A multi-field cooperative passive control device and method based on rigid geometric contour constraint natural air cavity phase change

Abstract

The present application belongs to the technical field of passive multi-physical field cooperative control, and particularly relates to a multi-field cooperative passive control device and method based on rigid geometric contour constraint natural air cavity phase change. The device comprises a first rigid member and a second rigid member, which form fixed, sliding or rotating cooperation, and are provided with a cooperation micro-gap of 0.02 mm to 0.2 mm therebetween; the rigid geometric air cavity coupling part is integrally formed on the cooperation surface and has a rigid geometric contour for constraining air cavity phase change evolution. Under external physical field excitation or relative motion, local negative pressure is formed in the micro-gap, natural air cavity periodic phase change is induced, the phase change path and pressure evolution are uniformly constrained by the rigid geometric contour, and the multi-field cooperative passive control of heat-flow-force-sound is realized in a single structure. The present application replaces the traditional discrete components with pure rigid structure, has no elastic element, no friction pair and no electric control unit, and is reliable in all working conditions.

Description

Technical Field

[0001] This invention belongs to the field of passive multiphysics field cooperative control technology, specifically relating to a multiphysics field cooperative control device and method based on rigid geometric contour constraints of natural cavitation phase transition. Background Technology

[0002] In applications such as thermal management of new energy vehicles, temperature control of energy storage systems, industrial fluid transportation, and high-end fluid equipment, physical quantities such as temperature, pressure, flow rate, vibration, and noise are often closely coupled. When one of these physical quantities fluctuates, the fluctuation is transmitted to other physical quantities through the system's internal coupling mechanism, leading to a shift in the overall system performance. To address this issue, existing multiphysics control schemes typically employ discrete components to independently control each physical quantity. For example, temperature control is achieved using thermistors, constant current and voltage regulation is achieved using spring valve core structures, vibration suppression is achieved using viscoelastic damping materials, and noise attenuation is achieved using porous sound-absorbing structures.

[0003] However, the aforementioned control schemes based on discrete components have several shortcomings in practical applications. First, such schemes are highly dependent on the constitutive properties of the materials themselves, such as elastic modulus, coefficient of friction, and viscosity, and these material properties are easily degraded by environmental factors during long-term service. Second, the system structure has many layers and a large number of components, resulting in a large overall size and an increase in potential failure points. Third, elastic elements, friction pairs, seals, and porous materials are prone to aging, wear, blockage, and performance drift under complex operating conditions such as high temperature, dust, or oil contamination. Fourth, if an active electronic control scheme is used for multi-field coordination, it requires an external power supply, sensors, and control circuits, further increasing the system complexity and limiting its applicability in environments without power supply, under strong vibration conditions, or under extreme temperature conditions.

[0004] Furthermore, in long-term practice in this field, natural cavitation has always been regarded as a harmful physical effect. The formation, development, and collapse of cavitation are often accompanied by pressure pulsation, structural vibration, noise radiation, and cavitation damage to material surfaces. Therefore, in the design of fluid machinery and related systems, the basic technical direction is usually to suppress cavitation generation or reduce cavitation intensity. Currently, there are no publicly disclosed technical solutions that use the phase transition process of natural cavitation as the core medium for multi-physics field synergistic control, nor are there any reports of achieving unified passive control of multiple fields (thermal-fluid-mechanical-acoustic) simultaneously based on the same rigid structure and the same physical mechanism. This technical bias, to some extent, limits the technical exploration space for passive multi-field control using phase transition dynamics. This invention aims to overcome the above-mentioned technical bias, transforming the periodic phase transition process of natural cavitation into a controllable control method, and providing a new technical path for passive synergistic control of multiple physics fields. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a device and method for achieving passive control of multiple fields of heat, flow, force and sound using a purely rigid structure, addressing the common problems in existing multiphysics field control schemes, such as reliance on material constitutive properties, complex structural hierarchy, easy performance degradation, and the fact that cavitation has long been regarded as a harmful phenomenon and has not been actively utilized.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution from a structural level:

[0007] A multi-field cooperative passive control device based on rigid geometric contour constraint of natural cavitation phase transition includes the following structural components: a first rigid member; a second rigid member, which forms a fixed fit, sliding fit, or rotational fit with the first rigid member, and a micro-gap is provided between the two opposite mating surfaces, the width of the micro-gap ranging from 0.02 mm to 0.2 mm; and a rigid geometric cavitation coupling part, which is integrally formed on the mating surface of the first rigid member or the second rigid member, the rigid geometric cavitation coupling part having a rigid geometric contour, the specific form of which is selected from a uniform gap surface, a linearly gradually changing gap surface, a variable curvature surface, or a multi-level stepped surface.

[0008] Based on the above structure, when the device is excited by an external physical field, or when relative motion occurs between the first and second rigid components, a local negative pressure region will form inside the mating micro-gap. This local negative pressure drives the environmental medium to be drawn into the micro-gap, thereby inducing the generation of natural cavitation. Under continuous external excitation or relative motion, the natural cavitation will undergo a periodic phase transition process including at least one of the following modes: bubble generation, compression, expansion, and collapse. During this process, the phase transition behavior of the natural cavitation is spatially constrained by the rigid geometric contour, and its phase transition path, volume change rate, and pressure evolution law are all determined by the geometric characteristics of the rigid geometric contour. Based on the above constraint mechanism, the periodic phase transition process of the natural cavitation will generate multi-field synergistic control forces acting on the components, thereby achieving unified control of multiple physical fields within a single structure.

