CN2720543Y - Small self-circulation cavitation mechanism experiment instrument - Google Patents
Small self-circulation cavitation mechanism experiment instrument Download PDFInfo
- Publication number
- CN2720543Y CN2720543Y CN 200420081665 CN200420081665U CN2720543Y CN 2720543 Y CN2720543 Y CN 2720543Y CN 200420081665 CN200420081665 CN 200420081665 CN 200420081665 U CN200420081665 U CN 200420081665U CN 2720543 Y CN2720543 Y CN 2720543Y
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- cavitation
- runner
- flow channel
- self
- supply tank
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Abstract
The utility model discloses a small self-circulation cavitation mechanism experiment instrument which is provided with a water supply tank of the self circulation, an underwater pump arranged in the water supply tank of the self circulation, a flow channel display cabinet arranged on the water supply tank of the self circulation, a cavitation display flow channel in wenshi type, a cavitation display flow channel of taper, the cavitation display flow channel of the rectangular bulkhead slot, the cavitation display flow channel of the streamline bulkhead display which are arranged in the flow channel display cabinet; the upper part of each flow channel is provided with a gas exhaust valve. The water outlets of the underwater pump are respectively connected with the each flow channel in the flow channel display cabinet by a plurality of upper water pipes; a flow adjusting valve is arranged at the upper water pipe; the stern of the flow channel display cabinet is provided with a lower water pipe which is connected with the water supply tank of the self circulation; a voltage-measuring point is arranged at the narrow point of the cavitation display flow channel of taper; the voltage-measuring point is connected with the nozzle on a cavitation cup by a communication pipe, and the other nozzle of the cavitation cup is connected with a vacuum meter by a communication pipe; the top of the cavitation cup is connected with a short pipe. The utility model has simple structure, low consumption, convenient and operation, directive viewing and easy grasp.
Description
Technical field
The utility model relates to teaching and experiment equipment, relates in particular to a kind of self-loopa cavitation mechanism experiment instrument of miniaturization.
Background technology
In some areas of liquid flow, or because flow velocity is too high, or boundary-layer separation, all can cause pressure to reduce, gas (or steam) cavity or hole appear so that be reduced to liquid stream inside, and this phenomenon is called cavitation (also being air pocket).After cavitation phenomenon took place, owing to be not liquid but gas in its hole, this had just destroyed liquid and has flowed successional prerequisite, and the pressure change in cavitation district is no longer obeyed general energy law.The cavitation mechanism experiment instrument is the experimental apparatus that is specifically designed to demonstration cavitation mechanism phenomenon.
Traditional cavitation experiment needs with main equipments such as decompression cabinet or circulating water chennels.Need build nearly hundred square metres building, its electric power is more than 50KW for this reason.It is ad hoc that this device generally is the production scientific research, is unsuitable for education experiment.Be used for the experimental demonstration teaching and exist certain drawback: one, the infrastructure construction engineering is huge, and the hundreds of easily thousands of square meters of floor area drop into huge; Its two, the huge equipment operation maintenance that brings thus of equipment is also complicated, operating cost is also higher; Its three, equipment is huge, work noise is big, and surrounding environment is produced noise pollution.
Summary of the invention
The purpose of this utility model provides a kind of self-loopa cavitation mechanism experiment instrument of miniaturization.
A kind of self-loopa cavitation mechanism experiment instrument of miniaturization, it is characterized in that it has the self-loopa supply tank, in the self-loopa supply tank, be provided with submersible pump, arrange the runner display case on the self-loopa supply tank, be provided with Wen's type cavitation in the runner display case and show runner, the convergent cavitation shows runner, rectangular gate groove cavitation shows runner, streamlined gate slot cavitation FLOW VISUALIZATION runner, each runner top is provided with vent valve, the submersible pump water delivering orifice connects each runner in the runner display case respectively by a plurality of upper hoses, flow control valve is set on the upper hose, runner display case afterbody is provided with downcomer and connects the self-loopa supply tank, the convergent cavitation shows that runner constriction place is provided with pressure tap, pressure tap is connected with communicating pipe with ozzle on the cavitation cup, another ozzle on the cavitation cup is connected with communicating pipe with vacuum meter, and the connection short tube is equipped with at cavitation cup top.
Advantage of the present utility model:
1) changes the huge practice of system in the past,, its whole experimental system is dwindled simplification, removed the dedicated experiments construction land from specially at The teaching design;
2) easy and simple to handle directly perceived, be easy to grasp, and be suitable for the modern teaching requirement;
3) adopted small-sized independent self-loopa water system, its electric power only is several hectowatts, and can reuse the experiment water body, so greatly conserve water and electric power resource.
Description of drawings
Accompanying drawing is a self-loopa cavitation mechanism experiment instrument structural representation.
