CN1052385A - Piston type momentum law tester - Google Patents
Piston type momentum law tester Download PDFInfo
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- CN1052385A CN1052385A CN 89109218 CN89109218A CN1052385A CN 1052385 A CN1052385 A CN 1052385A CN 89109218 CN89109218 CN 89109218 CN 89109218 A CN89109218 A CN 89109218A CN 1052385 A CN1052385 A CN 1052385A
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- piston
- momentum
- water
- jet
- force
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- Aerodynamic Tests, Hydrodynamic Tests, Wind Tunnels, And Water Tanks (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
Abstract
This piston type momentum law tester has changed the measuring method of traditional cheek weight, contends with jet to the momentum force that plate impact produced and replace the water pressure that acts on the piston, the momentum force measurement is converted to the measurement of fluid interior-point pressure.It also has can make water pressure automatically and momentum force balances each other and the special construction that can effectively eliminate the piston force of sliding friction.Advantage of the present invention is that measurement is convenient, stable, precision is high, water-saving is energy-conservation, both can verify momentum law, can measure the momentum correction factor of jet again, is the replacement instrument of hydrodynamics teaching experiment.
Description
The invention belongs to the experimental measurement instrument.
The fluid momentum law is one of fluid mechanics, hydraulic basic theories, and the experiment of momentum law is an indispensable content in the teaching link.The momentum law tester device has jet impulse type and jet reaction-type two classes.The former makes jet directly impact on flat board and the impulsive force that assay plate bore, and the latter is the reacting force when measuring current and penetrating in container.Although the form difference, various instruments both domestic and external all are the methods that adopts cheek weight on the mode of measuring momentum force at present.For example use the most general a kind of momentum law tester at present both at home and abroad, its mode is that jet is upwards impacted on an inverted flat board of level, dull and stereotyped at jet impact force effect lower compression spring behind, make it depart from the equilibrium position and produce displacement upwards.Then, flat board being applied weight pushes back on the original equilibrium position.At this moment added weight weight is the momentum force of jet impulse flat board.The shortcoming of this surveying instrument is: because the turbulent fluctuation of jet and the elastic oscillation of spring are gone here and there flat board up and down, very unstable, measuring accuracy can only reach 0.1, even is 0.3～0.5, therefore experimental result can not be verified momentum law quantitatively, more can't measure the momentum correction factor of jet.In addition, troublesome poeration during laboratory fees, requires acting head height (more than 5～10 meters), and water requirement is big, the energy consumption height.
The objective of the invention is to design a kind of momentum law tester, utilize hydraulic pressure directly to measure momentum force and momentum correction factor, measuring accuracy height, simple in structure, easy to use.
Primary structure of the present invention is as shown in Figure 1: be made up of momentum pipe 8, jet constant pressure water supply equipment 1,4,7,10 of water collectors.Momentum pipe 8 is by one side impact flat board 11, piston bush 18, mozzle 13, sluice narrow groove 19, piezometric tube 16 and the scale 17 that blade 15 and fair water fin 14 another sides are fixed with piston 12 to be housed to combine.The band blade impact flat board 11 should with axial inlet velocity vector
Vertically, thereby the velocity of discharge vector
With the inlet velocity vector
At an angle of 90.Piston can be free to slide in piston bush, aqueduct is located in the piston, one end water inlet inlet is fixed on and impacts dull and stereotyped central authorities, the piston bottom surface is passed in other end outlet, the narrow groove that sluices is located at the wall of piston bush, piston bush and piezometric tube are that one or sealing connect to one, and the jet constant pressure water supply equipment is made up of the fluid jet nozzle 4 of constant pressure water supply case 1, aperture or ozzle formula; Also can directly connect and form by constant pressure water supply pipe 5 and fluid jet nozzle 4.Water collector is made up of header tank 7 and drainpipe 10, by set screw 9 piezometric tube is fixed on the header tank.
