CN209102330U - A dual-purpose tester for fluid energy-momentum equation - Google Patents

Abstract

A fluid energy-momentum equation dual-purpose tester is composed of a fluid circulation device, an energy measurement part and a momentum measurement part, wherein the fluid circulation device comprises a laboratory table, a first circulation box, an overflow plate, an energy dissipation chamber, a fluid inlet, Overflow port, transfer bucket and second circulation box; energy measurement part includes measuring pipe, control valve, pressure measuring tube, pitot tube; momentum measurement part includes vertical jet chamber, vertical nozzle, replaceable curved surface, spring dynamometer, Bracket, fluid outlet, upper clamp, lower clamp, bolts. The utility model has a simple structure, and can use a set of equipment to simultaneously complete the two experimental measurements of the hydrodynamic momentum and the energy equation; a new measuring tube reading method is proposed, which reduces the difficulty of reading; the spring is used to measure the force, which greatly reduces the momentum equation Measured value error of medium jet impulse.

Description

A dual-purpose tester for fluid energy-momentum equation

technical field

The utility model relates to fluid mechanics and fluid mechanics experimental technology, in particular to an improved fluid energy momentum equation dual-purpose tester.

Background technique

In the experimental teaching of fluid mechanics, the energy equation and the momentum equation are usually explained and tested together. Existing instruments for energy and momentum equation experiments are often split, while single-function energy equation testers and momentum equation testers require a large experimental space. Most of the functions overlap. Therefore, it is very necessary to invent a dual-purpose tester for energy equation and momentum equation.

In addition, in the current experimental teaching of fluid mechanics, the lever theorem is generally used to measure the impact force of fluid flow, and then calculate the momentum. Since the lever at equilibrium is a metastable system, the slight disturbance of the impact force of the turbulent fluid will cause the lever to sway, thus greatly affecting the accuracy of the reading. According to experience, the existing experiment using the lever-type momentum equation experimental instrument generally has an error of 20% to 40%.

Utility model content

Purpose of the utility model: In view of the above-mentioned prior art, the present application provides a fluid energy-momentum equation dual-purpose experimental instrument that can simultaneously realize energy and momentum equation experiments in fluid mechanics experiments, and greatly improves the measurement accuracy of momentum equation data.

Technical solution: The fluid energy momentum equation dual-purpose tester described in this application includes a first circulation box, and a fluid inlet is arranged at the bottom of the first circulation box, and after the fluid enters the first circulation box, it overflows from the upper part and leads to the first circulation box. Second circulation box, the second circulation box is connected to the fluid inlet of the first circulation box through a pump; the first circulation box is connected to a measuring pipe, the distal end of the measuring pipe is provided with a control valve, and the measuring pipe is distributed on the There is a measuring point interface, and the measuring point interface is connected to the pressure measuring tube and the pitot tube at the same time through the pipeline; the end of the measuring pipeline is provided with a vertical nozzle, the vertical nozzle is located in the vertical jet chamber, and the vertical nozzle is on the same vertical line With replaceable curved surfaces and spring dynamometers, the fluid outlet of the vertical jet chamber is connected to a second circulation tank.

The first circulation tank is a constant liquid level tank, and the liquid level is kept constant by the overflow plate.

Further, an energy dissipation chamber is provided at the fluid inlet of the first circulation box, the energy dissipation chamber is isolated by a baffle plate, and a glass ball is also placed in the energy dissipation chamber.

The application is provided with multiple sets of pressure measuring tubes and pitot tubes, the number of which matches the number of measuring point interfaces. Each group of pressure measuring tubes and pitot tubes includes a pit tube and a pressure measuring tube, and each group is respectively connected to the corresponding measuring point interface through a connecting hose.

Further, the piezometric tube and the pitot tube are provided with colored light sheets for marking the water level.

There is a calibrated flow scale on the control valve that controls the fluid flow, which can change the jet size of the vertical nozzle.

The vertical jet chamber is a square plastic box with a fluid outlet at the bottom.

In order to facilitate the stable placement of the whole tester, a test table is also included for fixing each test device.

Further, the spring dynamometer is connected with the vertical jet chamber through a bracket, the bracket is fixed on the outside of the vertical jet chamber by bolts, the bracket is provided with an upper clamp and a lower clamp, and the spring dynamometer utilizes the upper clamp and the lower clamp. The lower clamp is fixed on the bracket.