Embodiment
The self-loopa cavitation mechanism experiment instrument of miniaturization has self-loopa supply tank 11, in self-loopa supply tank 11, be provided with submersible pump 14, arrange runner display case 5 on the self-loopa supply tank 11, be provided with Wen's type cavitation in the runner display case 5 and show runner 1, the convergent cavitation shows runner 2, rectangular gate groove cavitation shows runner 3, streamlined gate slot cavitation FLOW VISUALIZATION runner 4, each runner top is provided with vent valve 12, submersible pump 14 water delivering orifices connect each runner in the runner display case 5 respectively by a plurality of upper hoses, flow control valve 10 is set on the upper hose, runner display case 5 afterbodys are provided with downcomer and connect self-loopa supply tank 11, the convergent cavitation shows that runner 2 constriction places are provided with pressure tap 6, pressure tap 6 and being connected 8 usefulness communicating pipes of ozzle on the cavitation cup 9, another ozzle 8 on the cavitation cup 9 was connected with 13 usefulness communicating pipes of vacuum meter, and cavitation cup 9 tops are equipped with and are connected short tube 7.
The course of work of the present utility model is: start the cavitation mechanism experiment instrument, water body enters Wen's type cavitation demonstration runner in the runner display case, convergent cavitation demonstration runner, rectangular gate groove cavitation demonstration runner, four runners of streamlined gate slot cavitation FLOW VISUALIZATION runner through the submersible pump pressure-raising respectively by a plurality of upper hoses in the self-loopa supply tank, gets back to the self-loopa supply tank through the downcomer of four runner both sides again.High-velocity flow causes quite big vacuum when respectively flowing to the constriction place, and its vacuum tightness can be read by connecting the vacuum meter that the convergent cavitation shows runner larynx neck place pressure tap.Form three kinds of cavitations such as the type of vacillating, boundary separation type and swirl type respectively according to the flow channel shape difference.
Experiment content
This instrument can be in order to demonstration cavitation occurring principle, typical project cavitation phenomenon, runner build to the quantitative measurement of influence on cavitation and incipient cavitation number etc.
1, the demonstration of cavitation phenomenon
Under the condition of three valve wide opens of four runners, start water pump, can see in Wen's type cavitation and show that runner, convergent cavitation show that the throat of runner and rectangular gate groove cavitation show that the vaporific cavitation cloud of milky appears in the gate slot place of runner runner, Here it is cavitation phenomenon also can be heard the cavitation noise that is taken place by the cavitation district simultaneously.The cavitation zone analysis that shows according to instrument as can be known, the position that cavitation takes place easily is: the separation flow place of high velocity liquid stream border sudden change, as the deep hole import in the hydraulic engineering, overfull dam surface, gate slot, bifurcated pipe, construction out-of-flatness place, and the back side of the hydraulic turbine, turbine, water pump and propeller blade in the power machine and the afterbody of torpedo etc.
2, cavitation mechanism
Working fluid (is example with water) is depressed at normal atmosphere, and when temperature is raised to 100 ℃, the bubble not of uniform size that produces in the water body is exactly a cavitation during boiling.Corresponding temperature this moment (100 ℃), the steam pressure of water (standard atmospheric pressure) are called as vaporization pressure (p
ν), this phenomenon also can be not high in water temperature, and pressure is taken place when low.
This instrument can clear this phenomenon of demonstration generation.Inject half cup warm water (about 40 ℃ of water temperatures) earlier in the cavitation cup, the compress rubber gag is connected with ozzle (each 1 of cup both sides) then.Under the trunnion suction function, the air in the cavitation cup is sucked out.The vacuum meter reading increases thereupon.When vacuum tightness during near (10) m water column, water in the cup just comes to life.This is the phenomenon that cavitation under low pressure takes place normal-temperature water.Change the water in the cup temperature, vaporization pressure (p
ν) also have nothing in common with each other.The p of different water temperatures
νBe worth listed as following table.
The vaporization pressure of table 1 water
| Water temperature (℃) | 100 | 90 | 80 | 70 | 60 | 50 |
| Vaporization pressure p ν(KPa) | 101.33 | 70.10 | 47.34 | 31.16 | 19.92 | 12.16 |
| p ν/ γ (m water column) | 10.33 | 7.15 | 4.83 | 3.18 | 2.03 | 1.24 |
| Water temperature (℃) | 40 | 30 | 20 | 10 | 5 | 0 |
| Vaporization pressure p ν(KPa) | 7.38 | 4.24 | 2.34 | 1.18 | 0.88 | 0.59 |
| p ν/ γ (m water column) | 0.75 | 0.43 | 0.24 | 0.12 | 0.09 | 0.06 |
The reason that cavitation forms, available " gas nuclear theory " explanation.This theory is thought, always contains gas in the light water under the normal pressure, is present in water body with the imperceptible micronucleus state of naked eyes.This micronucleus is called gas nuclear, and diameter is greatly about 10
-5～10
-6Cm.When pressure dropped to a certain degree, gas nuclear just expanded, gathers the composition cavity.The existence of available experimental verification gas nuclear.Start experiment instrument, make it to occur the cavitation cloud, splash the water body in the cavitation district that flows through.Gas nuclear in the water breakthrough not before the cavitation district, and behind the cavitation district that flows through, but in the water breakthrough many minute bubbles appear then.These bubbles are exactly water body when flowing through the cavitation district, are formed by its gas nuclear accumulation of carrying under one's arms.