[0009] From a methodological perspective, this invention provides the following technical solution:

[0010] A multi-field collaborative passive control method for natural cavitation phase transition based on rigid geometric contour constraints includes the following steps: assembling a first rigid component and a second rigid component in a relative sliding or rotational fit, forming a fit micro-gap with a width of 0.02 mm to 0.2 mm between them, and setting a rigid geometric cavitation coupling part with a rigid geometric contour on the fit surface; placing the device in at least one physical field environment among temperature field, pressure field, flow field, or sound field, or causing relative motion between the two components, resulting in local negative pressure within the fit micro-gap, thereby inducing a periodic phase transition in the natural cavitation including at least one of bubble generation, compression, expansion, and collapse; using a preset rigid geometric contour to constrain the phase transition path, volume change rate, and pressure evolution law of the cavitation, so that the cavitation simultaneously completes latent heat exchange, pressure adaptive adjustment, flow stability control, vibration energy dissipation, and acoustic energy attenuation during the phase transition process, thereby achieving collaborative passive control of multiple physical fields of heat, flow, force, and sound within a single rigid structure.

[0011] Compared with the prior art, the beneficial effects of the present invention can be summarized in the following aspects:

[0012] Firstly, this invention transforms the phase transition process of natural cavitation from a harmful byproduct in traditional understanding into a core driving force for multi-physics field control. By using rigid geometric contours to spatially constrain the cavitation evolution process, the cavitation dynamics and phase transition energy exchange mechanism replace the dependence on material constitutive properties, thereby reducing common problems in traditional control mechanisms such as wear, fatigue, leakage, and temperature drift at the working principle level.

[0013] Secondly, this invention adopts a fully rigid open structure design, maintaining a micron-level gap between mating surfaces, eliminating solid-to-solid contact wear. Testing has verified that the device exhibits minimal performance degradation under long-term reciprocating operation, requires no seals, and has low maintenance requirements throughout its entire lifespan.

[0014] Third, based on the same cavitation phase change mechanism, this invention can simultaneously achieve multiple functions such as temperature response, pressure equalization, flow stabilization, vibration suppression and acoustic noise reduction within a single structure, which can effectively reduce the number of discrete functional components in the system, simplify the overall system configuration, and reduce the density of potential failure points.

[0015] Fourth, the control output characteristics of the present invention are jointly determined by the structural parameters of the rigid geometric profile and the law of cavitation dynamics. It is less affected by factors such as ambient temperature, humidity and impurity content of the medium, and can maintain relatively stable output performance under wide temperature range and complex working conditions.

[0016] Fifth, the overall structure of the present invention can be manufactured using conventional industrial materials and through mature processes such as injection molding, die casting or precision machining, thus possessing a good foundation for large-scale mass production and promising prospects for engineering application.

[0017] The present invention provides a multi-field collaborative passive control framework based on rigid geometric contour constraints for natural cavitation phase transitions, rather than a concrete product limited to a single gap or contour.

[0018] In summary, this invention provides a universal framework for multi-physics passive collaborative control across media, operating conditions, and excitation types. Any adaptive adjustments made by those skilled in the art, guided by the physical principles and structural paradigms disclosed in this invention, to the specific shape and parameters of the mating micro-gap width, rigid geometric profile, auxiliary structural combinations, material selection, and surface treatment processes for specific application scenarios, should be considered reasonable extensions of the technical concept of this invention, rather than independent inventions. Attached Figure Description

[0019] Figure 1 This is a three-dimensional schematic diagram of the overall appearance of the device of the present invention.

[0020] Figure 2 This is a schematic diagram of a multi-field coupling structure based on a uniform gap foundation.

[0021] Figure 3 This is a schematic diagram of a gradually changing gap advanced multi-field coupling structure.

[0022] Figure 4 A schematic diagram of a multi-stage stepped structure for enhancing multi-field coupling.

[0023] The markings in the attached diagram represent the following structures: 1-Upper plate component (first rigid component); 2-Lower plate component (second rigid component); 3-Boss (rigid geometric cavitation coupling part); 4-Uniform thin layer gap (fitting micro gap); 5-Contour line (rigid geometric contour); 6-Multi-level stepped structure (multi-level steps); 7-Integrated edge fine lip (self-cleaning micro lip); 8-Left side inlet guide slope (pre-negative pressure guide structure); 9-Right end plug.

[0024] like Figures 1 to 4 As shown in the figure, 7-the integrated fine lip (self-cleaning micro-lip) is integrally formed on the edge of the mating micro-gap, utilizing the high-pressure pulse generated by cavitation collapse to form a reverse micro-purge airflow, preventing impurities from entering; 8-the left inlet guide slope (pre-negative pressure guide structure) is set at the inlet of the micro-gap to assist in triggering cavitation under low-excitation conditions; 9-the right end plug is used to seal the end of the flow channel, ensuring that the fluid flows in a preset direction. The specific shapes and positions of the above structures are marked in the attached figures, and those skilled in the art can understand them in conjunction with the attached figures. Detailed Implementation

[0025] It should be noted that the external physical field excitation intensity, medium properties, and working condition boundaries vary significantly under different application scenarios, resulting in different requirements for the width of the mating micro-gap, the specific shape of the rigid geometric profile, and the configuration of auxiliary structures. Those skilled in the art will understand that within the framework of the total range of mating micro-gap (0.02mm to 0.2mm) and the types of rigid geometric profiles (uniform gap surface, linearly varied gap surface, variable curvature surface, multi-level stepped surface) disclosed in this invention, selecting suitable sub-ranges and profile combinations for specific working conditions is a conventional optimization method in the art and does not constitute an additional limitation on this invention. In other words, this invention provides a unified physical framework for multi-field collaborative passive control of cavitation phase transitions constrained by rigid geometric profiles, rather than a single implementation limited to a specific gap value or specific profile parameter.

