiltable tile (5) corresponding to the main vibration direction, and at the same time reduce the air supply pressure of the porous tiltable tile (5) opposite to it, forming a damping couple to suppress vibration. S4. Feedback optimization: Real-time acquisition of the radial vibration displacement signal of the rotor (1) after control, comparison of vibration suppression effect, storage of control process and corresponding result data into historical database, used for online optimization of LSTM neural network parameters and fuzzy rule base weights, to complete closed-loop control.

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