From above observation analysis as can be known, the existence of gas nuclear is the basis that forms cavitation, and the appearance of negative pressure is the condition that produces cavitation.
3, the measurement of hole number
On the engineering, often with following dimensionless group σ, as weighing the index whether actual current cavitation takes place:
In the formula, p
0, u
0Be respectively undisturbed pressure in measuring point upstream (definitely) and flow velocity; p
νVaporization pressure for liquid.
When runner somewhere σ is low to moderate certain value σ
0The time begin to take place cavitation (σ
0Be called incipient cavitation number or critical cavitation number).σ
0Different with the border condition.
This instrument can be measured σ
0, its method for measurement shows that with the convergent cavitation runner is that example is described as follows:
At first when shutting down, spreading convergent cavitation shows the runner flexible pipe, makes it and water delivering orifice can be moved to outside the case, uses so that measure flow.Then, the complete shut-down valve starts water pump, gradually opens the runner valve, and the vacuum meter reading increases thereupon, the aggravation of indicator swing simultaneously (showing that pulse pressure strengthens), and when vacuum increased to certain value, venturi began flickering cavity to occur, Here it is cavitation inception.Cavitation inception also can be differentiated by the noise that cavitation is sent, and can hear the tiny noise that bubble eruption sends during cavitation inception.
Measure the relevant physical quantity during cavitation inception just can count σ
0, comprise the letdown flow Q of runner
0, and venturi vacuum meter reading p
0(pressure relatively).
Example, this instrument convergent cavitation shows the runner discharge section area A ' of throat=0.6cm * 0.4cm, side contraction coefficient ε=0.95, actual area of passage A=0.228cm
2, actual measurement Q
0=335cm
3/ s, p
0/ γ=-6.73m and 29 ℃ of (p of water temperature thereof
ν/ γ=0.408m water column), so have:
Promptly surveying the critical cavitation number is 0.3.This instrument convergent cavitation shows that the actual maximum vacuum of runner can reach the 10m water column, and flow velocity is up to 18.8m/s.When 3 valve wide opens, record minimum hole number and can reach σ
Min=-0.004.Because of σ
Min＜＜σ
0So, produce strong cavitation.
Achievement is analyzed
1, the runner build is to influence on cavitation
This influence can be found out from the cavitation contrast of Wen's type cavitation demonstration runner, convergent cavitation demonstration runner.Under the identical condition of valve switch, Wen's type cavitation shows that the cavitation of runner shows that than convergent cavitation runner is serious.Show that the former cavitation inception number is greater than the latter.
This also can find out from the cavitation of two kinds of build lock grooves, and rectangular gate groove cavitation shows that runner, streamlined gate slot cavitation FLOW VISUALIZATION runner are respectively equipped with the streamlined groove that rectangular channel and downstream have the slope.Experiment shows, under equal flow condition, the former extent of cavitation is greater than the latter.As more domestic units to cavitation test that gate slot is done studies show that, the incipient cavitation number σ of rectangular channel
C1=2.0, and the streaming gate slot of 1: 2 side slope in downstream, its incipient cavitation number σ
C2=0.6.Even flow velocity during section pressure head 30m, still can prevent cavitation erosion up to 25m/s before the streaming gate slot.
Hence one can see that, and the runner build is one of essential condition that causes cavitation to the cavitation influence greatly.Under the high velocity stream condition, the residual steel bar end of overfull dam surface just can cause the large-area cavitation erosion of dam facing sometimes.Therefore, take place for preventing cavitation, it is smooth smooth that dam facing is tried one's best, the streamlining of trying one's best of runner build.
