149 results about "Free flow" patented technology

The invention discloses a hypersonic flight vehicle boundary layer transition prediction method considering wall surface ablation. The method comprises the following steps: determining a free incoming flow condition of a flight vehicle, a geometric shape of the flight vehicle and a wall surface ablation model; according to the given flight working condition, considering the wall surface ablation boundary condition, and calculating a basic flow field of the corresponding working condition by solving a Navier-Stokes equation; secondly, establishing a linear stability analysis equation by adopting LST, and performing flow stability analysis on the basic flow field by considering a linearization wall surface ablation condition to obtain disturbance growth rate distribution of small disturbances with different frequencies; according to the obtained disturbance growth rate distribution, an e-N method is adopted, envelope lines of amplification factor N values of disturbance of different frequencies in the flow direction are calculated, experience transition N values are compared, and the transition position is predicted. According to the method, basic flow field calculation and stability analysis of the wall surface ablation effect are considered, the flow state of the hypersonic aircraft in the flight process is met, and the boundary layer transition prediction position can be predicted more accurately.

A mechanical pump-free flow boiling heat sink, including an evaporator, a two-phase flow steam injector, a first condenser, a boiling pool and a second condenser. A vapor outlet of the evaporator is communicated with a vapor-phase inlet of the two-phase flow steam injector. A liquid-phase outlet of the evaporator is communicated with an inlet of the boiling pool. An outlet of the boiling pool is communicated with an inlet of the second condenser. An outlet of the second condenser is communicated with a liquid-phase inlet of the two-phase flow steam injector. An outlet of the two-phase flow steam injector is communicated with an inlet of the first condenser. An outlet of the first condenser is communicated with an inlet of the evaporator.

The invention discloses an incoming flow Mach number control method for a transient transonic wind tunnel airfoil test, and belongs to the technical field of wind tunnel airfoil tests. The problem that in the prior art, a traditional Mach number control method adopting a conventional plenum chamber reference point is difficult to be suitable for carrying out an airfoil test in a transient transonic wind tunnel is solved. According to the method, a standard airfoil model is selected, simulation calculation is carried out, and distribution of Mach numbers in the incoming flow direction of the airfoil model in the free flow state, namely the wind tunnel wall-free state, is obtained; s2, performing simulation calculation in a three-dimensional full-simulation state on the wind tunnel by adopting a standard airfoil model which is the same as the step S2, acquiring axial Mach number distribution of side wall center lines of test sections with different opening-closing ratios of the wind tunnel according to the opening-closing ratios, and calculating the axial Mach number distribution of the side wall center lines of the test sections with different opening-closing ratios; and analyzing to obtain a Mach number which is controlled in the incoming flow direction and is 3 times the chord length of the airfoil profile from the front edge of the airfoil profile, and carrying out a standard airfoil profile model wind tunnel test. According to the invention, the accuracy of simulating the incoming flow Mach number and the opening-closing ratio of the test section is improved, and the method can be applied to the temporary impulse transonic wind tunnel airfoil test.

The invention discloses an automatic driving decision-making method and system based on multi-modal heterogeneity feature fusion, and belongs to the technical field of automatic driving, and the method comprises the steps: S1, dividing a driving state: S101, employing a segmentation algorithm to carry out the feature division of the speed and track profile of a vehicle driving track; s102, based on a Newell stimulation-response theory and a dynamic time warping algorithm, establishing a dynamic response relationship between vehicles, and identifying a following flow state and a free flow state; s103, identifying a specific driving state; s2, constructing a car-following model by using the driving state: S201, constructing a driving state prediction module framework; s202, establishing an improved LSTM network for realizing multi-modal feature fusion; and S3, training a car-following model, and realizing cooperative training of driving state prediction and car-following behavior modeling through course learning and a multi-stage optimization strategy.

The invention discloses a microfluidic pre-focusing chip, and belongs to the technical field of microfluidics, the chip comprises a piezoelectric substrate, an interdigital transducer and a micro-cavity, the micro-cavity is bonded on the piezoelectric substrate, the micro-cavity comprises a main cavity channel, two ends of the main cavity channel are respectively provided with at least one sample input port and at least one sample output port, and the main cavity channel is connected with the interdigital transducer. The interdigital transducers are arranged on the piezoelectric substrate, located on the two sides of the main cavity channel respectively and arranged in the direction perpendicular to the flowing direction of a sample in the main cavity channel, the microcavity further comprises side cavity channels distributed on the two sides of the main cavity channel, filling liquid injection ports are formed in the side cavity channels, filling liquid is a liquid photocurable material, and the filling liquid injection ports are communicated with the main cavity channel. Meanwhile, the invention further discloses a design, manufacturing and application method of the chip, and the two-stage functions of pre-focusing and concentration can be effectively achieved under the sheath flow-free condition.

