Underwater intelligent thermal control system and method based on sensing skin and vortex generator

Abstract

The invention belongs to the related technical field of underwater vehicle thermal management and active flow control, and discloses an underwater intelligent thermal control system and method based on a sensing skin and a vortex generator. The system comprises a flexible dual-mode sensing module, a self-adaptive eddy current generation module and a closed-loop control module. The flexible dual-mode sensing skin adopts a multi-layer flexible structure and monitors the flow velocity and the temperature in real time; the vortex generator array adaptively adjusts an attack angle according to sensing data, and local heat transfer is enhanced by inducing a longitudinal vortex; and the closed-loop controller adjusts a driving signal based on a PID algorithm to realize dynamic thermal adjustment. The invention provides a flow control mechanism capable of self-adaptively adjusting according to a real-time thermal load, a sensing-decision-driving integrated closed-loop control system is constructed, whole-course intelligent thermal management from sensing to dissipation is realized, high-precision and decoupling synchronous measurement of the temperature and the flow speed of a surface flow field of a motor is promoted, and the temperature and the flow speed of the surface flow field of the motor are accurately measured. And the interference of temperature fluctuation on flow velocity measurement is overcome.

Description

Technical Field

[0001] This invention belongs to the technical field of thermal management and active flow control for underwater vehicles, and more specifically, relates to an intelligent underwater thermal control system and method based on sensor skin and vortex generator. Background Technology

[0002] Autonomous underwater vehicles (AUVs) are core equipment for deep-sea exploration, marine monitoring, and resource development. With increasingly demanding mission requirements, their propulsion systems are evolving towards higher power density, higher operating speeds, and greater autonomous intelligence. However, while increasing power density overcomes significant hydrodynamic resistance, it also leads to a sharp increase in the thermal load on the propulsion motors, making efficient and reliable thermal management a key technological bottleneck restricting the performance and reliability of AUVs.

[0003] Traditional propulsion motor cooling solutions primarily rely on liquid cooling technology due to its higher heat capacity and thermal conductivity compared to air. Existing technological approaches can be divided into two categories: The first is passive cooling strategies. These include increasing coolant flow rate, lowering coolant inlet temperature, or adding vortex generators at fixed angles in the flow channel, as well as designing advanced thermal structures such as multi-channel water jackets. While these methods can improve heat dissipation to some extent, they inherently lack the ability to sense and respond to spatially non-uniform and time-varying thermal loads. Fixed-structure vortex generators can only achieve optimal performance under specific operating conditions; when flow velocity or thermal load changes, their enhanced heat transfer effect will significantly decrease, and they may even lead to additional power consumption due to unnecessary flow resistance. In other words, traditional passive cooling systems are "open-loop" and cannot adaptively adjust according to the motor's real-time thermal state, making them inadequate for handling complex operating conditions such as variable speed and load in AUVs. The second category is active control attempts based on advanced sensing. In recent years, the development of flexible electronics technology has brought new possibilities for flow field sensing and thermal monitoring. Its conformal surface, thinness, and distributed integration capabilities make it ideal for deployment on the complex curved surfaces of AUVs. Flexible heat flow sensors, in particular, are considered key to intelligent thermal management because they can simultaneously quantify flow velocity and heat exchange kinetics by mapping convective heat loss. However, applying such flexible sensors to underwater environments with high thermal conductivity and variable temperatures presents a significant challenge: the temperature-flow velocity coupling effect. The sensor output signal is affected by both flow velocity and fluid temperature changes. Measurement drift caused by viscous heating or ambient temperature fluctuations is significant under high-speed flow, severely limiting its accuracy and reliability in complex underwater environments.