The course of work of the present invention is: the current under the constant pressure effect form jet through fluid jet nozzle 4 and are ejected in the impact dull and stereotyped 11, the runner that constitutes along blade passes the slit between the guide plate 14 and dull and stereotyped 11 again, then with go into jet and become 90 ° direction to leave to impact flat board 11.The dull and stereotyped piston 12 that promotes under jet impingement function slides in piston bush 18.When piston 12 when all propelling pistons overlap 18, piston is in extreme position, the narrow groove 19 of sluicing is all sealed by piston.At this moment, under jet impulse, a small gangs of current flow into piezometric tube through aqueduct 13 and piston bush 18, make liquid level rising in the piezometric tube, and the fluid column in the piezometric tube has the pressure opposite with jet direction to piston action.When the water level in the piezometric tube surpassed certain altitude, the water pressure that piston is subjected to was just greater than the momentum force of jet, and can promote piston and outwards move.So the narrow groove that sluices is partly opened, the water in the piezometric tube drains drawdown by the narrow groove that sluices.If drawdown is too much, momentum of impinging jet power is during greater than water pressure, piston can move again inwards, automatically regulate bleeder quantity and water level, water column in piezometric tube equates with the impact momentum power of jet to flat board the acting force of piston, and from the water yield that the water yield that aqueduct 13 flows to and the narrow groove 19 that sluices certainly flow out equate, the piezometric tube liquid-column height stablize constant till.But have bigger frictional resistance to exist when moving owing to piston, precision can not be higher.In order to overcome this frictional resistance, be provided with blade 15 impacting on the flat board, when current flow through blade, the flat board of band blade was subjected to the effect of rotating torque, just can drive piston and gyrate together, significantly reduced the friction force of piston when moving.Experiment showed, that the friction force that piston moves vertically is lower than 0.5% of impulsive force, can ignore in rotation.Like this, as long as just record the momentum force that the suffered water pressure of piston can be learnt jet.The effect one of header tank 7 is that anti-spray spatters outward, the 2nd, in order to fixing momentum pipe, the 3rd, compile current, the current after compiling after drainpipe 10 discharge, and at the exit of drainpipe measurement jet flow.
Experimental principle of the present invention is based on the momentum law of constant total stream, and its equation is:
Flat board with the band piston is a beaer, gets to break away from body as shown in Figure 4.Because of frictional resistance fx can ignore, the equation of momentum on the x direction is:
α
01ρQV
1X- (π)/4 γhD
2＝0
Wherein: V
1X=4Q/ π d
2
In last three formulas:
The density of ρ-fluid;
The flow of Q-fluid;
α
01, α
02-be respectively the momentum correction factor that flows into and flow out the fluid that breaks away from body;
-be respectively the average velocity that flows into and flow out the fluid that breaks away from body to vow;
V
1X-flow into to break away from the fluid average velocity of body along the x direction;
The severe of γ-fluid;
H-acts on the piezometric tube water colunm height of piston bottom surface circle centre position;
The diameter of D-piston;
The internal diameter in d-fluid jet nozzle exit.
In the experiment, under equilibrium state, as long as measure Q, h, D, d value, just can verify the momentum correction factor α of momentum law and mensuration jet
01Value.
Description of drawings:
Fig. 1 is the piston type momentum law tester structural representation.
Fig. 2 is a momentum tubular construction synoptic diagram.
Fig. 3 is that the dull and stereotyped A of impact shown in Figure 2 is to view.
Fig. 4 calculates accompanying drawing.
Symbolic significance among all figure:
1 is jet constant pressure water supply case among the figure, the 2nd, and voltage stabilizing orifice plate, the 3rd, overflow plate, the 4th, fluid jet nozzle, the 5th, water inlet pipe, the 6th, run-down pipe, the 7th, header tank, the 8th, momentum pipe, the 9th, set screw, the 10th, drainpipe, the 11st, impact flat board, the 12nd, piston, the 13rd, aqueduct, the 14th, guide plate, the 15th, blade, the 16th, piezometric tube, the 17th, scale, the 18th, piston bush, the 19th, narrow groove sluices.
As embodiment, the present invention trial-produces successfully in my laboratory, school.The jet constant pressure water supply equipment of this embodiment is a constant pressure water tank, and fluid jet nozzle is an ozzle, water tank length * wide * high=35 * 18 * 40 centimetres
3, ozzle d=1.20 centimetre, acting head H=13～30 of supply tank centimetre, maximum amount of jet Q
Max=300 centimetres
3/ second about, piston diameter D=2.0 centimetre, the piezometric tube height during balance on the piston central point is h=12～25 centimetre.The actual measurement precision reaches in 0.01.Satisfy the teaching requirement fully.The used constant pressure water tank of present embodiment, impact parts such as flat board, piston, piston bush, piezometric tube, header tank and be all transparent organic glass and make, be convenient to observation, the structure light and beautiful.Part student has had a fling at experiment, and the reflection teaching efficiency is fine.
Advantage of the present invention is that measurement is convenient, stable, precision is high, not only can verify momentum law, can also measure easily the momentum correction factor of jet, and water-saving is energy-conservation, uses extensively, and social benefit is remarkable.
