103 results about "Cavitation flow" patented technology

The invention discloses a numerical simulation method for axial flow pump blade tip gap leakage vortex cavitation. An axial flow pump cavitation flow field is subjected to numerical calculation by performing three-dimensional geometric modeling on the axial flow pump, dividing calculation grids and establishing a cavitation flow calculation fluid dynamics model and adopting a cavitation model corrected based on a vortex discrimination method, and the cavitation performance of the axial flow pump and the blade top gap leakage vortex cavitation flow characteristic are obtained through analysis.According to the method, the influence of vortex flow on the cavitation phase change process is fully considered, the reliability of a vortex cavitation numerical calculation result is improved, rapidand high-precision numerical prediction of axial flow pump blade tip gap leakage vortex cavitation is realized, and a good mathematical basis is laid for research on a flowing mechanism and an inhibition measure of axial flow pump blade top gap leakage vortex cavitation. meanwhile, the method can also be popularized and applied to numerical simulation research on blade top gap leakage vortex cavitation of other blade type hydraulic machines such as a mixed flow pump and a water turbine.

The invention relates to an unsteady cavitation flow-excited vibration multi-field synchronous measurement system for a water tunnel experiment and belongs to the ship and underwater vehicle engineering and water conservancy and hydropower engineering technology field. The system is composed of an experimental section, an experimental model, a high-speed camera, a synchronous trigger switch, a laser Doppler vibration meter, a data acquisition instrument, a data processing system/computer and display assembly and a light source. According to the system of the invention, rising edge voltage signals are generated through the synchronous trigger switch, trigger signals are controlled by using the voltage signals, and therefore, the signal acquisition starting instructions of the high-speed camera and the laser Doppler vibration meter are controlled quantitatively and precisely, and the quantitative and accurate synchronous measurement of an unsteady cavitation flow field and a structure field can be realized; and data obtained through multi-physical field synchronous acquisition are subjected to preprocessing, time-domain analysis, frequency-domain analysis and time-frequency analysis,and therefore, reliable analysis experimental data can be provided for the study of fluid-structure interaction characteristics.

The invention discloses a cavitation flow numerical simulation method based on a Liutex-Omega vortex recognition theory. The method specifically comprises the following steps of: judging a vortex region in a cavitation flow field by adopting a standardized Liutex-Omega vortex recognition coefficient L; effectively identifying a strong vortex region with rotating dominance, establishing a cavitation flow calculation fluid mechanics model based on a Liutex-Omega vortex identification coefficient omegaL partition according to a delay action mechanism of a strong vortex on a vapor-liquid condensation process in cavitation, and carrying out numerical calculation on a three-dimensional cavitation flow field to obtain vortex cavitation flow characteristics. Comparative analysis is carried out onan actual measurement result and an existing classical cavitation model calculation result; it is verified that the method can effectively reflect the vortex cavitation flow characteristics and the space-time evolution law of the vortex cavitation flow, the prediction precision of the vortex cavitation flow is remarkably improved, and the method can be popularized and applied to numerical simulation research of the vortex cavitation flow characteristics of three-dimensional hydrofoils, water pumps, water turbines, propellers and the like.

A fluid discharge apparatus adapted to discharge a cavitating stream of pressurized liquid along with the selective discharge of a secondary material, such as an abrasive, for removing dirt, debris, barnacles, marine growth, and other substances from submerged surfaces is provided. More particularly, the invention contemplates a introducing a pressurized liquid into a cavitation generating chamber to create and discharge a cavitating stream, and a secondary inlet for injecting abrasive material, such as silica, into the chamber to improve cleaning effectiveness. The gas bubbles within the cavitating liquid stream that essentially explode upon impacting debris resulting in tremendous pressure fluxuations provides improved effectiveness in removing debris and aquatic growth from the submerged surface. The combination of a secondary substance, such as an abrasive material, foam, or compressed gas enhances cleaning effectiveness. The invention further improves upon the control of such devices with controls, such as a pistol grip or rotational grip controllers, that allow the diver/operator to adjust flow rates and thrust without releasing his grasp. An improved hand-held apparatus is disclosed with a pistol grip and trigger actuator, and an improved wheeled vehicle is disclosed with improved control handles adapted to actuate valves and closure ports.