[0004] In summary, existing technologies exhibit a significant disconnect between perception and control: either they lack real-time, accurate sensing capabilities (e.g., passive cooling), or the sensing technology itself is unreliable in complex environments (e.g., flexible sensors are susceptible to temperature interference), making it difficult to construct a truly adaptive, high-precision underwater intelligent thermal control system. Therefore, there is an urgent need to design an underwater intelligent thermal control system and method based on sensing skin and vortex generators, capable of deeply integrating high-precision, interference-resistant flow field perception with rapid, adaptive flow control. This would effectively address the limitations of traditional liquid-cooled heat dissipation management technologies, significantly improve the adaptability and reliability of AUVs in complex marine environments, and provide strong technical support for deep-sea exploration. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides an underwater intelligent thermal control system and method based on sensor skin and vortex generator. Its purpose is to achieve intelligent thermal regulation and optimal energy management of the underwater vehicle propulsion system under dynamic operating conditions, thereby solving the technical problems of the lack of adaptability of existing passive cooling strategies and the limitation of measurement accuracy of traditional sensing technology in complex underwater environments by the temperature-flow velocity coupling effect.

[0006] To achieve the above objectives, according to one aspect of the present invention, an underwater intelligent thermal control system based on sensor skin and vortex generator is provided, comprising: A flexible dual-mode sensing module for real-time monitoring of the temperature and velocity of the flow field includes at least two flexible dual-mode sensing skins, which are respectively arranged upstream and downstream of the propulsion motor cooling channel. An adaptive eddy current generation module includes an array of eddy current generators driven by shape memory alloy actuators, which adaptively adjusts the angle of attack based on sensing data to induce longitudinal eddies to enhance local heat transfer. The closed-loop control module is used to receive data from the flexible dual-mode sensing module and drive the adaptive eddy current generator module according to a preset control strategy to achieve dynamic thermal regulation.

[0007] Preferably, the flexible dual-mode sensing skin adopts a multi-layer flexible structure, including a flexible printed circuit board, a dual-mode sensing layer, and an encapsulation layer arranged sequentially from bottom to top; the flexible printed circuit board serves as a substrate, and the encapsulation layer covers the outside to provide waterproof protection.

[0008] Preferably, the dual-mode sensing layer includes: a hot film element for sensing flow velocity by measuring convective heat loss; a cold film element arranged around the hot film element for measuring fluid temperature and dynamically compensating for the measurement results of the hot film element; and a flexible polyimide substrate for providing support.

[0009] Preferably, the flexible dual-mode sensing skin is attached to the wall of the propulsion motor cooling channel, and it is encapsulated with polyurethane waterproof material, with a total thickness not exceeding 100μm.

[0010] Preferably, the vortex generator has a triangular winglet structure, the material is polylactic acid, and the angle of attack can be continuously adjusted within the range of 0° to 90°.

[0011] Preferably, the shape memory alloy actuator is driven by Joule heating, and its heating current is adjusted by the pulse width modulation signal output by the closed-loop control module.

[0012] Preferably, the system further includes an angle sensor for real-time monitoring of the deflection angle of the vortex generator and feeding it back to the closed-loop control module.

[0013] Preferably, the closed-loop control module adopts a hybrid PID control algorithm, using the temperature difference between the upstream and downstream flexible dual-mode sensing skin as a feedback signal to adjust the angle of attack of the vortex generator.

[0014] Preferably, the vortex generator array is arranged within the propulsion motor cooling channel, located between the upstream and downstream flexible dual-mode sensing skins.

[0015] According to another aspect of the present invention, an underwater intelligent thermal control method based on sensing skin and a vortex generator is provided, comprising the following steps: S1. Real-time acquisition of temperature and velocity data of the flow field through upstream flexible dual-mode sensing skin; S2. Based on the real-time temperature data calculated in step S1, when it exceeds the preset threshold, the control module regulates the drive circuit to output current to heat and start the shape memory alloy driver, adjust the angle of attack of the vortex generator located in the middle, and feed back the angle signal to the closed-loop control module through the embedded angle sensor. S3. Based on the increase in the angle of attack of the vortex generator in step S2, a vortex is generated and the convective heat exchange in the downstream region is improved, thereby achieving the cooling effect in the downstream region; S4. Monitor the adjusted temperature and flow rate through the downstream flexible dual-mode sensor skin, calculate the upstream and downstream temperature difference, and monitor the cooling effect of the downstream area in S3. S5. Based on the comparison between the temperature difference calculated in step S3 and the preset downstream temperature value, the angle of attack of the vortex generator is iteratively adjusted through the closed-loop control module until the downstream temperature of the system reaches a stable thermal equilibrium state.