The application discloses a wind turbine wind parameter data correction method, device, equipment and medium, comprising: simulating multiple working conditions according to basic parameter information of a wind turbine, determining first simulation wind parameter data of a free flow position and second simulation wind parameter data of a target position point under each working condition based on simulation results, and determining a first correction parameter based on the first simulation wind parameter data and the second simulation wind parameter data. First actual wind parameter data of the free flow position and second actual wind parameter data of the target position point under each working condition are obtained, and a second correction parameter is determined. The first correction parameter is corrected based on the second correction parameter to determine a corrected first correction parameter. The wind parameter data under the target working condition is corrected according to the corrected first correction parameter. That is, the correction parameter obtained according to the actual running working condition is used to correct the simulation obtained correction parameter, so that the wind parameter data obtained according to the correction parameter is more accurate subsequently.

The invention relates to the technical field of intelligent traffic management systems, in particular to an appointment payment method based on expressway free flow toll collection. An existing free flow charging technology mainly adopts a postmortem fee deduction mode, the problem of fee deduction failure caused by insufficient account balance, payment channel faults and the like exists, then arrearage, overdue money and follow-up cost recovery are generated, and user experience and charging management efficiency are seriously affected. According to the invention, through establishing a whole-process management mode of beforehand reservation-in-event verification-after-event settlement, a user can set a travel plan and select a reservation payment mode through a terminal before travel, and the system generates an estimated cost based on a built-in charging standard; in the vehicle passing process, the road side sensing data and the vehicle positioning data are fused, and the consistency of the actual driving path and the reserved path is accurately verified; and finally, executing corresponding fee deduction operation according to a verification result.

A fluid compressor system has a scavenge loss limiter that increases the efficiency of the fluid compressor system by reducing the compressed working fluid recirculated into the airend through a scavenge flow. The scavenge loss limiter includes a scavenge hole positioned at a discharge end face of a rotor cavity of the compressor housing. As a rotor of the compressor system rotates, the rotor may intermittently restrict the free-flowing scavenge flow returning from a lubricant separation tank. The rotor may be a male rotor having a plurality of male lobes. As the discharge end clearance between the rotor and the discharge end face is tightly controlled and monitored, a better control of the scavenge flow returning to the rotor cavity is achieved.

The present application relates to the technical fields of anti-choking drinking water control, and provides an anti-choking drinking water control method and device, which comprises a cup body, a cup cover connected to the top side of the inner wall of the cup body through a sealing ring, an adjusting cavity fixedly connected to the bottom end of the cup cover, an extension pipe connected to the bottom end of the adjusting cavity through a splicing assembly, a gravity ball fixedly connected to the bottom end of the extension pipe, a through hole for ensuring water flow on the outer wall of the gravity ball, a suction nozzle fixedly connected to the top end of the cup cover, a rubber pad slidingly connected to the inner wall of the adjusting cavity, and a connecting pipe fixedly connected to the top end of the rubber pad. Through the threaded transmission cooperation of the spiral sleeve and the spiral rod, the rubber pad is vertically slid in the adjusting cavity, and then the blocking ball is opened under the negative pressure generated by the appropriate suction force, the waterway is opened under the negative pressure generated by the appropriate suction force, and the blocking ball quickly falls to block the bottom end of the adjusting cavity when there is no negative pressure, so as to avoid the free flow of residual water and realize the flexible adjustment of the suction force.

A writing tip assembly for dispensing a free-flowing low-viscosity ink from a writing instrument may include a micro-spring, a writing ball configured to transfer ink to a substrate, and a second ball between the writing ball and the micro-spring. The second ball is configured to transfer ink to the writing ball. A writing instrument for dispensing a free-flowing low-viscosity ink includes an ink reservoir, the writing tip assembly, and a feeder fluidically coupling the ink reservoir to the writing tip assembly.