A liquid pump includes an electronically controlled throttle inlet valve to control pump output. With each reciprocation cycle, a plunger displaces a fixed volume of fluid. When less than this fixed volume is desired as the output from the pump, the electronically controlled throttle inlet valve throttles flow past a passive inlet check valve to reduce output. As a consequence, cavitation bubbles are generated during the intake stroke. Cavitation damage to surfaces that define the inlet port passage are avoided by a specifically shaped and sized cavitation flow adjuster extending from the valve member of the passive inlet check valve. By positioning the cavitation flow adjuster in the inlet port passage, a flow pattern is formed in a way to encourage cavitation bubble collapse away from surfaces that could result in unacceptable cavitation damage to the pump.

The invention provides a combined type cavitator which comprises a cone part and a truncated-cone part. The cone part is arranged on the front section and the truncated-cone part is arranged on the rear section. The upper bottom face with the small diameter of the truncated-cone part is connected with the bottom face of the cone part. The diameter of the upper bottom face of the truncated-cone part is smaller than the diameter of the bottom face of the cone part. A pin hole is formed in the rear end of the truncated-cone part and used for allowing the combined type cavitator to be installed on a head of a navigation body. Due to the fact that the combined type cavitator is installed in the center of the head of the underwater navigation body, super-cavitation flow can be achieved at the low navigation speed or the large background pressure, and the problems that resistance is too large and the navigation speed is low when the navigation body navigates underwater are effectively solved.

The invention discloses a turbine pump inducer cavitation flow numerical prediction method based on low-temperature fluid, and belongs to the technical field of impeller machinery. The implementationmethod comprises the following steps: establishing an inducer model and an inlet and outlet runner model according to actual working conditions, and dividing grids; Establishing a computational fluidmechanics model, carrying out rotation correction on the turbulence model, and carrying out thermodynamic correction on the cavitation model; Setting and calculating boundary conditions of the single-phase steady flow to obtain a single-phase result; Calculating two-phase steady flow by taking a single-phase result as an initial value, and then changing inlet pressure and outlet mass flow to obtain calculation results of different working conditions; Calculating unsteady flow of the two phases by taking the two-phase steady result as an initial value to obtain an unsteady calculation result; By analyzing a calculation result, accurate flow field characteristic distribution, inducer performance and radial force dynamic characteristics of the inducer under the action of a flow field are obtained, the inducer is assisted to be designed and optimized, and the experiment cost and time are saved.

In a surface treating method of the present invention, a fluid suction passage 26 communicating with a fluid supply passage 25 via only a narrowed portion 27 is provided, so as to approximately concentrically surround the periphery of the fluid supply passage 25 having the narrowed portion 27 at one end thereof, and the sucking cavitation flow 5 is generated at the direct downstream of the narrowed portion 27, by sucking the processing fluid 8 into the fluid suction passage 26 using a suction pump 17, as well as a surface treating is performed on the treated surface 6a, by crushing the sucking cavitation flow 5 approximately perpendicular to the treated surface 6a.

The invention discloses an optimizing design method of two-phase low temperature liquid expansion machine cavitation resistance. The optimizing design method comprises the steps of considering vortexcavitation mechanism research, considering a low temperature fluid thermodynamics effect, of a two-phase low temperature liquid expansion machine, geometric parameter sensitivity analysis of vortex cavitation flow in the two-phase low temperature liquid expansion machine and characterized expression of complex vortex cavitation flow in the two-phase low temperature liquid expansion machine, building a flow field optimizing target function with the purpose of controlling vortex cavitation flow, conducting optimizing control on the vortex cavitation flow and parallelly solving a cavitation resistance optimizing design problem. By means of the method, the performance and running stability of the two-phase low temperature liquid expansion machine can be effectively improved.

The invention discloses a cone valve type dynamic visualization achieving device and method for a high-pressure fuel oil system of a diesel engine and belongs to the field of diesel engines. The cone valve type dynamic visualization achieving device is used for observing the flowing condition of fuel oil on a conical surface of a control valve and comprises a cone valve body, a pressure sensor, a valve element, a displacement sensor and a spring. Force borne by the valve element is changed to be balanced by regulating the pressure of an oil inlet of the cone valve body, so that the valve element is in the stable state again under the action of the spring, and the movement rule of the valve element and the change of a flow field in a flow channel are explored. By the adoption of the cone valve type dynamic visualization achieving device and method, measurement of cavitation flow parameters and observation of the development and change of bubbles can be conducted under a high pressure difference condition, and the dynamic change process of flowing of the fuel oil on the conical surface can be observed in real time.

To provide an erosion characteristics database and a method for constructing the same, an erosion prediction method and an erosion prediction system using the database for predicting a widespread erosion amount of a fluid machine or the like in a short time without the need for an operation of a model machine or an actual machine.