[0016] In summary, compared with the prior art, the underwater intelligent thermal control system and method based on sensor skin and vortex generator provided by the present invention have the following beneficial effects: 1. System intelligence and adaptability: A complete closed-loop control loop of "perception-decision-drive-verification" has been established, enabling the system to respond in real time to dynamically changing heat load and flow field conditions, realizing a leap from "passive cooling" to "active intelligent adjustment".

[0017] 2. High integration and strong environmental adaptability: The total thickness of the flexible skin does not exceed 100 μm. The entire system adopts a flexible and conformal design with extremely thin thickness, which can be seamlessly attached to complex curved surfaces. The waterproof encapsulation ensures its long-term reliability in high-pressure and corrosive underwater environments.

[0018] 3. High measurement accuracy and reliability: The innovative dual-mode (hot film / cold film) sensing structure and dynamic temperature compensation mechanism fundamentally solve the temperature-flow velocity measurement coupling problem in underwater high thermal conductivity environments, providing a stable and reliable data foundation.

[0019] 4. Significantly improved cooling efficiency: The adaptive vortex generator array actively generates longitudinal vortices, enabling precise control of the local flow field.

[0020] 5. Energy efficiency optimization: The closed-loop control strategy ensures that the vortex generator starts and operates at the optimal angle of attack only when needed, avoiding unnecessary flow resistance losses caused by a fixed vortex generator, and achieving the best balance between heat dissipation performance and energy consumption. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structural design of the underwater intelligent thermal control system of the present invention; Figure 2 This is a schematic diagram illustrating the working principle of the flexible dual-mode sensing skin of the present invention; Figure 3 This is a schematic diagram of the prototype of the underwater intelligent thermal control system of the present invention; Figure 4 This is a schematic diagram of the adaptive thermal regulation mechanism and system framework of the method of the present invention; Figure 5 This is a signal response curve of the dual-mode sensing skin of the present invention under a water flow of 0-20 m / s; Figure 6 This is a simulation result diagram of the system eddy current heat dissipation regulation of the present invention; In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-Cold element; 2-Hot film element; 3-Encapsulation layer; 4-Dual-mode sensing layer; 5-Flexible printed circuit board; 6-Vortex generator; 7-Shape memory alloy driver; 8-Upstream flexible dual-mode sensing skin; 9-Downstream flexible dual-mode sensing skin; 10-Vortex generator array; 11-Flow channel. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0023] Please see Figure 1 This embodiment provides an underwater intelligent thermal control system and method based on sensing skin and vortex generator, including: a flexible dual-mode sensing module, an adaptive vortex generator module, and a closed-loop control module; The flexible dual-mode sensing module is used for real-time monitoring of the temperature and flow rate of the flow field. It includes two flexible dual-mode sensing skins: an upstream flexible dual-mode sensing skin 8 and a downstream flexible dual-mode sensing skin 9, which are respectively arranged upstream and downstream of the propulsion motor cooling channel. Each flexible sensing skin adopts a multi-layer flexible structure, including a flexible printed circuit board 5, a dual-mode sensing layer 4, and an encapsulation layer 3 arranged sequentially from bottom to top, with a total thickness not exceeding 100μm. The flexible printed circuit board 5 serves as the substrate, and the encapsulation layer 3 covers the outside to provide waterproof protection, using polyurethane waterproof encapsulation.