[0026] In addition, the micro-convex damping structure, microporous filter structure, rigid reinforcing ribs, and multi-stage cavitation cavities are optional auxiliary structures for optimization, which are not individually labeled in the accompanying drawings. It should be noted that the above-mentioned auxiliary structures are all conventional structures known in the art, and their functions are respectively to enhance damping, filter impurities, improve structural stiffness, and buffer cavitation collapse impact. Those skilled in the art can select and use the above-mentioned auxiliary structures according to actual working conditions, and can combine them with the core structure of this invention without creative effort.

[0027] As a further optimization of the above-mentioned auxiliary structure, in some embodiments, the self-cleaning micro-lip can be constructed as a ring of continuous or discontinuous micro-protrusions around the outer periphery of the mating micro-gap, with a height slightly greater than the width of the mating micro-gap (for example, when the mating micro-gap is 0.10 mm, the lip height can be set to 0.15 mm to 0.5 mm), thereby intercepting solid particles larger than the mating micro-gap entrained in the fluid to the outside of the lip. A settling groove can be provided at the root of the lip, and the intercepted particles fall into the settling groove under the action of gravity or fluid disturbance, avoiding accumulation at the root of the lip. At the same time, the inlet edge of the mating micro-gap can be constructed as a chamfered structure with a preset acute angle (for example, a 30° acute edge). When the first rigid member and the second rigid member move relative to each other, the acute edge forms a self-cleaning blade, removing particles adhering to the mating surface and pushing them into the settling groove. Furthermore, the high-pressure pulses generated by the periodic collapse of cavitation can be used to form a reverse micro-purge airflow, dislodging tiny particles about to enter the gap from the inlet region. This function is automatically achieved by the coupling effect of the self-cleaning microlip and the phase change of cavitation, without the need for an additional power source. All of the above structures are geometric features integrally formed on a rigid component, without any moving parts or electronic control components.

[0028] To improve the device's resilience to accidental impacts, overload conditions, and long-term cavitation collapse, in some embodiments, the multi-stage cavitation cavity can be further constructed as follows: near the relative motion limit positions of the two rigid components, multiple closed or semi-closed cavities with progressively decreasing volumes are provided. When the components rapidly approach their limit positions, the cavitation cavities are forced through the progressively narrowing cavities, generating progressively increasing hydraulic torques, thereby absorbing impact kinetic energy and preventing rigid collisions at the mating surfaces of the two rigid components. Regarding cavitation protection, several tiny pits or guide channels can be pre-set in areas prone to cavitation collapse (e.g., downstream of the diffusion section of the mating micro-gap or at the step of the multi-stage stepped surface) to guide the cavitation cavitation to collapse at designated locations, releasing the collapse energy to non-functional sacrificial areas, thereby protecting the geometric accuracy of the main contour surfaces. Furthermore, the first and second rigid components can be coated with anti-cavitation coatings, such as diamond-like carbon (DLC) coatings or physical vapor deposition (PVD) hard coatings, at least on their mating surfaces, to further improve the surface's resistance to cavitation. The aforementioned buffer and protection structures are all purely passive structures, do not rely on any external energy or control, and do not change the macroscopic shape of the rigid geometric contour or the cavitation phase change regulation principle.

[0029] To lower the cavitation triggering threshold of the device under low-excitation conditions (such as low flow rate, small temperature difference, and weak sound field), in some embodiments, the pre-negative pressure guiding structure can be further optimized as follows: a guiding ramp that gradually narrows along the flow direction is set at the inlet end of the mating micro-gap. The contraction rate of this ramp is greater than the gap change rate of the downstream main working section, thereby forming a stronger local acceleration effect in the inlet region, so that the negative pressure threshold required for cavitation triggering can be reached under a relatively low external excitation intensity. As an alternative or supplementary solution, one or more small turbulence structures (such as micro-protrusions or micro-dimples) can be preset in the inlet region of the mating micro-gap to induce the generation of cavitation nuclei in advance by utilizing their local disturbance to the flow field. The above structures are all geometric features integrally formed on rigid components, and their setting does not affect the multi-field coordinated control performance of the device under normal excitation conditions.

[0030] To make the technical solution, structural features, and achieved technical effects of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be noted that the embodiments described below are only some embodiments of the present invention, and not all embodiments. Based on the technical concept of the present invention, all other implementation schemes obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0031] This invention provides a multi-field collaborative passive control device and method for natural cavitation phase transition based on rigid geometric contour constraints. Its core concept is to transform the physical effect of natural cavitation phase transition, which is regarded as an adverse factor in the traditional understanding of technology, into a driving force for multi-physics field regulation. By applying spatial constraints to the phase transition evolution process of cavitation through rigid geometric contours, the traditional regulation method that relies on material constitutive properties is replaced by cavitation dynamics and energy exchange during the phase transition process.

[0032] The physical principles and the derivation basis of the key parameters of this invention will be explained in detail below.

[0033] In this invention, the so-called "natural cavitation phase transition" refers to the process where, under the excitation of at least one physical field (temperature field, pressure field, flow field, or sound field), a negative pressure region is formed inside the micro-gap due to a local pressure reduction, causing the surrounding medium to be drawn into this region and form a gas phase accumulation zone. Under the continuous action of external excitation, this gas phase accumulation zone undergoes a periodic process of generation, compression, expansion, and collapse. In the above process, the generation, compression, expansion, and collapse of bubbles include at least one mode, and the pressure changes, volume changes, and energy exchanges accompanying the phase transition together constitute the driving force for multi-field regulation.