A method for predicting erosion of a fluid machine surface due to cavitation, the method including: calculating erosion intensity distribution in each area of the fluid machine surface from cavitation flow field characteristics obtained using cavitation CFD in a flow path formed by the fluid machine; determining radius distribution and center position distribution of a representative sphere and the number of shape deformations by the representative sphere for assuming an erosion surface having a porous surface property based on the erosion intensity distribution; determining a fluid machine surface to be predicted as an approximate erosion surface; and calculating a shape after deformation of the approximate erosion surface based on the radius distribution and the center position of the representative sphere and the number of shape deformations by the representative sphere.

A fluid discharge apparatus adapted to discharge a cavitating stream of pressurized liquid along with the selective discharge of a secondary material, such as sand, for removing dirt, debris, barnacles, marine growth, and other substances from surfaces is provided. More particularly, the invention contemplates a secondary hose inlet and nozzle outlet for discharging abrasive material, such as silica, to improve cleaning effectiveness. The combination of a secondary fluid or abrasive substance with the gas bubbles within the cavitating liquid stream that essentially explode upon impacting debris resulting in tremendous pressure fluxuations provides improved effectiveness in removing debris and aquatic growth from the submerged surface. The invention further improves upon the control of such devices with controls that allow the diver/operator to adjust flow rates and thrust without releasing his grasp. An improved hand-held apparatus is disclosed with a pistol grip and trigger actuator, and an improved wheeled vehicle is disclosed with improved control handles adapted to actuate valves and closure ports.

The invention discloses a strong shear type central jet cavitation generator. The strong shear type central jet cavitation generator comprises a high-pressure water supply pipe, a nozzle, a water return cavity, a retaining plate, a flow discharge chamber and a flow discharge pipe. The strong shear type central jet cavitation generator is characterized in that high-pressure working flow pressure is converted into kinetic energy by utilizing the nozzle to form high-speed jet; the turbulent fluctuation of the high-speed flow is enhanced by the annular boss at the inner edge of the outlet of the nozzle; return flow is formed by the throat pipe of the water return cavity and the retaining plate, the return flow and the central high-speed jet form a strong shear effect at a position between the outlet of the nozzle and the inlet of the throat pipe, and strong shear cavitation is formed; when the strong shear cavitation flow moves along the conical pipe of the water return cavity, bubbles in the cavitation flow collapse under high pressure to form impact waves and micro-jet, and high temperature and high pressure are generated at the same time. Compared with a same-type shear cavitation generator, the strong shear type central jet cavitation generator is large in shear layer, large in speed difference and strong in shear effect; compared with a cavitator, the strong shear type central jet cavitation generator is good in cavitation effect and high in cavitation intensity.

The invention discloses a numerical prediction method for internal reflux and reflux vortex cavitation of a vane pump. The numerical prediction method is used for predicting the internal reflux and reflux vortex cavitation phenomenon of the vane pump when the vane pump operates under a small-flow working condition. The method comprises the following steps: 1) separately carrying out numerical calculation on steady flow in a pump and cavitation flow in the pump under different working conditions in CFD software, extracting flow field information, and obtaining impeller cavitation bubble distribution; and (2) based on a numerical calculation result in the step (1), carrying out numerical calculation of unsteady flow in the pump , and setting related pressure pulsation monitoring points, andperforming unsteady numerical simulation on the typical working condition points, and extracting flow field and pressure pulsation information; and 3) comparing the dominant frequencies of the monitoring points based on the step 2), carrying out phase correlation analysis on the pressure pulsation signals to obtain the number of unstable flow units and corresponding axial and radial characteristics, and comparing and analyzing critical working condition points of backflow and backflow vortex cavitation based on the flow field information of the step 1) and the step 2).

The invention relates to an unsteady cavitation flow field visualization test data processing method, and belongs to the multiphase fluid mechanics technical field; the method can fully considers the cavitation flow unsteady characteristics, thus improving the visualization test data processing efficiency, and reducing cost; the method can make statistics analysis for an unsteady cavitation flow field structure, thus accurately and efficiently obtaining the unsteady cavitation flow field characteristic parameters like a cavity shedding period, a cavity area and a cavitation vortex strip average length, and improving the unsteady characteristic display effect.