Preferably, the replaceable curved surface has three types: 90 degrees, 135 degrees and 180 degrees, and is installed at the end of the spring dynamometer. The replaceable curved surface is placed 4 to 5 cm directly above the vertical nozzle; the axis of the spring dynamometer must be kept in line with the vertical nozzle.

The unexplained parts involved in the present invention are the same as the prior art or implemented by using the prior art.

Beneficial effects: Compared with the prior art, the tester of the present application is simplified in mechanism and diversified in functions, and the impact force is changed by using a control valve, so that the momentum equation experiment can not only change the deflection angle of the jet, but also change the flow velocity of the jet, so as to realize the functional improvement. Enhanced; the theoretical value of impact force is obtained by measuring and calculating with pitot tubes and piezometric tubes, eliminating the need for manual measurement steps; and the device of the present application realizes the improvement of measurement accuracy by improving the measurement method, and is marked by red plastic sheets (or other bright colors). , reduce the reading error of the pressure measuring tube and the pitot tube, and improve the lever measurement to the spring dynamometer measurement. The former belongs to the metastable device, and the observation and judgment error is large, which leads to unstable readings, while the spring dynamometer fluctuates less and the readings are more stable. Stable and reduce errors.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the present utility model;

Figure 2 is a schematic structural diagram of the vertical jet chamber of the present invention.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is further described:

As shown in Figure 1, an improved dual-purpose experimental apparatus for fluid energy and momentum equations includes a fluid circulation device, an energy measurement part and a momentum measurement part; the fluid circulation device includes a laboratory table 11, a first circulation box 12, and an overflow plate 13 , energy dissipation chamber 14, fluid inlet 15, overflow port 16, transfer bucket 17, second circulation box 18 and pump 19; the energy measurement part includes measurement pipeline 21, control valve 22, pressure measurement tube 23, pitot tube 24, The measuring point interface 25; the momentum measuring part includes a vertical jet chamber 31, a vertical nozzle 32, a replaceable curved surface 33, a spring dynamometer 34, a bracket 35, a fluid outlet 39, an upper clamp 36, a lower clamp 37, and a bolt 38.

A first circulation box 12 is placed on the leftmost side of the experimental table 11 , and the first circulation box 12 includes an overflow plate 13 and an energy dissipation chamber 14 . The overflow plate 13 is arranged at the left 1/3 of the first circulation box 12, the energy dissipation chamber 14 is arranged at the right side of the overflow plate 13, the energy dissipation chamber 14 has glass balls built in, and the right side is connected to the first circulation box. 12 Other parts are separated by baffles. In addition, an overflow port 16 is provided on the left side of the overflow plate 13, which is connected to the second circulation tank 18 through a pipeline. The second circulation box 18 is installed directly below the experimental table 11 ; a pump 19 is installed at the lower left of the experimental table 11 for pumping the fluid from the second circulation box 18 into the first circulation box 12 to realize the circulation test.

It is worth noting that the function of the first circulation tank 12 is to provide stable fluid pressure for the experiment. The overflow plate 13 is used to keep the fluid level in the first circulation box 12 constant; the energy dissipation chamber 14 is used to consume the kinetic energy of the inflowing fluid; the overflow port 16 is used to complete the recovery of the fluid.

Wherein, the left end of the measuring pipe 21 is directly installed on the lower part of the right side of the first circulation box 12, and a plurality of measuring points are arranged on the measuring pipe 21, and each measuring point is provided with two measuring point interfaces 25, which can be respectively provided by hoses. Connected with the Pitot tube 24 and the pressure measuring tube 23; the Pitot tube 24 and the pressure measuring tube 23 are placed in groups, each group contains a Pitot tube and a pressure measuring tube, and each group is connected to the corresponding measuring tube through a connecting hose. on the point interface; all tubes are internally provided with red light flakes. A control valve 22 for controlling the fluid flow is provided on the right side of the measuring pipe 21, and a scale corresponding to the approximate flow rate is provided on the control valve 22, and the flow rate can be roughly adjusted according to the scale. The end of the measuring pipe 21 is connected to the vertical jet chamber 31 .