2, the demonstration of cavitation tube coupling stream principle of device
Be to be noted that the one side that cavitation is not only harmful, also have available one side.Cavitation tube coupling stream device is exactly an example.The liquid fuel supply of liquid-propellant rocket engine requires not to be subjected to the influence of atmospheric pressure fluctuation.In other words, though rocket in space, its back pressure is lower than under the atmospheric situation than ground, still requires fuel duty to remain unchanged.For this reason, in the rocket engine woven hose, be provided with a kind of restriction device of Wen's cavitation pipe, supply with the requirement of fuel in order to realize constant basis.This instrument can be demonstrated this principle of work.Method is, when 3 valve wide opens, measures the outflow that convergent cavitation under two kinds of tailwater levels shows runner: the one, raise tailwater level (tail is pressed and increased), do not disappear with the cavitation cloud and exceed (example survey 426cm
3/ s); The 2nd, reduce tailwater level (the tail pressure drop is low) drop 1m, measure flow (the real 430cm that is measured as of example again
3/ s).Both are almost equal.Show that the variation of tail pressure does not influence cavitation pipe conveyance capacity.Its reason is: venturi throat has produced the height cavitation, and pressure is near complete vacuum.Cavitation has been destroyed the continuity of liquid stream, and energy equation is inapplicable at this.At this moment, even the afterbody back pressure reduces again, (because of near complete vacuum) also can not fall in throat's pressure again.Thereby this moment, the venturi inflow-rate of water turbine depended on venturi fore pressure (voltage supply) fully.If voltage supply is constant, even tail is pressed with change, flow is still constant.
The cavitation pipe also is widely used in other field.For example, refrigerant liquid because of cavitation takes place pressure drop, becomes gaseous state by liquid state when high velocity stream is crossed Venturi tube under driven compressor.Need during vaporizing liquid from drawing a large amount of heat energy on every side, thereby reach refrigeration.Afterwards, compressor condenses a gas into a liquid again, and discharges big calorimetric, drains into atmosphere by heat radiator, thereby has finished exchange heat.
Claims (1)
1, a kind of self-loopa cavitation mechanism experiment instrument of miniaturization, it is characterized in that it has self-loopa supply tank (11), in self-loopa supply tank (11), be provided with submersible pump (14), self-loopa supply tank (11) is gone up and is arranged runner display case (5), be provided with Wen's type cavitation in the runner display case (5) and show runner (1), the convergent cavitation shows runner (2), rectangular gate groove cavitation shows runner (3), streamlined gate slot cavitation FLOW VISUALIZATION runner (4), runner display case (5) top is provided with vent valve (12), submersible pump (14) water delivering orifice connects each runner in the runner display case (5) respectively by a plurality of upper hoses, flow control valve (10) is set on the upper hose, runner display case (5) afterbody is provided with downcomer and connects self-loopa supply tank (11), the convergent cavitation shows that runner (2) constriction place is provided with pressure tap (6), pressure tap (6) is connected with communicating pipe with ozzle (8) on the cavitation cup (9), another ozzle (8) on the cavitation cup (9) is connected with communicating pipe with vacuum meter (13), and cavitation cup (9) top is equipped with and is connected short tube (7).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200420081665 CN2720543Y (en) | 2004-07-23 | 2004-07-23 | Small self-circulation cavitation mechanism experiment instrument |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200420081665 CN2720543Y (en) | 2004-07-23 | 2004-07-23 | Small self-circulation cavitation mechanism experiment instrument |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2720543Y true CN2720543Y (en) | 2005-08-24 |
Family
ID=35009501
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200420081665 Expired - Lifetime CN2720543Y (en) | 2004-07-23 | 2004-07-23 | Small self-circulation cavitation mechanism experiment instrument |
Country Status (1)
| Country | Link |
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| CN (1) | CN2720543Y (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100389442C (en) * | 2004-07-23 | 2008-05-21 | 浙江大学 | Small self circulation cavitation mechanism test instrument |
| CN100446052C (en) * | 2006-10-18 | 2008-12-24 | 成都理工大学 | Pressure-bearing whole well water-pumping simulation device |
| CN104835390A (en) * | 2015-04-30 | 2015-08-12 | 王英英 | Jet apparatus suitable for physics teaching |
| WO2022222565A1 (en) * | 2021-04-20 | 2022-10-27 | 中国石油大学(华东) | Hydrodynamic cavitation generation apparatus and method |
-
2004
- 2004-07-23 CN CN 200420081665 patent/CN2720543Y/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100389442C (en) * | 2004-07-23 | 2008-05-21 | 浙江大学 | Small self circulation cavitation mechanism test instrument |
| CN100446052C (en) * | 2006-10-18 | 2008-12-24 | 成都理工大学 | Pressure-bearing whole well water-pumping simulation device |
| CN104835390A (en) * | 2015-04-30 | 2015-08-12 | 王英英 | Jet apparatus suitable for physics teaching |
| WO2022222565A1 (en) * | 2021-04-20 | 2022-10-27 | 中国石油大学(华东) | Hydrodynamic cavitation generation apparatus and method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Effective date of abandoning: 20080521 |
|
| C25 | Abandonment of patent right or utility model to avoid double patenting |