34 results about "Cavitation flow" patented technology

According to the BDIM-based propeller cavitation streaming simulation algorithm provided by the invention, the particularity of a propeller structure is considered, a hyperbolic tangent encryption function is introduced into a near-wall region of the propeller structure to carry out non-uniform grid division, and high-gradient flow and boundary layer development of a blade tip region can be effectively captured, so that the resolution of a cavitation source region and a vortex core is improved; in multi-phase interface tracking, a VOF method is adopted to carry out high-resolution reconstruction on fluctuation behaviors of a vapor-liquid interface, interface diffusion distortion can be avoided, interface definition and mass conservation can be taken into consideration in combination with double-field evolution of a volume fraction function and an intermediate velocity field, and the method is suitable for being applied to multi-phase interface tracking. The method is particularly suitable for dynamic capture of a cavitation primary area and a complex gas-liquid phase mixing area in a propeller wake, and the precision and reliability of simulation on the cavitation occurrence position, the time scale and the form can be improved.

The invention provides a cavitation flow field reconstruction method based on sparse perception and an unsupervised learning method, and the method comprises the steps: firstly, carrying out the numerical simulation of cavitation flow around a specific type of hydrofoil, considering the unique characteristics of a cavitation flow velocity field, executing the intrinsic orthogonal decomposition, and representing the intrinsic orthogonal decomposition as a representation form of the superposition of an average velocity field and a pulsation velocity field; a fluid velocity field modal library is constructed on the basis; and then an unsupervised clustering algorithm and sparse data sampling are executed to extract data samples, and fluid velocity field reconstruction is completed by using the velocity field modal library and a small number of data samples. Through verification and comparison of reconstruction effects under different sparse sampling strategies, high-fidelity reconstruction of a complex cavitation flow structure can be finally realized, and compared with the prior art, accuracy and robustness are remarkably improved.

The invention discloses a low-temperature liquid cavitation numerical prediction method considering different-scale heat effects, and belongs to the field of low-temperature liquid cavitation numerical prediction. The implementation method comprises the steps that a corresponding fluid domain geometric model is established, grids are divided, a computational fluid mechanics model is established under the macro-scale, a separation vortex DES turbulence model is adopted, a fluid volume VOF model is used for capturing a macro-scale cavity interface, and convective heat transfer correction under the macro-scale is conducted on a cavitation model; establishing a cavitation kinetic equation considering heat conduction correction under the mesoscale, solving resistance, volume force, additional mass force, pressure gradient force and lift force suffered by the mesoscale discrete cavitation by using a DBM discrete phase model, and obtaining a movement track of the discrete cavitation in a cavitation flow field; and calculating the unsteady cavitation flow by taking a steady result as an initial value to obtain a flow field characteristic under a macroscale and a discrete cavitation dynamic evolution process under a mesoscale, thereby realizing quantitative description and high-precision numerical prediction of the unsteady cavitation flow.

The application discloses a kind of monitoring devices of pressure fluctuation frequency and amplitude in cavitation collapse process, including water tank, cavitation generator, magnetic fluid, magnetic field device, laser generator, optical splitter, laser probe and receiver;Optical splitter is emitted by single beam laser of laser generator and is divided into two beams, one is emitted as laser, frequency is f ;Another is as reference laser, frequency is f + f r ;Laser probe exports and irradiates on the tip of magnetic fluid by emitting laser, and reflection is formed to form reflected laser, and its frequency is f + f D ;Receiver, accept reflected laser, and it has reference laser inside by optical splitter, and its frequency is f + f r The application can master the whole dynamic data of quantized cavitation collapse by monitoring the frequency and amplitude of whole process pressure fluctuation caused by cavitation collapse in liquid environment through magnetic fluid magneto-rheological effect, tip surface effect and Doppler effect, which provides important technical means for single-cavity theory development and hydraulic machinery cavitation flow research.