The invention relates to a detachable cryogenic liquid cavitation flow observational test section, which belongs to the technical field of fluid mechanical engineering, cryogenic engineering and aerospace engineering. The detachable cryogenic liquid cavitation flow observational test section comprises temperature sensors and pressure sensors, wherein the temperature sensors and the pressure sensors are installed on a runner lower panel through installation holes; the runner lower panel is in contact connection with a pipeline inside a basic runner through a notch at the lower part of the basic runner, and is fixedly connected on the basic runner through a pressing gasket; a visual observation window is formed in a notch at the upper part of the basic runner, and two buffer gaskets are installed on both sides of the visual observation window separately; a connecting bayonet is fixedly connected on the basic runner; and both sides of the basic runner are provided with flange plates. The detachable cryogenic liquid cavitation flow observational test section is assembled by adopting a plurality of parts, is simple in structure, has few components, greatly reduces cost when compared with an integrated visual test section made of glass materials entirely, is convenient in detachment and installation, and is not prone to damage during the detachment and installation process.

The invention discloses a method for forecasting the effect of internal waves and ventilation cavitation bubbles. According to the method, a navigation body model and a three-dimensional calculation basin are established on the basis of a three-dimensional geometric modeling method, calculation basin grids are divided on the basis of a grid division method, a multi-phase calculation fluid mechanics model of natural cavitation and ventilation cavitation is established, and initial boundary conditions are set for flow field numerical calculation of a three-dimensional calculation domain; when the cavitation phenomenon reaches a stable period, coupling the internal wave model, and calculating the action of the internal wave on the cavitation form and the hydrodynamic force of the flow field;and processing and analyzing the calculation result based on a post-processing program to obtain the influence of the internal wave on the cavitation form change. The method can be applied to flow field calculation of multi-phase cavitation and ventilation cavitation flow, the cavitation form and the hydrodynamic force of the flow field can be finely calculated, and the cavitation form evolution and hydrodynamic change process when the cavitation and ventilation cavitation reach the stable state and a navigation body encounters internal waves can be calculated in a numerical simulation mode.

The invention discloses a water tunnel test device capable of generating oscillating freestream. The water tunnel test device is composed of a control system I, a transmission mechanism II, an oscillation generator III and a water tunnel test platform IV. The control system comprises an industrial control computer, a controller, a servo motor and an angular speed sensor. The transmission mechanismcomprises a connecting rod, a rotating pair, a flywheel, a bearing and a moveable seal. The oscillation generator comprises a hydrofoil and a hydrofoil connecting shaft. The test platform comprises acirculating water tunnel and an underwater vehicle model. The test device is simple in structure and suitable for the cavitation flow test of various test models.

The invention belongs to the field of engineering computational fluid mechanics, and particularly relates to a numerical simulation method for rotational turbulence in compressible cavitation flow. The method mainly comprises the following steps: calculating a vortex viscosity coefficient and sub-lattice stress by adopting a compressible nonlinear sub-lattice model, introducing an adjusting factorto correct the sub-lattice stress, creating a compressible nonlinear sub-lattice model base class, and implanting the compressible nonlinear sub-lattice model into the compressible cavitation flow solver. According to the method, the influence of the rotational turbulence in the compressible cavitation flow is considered, the stability of compressible cavitation flow calculation is ensured by introducing an adjustment factor, the requirements of compressible cavitation flow simulation on grids can be effectively reduced, and the calculation efficiency is improved. Meanwhile, a new thought isprovided for deeply researching the influence of compressibility in compressible cavitation flow on rotational turbulence.

The invention discloses a finite-volume-method-based simulation method of cavitation flow in a water pipe. The method includes: building a transient flow basic control equation containing free gas; building a grid system containing free gas according to a finite volume method (FVM), and performing control equation discrete; using a Godunov format with space-time second order accuracy to calculate the flux of a control unit interface during pure convection; introducing a source item into the solution to obtain the second order explicit FVM-Godunov format of the discrete equation solution; using two methods to correct pressure according to pressure obtained by calculation, and calculating cavitation volume. The finite-volume-method-based simulation method has the advantages that false numerical oscillation is inhibited by introducing a slope limiter; the influence of the free gas and cavitation on the pressure is considered successfully by introducing the pressure correction coefficient C-ap, unreal pulses near the pressure peak of the cavitation flow are eliminated, and the cavitation in a water pipe system is simulated accurately.