[0024] The dual-mode sensing layer 4 integrates a nickel-based thermistor, comprising a hot-film element 2 and a cold-film element 1. The hot-film element 2 is supplied with a large current and senses the flow rate by measuring its convective heat loss; the cold-film element 1, supplied with a weak current and arranged around the hot-film element 2, acts as a thermometer for accurately measuring the fluid temperature. Specifically, each hot-film element 2 is surrounded by a concentric ring of cold-film elements 1. The real-time temperature signal output by the cold-film element 1 is used to dynamically compensate the flow rate measurement signal of the hot-film element 2, thereby effectively decoupling the temperature-flow rate coupling effect. The adaptive vortex generation module includes a vortex generator array driven by a shape memory alloy actuator 7, used to adaptively adjust the angle of attack based on sensor data to induce longitudinal vortices and enhance local heat transfer. The vortex generator array is arranged within the propulsion motor cooling channel, located between the upstream and downstream flexible dual-mode sensing skins. The vortex generator 6 is preferably an equilateral triangular winglet structure made of polylactic acid. The shape memory alloy actuator 7 is heated and driven by the Joule effect, and its heating current is adjusted by a pulse width modulation signal output from the closed-loop control module. When it contracts due to heat, it drives the vortex generator 6 to deflect around the hinge axis, thereby achieving continuous and controllable adjustment of its angle of attack within the range of 0° to 90°. The adaptive vortex generation module actively intervenes in the flow field by changing the angle of attack, inducing longitudinal vortices of controllable intensity in the flow channel, breaking the thermal boundary layer, promoting the mixing of the core cryogenic fluid and the wall high-temperature fluid, thereby significantly enhancing convective heat transfer.

[0025] A closed-loop control module receives data from the flexible dual-mode sensing module and drives the adaptive eddy current generator module according to a preset control strategy to achieve dynamic thermal regulation. The closed-loop control module is based on a microcontroller and employs a hybrid PID control algorithm. This module receives real-time temperature and flow rate data from the upstream flexible dual-mode sensing skin 8 and the downstream flexible dual-mode sensing skin 9, using the temperature difference between the upstream and downstream flexible dual-mode sensing skins as a feedback signal to adjust the angle of attack of the eddy current generator. The system also includes an angle sensor for real-time monitoring of the eddy current generator's deflection angle and feeding it back to the closed-loop control module.

[0026] Please see Figure 2 This is a schematic diagram illustrating the working principle and structure of the flexible dual-mode sensing skin of the present invention. It demonstrates the collaborative working mode of the hot film element 2 and the cold film element 1 arranged around it. The hot film element 2 senses the flow velocity by measuring convective heat loss, while the cold film element 1 acquires the fluid temperature in real time for dynamic temperature compensation of the flow velocity signal from the hot film element, thereby achieving decoupled high-precision measurement of temperature and flow velocity. Simultaneously, Figure 2 It also illustrates that the flexible sensing skin is a thin-layer composite structure consisting of a flexible printed circuit board 5, a dual-mode sensing layer 4, and an encapsulation layer 3.

[0027] Please see Figure 3 This diagram illustrates the physical arrangement of the prototype system in an arc-shaped cooling channel. It shows the installation positions and spatial relationships of the upstream flexible dual-mode sensing skin 8, the vortex generator array 10, and the downstream flexible dual-mode sensing skin 9 within the channel 11. The flexible dual-mode sensing skin is attached to the wall of the propulsion motor cooling channel, exhibiting conformal attachment capability to curved surfaces. The vortex generator array 10 is arranged within the propulsion motor cooling channel, positioned between the upstream flexible dual-mode sensing skin 8 and the downstream flexible dual-mode sensing skin 9. Through the conformal attachment capability of the flexible dual-mode sensing skin to complex curved surfaces and the optimized layout of the vortex generator array within the channel, the integration feasibility and structural compactness of the system of this invention in the cooling channel of a real underwater vehicle are achieved.

