CN100374842C

CN100374842C - Flat plate wall fluid friction resistance mensuring device based on open circulation

Info

Publication number: CN100374842C
Application number: CNB2005101320807A
Authority: CN
Inventors: 周刚; 邵天敏; 陈大融
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2005-12-23
Filing date: 2005-12-23
Publication date: 2008-03-12
Anticipated expiration: 2025-12-23
Also published as: CN1793810A

Abstract

The present invention relates to a device for measuring the friction resistance of fluids on a flat plate wall surface based on open circulation, which belongs to the technical field of hydrodynamic measurement and comprises a water pool, a buffer water tank, a water flow pipeline and a force measuring element. The buffer water tank is respectively communicated with the water pool and water flow pipeline which is communicated with the water pool through a bent pipe. The water flow pipeline is composed of a diameter changing segment, a development segment and an experiment segment, wherein the experiment segment is a rectangular cross section and a measured experiment piece of a flat plate is arranged in the experiment segment as a plate wall of the experiment segment. The measuring device of the invention has the advantages of simple structure, convenient operation and control, easy processing and production for the measured experiment piece of the flat plate as a part of a flow passage, and convenient chucking. The device can directly measure the wall surface resistance of the fluids when the fluids flow through the surface of the experiment piece, is used for studying the resistance of the experiment pieces of the flat plates with different surface properties and patterns under different flow rates, and can be widely used for studying resistance on occasions, such as resistance reduction for the pipeline, water surfaces and navigating bodies in water, etc.

Description

A kind of flat plate wall fluid friction resistance measurement apparatus based on open circulation

Technical field

The present invention relates to a kind of flat plate wall fluid friction resistance measurement apparatus, be used for the measurement of flat plate wall fluid friction resistance under 0～15m/s flow velocity, belong to the hydrodynamics technical field of measurement and test based on open circulation.

Background technology

Flow at fluid line, occasion such as sail body in the hydraulic, water, the frictional resistance between fluid and solid wall surface is the key factor that influences energy resource consumption and task performance.The surface nature of solid comprises geometrical property and physicochemical characteristics, affects the solid-liquid interface friction to a great extent.Carry out the research of this respect, for energy savings, improve working condition, improve work efficiency significant.

At present, the measurement of object suffered resistance (comprising body resistance and frictional resistance etc.) in streaming flow generally is to carry out in large-scale water hole, towing basin etc. and some small, dedicated measurement mechanisms.General dynamic formula and gravity-type on the type of drive of water hole, wherein dynamical type is to drive water cycle by motor-driven turbine, general power consumption is big, flow velocity is high, the flow state less stable, builds, the operation expense height.The water hole is divided into open cycle again and closes two kinds of circulations, and the open cycle formula is higher with respect to closing the circulation power consumption, but flow state is not subject to the influence of disturbing factor; Gravity-type is to rely on the position potential energy of water to drive to flow, and general flow velocity is lower, but the flow field is more uniform and stable, and water tank is high more, and flow velocity is big more, have in addition up to more than 10 meters; The general floor area of towing basin is big, the cost height.The small, dedicated measurement mechanism all designs at a certain problem, and stock size is little, cost is low, with strong points.From test specimen and functional perspective, test specimen integral body is in the fluid, although multinomial measurements such as resistance, flow field, pressure can be realized in large-scale water hole, towing basin etc., the test model stock size is bigger, and it is difficult to make, and cost is higher; And the small, dedicated device has is research object with the fluid, and what have is research object with whole segment pipe or ducted certain parts then.On the metering system of fluid resistance, the existing multicomponent balance that utilizes is directly measured, and pressure drop is arranged again, utilize in addition the velocity flow profile indirect calculation etc.; But, generally do not measure single-measurement wall resistance.

Summary of the invention

The objective of the invention is to propose a kind of flat plate wall fluid friction resistance measurement apparatus, change the structure of load-sensing unit in the existing proving installation, make testing apparatus simple in structure based on open circulation, test process simple to operate, test is reliable.

The flat plate wall fluid friction resistance measurement apparatus based on open circulation that the present invention proposes comprises pond, buffer tank, water pipe and load-sensing unit; The water inlet end of described buffer tank is connected with the pond by water pump and pipeline, be provided with dividing plate in the buffer tank, dividing plate is provided with circular hole, and the water side of buffer tank is connected with water pipe by the mozzle of being located in the buffer tank, and water pipe is connected with the pond by bend pipe; Described water pipe is made up of reducer, development section and experimental section, and experimental section is the square-section, and tested flat test piece places experimental section, becomes the wooden partition of experimental section; Described load-sensing unit comprises support, auxiliary support bar and force cell, the tested flat test piece relative fixed of the top of support and described water pipe experimental section, the bottom-hinged of support is in the bottom of load-sensing unit outer cover, the middle part of support is supported by auxiliary support bar, force cell is fixed on the opposite side of load-sensing unit outer cover, and the probe of force cell is contacting with mid-stent with position that auxiliary support bar corresponds to.

The flat plate wall fluid friction resistance measurement apparatus that the present invention proposes based on open circulation, its advantage is:

1, apparatus of the present invention are simple in structure, operate and control easy, and by the Frequency Converter Control pump rotary speed, the electromagnetic flowmeter survey flow also is converted to flow velocity, can realize easily that the flow velocity in 0～15m/s is regulated and monitoring in real time continuously, make measurement more reliable;

2, buffer tank inside is equipped with dividing plate and mozzle, has improved flow field state greatly;

3, the tested flat test piece in this device is as the part of runner, and single face participates in measuring, and processing and fabricating is simple, is installed conveniently;

4, realize the mechanical transfer and the amplification of flat test piece wall resistance by lever system, utilize computer real-time to show go forward side by side line data collection, storage and Treatment Analysis etc.