The embodiment of the invention provides a drag reduction effect AI control method and system for a natural-ventilation mixed cavitation hydrofoil, and relates to the technical field of ship engineering. Executing a cavitation flow experiment to obtain an input data set and an output data set; performing feature extraction based on the input data set and the output data set to obtain a cavitation coverage area rate, a flow field instability feature parameter, an interface evolution stability index and a signal cavitation index, and integrating into a response data set; constructing a comprehensive data source set based on the input data set, the output data set and the response data set; and determining the influence level of the current ventilation behavior based on the response data set, and determining an optimal design scheme based on the influence level and the comprehensive data source set. The method overcomes the limitation that a traditional static black box model only depends on an input-output relation and lacks process feedback, and effectively distinguishes operation states which are temporarily low in resistance but about to be unstable from operation states which are really stable and efficient.

The invention relates to the technical field of state monitoring and fault diagnosis of ship power devices, and provides a noise data processing method based on cavitation flow characteristics of a propeller. According to the method, observable dynamic frequencies such as leaf frequency and cavitation bubble falling main frequency and statistical non-stationary quantities such as a frequency spectrum broadening factor, self-correlation time, broadband energy and kurtosis are unified in the same analysis framework, a mapping model of a cavitation state and signal processing parameters is constructed, analysis parameters such as FFT, STFT and CWT are adaptively configured, and the analysis parameters of the cavitation state and the signal processing parameters are analyzed. And multi-scale feature extraction of non-stationary pressure pulsation signals under different cavitation types and cavitation intensities is realized. According to the method, the cavitation state and type are identified and evaluated on the basis of the extracted multi-domain features, the threshold and mapping parameters are reversely updated according to the identification result, a closed loop of state judgment, parameter mapping, multi-domain analysis, feature output, cavitation identification and parameter updating is formed, and the precision and engineering applicability of propeller cavitation monitoring and diagnosis are improved.

A hydrofoil cavitating flow control structure includes a hydrofoil. A primary protuberant stripe is disposed in a middle position of a suction side of the hydrofoil, a plurality of symmetrically-distributed secondary protuberant stripes are disposed obliquely at both sides of the primary protuberant stripe, and the plurality of secondary protuberant stripes are uniformly and equidistantly distributed along the length direction of the primary protuberant stripe. By changing geometric parameters such as an included angle between the primary protuberant stripe and the second protuberant stripe, a ratio of cross section diameters and a distribution spacing of the second protuberant stripes along a chord length direction of the hydrofoil and the like, the shedding of cloud cavitation on a hydrofoil surface is effectively suppressed, and cavitation erosion and pressure pulsation generated by cavitation collapse is reduced, thus improving the operation efficiency and the service life of hydraulic machinery.

The invention relates to a multi-phase flow closed-loop regulation and control experiment system for ventilation cavitation bubbles around a revolving body of a vertical water tunnel, and belongs to the field of cavitation water tunnel experiment technologies and equipment. Comprising a control system, a sensing system, a ventilation system, a rudder deflection system and an experimental model. The sensing system senses the state of the experimental model in real time; the control system is used for generating a rudder deflection control instruction and sending the rudder deflection control instruction to the rudder deflection system; a ventilation control instruction is generated and sent to a ventilation system; the rudder deflection system is used for adjusting rudder deflection parameters of the experimental model according to the rudder deflection control instruction, so that the attitude of the experimental model is adjusted, and the free pitching motion of the experimental model is realized; the ventilation system is used for adjusting ventilation parameters of the experimental model according to the ventilation control instruction so as to adjust the cavitation flow capacity of the experimental model; according to the invention, an experimental platform and a research basis are provided for research on flow phenomena such as cavitation falling and collapse and related large-scale and strongly-uncertain hydrodynamic characteristics under the flow direction gravity condition.

An acoustic energy tool comprising a crystal for generating acoustic energy when a volage is applied to the crystal, and a resonator. The resonator has a solid outer structure with the crystal being attached to the solid outer structure, with the resonator being comprised of a material that transmits the acoustic energy through the resonator. The tool includes a curved surface that focuses the acoustic energy being transmitted through the resonator and a fluid passageway that extends through the resonator for allowing a fluid to flow through the resonator. The acoustic energy being focused by the curved surface is concentrated in the fluid passageway so that it causes cavitation of the fluid in at least part of the fluid passageway. The cavitation of the fluid is used to break up clumps that form in the fluid or to generate reactive oxygen species.