[0028] Please see Figure 4 This paper provides an underwater intelligent thermal control method based on sensor skin and vortex generator, including the following steps: S1. The temperature and velocity data of the flow field are acquired in real time through the upstream flexible dual-mode sensing skin 8; Specifically, the upstream flexible dual-mode sensing skin 8 monitors water temperature in real time through its cold film element, with a measurement range of -10 to 100°C, ensuring accurate capture of ambient temperature. Simultaneously, the hot film sensor measures flow velocity, ranging from 0 to 6 m / s. The signal from the hot film sensor is dynamically compensated for temperature drift through a concentric cold film ring, thereby eliminating interference from water temperature fluctuations on flow velocity measurement and significantly improving data reliability. S2. Based on the real-time temperature data calculated in step S1, when it exceeds the preset threshold, the control module regulates the drive circuit to output current to heat and start the shape memory alloy driver, adjust the angle of attack of the vortex generator located in the middle, and feed back the angle signal to the closed-loop control module through the embedded angle sensor. Specifically, when the upstream flexible dual-mode sensing skin 8 detects that the temperature exceeds the preset safety threshold, the system enters the threshold triggering and drive adjustment stage. The microcontroller in the closed-loop control module calculates the drive signal based on the hybrid PID control algorithm and outputs current to the shape memory alloy driver 8 in the form of pulse width modulation (PWM). The driver contracts under the Joule heating effect, precisely driving the connected triangular vortex generator 7 to deflect around the axis. The angle of attack can be continuously adjusted within the range of 0° to 90°, with a full stroke response time of less than 1.5 seconds and an angle error of less than 2°. The angle sensor integrated at the hinge provides real-time feedback of the deflection angle, forming an inner-loop position feedback to ensure the accuracy of the action. S3. Based on the increase in the angle of attack of the vortex generator in step S2, a vortex is generated and the convective heat exchange in the downstream region is improved, thereby achieving the cooling effect in the downstream region; Specifically, the longitudinal vortex disturbance flow field generated by the adaptive vortex generator array 10 enhances the heat transfer intensity in the downstream region. S4. Monitor the adjusted temperature and flow rate through the downstream flexible dual-mode sensor skin 9, calculate the upstream and downstream temperature difference, and monitor the cooling effect of the downstream area in S3. Specifically, the downstream flexible dual-mode sensing skin 9 is responsible for verifying the adjustment effect. The cold film and hot film sensors of the downstream flexible dual-mode sensing skin 9 monitor the adjusted water temperature and flow rate, respectively, and compare and analyze the data with the data of the upstream flexible dual-mode sensing skin 8; S5. Based on the comparison between the temperature difference calculated in step S3 and the preset downstream temperature value, the angle of attack of the vortex generator is iteratively adjusted through the closed-loop control module until the downstream temperature of the system reaches a stable thermal equilibrium state.

[0029] Specifically, the system evaluates the adjustment effect by calculating the temperature difference between the upstream flexible dual-mode sensing skin 8 and the downstream flexible dual-mode sensing skin 9. If the temperature difference does not reach a stable state, a hybrid PID algorithm dynamically adjusts the driving current of the shape memory alloy actuator at a frequency of 0.1 Hz, iteratively optimizing the angle of attack of the vortex generator. Through a continuous "sensing-decision-drive-verification" closed loop, the system ultimately stabilizes the downstream temperature at the target value, achieving dynamic thermal balance and optimization of overall energy consumption.

[0030] Please see Figure 5 This figure provides the standard signal response curves of the flexible dual-mode sensing skin within a water flow velocity range of 0-20 m / s. It demonstrates the calibration relationship between the output voltage of the hot-film element and the flow velocity, as well as the independent response characteristics of the cold-film element to temperature changes. Although the voltage change rate (water temperature signal) measured by the cold-film element in the flow channel exhibits significant fluctuations due to heat generated during equipment operation, the voltage change rate of the hot-film element steadily decreases with increasing flow velocity, consistent with the theoretical curve. This verifies the effectiveness of the dynamic temperature compensation mechanism and indicates that the sensing skin can achieve stable and accurate flow velocity measurement over a wide temperature range, laying a solid sensing foundation for the intelligent control of the system.

[0031] Please see Figure 6 This figure illustrates the simulation results of vortex cooling regulation based on computational fluid dynamics (CFD). A 40°C heating film was placed upstream and downstream of the vortex generator in the flow channel, with the fin angle set to 90°, the water temperature at 20°C, and the flow velocity at 6 m / s. A turbulence model was established for simulation. By comparing the temperature contour maps and velocity field distributions within the cooling channel upstream and downstream of the vortex generator (before and after turbulence), the simulation intuitively reveals the crucial role of adaptive vortices in disrupting the thermal boundary layer and promoting the mixing of hot and cold fluids. On the near-wall surface temperature contour map, after applying vortex control, the area of ​​the high-temperature region significantly decreased, and the average wall temperature effectively reduced. This verifies at the system level the significant effect of the proposed method in improving local heat transfer efficiency and achieving intelligent thermal management.