5, this device can directly be measured fluid and flows through test specimen suffered wall resistance of when surface, be used to study the resistance of flat test piece under different in flow rate, can be widely used in the research of occasion resistance such as sail body in pipeline drag reduction, the water surface and the water with different surfaces character and pattern.

Description of drawings

Fig. 1 is the structural representation of proving installation of the present invention.

Fig. 2 is the structural representation of load-sensing unit in apparatus of the present invention.

Among Fig. 1 and Fig. 2, the 1st, water pump, the 2nd, pond, the 3rd, venting valve, the 4th, dividing plate, the 5th, electromagnetic flowmeter, the 6th, buffer tank, the 7th, tensimeter, the 8th, vent valve, the 9th, mozzle, the 10th, reducer, the 11st, development section, the 12nd, experimental section, the 13rd, bend pipe, the 14th, load-sensing unit, the 15th, hinge, the 16th, auxiliary support bar, the 17th, support, the 18th, tested flat test piece, the 19th, transparency glass plate, the 20th, force cell, the 21st, outer cover.

Embodiment

The flat plate wall fluid friction resistance measurement apparatus based on open circulation that the present invention proposes, its structure as shown in Figure 1.Comprise pond 2, buffer tank 6, water pipe and load-sensing unit 14.The water inlet end of buffer tank 6 is connected with pond 2 by water pump 1 and pipeline, be provided with dividing plate 4 in the buffer tank, dividing plate 4 is provided with circular hole, and the water side of buffer tank 6 is connected with water pipe by the mozzle of being located in the buffer tank 9, and water pipe is connected with pond 2 by bend pipe 13.Water pipe is made up of reducer 10, development section 11 and experimental section 12, and experimental section 12 is the square-section, and tested flat test piece 18 places experimental section 12, becomes the wooden partition of experimental section 12.Load-sensing unit 14 comprises support 17, auxiliary support bar 16 and force cell 20.Tested flat test piece 18 relative fixed of the top of support 17 and described water pipe experimental section 12, the bottom of support is hinged on the bottom of load-sensing unit outer cover 21 by hinge 15, the middle part of support 17 is supported by auxiliary support bar 16, force cell 20 is fixed on the opposite side of load-sensing unit outer cover 21, and the probe of force cell 20 is contacting with the middle part of support 17 with position that auxiliary support bar 16 corresponds to.

Below in conjunction with accompanying drawing, introduce the course of work of an embodiment of apparatus of the present invention:

Water pump 1 is fetched water from pond 2, enters square buffer tank 6 through electromagnetic flowmeter 5.The about 0.25m of buffer tank 6 volumes ³, inside is equipped with dividing plate 4 and mozzle 9, and dividing plate 4 is provided with the circular hole (not shown), and its effect is the flow field uniformity that improves in the buffer tank.The top of buffer tank is equipped with monitor force table 7 and vent valve 8, is used for getting rid of the gas of water tank and runner, and the bottom is equipped with venting valve 3.The average discharge of electromagnetic flowmeter 5 real-time experiments of measuring sections, and be scaled flow velocity according to channel size.Fluid makes pipeline become the square-section by round section via the curve transition joint after mozzle 9 flows out buffer tank 6.Subsequently, the fluid length of flow across enters experimental section 12 greater than the development section 11 of 0.6m, and this segment length is as the criterion with the size of test specimen.Experimental section 12 tops are a cover plate, are inlaid with transparent glass plate 19, are used for the observation of test process and take pictures; Glass plate 19 is fixed by jig, can take away easily, simultaneously also being installed of convenient tested flat test piece 18; Experimental section 12 bottoms are tested flat test piece 18, and it also is the part (not having blocking experiment) of runner simultaneously.After flowing through experimental section 12 about 100mm, fluid is directly discharged, and enters pond 2 through bend pipe 13.

Fig. 2 is the structural representation of experimental section and resistance load-sensing unit.On sample stent 17, hinge 15 links together support 17 and outer cover 21 by magnetic force or screw retention for flat test piece 18.One side of support 17 is the support bars 16 that are used for auxiliary positioning, and opposite side contacts with the contact of sensor 20.Under the effect of resistance to water-flow, flat test piece 18 is together with the rotation of support 19 around hinge 15 generation minute angles, and power is delivered on the sensor 20 through contact, and force signal is converted into electric signal, with after circuit amplifies, utilize computing machine to carry out data acquisition, storage and Treatment Analysis.

Claims

1. the flat plate wall fluid friction resistance measurement apparatus based on open circulation is characterized in that this device comprises pond, buffer tank, water pipe and load-sensing unit; The water inlet end of described buffer tank is connected with the pond by water pump and water pipe, be provided with dividing plate in the buffer tank, dividing plate is provided with circular hole, and the water side of buffer tank is connected with water pipe by the mozzle of being located in the buffer tank, and water pipe is connected with the pond by bend pipe; Described water pipe is made up of reducer, development section and experimental section, and experimental section is the square-section, and tested flat test piece places experimental section, becomes the wooden partition of experimental section; Described load-sensing unit comprises support, auxiliary support bar and force cell, fixedly connected with the tested flat test piece of described water pipe experimental section in the top of support, the bottom-hinged of support is in the bottom of load-sensing unit outer cover, the middle part of support is supported by auxiliary support bar, force cell is fixed on the opposite side of load-sensing unit outer cover, and the contact of force cell is contacting with mid-stent with the corresponding position of auxiliary support bar.