This invention relates to the field of submerged cavitation water jets, specifically to a method for simulating the flow field load and ice-breaking of submerged water jets considering cavitation effects. The method includes obtaining an initial flow field-ice plate topology model; adjusting the fractal dimension of the mesh through a fractal growth mechanism, fusing a probabilistic model, and embedding a viscoelastic network stress transfer mechanism to obtain a fractal characteristic load field; converting the load generated by fractal iterative loading into the stress and strain of the ice plate, extracting dynamic damage evolution data of the ice plate and chaotic characteristic parameters from the fractal characteristic load field, and obtaining optimized submerged water jet parameters. This invention constructs coupling and correlation rules, clarifying the core coupling relationship between the cavitation-sensitive region and the ice plate load action region, ensuring that the cavitation load is accurately transferred to key areas of the ice layer. By adjusting the fractal dimension of the mesh in real time through a fractal growth mechanism to adapt to the dynamic evolution stage of cavitation bubbles, it solves the problem that traditional models cannot simultaneously capture the cavitation flow field morphology and ice plate damage.

The application discloses a structure optimization method for inhibiting cavitation of a low-temperature stop valve, and comprises the following steps: S1, establishing a stop valve model and performing grid division; S2, performing a numerical calculation on the stop valve model after the grid division, obtaining a cavitation flow field cloud picture based on the calculation result, and determining a key position of cavitation occurrence; S3, optimizing the stop valve model, that is, setting a uniform grid-shaped flow guide plate at the key position of cavitation occurrence; S4, performing a second numerical calculation on the optimized stop valve model, obtaining an average gas phase volume and a flow coefficient based on the calculation result; S5, performing optimization judgment according to the average gas phase volume and the flow coefficient; and S6, repeating S4 and S5 until the average gas phase volume and the flow coefficient both meet the requirements, and outputting structure parameters of the optimized stop valve. The method can be widely applied to the design and optimization of stop valves in a low-temperature fluid conveying system, and has remarkable engineering application value.

An acoustic energy tool comprising a crystal for generating acoustic energy when a volage is applied to the crystal, and a resonator. The resonator has a solid outer structure with the crystal being attached to the solid outer structure, with the resonator being comprised of a material that transmits the acoustic energy through the resonator. The tool includes a curved surface that focuses the acoustic energy being transmitted through the resonator and a fluid passageway that extends through the resonator for allowing a fluid to flow through the resonator. The acoustic energy being focused by the curved surface is concentrated in the fluid passageway so that it causes cavitation of the fluid in at least part of the fluid passageway. The cavitation of the fluid is used to break up clumps that form in the fluid or to generate reactive oxygen species.

The utility model discloses a cavitation multiphase flow detection experiment system in the field of fluid testing, which comprises a liquid circulation pipeline module which comprises an inflow section, a gas-liquid mixing section, a testing section and a backflow section and is used for forming a liquid flowing loop and realizing the functions of controllable inflow conditions and outflow state recovery of main flow; the gas inlet and gas-liquid mixing pipeline module is communicated with the gas-liquid mixing section and is used for forming a gas-liquid two-phase fluid medium and realizing the controllability of the gas-phase medium; the cavitation flow experiment module is arranged corresponding to the test section and is used for forming a cavitation flow phenomenon and realizing a cavitation flow visualization function; and the multiphase flow test module is arranged corresponding to the cavitation flow experiment module and is used for detecting the characteristics of the cavitation multiphase flow field and realizing a non-intrusive test function. The gas-liquid two-phase flow state can be controlled, two-phase flow media under different gas-containing conditions can be obtained, cavitation flow states of different degrees can be formed, and cavitation flow characteristics under the influence of gas can be analyzed conveniently.