[0032] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An underwater intelligent thermal control system based on sensor skin and vortex generator, characterized in that: include: A flexible dual-mode sensing module for real-time monitoring of the temperature and velocity of the flow field includes at least two flexible dual-mode sensing skins, which are respectively arranged upstream and downstream of the propulsion motor cooling channel. An adaptive eddy current generation module includes an array of eddy current generators driven by shape memory alloy actuators, which adaptively adjusts the angle of attack based on sensing data to induce longitudinal eddies to enhance local heat transfer. The closed-loop control module is used to receive data from the flexible dual-mode sensing module and drive the adaptive eddy current generator module according to a preset control strategy to achieve dynamic thermal regulation.

2. The underwater intelligent thermal control system based on sensor skin and vortex generator as described in claim 1, characterized in that: The flexible dual-mode sensing skin adopts a multi-layer flexible structure, including a flexible printed circuit board, a dual-mode sensing layer, and an encapsulation layer arranged sequentially from bottom to top; the flexible printed circuit board serves as a substrate, and the encapsulation layer covers the outside to provide waterproof protection.

3. The underwater intelligent thermal control system based on sensor skin and vortex generator as described in claim 2, characterized in that: The dual-mode sensing layer includes: a hot film element for sensing flow velocity by measuring convective heat loss; and a cold film element arranged around the hot film element for measuring fluid temperature and dynamically compensating for the measurement results of the hot film element.

4. The underwater intelligent thermal control system based on sensor skin and vortex generator as described in claim 1, characterized in that: The flexible dual-mode sensing skin is attached to the wall of the propulsion motor cooling channel and is encapsulated with polyurethane waterproof material, with a total thickness not exceeding 100μm.

5. The underwater intelligent thermal control system based on sensor skin and vortex generator as described in claim 1, characterized in that: The vortex generator has a triangular winglet structure made of polylactic acid, and the angle of attack can be continuously adjusted within the range of 0° to 90°.

6. The underwater intelligent thermal control system based on sensor skin and vortex generator as described in claim 1, characterized in that: The shape memory alloy actuator is driven by Joule heating, and its heating current is adjusted by the pulse width modulation signal output by the closed-loop control module.

7. The underwater intelligent thermal control system based on sensor skin and vortex generator as described in claim 1, characterized in that: The system also includes an angle sensor for real-time monitoring of the deflection angle of the vortex generator and feeding it back to the closed-loop control module.

8. The underwater intelligent thermal control system based on sensor skin and vortex generator as described in claim 1, characterized in that: The closed-loop control module adopts a hybrid PID control algorithm, using the temperature difference between the upstream and downstream flexible dual-mode sensing skin as a feedback signal to adjust the angle of attack of the vortex generator.

9. The underwater intelligent thermal control system based on sensor skin and vortex generator as described in claim 1, characterized in that: The vortex generator array is arranged inside the propulsion motor cooling channel, located between the upstream and downstream flexible dual-mode sensing skins.

10. An underwater intelligent thermal control method based on sensor skin and vortex generator, applied to the system as described in any one of claims 1-9, comprising the following steps: S1. Real-time acquisition of temperature and velocity data of the flow field through upstream flexible dual-mode sensing skin; S2. Based on the real-time temperature data calculated in step S1, when it exceeds the preset threshold, the control module regulates the drive circuit to output current to heat and start the shape memory alloy driver, adjust the angle of attack of the vortex generator located in the middle, and feed back the angle signal to the closed-loop control module through the embedded angle sensor. S3. Based on the increase in the angle of attack of the vortex generator in step S2, a vortex is generated and the convective heat exchange in the downstream region is improved, thereby achieving the cooling effect in the downstream region; S4. Monitor the adjusted temperature and flow rate through the downstream flexible dual-mode sensor skin, calculate the upstream and downstream temperature difference, and monitor the cooling effect of the downstream area in S3. S5. Based on the comparison between the temperature difference calculated in step S3 and the preset downstream temperature value, the angle of attack of the vortex generator is iteratively adjusted through the closed-loop control module until the downstream temperature of the system reaches a stable thermal equilibrium state.

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