[0034] The thermodynamic premise upon which this invention relies is that the size of the micro-gap is limited to the range of 0.02 mm to 0.2 mm. At this scale, the heat transfer area to volume ratio of the medium within the gap is extremely high. Under quasi-static conditions or low-frequency excitation, the heat exchange rate inside the micro-gap is much greater than the cavitation compression / expansion rate, which can be considered an isothermal process under engineering approximation. Under high-frequency excitation, the process is closer to adiabatic, but the control mechanism of this invention does not rely on the isothermal assumption; the inverse relationship between cavitation pressure and volume can still serve as the basis for qualitative analysis. Simultaneously, the gaseous medium within the micro-gap is mainly replenished through environmental suction, with no significant leakage loss; therefore, the molar number of the gas remains approximately constant. Based on the above premises, the ideal gas law remains applicable in the micro-gap cavitation phase transition process involved in this invention.

[0035] Further analysis is conducted on the mechanism of multiphysics excitation on the internal medium of the mating microgap. When an external physical field excitation is applied to the device, the volume of the medium within the microgap will change dynamically. This rate of volume change can be described by the following relationship:

[0036]

[0037] in, This represents the relative velocity or the equivalent velocity caused by the sound field. This indicates the width of the mating surface perpendicular to the direction of fluid flow. This indicates the local width of the fit micro-gap.

[0038] When the local pressure inside the micro-gap drops below the ambient atmospheric pressure, and the pressure difference between the inside and outside of the cavity... When the pressure reaches approximately 2 kPa, outside air is drawn into the gap and forms a stable gas phase region, thus creating a natural cavitation. During the compression phase of the cavitation, the pressure inside the cavitation... Its volume The isothermal form that satisfies the ideal gas law between them:

[0039]

[0040] in, The initial pressure under standard atmospheric pressure. This represents the initial volume of the cavitation.

[0041] Applying the above state equation to displacement Differentiating the derivative, we can obtain the gradient expression for the pressure inside the cavitation along the displacement direction:

[0042]

[0043] In this expression, This is a volume function of the gas phase region within the micro-gap. This is the rate of change of volume with displacement. It should be noted that... This rate of change is not a free variable, but is uniquely determined by the geometry of the rigid geometric profile. Therefore, the pressure gradient formula above reveals the core control logic of this invention: the variation law of the cavitation pressure distribution along the path depends entirely on the volume change rate distribution determined by the rigid geometric profile. This formula is derived based on the ideal gas law and is applicable to working conditions where the number of gas moles inside the cavitation is approximately constant and the temperature change is controllable. Within the parameter range of this invention (gap 0.02~0.2mm, Reynolds number <1000, excitation frequency <500Hz), the deviation between this simplified model and the measured pressure distribution is less than 10%, meeting the engineering design requirements.

[0044] By pre-setting the form of the rigid geometric profile, the volume change rate of different features can be obtained. This distribution allows for the artificial control of the cavitation pressure gradient distribution, ultimately enabling the device to exhibit differentiated multi-field response characteristics. The specific correspondences are as follows:

[0045] (1) When the rigid geometric profile adopts a uniform gap surface, the width of the fit micro-gap remains constant along the extension direction. Approximately zero, the cavitation pressure remains essentially constant within the effective stroke. This profile is suitable for providing multi-field stabilization regulation at the fundamental level.

[0046] (2) When the rigid geometric profile adopts a linearly varied gap surface, the gap width changes linearly along the displacement direction. As a constant, the cavitation pressure changes linearly. This profile helps to broaden the device's adaptability to fluctuations in operating conditions.

[0047] (3) When the rigid geometric profile adopts a variable curvature surface, the gap width changes nonlinearly with displacement. Distributed according to a preset nonlinear law. By reasonably designing the curvature parameters, the cavitation pressure gradient can be kept approximately constant within a specific stroke range, thereby achieving constant-characteristic multi-field output.

[0048] (4) When the rigid geometric profile adopts a multi-level stepped surface, the gap width changes in a segmented step manner. The corresponding distribution exhibits a piecewise step-like distribution. This profile provides nonlinear, strongly coupled regulation characteristics, making it suitable for multi-field coordinated control under extreme conditions.

[0049] Using the above method, rigid geometric contours are employed to... By planning the distribution, the pressure response, phase change rate, and collapse intensity of the cavitation can be uniformly controlled, enabling the device to simultaneously achieve multiple functions such as temperature response, flow stability, pressure equalization, vibration damping, and acoustic dissipation within the same structure.

[0050] Furthermore, when different types of external physical fields act on the device, the phase transition behavior of the cavitation will produce differentiated adaptive responses.

[0051] Specifically, under the coupling effect of the temperature field, an increase in the temperature of the fluid medium will lead to a corresponding increase in its saturated vapor pressure. This makes cavitation easier to form, and the volume expansion after formation is more significant. The increase in cavitation volume leads to a decrease in the effective flow cross-sectional area of ​​the micro-gap, which in turn causes the thermal flux flowing through the gap to automatically decrease. This mechanism forms a negative feedback isothermal control effect.

[0052] Under the coupling effect of the pressure field, when the inlet pressure increases, the cavitation is compressed, and its internal pressure increases accordingly. The increase in cavitation pressure enhances the throttling effect, thereby suppressing fluctuations in the outlet pressure and achieving a pressure stabilization function.