This utility model relates to the field of fertilizer and water transportation technology, and discloses a distribution device for bio-organic fertilizer processing, including a cylinder and a guide channel. The guide channel is provided at the top of the outer wall of the cylinder, and a partition is provided inside the cylinder. A through hole is opened on the front surface of the partition. A grooved plate is fixedly connected to the top of the partition, and a pair of insert rods are fixedly connected to the bottom of the grooved plate. This distribution device for bio-organic fertilizer processing, through the cooperation of the cylinder, guide channel, partition, through hole, grooved plate, insert rods, and insert hole, allows the cylinder to be installed in a fertilizer and water transport vehicle. When the cylinder is filled with an appropriate amount of fertilizer and water and is being transported, the partition divides the interior of the cylinder into two areas. The through hole allows the flow of fertilizer and water on both sides of the partition, restricting the free flow of fertilizer and water. This helps reduce large swings caused by the large inertia of the fertilizer and water, thereby improving the stability during fertilizer and water transportation and significantly reducing the probability of production accidents caused by fertilizer and water splashing.

Techniques described herein involve an electronics-free downhole flow sensor. For example, a system can include a receiver positioned at a surface of a wellbore. A flow sensor can be positioned downhole in the wellbore. The flow sensor can include a wire positioned within a flow path of downhole fluid in the wellbore. The wire can oscillate based on flow of the downhole fluid. The flow sensor can also include a variable reluctance sensor that can detect an electrical signal that is generated by oscillation of the wire. The variable reluctance sensor can transmit the electrical signal to the receiver. The receiver may determine a resonant frequency based on the electrical signal and may determine a fluid velocity of the downhole fluid based on the resonant frequency.

The invention discloses an automatic driving vehicle turning speed regulation and control method taking view limitation into consideration. The method comprises the steps that 1, the length of a straight road section, influencing a vehicle, of the upstream of an inflection point is calculated; 2, acquiring the distance between the vehicle and the bending point; 3, calculating the free flow speed of the vehicle; 4, calculating the acceleration which only considers the view limitation of the curve; 5, calculating the acceleration which only considers the front vehicle; 6, the vehicle speed is regulated and controlled according to the front traffic condition; and 7, circulating the steps until the control time is over. According to the invention, the speed of a turning vehicle can be adjusted in real time according to the radius of the curve and the traffic condition of the road ahead before entering the curve, so that the vehicle can keep a reasonable turning speed when the view of the vehicle is limited, the vehicle can be braked in time when danger is found ahead, and the running safety of the vehicle on the curve is improved.

The invention relates to a carburettor and to a two-stroke engine with a carburettor, the carburettor having a carburettor body in which an air intake channel section is configured. A throttle flap for controlling the free flow cross-section of the air intake channel section is pivotably supported in the carburettor body on a throttle shaft. The air intake channel section has a first longitudinal centre axis in the region of the throttle shaft. The throttle flap has a first end position and a second end position, in which the throttle flap releases a greater flow cross-section of the air intake channel section than in the first end position. Arranged upstream of the throttle shaft is a partition wall section, against which the throttle flap lies in the second end position. Upstream of the partition wall section is provided a choke flap, which can be pivoted between a first end position and a second end position. The throttle flap and the choke flap overlap in the direction of the first longitudinal centre axis in their second end positions. The carburettor is provided for a two-stroke engine.

The invention relates to a set of separator inserts (II, II-a, II-b,...) for a separator having a frame (I) on which one of the separator inserts (II, II-a, II-b,...) of the set of separator inserts (II, II-a, II-b,...) is exchangeably arranged at a time, wherein each of the separator inserts is designed to separate a free-flowing suspension (S) in a centrifugal field into at least two phases (LP, HP) of different densities and forms a pre-assembled exchangeable unit for insertion into the frame (I) of the separator and has at least the following: a rotor (2) which can be rotated about an axis of rotation (D) during operation and has a drum (3) that can be rotated during operation and that has one or more openings; a separating means (6) arranged in the drum (3); an inflow and outflow system having at least one inlet (311, 312) for a free-flowing suspension to be processed and having two or more outlets (313, 314) for discharging the centrifugally separated phases from the drum (3), wherein at least two separator inserts (II, II-a, II-b,...) of the set have different inflow and outflow systems (31), and / or at least two separator inserts (II, II-a, II-b,...) of the set have drums (3) having drum casings with different geometries.