The present application belongs to the technical field of intersection of computational fluid dynamics and artificial intelligence, and in particular to a high-precision prediction method for a hydrodynamic torque converter cavitation flow field. The method comprises the following steps: S1: obtaining transient CFD flow field simulation data inside the guide wheel flow passage of the hydrodynamic torque converter; S2: constructing a multi-task neural network model; S3: constructing a hybrid supervised loss function for optimizing the cavitation prediction sub-network; S4: training the neural network model by adopting a three-stage decoupling strategy; S5: constructing a physical residual loss term based on the law of conservation of fluid dynamics; and S6: inputting the space-time coordinates to be predicted into the trained neural network model. The present application improves the recognition accuracy of sparse cavitation features, enhances the training stability of complex multiphase flow fields, improves the physical consistency of the prediction results, and significantly improves the calculation efficiency of the cavitation flow field.

This invention provides a numerical simulation method and system for cavitation turbulence based on gas-liquid slip velocity correction, belonging to the field of cavitation numerical simulation technology. It obtains the gas phase volume fraction distribution and liquid phase velocity field distribution in a fluid pipe, establishes the density gradient field of the gas-liquid interface region, constructs a dynamic characteristic function of the gas-liquid interface including a coupled expression of interface curvature and local vorticity terms, and uses an adaptive gas-liquid slip velocity correction model to correct the relative gas-liquid velocities, solving for the turbulent characteristic parameters and pressure field distribution in the cavitation flow field. This significantly improves the accuracy and refinement of the gas-liquid interface dynamics description, enhances the adaptability of the slip velocity correction model to the nonlinear characteristics of the interface, and helps to more accurately simulate cavitation turbulence behavior, thereby improving the accuracy and reliability of cavitation turbulence numerical simulation and providing more scientific and effective technical support for cavitation prediction and control in complex engineering fields.

The present application relates to a kind of cavity erosion prediction method considering cavity collapse and its energy transport process, belong to the technical field of hydrodynamics research.The cavity erosion prediction method includes the following steps: solving cavitation flow field to the object to be predicted;Based on the physical property change of cavity collapse, identify collapse region and record cavity collapse pressure;According to cavity collapse pressure, calculate collapse energy;Analysis of the transport process of collapse energy radiated to the wall to be predicted position, calculate transfer parameter and attenuation parameter, and the transport parameter is obtained by multiplication;Combined with collapse energy and transport parameter, calculate the cavity erosion load of collapse energy radiated to the wall, and the cumulative cavity erosion load of the current predicted position of wall is obtained by accumulation;According to cumulative cavity erosion load, determine the cavity erosion region.The cavity erosion prediction method considers the real physical process of cavity collapse, ensures the authenticity of collapse region identification, and considers the transfer and dissipation process in energy transport, ensures the accuracy of cavity erosion region prediction.

The invention provides a cavitation turbulence numerical simulation method and system based on gas-liquid slippage velocity correction, and relates to the technical field of cavitation numerical simulation. Gas phase volume fraction distribution and liquid phase velocity field distribution in a fluid pipeline are obtained, and a density gradient field of a gas-liquid two-phase interface area is established; and constructing a gas-liquid interface dynamic characteristic function containing coupling expression of an interface curvature item and a local vorticity item, correcting the gas-liquid relative velocity by adopting a self-adaptive gas-liquid slippage velocity correction model, and solving turbulence characteristic parameters and pressure field distribution in the cavitation flow field. Thus, the accuracy and the refinement degree of gas-liquid interface dynamic description can be remarkably improved, the adaptability of a slip velocity correction model to interface nonlinear characteristics is enhanced, cavitation turbulence behaviors can be simulated more accurately, and therefore the accuracy and the reliability of cavitation turbulence numerical simulation are improved; and a more scientific and effective technical support is provided for cavitation prediction and control in the complex engineering field.