[0053] Under the coupling effect of the flow field, as the fluid velocity increases, the local pressure within the micro-gap further decreases, and the intensity of cavitation formation increases accordingly. The increase in cavitation volume and the acceleration of the phase transition rate lead to a corresponding increase in damping force, thereby achieving velocity-adaptive damping adjustment.

[0054] Under the effect of acoustic field coupling, the propagation of sound waves causes periodic pulsation changes in the volume of the micro-gap. The cavitation then undergoes a periodic compression and expansion process, during which sound wave energy is dissipated and converted into heat energy, thereby achieving acoustic noise reduction.

[0055] When multiple physical fields act on the device simultaneously, the response resulting from the cavitation phase transition exhibits a linear superposition of the individual effects of each physical field. To verify the synergistic stability under the combined action of multiple fields, tests were conducted under the combined excitation of four fields: temperature (50±10℃), pressure (200±50 kPa), flow (2±0.5 L / min), and sound (100 dB, 500 Hz). The sample size was... Test results show that the outlet flow fluctuation rate is ±2.1%, the temperature response accuracy is ±1.2℃, the vibration attenuation rate is 42%, and the noise reduction is 5.8 dB. No significant nonlinear interference or performance degradation was observed when the individual field effects were combined across multiple fields (the variation range of each indicator was less than 15% of the single field effect value). The aforementioned coupling mechanism is entirely determined by the structural parameters of the rigid geometric profile and the micro-gap dimensions, requiring no reliance on sensors, electronic control units, or external energy supply, and falls within the scope of purely physical adaptive multi-field cooperative control.

[0056] Based on the above analysis of physical principles, the basis for determining the key structural parameter in this invention—the micro-gap width range of 0.02 mm to 0.2 mm—is further explained. Within the micro-scale gap, the flow resistance of the airflow is inversely proportional to the cube of the gap width. When the gap width is less than 0.02 mm, the airflow resistance is large, making it difficult for outside air to be drawn into the micro-gap in a timely manner, and the pressure difference between the inside and outside of the cavity is difficult to establish effectively, resulting in poor cavitation formation; in addition, this size range is close to the limit of conventional precision machining. When the gap width is greater than 0.2 mm, the gap's ability to retain gas molecules weakens, the gas leakage rate is too high in a static state, and it is difficult to maintain an effective retention pressure; in dynamic processes, the cavitation cavity volume is too large, the compression ratio is insufficient, the phase transition intensity is weak, and a stable control effect cannot be formed.

[0057] To verify the definition of the critical gap range, this invention designed a comparative test experiment on the transboundary gap. The test was conducted under standard atmospheric pressure, air / water medium, and an ambient temperature of 23℃±2℃. The test results are summarized in Table 1.

[0058] Table 1: Comparison Test Results of Exceeding Gaps

[0059] 0.015 no 0.5 <1 no 0.020 yes 5.2 35 yes 0.100 yes 12.5 42 yes 0.200 yes 6.8 22 yes 0.250 no 1.2 <2 no

[0060] As shown in Table 1, when the gap is less than 0.02 mm, cavitation cannot be formed due to excessive airflow resistance; when the gap is greater than 0.20 mm, cavitation control fails due to excessive gas leakage rate. Therefore, the range of 0.02 mm to 0.20 mm constitutes the effective parameter range for cavitation control in the technical solution of this invention. Within this range, when the gap width is 0.10 mm, the airflow resistance is moderate, the air suction response time is less than 5 ms, the gas retention pressure can reach 10 kPa to 15 kPa, and the pressure holding time exceeds 30 minutes, demonstrating superior overall performance.

[0061] Static pressure holding performance is the fundamental guarantee for dynamic multi-field control capability. Higher holding pressure and longer holding time indicate better cavitation stability within the micro-gap, enabling more stable multi-field coordinated control under complex operating conditions such as dynamic heat exchange, pressure fluctuations, flow field pulsation, and acoustic field excitation. Comparative verification shows that gaps with holding pressure ≥ 5 kPa and holding time ≥ 20 min (0.02 mm to 0.20 mm) can achieve the invention's objective under multi-field combined excitation.

[0062] Regarding adaptability to various operating conditions, this invention provides a modular alternative substrate solution. Specifically, components can be fabricated using materials such as glass fiber reinforced engineering plastics, aluminum alloys, or cold-rolled steel. Testing has shown that, within a temperature range of -40°C to 120°C, by selecting matching materials or using material combinations with mutually compensating coefficients of thermal expansion, the variation in micro-gap can be controlled within 0.005 mm. All of the above materials can be integrally molded using conventional injection molding, die casting, or precision machining processes.

[0063] To verify that the regulation mechanism of this invention originates from cavitation phase transition rather than the traditional viscous throttling effect, a comparative experiment was designed. The experiment used the same asymmetric wedge-shaped profile sample (with a micro-gap of 0.10 mm) and was conducted in both conventional media (water) and fully degassed deionized water environments. The degassed water was boiled and maintained at a gentle boil for 30 minutes, then covered with a low-volatility oil film and sealed to room temperature. The measured dissolved oxygen content was less than 1 ppm.

[0064] The test conditions were: inlet pressure 200 kPa, temperature 60℃, and flow rate 2 m / s. Experimental results showed that in a degassed water environment, the multi-field control effect attenuated by more than 60%, and the control characteristics were essentially lost. This result proves that the core control mechanism of this invention is fundamentally different from the traditional mechanisms based on viscous damping or frictional control.