The application provides a nutrition pump, which comprises a pump main machine, a first driving mechanism, a switching piece and an anti-falling piece arranged on the pump main machine; the first driving mechanism is connected with the switching piece and drives the switching piece to move between at least two positions; the first driving mechanism is connected with the anti-falling piece and drives the anti-falling piece to move between at least two positions. The nutrition pump provided by the application can lock the fluid conveying mechanism on the pump main machine, can avoid abnormal falling of the fluid conveying mechanism and can prevent the free flow phenomenon from occurring.

The application relates to a liquid sheet injection system and method for X-ray free electron laser experiments, which comprises a pneumatic nozzle device, a flow control device, a signal acquisition device and a vacuum device; the pneumatic nozzle device and the signal acquisition device are respectively arranged in the vacuum device, the pneumatic nozzle device comprises a tube assembly, a gas capillary and a liquid capillary are respectively arranged in the tube assembly, and the gas capillary and the liquid capillary are connected with the flow control device; the end of the liquid capillary comprises two symmetrically arranged flow guide inclined surfaces, two symmetrically arranged abutting inclined surfaces and a bottom surface, the flow guide inclined surfaces and the abutting inclined surfaces are alternately distributed around the bottom surface, and a first outlet is arranged on the bottom surface; a gas micro-flow channel is formed between the end inner wall of the tube assembly and the flow guide inclined surface, and a second outlet is arranged at the end of the tube assembly. The application utilizes the compression and shearing effect of high-speed gas on liquid to generate a free-flowing liquid sheet with a sub-micron thickness under vacuum.

The utility model discloses a dewatering device for a flotation plate-and-frame filter press, and belongs to the technical field of coal dressing filter pressing. Angle blowing air inlet holes are formed in the two ends of the upper sides of a thrust plate and a pressing plate of the filter press, angle blowing air supply pipelines are connected to the angle blowing air inlet holes of the thrust plate and the pressing plate, and air blowing pneumatic valves are arranged on the angle blowing air supply pipelines; angle blowing air inlet holes are also formed in the two ends of the upper sides of the diaphragm plate and the compartment plate between the thrust plate and the pressing plate, so that an internal filtering structure is completely broken through and is used for introducing secondary inlet air; the corner blowing air supply pipeline is connected with a corner blowing free flow drainage pipe, and the corner blowing free flow drainage pipe is connected with a drainage pneumatic valve; drain holes are formed in two ends of the lower sides of the diaphragm plate and the compartment plate; the problems of high moisture content, low efficiency and high labor intensity of a common plate and frame type membrane filter press are solved.

The invention relates to the technical field of wind power generation, and discloses a wind generating set upstream and downstream whole-process full-space-time turbulent wind calculation method which comprises the following steps: carrying out regional division on a wind field of a target wind generating set; obtaining an upstream free incoming flow area of the fan, a near-field wind wheel front area of the fan, a near-field wind wheel rear area of the fan and a downstream wake flow area of the fan; respectively establishing an instantaneous wind speed field of a free incoming flow region, an instantaneous wind speed field of a region in front of a near-field wind wheel of a fan, an instantaneous wind speed field of a region behind the near-field wind wheel of the fan and an instantaneous wind speed field of a downstream wake flow region of the fan; and performing interpolation weighting processing on the instantaneous wind speed field of the free incoming flow area, the instantaneous wind speed field of the area in front of the wind wheel, the instantaneous wind speed field of the area behind the wind wheel and the instantaneous wind speed field of the wake flow area at the downstream of the fan to generate an upstream and downstream whole-process full-space-time turbulent wind field of the wind generating set. The invention provides a full-process and full-space-time turbulent wind high-precision calculation method, which is beneficial to precise design and optimization of a wind generating set.

The present invention discloses an intelligent flow control method and system for an air-breathing high-speed aircraft, relating to the field of flow control of aircraft aerodynamic performance, including: S1, arranging a suction module on the compression surface of the aircraft's air inlet and / or at a location within the aircraft that is prone to flow separation; S2, arranging a blowing module in an area on the aircraft's outer surface where drag reduction is required; S3, using a control system to control the air source obtained by a driving module from the suction module and delivering it to the blowing module through a regulating valve. The present invention provides an intelligent flow control method for an air-breathing high-speed aircraft, which achieves air source-free flow control of the aircraft and can simultaneously achieve flow control of both suction and blowing, that is, improving the aerodynamic performance of the air inlet through suction and improving the aerodynamic performance of the aircraft's outer surface through blowing, thereby reducing drag.