As shown in FIG. 2 , the vertical jet chamber 31 is a plastic box with a square opening, in which a vertical nozzle 32 , a replaceable curved surface 33 , a spring dynamometer 34 , a bracket 35 and a fluid outlet 39 are placed. The vertical nozzle 32 is directly installed at the end of the measuring pipe 21; the bracket 35 is fixed on the outer side of the vertical jet chamber 31 by bolts 38, and the spring dynamometer 34 is fixed on the bracket 35 by the upper clamp 36 and the lower clamp 37; it is worth noting Yes, the axis of the spring dynamometer 34 must be kept in line with the vertical nozzle 32. The replaceable curved surface 33 has three types: 90 degrees, 135 degrees and 180 degrees. It is installed at the end of the spring dynamometer 34 and should be placed 4 to 5 centimeters directly above the vertical nozzle 32 . The fluid outlet 39 is arranged at the bottom of the vertical jet chamber 31, facing the adapter bucket 17; the adapter bucket 17 is arranged directly below the vertical jet chamber 31, and is connected to the second circulation box 18 through a pipeline.

Application example:

A proper amount of water is stored in the second circulation box 18, and the pump 19 is started; the water in the second circulation box 18 is lifted by the pump 19 and enters the energy dissipation chamber 14 from the fluid inlet 15, and then collides with the glass ball and the baffle plate, consuming kinetic energy; thereafter, The water rises slowly in the first circulation tank 12 , and begins to overflow when the water level reaches the height of the overflow plate 13 ; the overflowed water is discharged into the second circulation tank 18 through the overflow port 16 . After that, the water level of the first circulation tank 12 is kept constant.

Open the control valve 22, and the water flow in the control pipeline is stabilized in a low flow state. After the water level of the first circulation tank 12 is constant, check whether the liquid level of the pit tube 24 and the pressure measuring tube 23 is flush; When the liquid level of the pitot tube 24 and the pressure measuring tube 23 is flush and there are no air bubbles in the measuring tube 21, observe the scale corresponding to the position of the red plastic sheet in the measuring tube corresponding to different measuring points, and the scale is the water head of each measuring tube. From this, the total head and the piezometric head are obtained. Change the water flow by rotating the control valve handwheel, measure the total water head and piezometric pipe water head at different measuring points, and then complete the measurement of the energy equation experiment.

In addition, in the energy equation experiment, the elevation difference between the pitot tube and the pressure measuring tube is the kinetic energy of the unit mass of the liquid corresponding to the measuring point, from which the flow velocity at this point can be obtained, and the accurate value of the flow rate in the pipe can be further obtained.

Further, the water flows into the vertical jet chamber 31 through the measuring pipe 21, and then hits the center area of the replaceable curved surface 33 after passing through the vertical nozzle 32; since the centerline of the jet is coincident with the axis of the replaceable curved surface 33, it acts on the replaceable curved surface 33. The magnitude of the force is equal to the magnitude of the impact force of the jet; the reading of the spring dynamometer 34 is read to obtain the impact force of the jet and then the reaction force of the curved surface to the water flow. According to the flow data obtained in the energy equation experiment, it is approximately considered that water is an incompressible fluid, and the flow rate of the jet at the vertical nozzle can be obtained through the momentum equation, and then the theoretical value of the surface impact force can be obtained; the theoretical value and the energy equation can be obtained. Comparing the measured values in the experiment, the momentum equation experiment can be completed. By analogy, the replaceable surface is replaced with 135 degrees and 180 degrees, and the momentum equation experiment can be carried out under the condition of changing the angle of water flow speed.