[0065] The following parallel embodiments further illustrate the specific implementation of the present invention. All embodiments are based on the same cavitation phase transition control principle described above, differing only in the rigid geometric contour form used in the rigid geometric cavitation coupling section, to adapt to different multi-field collaborative control requirements. All devices in all embodiments adopt a one-piece molded structure, with a nominal gap value of 0.10 mm and a surface roughness Ra ≤ 0.8 μm.

[0066] Example 1: Multi-field Cooperative Control of Uniform Gap Surface

[0067] This embodiment demonstrates the specific application of the core principle in basic multi-field stability adjustment functions. The rigid geometric cavitation coupling part adopts a uniform gap profile, with a micro-gap width that is constant at 0.10 mm.

[0068] The test conditions were set as follows: medium: water; inlet pressure: 150 kPa; temperature: 50℃; flow rate: [missing information]. The excitation frequency is 200 Hz. According to actual measurements, the flow fluctuation rate of the device in this embodiment is ±2%, the temperature response accuracy is ±1℃ (steady-state accuracy), the vibration attenuation rate is 45% (measured by acceleration amplitude attenuation), and the mid-to-high frequency noise reduction is 6 dB (test frequency band 200 Hz to 1000 Hz).

[0069] Based on the above tests, the manufacturing process of the prototype in this embodiment is further described. The prototype is integrally molded using glass fiber reinforced PPS material through injection molding. The fitment gap width is 0.10 mm, the machining tolerance is controlled within ±0.02 mm, and the surface roughness of the mating surface is Ra 0.8 μm. The specific testing steps are as follows: The prototype is installed in a fluid circulation pipeline system, and the inlet pressure is set to 150 kPa, the temperature to 50℃, and the flow rate to... An external excitation with a frequency of 200 Hz was applied. After the system had been running stably for 30 seconds, the flow fluctuation amplitude, temperature response deviation, vibration acceleration, and noise level data were recorded simultaneously. The above test was repeated 5 times, and the arithmetic mean was taken as the final result. The above tests were conducted in accordance with GB / T 6881.2-2017 "Acoustic Reverberation Chamber Sound Absorption Measurement" and conventional fluid testing standards in this field. The test equipment was calibrated, and the data were taken as the average value ± standard deviation.

[0070] Example 2: Multi-field Cooperative Control of Linear Gradual Gap Surface

[0071] This embodiment demonstrates the specific application of the core principle in broadening the range of operating conditions it can adapt to. The rigid geometric cavitation coupling section adopts a linearly gradient gap profile with a linear gap contraction rate. Take 0.01, effective length It is 50 mm, which meets the requirements. .

[0072] The test conditions were set as follows: pressure fluctuation range of 100 kPa to 300 kPa, temperature circulation between 40℃ and 80℃, and flow rate variation range. to Actual measurements showed that, compared to a standard throttling orifice without cavitation control, the flow stabilization accuracy of the device in this embodiment was improved by 60%; the damping force changed smoothly during relative motion, and no sudden impact phenomena were observed.

[0073] In terms of prototype manufacturing, this embodiment uses stainless steel material and is prepared through precision machining. (Gap linear shrinkage rate) The effective length of the rigid geometric profile is 0.01. It is 50 mm. The product value is 0.5 mm.

[0074] Example 3: Multi-field Cooperative Control of Variable Curvature Surfaces

[0075] This embodiment demonstrates the specific application of the core principle in constant-characteristic multi-field output functionality. The rigid geometric cavitation coupling section adopts a variable curvature surface profile with a curvature radius... (The arithmetic mean of the radii of curvature at any point on the contour is taken as 300mm, and the effective length is...) It is 50 mm, which meets the requirements. .

[0076] The test conditions were set as follows: inlet pressure 200 kPa ± 10%, temperature 60℃ ± 2℃, and flow rate... Actual measurements show that the multi-field output fluctuation (measured by outlet flow fluctuation) of the device in this embodiment does not exceed ±1.5%; after 1000 continuous operating cycles, the performance degradation is less than 0.5%.

[0077] Regarding prototype manufacturing, this embodiment uses aluminum alloy material and a die-casting process to form a single piece. Minimum radius of curvature. The effective length of the rigid geometric profile is 300 mm. It is 50 mm. The ratio is 6.

[0078] Example 4: Multi-level stepped surface multi-field cooperative control

[0079] This embodiment demonstrates the specific application of the core principle in nonlinear strong coupling adjustment function. The rigid geometric cavitation coupling part adopts a 4-stage stepped profile, with a single-stage gap increment of 0.04 mm, an initial gap of 0.08 mm, and a final stage gap of 0.20 mm.

[0080] The test conditions were set as follows: sound pressure level 110 dB, pressure fluctuation range 50 kPa to 500 kPa, temperature change range -20℃ to 100℃, and flow velocity change range 0.5 m / s to 5 m / s. Actual measurements showed that the full-band A-weighted noise reduction of the device in this embodiment reached 9 dB, and the multi-field collaborative control function was stable and reliable.

[0081] In terms of prototype manufacturing, this embodiment uses glass fiber reinforced POM material and integrally molded through injection molding. The multi-level stepped surface is set to 4 levels, with the gap between each level increasing by 0.04 mm. The initial fit micro-gap is 0.08 mm, and the final fit micro-gap is 0.20 mm.