The present invention has broken through the conventional method that the weighting material of continuing to use is for a long time measured momentum force, replace the water pressure that acts on the piston momentum force that jet produces plate impact that contends with, the momentum force measurement is converted to the measurement of fluid interior-point pressure, and is provided with aqueduct and the narrow groove that sluices On can automatically adjust water pressure structure. Effectively overcome the dynamic fluctuation of weighting procedure and reached tired lock that balance causes, time-consuming, the drawback such as precision is low by artificial counterweight. Experiment through embodiment shows that the present invention reaches the required time of stable state, about the dull and stereotyped beginning of jet impulse only needs 1 fen half. Thereby reduced to about 20 minutes the time of momentum law by original about 50 minutes, because making piston ceaselessly rotate, blade effectively overcome again the frictional force when piston moves vertically, in the experiment such as present embodiment, the height h that records pressure-measuring pipe under the poised state is 20.5 centimetres, we sop up about about 0.1 centimetre of pressure measurement liquid in pipe with suction pipe then, the result is under the automatic adjusting of piston, and water level can be returned to 20.5 centimetres again very soon. On the contrary, we add about 0.1 centimetre water again in pressure-measuring pipe, can be returned to 20.5 centimetres under the automatic adjusting of piston equally, prove that this instrument has very high sensitivity. The momentum correction factor α of general ozzle jet01Be about 1.02～1.05, surpassed 5% such as the error of instrument own, instrument can only qualitative checking momentum law and can not measure α01Value, Here it is in the past any momentum law tester all can't measure the reason of momentum correction factor. Because certainty of measurement of the present invention can reach in 0.01, so can measure more exactly α01Value, this is front no only creation. Present embodiment is surveyed to such an extent that the arc inlet nipple momentum correction factor that goes out stream is 1.03.
The present invention can be widely used in the education experiment of the engineering fluid mechanics of the specialties such as the relevant machinery of university and secondary specialized school technical school, building, water conservancy, environmental protection, chemical industry, metallurgy, traffic, aviation, is the update instrument of existing momentum law instrument. Therefore, has very big social benefit.
Claims (6)
1, piston type momentum law tester, be water to be ejected into through fluid jet nozzle impact flat board, determine momentum force by force measuring machine, feature of the present invention is that described one side of impacting dull and stereotyped (11) is equipped with blade (15) and fair water fin (14), another side has piston (12), piston can be free to slide in coaxial piston bush (18), and piston bush and piezometric tube (16) connect to one for one or sealing.
2,, it is characterized in that to vow with axial inlet velocity with the impact flat board (11) of blade according to the experiment instrument of claim 1
Vertically.
3, according to the experiment instrument of claim 1, it is characterized in that in piston (12), being equipped with aqueduct (13), an end of its water inlet is fixed on the central authorities that impact dull and stereotyped (11), and an end of water delivering orifice then passes the piston bottom surface.
4,, it is characterized in that being provided with the narrow groove (19) that sluices at the wall of piston bush (18) according to the experiment instrument of claim 1.
5, according to the experiment instrument of claim 1, it is characterized in that piezometric tube (16) is fixed on the header tank (7) by set screw (9), scale (17) is carved with on the surface of piezometric tube.
6,, it is characterized in that constant pressure water supply case (1), impact dull and stereotyped (11), piston (12), piston bush (18), piezometric tube (16) and header tank (7) are transparent organic glass and make according to the experiment instrument of claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 89109218 CN1017757B (en) | 1989-12-08 | 1989-12-08 | Piston type momentum law tester |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 89109218 CN1017757B (en) | 1989-12-08 | 1989-12-08 | Piston type momentum law tester |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1052385A true CN1052385A (en) | 1991-06-19 |
| CN1017757B CN1017757B (en) | 1992-08-05 |
Family
ID=4857914
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 89109218 Expired CN1017757B (en) | 1989-12-08 | 1989-12-08 | Piston type momentum law tester |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1017757B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100416623C (en) * | 2006-01-18 | 2008-09-03 | 浙江大学 | Self-circulation electrical momentum law experimental instrument |
| CN104655336A (en) * | 2015-01-19 | 2015-05-27 | 江苏大学 | Water spraying propulsion pump structure capable of measuring dynamic exciting force of blade |
| CN104882048A (en) * | 2015-06-02 | 2015-09-02 | 浙江大学 | Piston-type momentum experiment instrument with teaching effect flow digital-display function |
-
1989
- 1989-12-08 CN CN 89109218 patent/CN1017757B/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100416623C (en) * | 2006-01-18 | 2008-09-03 | 浙江大学 | Self-circulation electrical momentum law experimental instrument |
| CN104655336A (en) * | 2015-01-19 | 2015-05-27 | 江苏大学 | Water spraying propulsion pump structure capable of measuring dynamic exciting force of blade |
| CN104882048A (en) * | 2015-06-02 | 2015-09-02 | 浙江大学 | Piston-type momentum experiment instrument with teaching effect flow digital-display function |
| CN104882048B (en) * | 2015-06-02 | 2017-08-08 | 浙江大学 | A kind of piston type momentum testing equipment for possessing teaching efficiency flow digital display |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1017757B (en) | 1992-08-05 |
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