The test apparatus in this application example is composed of a fluid circulation device, an energy measurement device and a momentum measurement device. The functions of the fluid circulation device include fixing all the experimental instruments, storing the experimental fluid, circulating the experimental fluid, and ensuring the stability of the circulating fluid; energy; The function of the measuring device includes measuring and calculating the head loss under various conditions such as necking and sudden expansion, and obtaining the head change curve of the total head piezometer; in addition, it can also calculate the flow rate of the pipeline to obtain the flow velocity data, and provide flow velocity data support for the momentum equation experiment. The function of the momentum measuring device is to use a spring dynamometer to measure the impact force of the water flow and compare it with the impact force calculated by the momentum equation, so as to verify the correctness of the momentum equation. Among them, the measurement principle of the energy measurement part: the measurement pipe is equipped with a necking of the pipe diameter, sudden expansion, vertical corners and other changes in the shape of the inner section of the pipe, and the water head h1 of the piezometric pipe at this point is measured by the principle of the connector, and the water head is the unit of this point. The sum of potential energy and pressure energy of mass water; Pitot tube is a curved thin tube facing the direction of water flow. The water flow at the measuring point enters the thin tube and no longer flows, so that the kinetic energy of the water at this point is converted into potential energy. The face represents the total head h2. The difference between the total water head and the pressure measuring tube head is the flow velocity head h3, and the flow velocity u at the measuring point can be obtained from the measured pipe radius D and the flow velocity u at the measuring point, and the pipe flow rate Q can be obtained; It is adjusted by adjusting the control valve to control the flow. Momentum measurement part measurement principle: the force of the jet on the replaceable curved surface and the force of the spring dynamometer on the replaceable curved surface are on the same line, so the reading of the spring dynamometer is used to characterize the impact force of the jet. Use the flow rate Q and the nozzle diameter d to obtain the jet flow velocity, and use the momentum equation to obtain the theoretical value of the jet impact force, which is compared with the measured value.

Claims (10)

1. a kind of dual-purpose tester of the fluid energy equation of momentum, it is characterised in that:

Including first circulation case (12), first circulation case (12) bottom is equipped with fluid inlet (15), and fluid enters first and follows Second circulation case (18) are imported from top overflow after ring case (12), the second circulation case (18) is connected to first by pumping (19) The fluid inlet (15) of circulating box；

One measurement pipeline (21) of first circulation case (12) connection, the measurement pipeline (21) are distally equipped with a control valve (22), it is distributed with measuring point interface (25) on the measurement pipeline (21), the measuring point interface (25) connects survey by pipeline simultaneously Pressure pipe (23) and Pitot tube (24)；

The end of measurement pipeline (21) is equipped with a perpendicular nozzle (32), and the perpendicular nozzle (32) is located at vertical fluid room (31) in, the same vertical line of the perpendicular nozzle (32) is equipped with replaceable curved surface (33) and weight beam (34), described to hang down The fluid outlet (39) of direct projection flow chamber is connected to second circulation case (18).

2. the dual-purpose tester of the fluid energy equation of momentum according to claim 1, which is characterized in that the first circulation case (12) it is constant level case, keeps fluid level in case constant by overflow plate (13).

3. the dual-purpose tester of the fluid energy equation of momentum according to claim 1, which is characterized in that the first circulation case Fluid inlet (15) at be equipped with energy dissipating room (14), the energy dissipating room (14) is isolated by resistance punching, the energy dissipating room in and also It is placed with glass marble.

4. the dual-purpose tester of the fluid energy equation of momentum according to claim 1, which is characterized in that be equipped with multiple groups pressure-measuring pipe (23) match with Pitot tube (24), quantity with measuring point interface (25) quantity.

5. the dual-purpose tester of the fluid energy equation of momentum according to claim 1, which is characterized in that the vertical fluid room It (31) is a square plastic box.

6. the dual-purpose tester of the fluid energy equation of momentum according to claim 1, which is characterized in that further include a laboratory table (11), for fixing each experimental rig.

7. the dual-purpose tester of the fluid energy equation of momentum according to claim 1, which is characterized in that the weight beam (34) it is linked together by bracket (35) with vertical fluid room (31).

8. the dual-purpose tester of the fluid energy equation of momentum according to claim 7, which is characterized in that on the bracket (35) Equipped with upper fixture (36) and lower fixture (37), weight beam (34) is fixed on bracket using upper fixture (36) and lower fixture (37) (35) on.

9. the dual-purpose tester of the fluid energy equation of momentum according to claim 1, which is characterized in that the replaceable curved surface (33) there are 90 degree, 135 degree and three kinds of 180 degree.

10. the dual-purpose tester of the fluid energy equation of momentum according to claim 1, which is characterized in that the replaceable song Face (33) is placed in the surface 4-5 centimeters of perpendicular nozzle (32).