[0082] It is important to understand that the design goal of the self-cleaning microlip and pre-negative pressure guiding structure is to guide impurities and maintain unobstructed cavitation channels in conventional industrial fluid environments (typical suspended particle size distribution of 1μm to 100μm, concentration ≤50mg / L), rather than to handle extremely dirty media containing large-sized hard foreign objects (such as welding slag, chips, rust, fibrous impurities). For the latter type of working conditions, those skilled in the art would typically configure a pre-filter, cyclone separator, or magnetic adsorption device at the system level. This is a standard practice in fluid system design and does not affect the effective operation of the device of this invention in a pre-treated fluid environment. Similarly, the cavitation triggering mechanism of the present invention relies on the formation of local negative pressure within the micro-gap. Under extremely low excitation conditions (such as flow velocity <0.1m / s, temperature difference <5℃, sound pressure level <80dB), cavitation may not be stably triggered. In this case, the triggering threshold can be reduced by adding the pre-negative pressure guiding structure or micro-turbulence structure, or the triggering conditions can be met by adjusting the operating parameters at the system level. This is also a conventional operating condition adaptation method in the art.

[0083] Comparative Experiment: Verification of Multi-Field Synergistic Effect

[0084] To further verify the superiority of multi-field cooperative control over traditional solutions, the following four configurations were designed for comparative testing:

[0085] (1) Configuration A: No cavitation state (gap > 0.2 mm);

[0086] (2) Configuration B: There is cavitation but the gap is greater than 0.2 mm (cavitation constraint is unstable);

[0087] (3) Configuration C: has cavitation and rigid geometric contour constraints (technical solution of the present invention);

[0088] (4) Configuration D: Traditional electric thermal management valve.

[0089] The test was conducted under the same operating conditions, with the following parameters: inlet pressure 200 kPa ± 20%, temperature 50℃ ± 10%, and flow rate...

[0090] The test results are as follows:

[0091] (1) Configuration A: Flow fluctuation ±15%, temperature fluctuation ±5℃, cannot achieve effective control;

[0092] (2) Configuration B: Flow rate fluctuation ±8%, temperature fluctuation ±3℃, poor control accuracy;

[0093] (3) Configuration C: Flow fluctuation ±2%, temperature fluctuation ±1℃, vibration attenuation rate 45%, noise reduction 6 dB;

[0094] (4) Configuration D: Flow fluctuation ±3%, temperature fluctuation ±1.5℃, requires external power of 20W, response delay of about 200 ms.

[0095] The above comparison results show that the rigid geometric constraint and cavitation phase change coupling scheme proposed in this invention exhibits quantifiable advantages in terms of accuracy and energy efficiency in multi-field collaborative control.

[0096] To further enhance the device's durability under extreme conditions and its stability across the entire temperature range, in some embodiments, the present invention may also include the following internal structure:

[0097] (1) Overpressure buffer structure: A passive buffer rigid ridge is integrally formed at the end of the mating micro-gap or at the relative motion limit position. The rigid ridge is a micro-protrusion structure extending along the width direction of the mating surface, with a height of 1.5 to 3 times the mating micro-gap, and an arc-shaped or trapezoidal cross-section. When an overpressure impact occurs or the component rapidly approaches the limit position, the rigid ridge absorbs the impact energy through local elastic deformation, maintains the stability of the cavitation constraint within the micro-gap, and prevents cavitation collapse or pressure field instability. Tests show that under 200% rated pressure impact, the device's control performance fluctuation is ≤5%, and it immediately returns to normal operation after the impact is released.

[0098] (2) Large Particle Impurity Protection Structure: A pre-swirl flow guide structure is integrally formed at the inlet end of the mating micro-gap. This structure consists of spiral guide grooves or guide ridges arranged circumferentially along the inlet. It utilizes the fluid's own kinetic energy to form a centrifugal swirling flow field in the inlet area, throwing solid particles with a diameter greater than 0.1 mm to the outer edge of the inlet and discharging them without the need for an external filter. At the same time, the mating micro-gap is set as a micro-expansion channel with an expansion rate of 0.5% to 1% along the flow direction. The gap only gradually increases along the flow direction without any narrowing or abrupt changes, allowing impurities with a diameter ≤0.1 mm to pass through smoothly. The self-cleaning micro-lip, integrally formed at the edge of the mating surface, uses the reverse instantaneous jet generated by cavitation collapse to blow away the micro-dust particles attached to the inlet. The above structures work together to ensure continuous operation for 500 hours without clogging or jamming in NAS12 grade contaminated oil or dusty fluids.

[0099] (3) Full-temperature-range thermal compensation structure: The first rigid component and the second rigid component are made of the same material or a combination of materials with matching coefficients of thermal expansion. A thermal deformation release groove is set in the non-working area of ​​the mating surface. The thermal deformation release groove is an annular or strip-shaped groove set along the outer periphery of the mating surface, with a depth of 5 to 10 times the micro-gap of the mating surface. When the temperature changes, the thermal expansion deformation of the material is absorbed by the release groove. The change in the micro-gap of the mating surface is controlled within 0.002 mm in the full-temperature range of -50℃ to 150℃, and the control performance decay is ≤2%, completely eliminating the risk of gap displacement and functional failure caused by temperature drift.

[0100] The aforementioned upgraded structures are all geometric features integrally formed on rigid components, without any moving parts, elastic elements, or electronic control units. They do not change the core mechanism of this invention, which utilizes rigid geometric constraints and natural cavitation phase change coupling for multi-field collaborative passive control.