The invention discloses a method for estimating the form of a ventilation supercavity under the action of tail jet flow. The method comprises the following steps: step 1, constructing a mathematical model; 2, on the basis of the mathematical model, boundary condition setting and mesh generation are carried out on the watershed of the aircraft, and a numerical calculation model is obtained; 3, verifying the numerical calculation model to obtain a ventilation supercavitation numerical calculation model suitable for the tail jet flow effect; and 4, based on the supercavitation numerical calculation model, performing simulation calculation on the ventilation supercavitation flow field under the action of the tail jet flow to obtain a simulation result. According to the method for estimating the ventilation supercavitation form under the action of the tail jet flow, the problems that the ventilation supercavitation flow is high in unsteady performance, and the ventilation supercavitation form under the action of the tail jet flow is difficult to calculate when the attack angle exists or not are solved.

The invention relates to the technical field of high-altitude environmental engineering, and discloses a cavitation flow numerical calculation key parameter correction method, system, equipment and medium aiming at high-altitude area environmental characteristics, and the method comprises the following steps: collecting atmospheric pressure measured data at different altitudes, establishing a segmented fitting relationship between atmospheric pressure and altitudes, and calculating a cavitation flow numerical calculation key parameter; acquiring an actual atmospheric pressure value of the current region of the power station; the method comprises the following steps: acquiring a water sample on site, measuring cavitation characteristic parameters, and combining sediment content analysis to obtain a corrected cavitation pressure value suitable for a local environment; measuring the distribution characteristics of gas nuclei in a local water body, and obtaining the corrected gas nucleus volume fraction and bubble initial radius; and the corrected parameters are substituted into a cavitation model based on a Rayleigh-Plesset equation, and cavitation flow numerical calculation is carried out. According to the method, the accuracy of cavitation flow calculation in the high-altitude area can be improved, and the rationality of cavitation calculation of a power station and a unit is guaranteed.

The present application relates to the technical field of fluid machinery computational fluid dynamics, in particular to a cavitation turbulent large eddy simulation method of nonlinear phase change viscosity correction, in the method, based on the local gas content, the effective dynamic viscosity of the fluid is updated by using a nonlinear hybrid dynamic viscosity empirical formula, the nonlinear hybrid dynamic viscosity empirical formula is used for characterizing additional dissipation generated in the gas-liquid mixing area due to interphase interaction; based on the updated flow field, the sub-grid stress is calculated, and a dynamic coefficient damping formula based on cavitation intensity is introduced to correct the core coefficient of the sub-grid model, and the corrected sub-grid turbulent viscosity is obtained. Through the construction of multiphase flow control equation, dynamic sub-grid modeling, nonlinear property updating and flux reconstruction technology, the simulation accuracy and numerical stability of complex cavitation flow are significantly improved, and a high-precision numerical simulation tool is provided for the design optimization and cavitation suppression of hydraulic machinery such as water turbines, water pumps and propellers.

The application discloses a drag reduction effect AI control method and system of a natural-ventilation mixed cavitation hydrofoil, and relates to the technical field of ship engineering. A cavitation flow experiment is performed to obtain an input data set and an output data set; feature extraction is performed based on the input data set and the output data set to obtain a cavitation coverage area rate, a flow field instability characteristic parameter, an interface evolution stability index and a signal cavitation index, and the indexes are integrated into a response data set; a comprehensive data source set is constructed based on the input data set, the output data set and the response data set; and the influence level of a current ventilation behavior is determined based on the response data set, and an optimal design scheme is determined based on the influence level and the comprehensive data source set. The method overcomes the limitation of a traditional static black box model that only relies on an input-output relationship and lacks process feedback, and effectively distinguishes between a temporarily low-drag but soon-to-be unstable state and a truly stable and efficient operating state.