The invention discloses a numerical prediction method for impeller tip clearance cavitation of an axial flow pump, belonging to the technical field of impeller machinery simulation. It includes the establishment of the internal flow channel of the axial flow pump and the meshing of its three-dimensional watershed, the construction of the numerical calculation model of the clearance cavitation flow, the numerical calculation of the steady cavitation flow field inside the axial flow pump, the solution of the unsteady cavitation flow field inside the axial flow pump, and the numerical predictionand examination of the clearance cavitation region of the impeller tip of the axial flow pump. The invention considers the influence of the local vortex motion of the blade tip clearance on the cavitation flow, by adding the flow parameters reflecting the local rotational motion characteristics of the flow field into the cavitation model, the credibility of the numerical prediction of the cavitation of the impeller tip clearance of the axial flow pump is improved, and the cavitation region of the impeller tip clearance of the axial flow pump can be predicted accurately, which has important theoretical value and engineering practical significance.

The invention provides a supercavitation navigation body and a cavitation flow control method using wake flow ejection. The navigation body comprises a cavitator and a navigation body, the cavitator is arranged at the head of the navigation body, a vent hole is formed in the rear side of the cavitator, an air chamber is arranged in the navigation body, the air chamber and the vent hole are connected through a vent pipeline, an air valve is arranged on the vent pipeline, and an exhaust nozzle capable of spraying gas jet flow is arranged at the tail of the navigation body. After initial cavitation is formed in the navigation body, a low-pressure gas channel is formed from the cavitator to the exhaust nozzle, the gas jet flow sprayed out of the exhaust nozzle flows back forwards in a natural entrainment mode, a gas is supplemented for the cavitation, the cavitation form is maintained, and therefore active control over the cavitation form and the stability problem is achieved.

The invention provides a method for simulating a cavitation flow with a multi-scale self-adaption model, and relates to the technical field of cavitation flow simulation. The simulation method accurately simulates large-scale cavitation interfaces and small-scale discrete bubbles and integrates a variety of algorithms or methods, comprising a continuous cavitation interface capture algorithm for volume fraction that discrete bubbles account for, a grid dynamic splitting method, a material derivative algorithm of discrete bubbles, a discrete bubbles growth collapse and merging breakage algorithm, and a discrete bubbles and continuous gas conversion algorithm. The simulation method accurately simulates large-scale cavitation interfaces and small-scale discrete bubbles, makes up for the shortcomings in traditional numerical calculation methods and realizes a complete description for multi-scale different cavitation morphologies.

The invention discloses a compression wave observation experiment device in a single-cavitation flow field, and belongs to the field of cavitation dynamics. The device comprises a parallel continuous light source, an optical assembly, an experimental water tank, a high-speed camera, a pulse laser, a synchronizer, a computer and an image processing module. Parallel light generated by the parallel continuous light source irradiates the experimental water tank after passing through the optical assembly; the light source assembly enables the imaging picture of the high-speed camera to be uniformly darkened; the pulse laser induces liquid in the experimental water tank to generate laser cavitation bubbles; the synchronizer triggers the pulse laser and the high-speed camera to work synchronously, and images shot by the high-speed camera are stored by the computer; and the image processing module calculates the gray value change intensity and change direction of the image through a convolution kernel operator so as to extract the wavefront contour of the compression wave and calculate the propagation speed and position of the compression wave. According to the invention, the position and speed information of the compression wave can be quantitatively extracted, and an experimental basis is provided for comprehensive analysis and research of cavitation flow field wave system characteristics, cavitation collapse energy conversion and cavitation erosion failure mechanisms.

The invention discloses a flow control method for inhibiting surface cavitation phenomenons of an underwater vehicle and a hydrofoil. The method comprises the steps that porous medium materials are adopted and fixed to the local or total fixing wall surface of the underwater vehicle or the hydrofoil, and the specific fixing position is one of the following situations: A, the porous medium materials are fixed to the upstream region of the primary cavitation position of the fixing wall surface of the underwater vehicle or the hydrofoil; B, the porous medium materials are fixed to the neighborhood of the primary cavitation position of the fixing wall surface of the underwater vehicle or the hydrofoil; C, the porous medium materials are fixed to the corresponding cavitation region of the fixing wall surface of the underwater vehicle or the hydrofoil; D, the porous medium materials are fixed to the corresponding cavitation tail portion and the neighborhood region of the fixing wall surface of the underwater vehicle or the hydrofoil; E, the porous medium materials are fixed to the corresponding cavitation tail downstream region of the fixing wall surface of the underwater vehicle or the hydrofoil. According to the flow control method, the cavitation flow phenomenons of the porous medium neighborhood even the fixing wall surface of the whole underwater vehicle or the hydrofoil are effectively inhibited.