The present invention discloses a method for configuring quasi-free-flow pre-transaction toll lanes on highways, which belongs to the field of highway technology and includes the following steps: S1: pre-processing and analyzing vehicle traffic big data, and setting a toll standard for each lane of the highway; S2: based on path planning technology, guiding vehicles to travel on lanes with the least traffic volume, automatically identifying vehicles, automatically settling vehicle fees, and allowing vehicles to pass quickly; S3, vehicle traffic situation prediction and early warning: fault prediction and health management of vehicle traffic conditions in each lane on the highway. The present invention solves the existing problem of being unable to intelligently optimize lanes and achieve quasi-free flow of vehicle traffic, reducing road utilization, and causing traffic congestion. The present invention achieves quasi-free flow during vehicle traffic by intelligently optimizing lanes, thereby achieving the purpose of improving road utilization and reducing congestion, and can meet the needs of modern society for efficient and fast transportation.

The present invention discloses a slope-compensated acceleration estimation method based on trajectory data, comprising the following steps: 1. obtaining trajectory data of a vehicle traveling on a slope and a horizontal section; 2. calibrating the vehicle's free flow speed using the trajectory data of the horizontal section; 3. analyzing the slope trajectory data to construct a slope acceleration model; 4. assuming that the expected acceleration of the horizontal section and the compensated acceleration of the slope conform to a normal distribution, according to the acceleration model, obtaining the probability density of the observed acceleration, the posterior probability of the compensated acceleration, and the joint probability distribution of the two; 5. Based on the joint probability distribution, constructing a compensated acceleration estimation model using an expectation-maximization algorithm and performing iterations to obtain the mean and variance of the expected acceleration of the horizontal section and the mean and variance of the compensated acceleration of the slope. The present invention can identify the additional compensated acceleration given to the vehicle by the driver on a slope, thereby better explaining the impact of driving behavior on road capacity.

The application discloses a kind of temporary shock cross-speed wind tunnel airfoil test's Mach number control method, belong to wind tunnel airfoil test technical field.The existing technology is solved in traditional Mach number control method using conventional chamber reference point, it is difficult to be applicable to the problem that temporary shock cross-speed wind tunnel carries out airfoil test;The application selects standard airfoil model, carries out simulation calculation, obtains the distribution of airfoil model Mach number in free flow, i.e.no wind tunnel wall state;Using the same standard airfoil model as step S2, simulation calculation is carried out to the three-dimensional full simulation state of wind tunnel, according to the opening-closing ratio, the axial Mach number distribution of wind tunnel different opening-closing ratio test section side wall center line is obtained, in wind tunnel, by analysis, the Mach number at 3 times airfoil chord length from the leading edge of airfoil in flow direction is controlled to carry out standard airfoil model wind tunnel test.The application improves the precision of simulated flow Mach number and test section opening-closing ratio, and can be applied to temporary shock cross-speed wind tunnel airfoil test.

The utility model relates to the field of reaction kettles, and particularly discloses a high-efficiency energy-saving chemical reaction kettle which comprises a reaction kettle, a driving motor is mounted at the upper end of the reaction kettle, the lower end of the driving motor penetrates through the interior of the reaction kettle and is connected with a driving shaft, outer stirring frames are mounted on the outer side of the driving shaft in an array manner, and inner stirring frames are arranged in the outer stirring frames; springs are connected between the inner stirring frame and the outer stirring frame in an array mode, an anti-disengaging base plate is installed at the end, close to the springs, of the inner stirring frame, and an embedded through hole is formed in the inner stirring frame. The inner stirring frame in the outer stirring frame can be thrown out under the action of centrifugal force, so that the distance from the outer stirring frame to the inner side wall of the reaction kettle and the distance from the inner stirring frame to the inner side wall of the reaction kettle can be integrally reduced, and meanwhile, liquid can freely flow through embedded through holes formed in the inner stirring frame; therefore, in the stirring process, the internal liquid has a flow velocity difference, a certain vortex is formed, and the stirring and mixing efficiency is improved.