[0101] In terms of manufacturing process, all structural features of the device of this invention can be integrally formed using conventional injection molding, die casting, or precision machining processes. Taking a nominal gap value of 0.10 mm as an example, under the condition of tolerance control of ±0.02 mm, the mass production yield can reach over 99.9%. The device requires no external energy supply, no sealing components, and has no replaceable vulnerable parts during operation, making it essentially maintenance-free throughout its entire life cycle. This invention can be widely applied in fields such as thermal management systems for new energy vehicles, temperature control systems for energy storage devices, industrial fluid control systems, HVAC systems, acoustic noise reduction devices, and microbubble generators.

[0102] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It should be noted that any modifications, equivalent substitutions, or improvements made to the above embodiments within the scope of the inventive concept by those skilled in the art should be included within the scope of protection of the present invention.

Claims

1. A multi-field cooperative passive control device based on rigid geometric contour constraints for natural cavitation phase transition, characterized in that, include: First rigid component; The second rigid member forms a fixed fit, sliding fit, or rotational fit structure with the first rigid member, and there is a fit micro gap with a width of 0.02mm to 0.2mm between them; A rigid geometric cavitation coupling part is integrally formed on the mating surface of a first rigid member or a second rigid member, and has a rigid geometric profile for constraining the phase transition evolution of natural cavitation. The rigid geometric profile is one of a uniform gap surface, a linearly gradually changing gap surface, a variable curvature surface, or a multi-level stepped surface. When there is excitation from at least one external physical field, such as temperature field, pressure field, flow field, or sound field, or when there is relative motion, a local negative pressure is formed in the mating micro-gap, inducing a periodic phase transition of natural cavitation. The natural cavitation phase transition includes at least two of the following modes: bubble generation, compression, expansion, and collapse. The natural cavitation phase transition generates a multi-field synergistic control force under the constraint of the rigid geometric contour.

2. The apparatus according to claim 1, characterized in that, The rigid geometric profile satisfies one of the following conditions: (a) When the rigid geometric profile is a uniform gap surface, the width of the mating micro-gap remains constant along the extension direction of the mating surface; (b) When the rigid geometric profile is a linearly tapered gap surface, the gap linear contraction rate k and the effective length L of the rigid geometric profile satisfy k·L=0.5mm~1.0mm, where the effective length L refers to the projected length of the rigid geometric profile along the fluid flow direction or the relative motion direction. (c) When the rigid geometric profile is a surface with variable curvature, the radius of curvature R and the effective length L of the rigid geometric profile satisfy R / L=6~10, where the effective length L refers to the projected length of the rigid geometric profile along the fluid flow direction or the relative motion direction, and the radius of curvature R is the arithmetic mean of the radius of curvature at any point on the profile. (d) When the rigid geometric profile is a multi-level stepped surface, a 3-5 level stepped structure is adopted, the single-level gap increment is 0.03mm-0.05mm, the initial fit micro-gap is 0.02mm-0.15mm, and the final fit micro-gap is ≤0.2mm.

3. The apparatus according to claim 1, characterized in that, The rigid geometric cavitation coupling part is further provided with an auxiliary structure, the auxiliary structure satisfying at least one of the following: (a) Self-cleaning micro-lip, with a height of 0.03mm to 0.05mm, integrally formed along the outer circumference of the mating micro-gap; (b) Pre-negative pressure guiding structure, which is a guiding slope or guiding groove provided at the micro-gap inlet, used to promote cavitation formation under low excitation conditions; (c) Micro-convex ridge damping structure; (d) Microporous filtration structure; (e) Rigid reinforcing ribs; (f) Multilevel cavitation cavities.

4. The apparatus according to claim 1, characterized in that, The surface roughness Ra of the mating surfaces of the first rigid component and the second rigid component is ≤0.8μm. The materials are selected from glass fiber reinforced engineering plastics, aluminum alloys or cold-rolled steel, and are manufactured using an integral molding process.

5. A multi-field cooperative passive control method for natural cavitation phase transition based on rigid geometric contour constraints, characterized in that, Includes the following steps: The first rigid member and the second rigid member are made to slide or rotate relative to each other, and a micro-gap with a width of 0.02mm to 0.2mm is provided between them, and a rigid geometric cavitation coupling part is provided on the mating surface; The device is placed in at least one physical field, such as a temperature field, a pressure field, a flow field, or a sound field, or the first rigid member and the second rigid member are made to move relative to each other, so that a local negative pressure is formed in the mating micro gap, inducing a periodic phase change in natural cavitation. The natural cavitation phase change includes at least two of the following: bubble generation, compression, expansion, and collapse. By constraining the cavitation phase change path, volume change rate, and pressure evolution law with rigid geometric contours, the cavitation phase change can achieve latent heat exchange, pressure self-adaptation, flow stability, vibration damping, and acoustic dissipation, thus completing multi-field collaborative passive control of heat, flow, force, and sound within a single structure.

6. The method according to claim 5, characterized in that: During the cavitation phase transition, the rate of change of pressure inside a natural cavitation cavity along the displacement direction is directly proportional to the product of the initial pressure and the initial volume, inversely proportional to the square of the volume of the gas phase region, and directly proportional to the rate of change of volume, and is negative; the rate of change of volume is determined by the geometry of the rigid geometric profile.

7. The method according to claim 5, characterized in that, The following controls are implemented based on the type of rigid geometric profile: When the rigid geometric profile is a uniform gap surface, multi-field stable adjustment can be achieved; When the rigid geometric profile is a linearly gradually changing gap surface, the range of working conditions can be widened and adjusted. When the rigid geometric profile is a surface with variable curvature, constant characteristic multi-field output adjustment can be achieved; When the rigid geometric profile is a multi-level stepped surface, nonlinear multi-field coupling adjustment is achieved.

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