22 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 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.

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 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 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 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 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.

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.

The utility model discloses a fuel oil low-cavitation flow control end structure of an oil injector and the oil injector, and relates to the technical field of oil injectors, the fuel oil low-cavitation flow control end structure of the oil injector comprises a control valve seat, a control cavity is arranged in the control valve seat, and a control piston is connected in the control cavity in a sliding mode. An upper cavity is formed between the control piston and the top end in the control cavity, a control end oil inlet hole is formed in the side wall of the control valve seat, a control end oil outlet hole is formed in the top end of the control cavity, and the control end oil inlet hole and the control end oil outlet hole are both communicated with the upper cavity. The upper end of the control end oil outlet quantity hole is connected with a diffusion taper hole, the diameter of the diffusion taper hole is gradually increased from bottom to top, and a plugging control device is arranged at the upper end of the diffusion taper hole and can plug the diffusion taper hole. The cavitation problem of the control end of the oil sprayer can be effectively solved.

This invention provides a numerical prediction method for cavitation noise in bladed pump-jet propulsion. It conducts steady and unsteady numerical simulations of the internal flow of the bladed pump-jet propulsion, analyzing its hydrodynamic performance and internal flow field. Secondly, it performs numerical simulations of the propulsion's cavitation flow, comparing and analyzing the propulsion's hydrodynamic performance under non-cavitation and cavitation states. It also analyzes the cavitation flow field of the propulsion at different speeds and cavitation numbers, exploring the cavitation evolution law and its dynamic characteristics. Finally, based on the unsteady calculation results of the internal flow of the bladed pump-jet propulsion, combined with acoustic finite element method calculations and spherical cavitation radiation theory, it numerically simulates the noise induced by the cavitation flow inside the propulsion, analyzing the relationship between the propulsion's cavitation flow and its induced cavitation noise. This aims to provide a reasonable and effective prediction method for the numerical prediction of cavitation noise in bladed pump-jet propulsion, possessing significant theoretical and engineering value.

The application discloses a kind of non-steady cavitation flow internal flow field structure measurement system.The measurement system is composed of closed cavitation hydraulic circuit and synchronous radiation X-ray fast imaging system, and the cavitation hydraulic circuit includes experimental section, water storage tank, variable frequency circulating pump, cooling water tank, pipe type electric heater, turbine flowmeter and K-type thermocouple;X-ray fast imaging system includes synchronous radiation light source, shutter device, optical magnifier, X-ray detector, 90° reflector and high-speed CCD camera.The measurement method of the measurement system is also disclosed.The application generates non-steady cavitation flow in the experimental section of cavitation hydraulic circuit, and builds an imaging system based on high-energy high-frequency pulsed synchronous radiation X-ray, which breaks through the optical shielding problem of cavitation vapor-liquid mixture, realizes high spatiotemporal resolution cavitation internal vapor-liquid two-phase form visualization and velocity field measurement, and solves the problem that conventional optical measurement technology cannot accurately obtain cavitation internal information.