The invention discloses a rapid flow field prediction method based on cooperation of data driving and CFD calculation, and belongs to the technical field of numerical simulation of aircrafts. Extracting geometric features of the airfoils in the data set; reducing dimensions of flow field variables in the data set; building an off-line data driving model of the airfoil flow field prediction task; an off-line data driving model is adopted to provide an initial solution for a high-order discontinuous finite element method (DGM) of airfoil streaming simulation; and iterating to a steady state based on an initial flow field provided by a data driving model by adopting a high-order discontinuous finite element method. The airfoil flow field rapid prediction method based on cooperation of data driving and CFD calculation is suitable for rapid evaluation of aerodynamic performance of an aircraft airfoil design link, and the simulation efficiency of an original discontinuous finite element method based on far-field free flow initialization can be improved by about three times; and the method is hopefully expanded and applied to rapid pneumatic evaluation of the whole aircraft.

The invention relates to an optimization design method and system for a Venturi tube contraction section under a free flow condition and a storage medium, and belongs to the technical field of fluid machinery and stirring equipment. The technical problem to be solved is to accurately solve the hydraulic performance of the contraction section of the Venturi tube under the free flow condition, establish a function relationship between an acceleration ratio and a contraction ratio and solve the optimal contraction ratio. The technical scheme is characterized in that the diameter range of an inlet of the Venturi tube is determined; establishing a fluid computational domain model, wherein an inner side outlet and an outer side outlet of the Venturi tube are respectively set as independent pressure outlet boundaries; cFD numerical simulation is carried out on contraction sections of the Venturi tube under different contraction ratios based on a fluid computational domain model, and inlet flow velocity data and throat flow velocity data are obtained; calculating an inlet reduction ratio K1 and an in-tube speed-up ratio K2, and performing regression analysis fitting to obtain a function relation expression of K1 and K2 respectively changing along with the shrinkage ratio; and solving the optimal shrinkage ratio under the target condition according to the function relational expression, and outputting a size parameter.

The invention discloses a traffic flow organization method of traffic flow array and signal cooperation based on lane control and management. The method comprises the following steps: 1) planning a road section; performing function division and arrangement on the road sections from the intersection to the rear according to the sequence of the dynamic green waiting road section, the static red waiting road section and the free flow road section; 2) signal and traffic flow cooperative control; 2.1) in the red light period, vehicles on the dynamic green waiting road section run slowly according to a preset control speed; the static red waiting road section conveys the grouped vehicles to the dynamic green waiting road section and receives the vehicles on the free flow road section; vehicles on the free flow road section enter a team queue when vacancies exist on the static red waiting road section, otherwise, the vehicles are queued; 2.2, in the green light period, vehicles on the dynamic green waiting road section rapidly pass through the intersection at the free flow speed, the dynamic green waiting road section is emptied, the static red waiting road section starts to queue up and form a team according to the direction lanes, and vehicles on the free flow road section enter the static red waiting road section.

The anti-backflow tee joint comprises a vertical pipe and an inclined pipe, the vertical pipe is connected into a drainage vertical pipe, and the inclined pipe is connected to the side wall of the vertical pipe and connected with a ventilation vertical pipe; wherein a speed reduction structure is arranged in the inclined pipe, and the speed reduction structure is configured to reduce the flow speed of water flow entering the inclined pipe from the vertical pipe twice in sequence. Water flow at the root of the drainage stand pipe can be prevented from flowing back into the ventilation pipeline due to bottom positive pressure or in the natural downward flowing process, and it can be guaranteed that airflow in the ventilation pipeline flows freely.

The utility model discloses a boning flat file internally provided with a liquid channel. The boning flat file comprises an outer tube, a first connecting pipe and an inner pipe are arranged at one end of the outer pipe, and the inner pipe is arranged in the outer pipe; a liquid channel boss is arranged on one side of the inner pipe; the middle pipe is positioned between the inner pipe and the outer pipe; one end of the middle pipe is connected with one end of the first connecting pipe; the positioning pin is arranged at the other end of the middle pipe and is used for fixing the connection between the outer pipe and the middle pipe; the flat file assembly is connected with the first connecting pipe; and the driving shaft is positioned in the inner tube and is connected with the flat filing assembly. The driving shaft is sleeved with the inner pipe, the inner pipe is sleeved with the middle pipe, the middle pipe is sleeved with the outer pipe, the inner pipe, the middle pipe and the outer pipe jointly form a smooth liquid channel, and it is ensured that liquid can freely flow in the channel. In addition, the outer pipe and the middle pipe are stably connected through the positioning pin, the stability of the structure is enhanced, and installation and maintenance are convenient.