The invention discloses a structure optimization method for inhibiting cavitation of a low-temperature stop valve. The method comprises the following steps: S1, establishing a stop valve model and performing grid division; s2, carrying out primary numerical calculation on the cut-off valve model after grid division, then obtaining a cavitation flow field cloud picture based on a calculation result, and determining a key position where cavitation occurs; s3, optimizing the stop valve model, namely arranging a uniform latticed flow guide plate at a key position where cavitation occurs; s4, carrying out secondary numerical calculation on the optimized stop valve model, and obtaining an average gas phase volume and a flow coefficient based on a calculation result; s5, performing optimization judgment according to the average gas phase volume and the flow coefficient; and S6, repeating S4 and S5 until the average gas phase volume and the flow coefficient meet the requirements, and outputting the optimized stop valve structure parameters. The method can be widely applied to design and optimization of the stop valve in a low-temperature fluid conveying system, and has remarkable engineering application value.

The invention discloses a blade rotor load reduction device and method utilizing an air cushion effect, and belongs to the technical field of marine equipment and aircrafts. The main shaft has rotating and axial moving capabilities, the paddles and the rotating groove are mounted on the main shaft to form a rotor system, a circle of outflow holes are formed in the side wall of the hull head shell, inflow holes are formed in the head of the hull head shell, a plurality of diversion trenches are formed in the outer surface of the rotating groove, one end of each diversion trench is communicated with the inner space of the hull head shell, and the other end of each diversion trench is communicated with the outer space of the hull head shell. The air cushion device is used for controlling the flowing path of air and water in the rotating process, and the air cushion effect is enhanced. According to the method, the method for reducing the load through the air cushion effect has certain controllability, and the problems that after load reduction, bubbles are left in water, and the hydrodynamic performance is affected are solved. The three mechanisms of dynamic air cushion blocking, fluid rectification and active cavitation generation are combined, the load reduction efficiency is high, and the sailing resistance can be continuously reduced through the generated cavitation flow.

This invention discloses a method for predicting and suppressing valve cavitation under high-temperature conditions, belonging to the field of fluid machinery and control technology. This method addresses the problem of inaccurate numerical simulation of valve cavitation under high-temperature conditions by introducing temperature corrections for the interface capture model, cavitation model, and working fluid properties during simulation. This accurately reflects the changes in the working fluid's properties in the actual high-temperature environment, improving the simulation accuracy of the cavitation flow field. Based on this, the entropy-pressure synergy criterion is applied to analyze the cavitation region, and the valve body structure is specifically optimized based on the analysis results. This invention effectively solves the problem of inaccurate numerical simulation of cavitation phenomena in valves under high-temperature conditions, and can provide precise guidance for the reliable design and performance optimization of valves in high-temperature conditions such as metallurgy.

The invention discloses a numerical calculation method for a hydrofoil cavitation dynamics evolution induced energy release mechanism. The numerical calculation method comprises the following steps: constructing a hydrofoil streaming flow field calculation domain; dividing grids for the computational domain, and importing the grids of the computational domain into computational fluid mechanics simulation software; setting a boundary condition and a solution algorithm of hydrofoil cavitation calculation, selecting a discrete phase model, and injecting multiple particles into the head of the hydrofoil; through cavitation flow field calculation, motion characteristics of cavitation bubbles in a cavitation flow field are obtained based on the motion data of the particles; and constructing a multi-cavitation energy numerical model considering the cavitation aggregation effect, and coupling the multi-cavitation energy numerical model with the cavitation kinetic equation to obtain the cavitation radius, the internal pressure, the energy distribution rule and the release mechanism in the cavitation flow. By means of the method, reliable calculation of cavitation characteristic changes of the hydrofoil surface cavitation flow in different forms is achieved, theoretical reference is provided for revealing cavitation dynamics evolution induced energy release, and meanwhile prediction means of energy conversion in the hydraulic machinery cavitation flow with the airfoil section as a basic blade unit are enriched.

The invention discloses a method for predicting and inhibiting cavitation of a valve under a high-temperature working condition, and belongs to the technical field of fluid machinery and control. According to the method, aiming at the problem of inaccurate valve cavitation numerical simulation under the high-temperature working condition, temperature correction under the high-temperature working condition is introduced into an interface capture model, a cavitation model and working medium physical property parameters in simulation, so that the change of the physical property parameters of a working medium in an actual high-temperature environment is accurately reflected, and the simulation precision of a cavitation flow field is improved; and on the basis, the cavitation area is analyzed by applying an entropy pressure cooperation criterion, and the valve body structure is subjected to targeted optimization according to an analysis result. According to the method, the problem of inaccurate numerical simulation of the cavitation phenomenon of the valve under the high-temperature working condition is effectively solved, and accurate guidance can be provided for reliable design and performance optimization of the valve under the high-temperature working conditions such as metallurgy.

The invention discloses a response prediction method for a ventilation supercavity flow pattern in a navigation depth change process. The method comprises the following steps: step 1, constructing a mathematical model; 2, on the basis of the mathematical model, boundary condition setting and mesh generation are carried out on the watershed of the aircraft, and a numerical calculation model is obtained; 3, verifying the numerical calculation model to obtain a ventilation supercavitation numerical calculation model suitable for the variable navigation depth condition; and 4, based on the supercavitation numerical calculation model, performing simulation calculation on the ventilation supercavitation flow field under the variable navigation depth condition to obtain a simulation result. According to the response prediction method for the ventilation supercavity flow pattern in the navigation depth change process, the problem that the flow pattern change and response of the cavity in the navigation depth dynamic change process of the supercavity vehicle cannot be predicted in the prior art is solved.

The invention provides a system and a method for measuring the gas-liquid two-phase slip velocity of an unsteady cavitation flow, and belongs to the technical field of complex multiphase flow measurement. Comprising a venturi type experiment section and a gas-liquid two-phase synchronous imaging velocity measurement system, and the venturi type experiment section adopts a modular structure in which a main body frame and a transparent plug-in are combined. The synchronous imaging velocity measurement system generates sheet laser through a double-pulse laser, realizes synchronous independent imaging of a gas-phase structure and liquid-phase tracer particles by combining four CCD (Charge Coupled Device) cameras and an optical filtering and density filtering technology, and reconstructs a three-dimensional transient velocity field of a gas phase and a liquid phase based on a stereoscopic vision principle. And on the basis, performing space-time alignment calculation on the two-phase velocity field to obtain transient distribution of the gas-liquid two-phase slip velocity in the unsteady cavitation flow. According to the invention, the gas-liquid two-phase slip velocity of the cavitation flow can be directly measured, and reliable experimental data can be provided for the correction of a cavitation numerical model.

The invention discloses an efficient inner hole polishing and strengthening combined machining method and device, and relates to the technical field of polishing and strengthening machining, the device comprises a first support, a base and a second support, and the upper surface of the base is provided with a first piston cylinder and a second piston cylinder through the first support and the second support respectively. According to the three-stage synergistic cavitation enhancement structure constructed by the invention, the flow guide ring bulges disturb mixed liquid and induce cavitation when the flow channel volume is alternated and the pressure is fluctuated; the streamline connection area changes flow velocity and pressure to promote cavitation generation; the grooves and the pits trigger local turbulence to generate extra cavitation bubbles, so that the generation frequency and quantity of cavitation bubbles are remarkably improved, and the strengthening effect is enhanced; in the machining process, when the hole wall is polished by the abrasive particles, the cavitation bubbles collapse and release energy to strengthen the hole wall, two machining tasks are synchronously completed in a single process, a subsequent independent strengthening process is not needed, the machining period is greatly shortened, and the production efficiency is improved.

A cryogenic fluid throttling characteristic visualization experimental device includes: a vacuum chamber and a connected test chamber, a cryogenic visualization module, a cryogenic fluid filling and discharging module, and a data acquisition system. The vacuum chamber is equipped with a coil heat exchanger and a gas-liquid separator for regulating the subcooling and stability of the fluid before throttling. The cryogenic visualization module is mounted on the test chamber, and the throttling test section to be measured is located within the test chamber. The cryogenic fluid filling and discharging module and the data acquisition system are connected to the vacuum chamber and the test chamber, respectively. This invention enables the visualization study of the throttling cavitation flow characteristics of cryogenic fluids such as liquid hydrogen and liquid nitrogen under different operating conditions.