SU757850A1 - Device for measuring levels and slopes - Google Patents

Description

The invention relates to hydraulic measurements and can be used to measure levels and the free surface inclines · _ watercourse in spatial hydraulic delyah ⁵ and MO in trays in laboratory experiments.

The known devices for measuring the levels and slopes of the free surface of a watercourse, which contain a pressure sensor connected to the recorder, have a low measurement accuracy [ί].

The closest technical solution to the invention is a device for measuring the slopes of the free surface of a watercourse containing pressure receivers connected to the differential pressure gauge cameras, · recorder H. 20

Using this device, the flow surface oscillations cannot be recorded, because the system has a large time constant due to the fact that the pressure is transmitted 25 not directly into the chambers of the differential pressure gauge, but through the height of the piezometer fluid columns in which they are damped (inertia due to the time the fluid flows into the cavity a piezometer 30

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ra). In addition, the device has additional measurement errors due to the fact that there is no reference pressure plane (bench), and the difference in piezometric heights is measured directly between the specified points, while with their considerable separation the long-period oscillations of the free flow surface at these points can pass different phases and register the system.

Such a hydraulic circuit does not allow measuring the level of the free surface of the watercourse relative to the reference level (for example, on spatial hydraulic models) ..

The aim of the invention is to eliminate the disadvantages of the known device, namely, improving the reliability of work, expanding the functionality and improving the accuracy of measurements, as well as the implementation of remote measurement at several points.

This is achieved by the fact that

introduced a reference device, three cranes with a common handle for three directions each, a interrogator switch,

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The pressure and receiver devices are connected to the inputs, the first valve is connected to the output of the interrogation switch and the differential pressure gauge chamber, the second crane is connected to the reference device and the second differential pressure gauge chamber, the third valve is connected to both differential pressure gauge cameras, and all three taps and a poll, a ny switch are also connected to the water mains.

The invention is illustrated in the drawing.

FIG. 1 is a schematic diagram of the proposed device, in which the position of the switches corresponds to the zero setting mode /

; in fig. 2 - the position of the three cranes ^; common handle in various modes of operation of the device.

The device contains acting as pressure receivers installed at different points of the hydraulic model (at different water levels), tubes 1-1, 1-2 ... 1-n, connecting pipes 2, a reference device 3, a differential pressure gauge with working chambers 4-1 and 4-2 and a membrane 5, made in the form of a multi-way valve, interrogation switch b, to the inputs of which pressure receivers and a reference device are connected, and to the output exit - pipeline 2-1, connected by successive rotation of the handle of this switch to elements 3.1 -1 ,,. 1 p. The first crane 7, the second crane 8 and the third crane 9 are made in three directions each, their handles are fixed on a common axis (for example, a cork three-row crane in three directions), while simultaneously installing them in one of the three positions, two connected to to this pipeline valve. The measuring part consists of a differential pressure meter built on a mechanotronic lamp, the movable rod of which is rigidly connected to the membrane 5 of the differential pressure meter, an unbalanced DC bridge 10, a reading switch 11, a recorder (recorder) 12.

The operation of the device.

Measurement of levels and slopes is the measurement of the piezometric height (pressure) relative to the reference pressure plane (reference point).

where d P is the pressure difference recorded by the differential pressure gauge between the reference plane (reference point) and the pressure at the measured point;

AN- is a level measurement relative to the reference one.

Bias on the plot

-ι ANPK. ΔΗί'ΔΗκ. δΡ (, ' ^β ί, κ''

where with a sufficient degree of accuracy for water in laboratory installations it is possible to take q * = 1, is the distance of the section between two points on which the slope is determined.

Piezometric height (pressure) in the measured point (vertical) is perceived by pressure receivers 1-1,

1-2 ... 1-p, the hydrostatic pressure is transmitted through pipelines (for example, plastic flexible tubes) 2 through the interrogation switch 6, pipeline 2-1 and valve 7 to one of the working chambers of the differential pressure gauge 4-1, to another working chamber of the differential pressure gauge 4-2 pressure is supplied through the pipeline from the level of the reference point 3. The received signal (differential pressure) on the differential pressure gauge from the diagonal of the DC bridge 10 is fed to the reading device 11. When measuring the surface relief of the flow, the signal from the bridge diagonal is fed to the recorder c) 12 (in this mode the measurement lines 2 must have a minimum length to eliminate the pressure pulsation damping).

The device with the help of cranes 7, 8 and 9 of three directions and rigidly interconnected (a single design with one control knob) is displayed on three modes of operation. Switching scheme (position of cranes) in all three modes of operation of the device with cranes 7,

8 and 9 are shown in FIG. 2. In the first mode, the taps 7, 8 and 9 are set to the position where the hydraulic measuring part is flushed (released from air bubbles) - pipelines connecting the outlets of the cranes 7 and 8 with the differential pressure gauge cameras and the cameras themselves differential pressure gauge 4-1 and 4-2, while the water outflows from chambers 4-1, 4-2 through the outlets of chambers 4-1, 4-2 and tap 9. In the second mode, the knob of taps 7, 8 and 9 rotates 120 ° counterclockwise with respect to the first position (see Fig. 2), flushing is performed (release from air pipe)

2-1, interrogation switch 6 of all pressure receivers 1-1 ... 1-p and their pipelines, alternately connecting them via interrogation switch 6 to one of the outlets of the crane 7. At the same time, the entire hydraulic path of the reference point 3 connected to one of outputs of the crane 8, while the level of the frame 3 is not changed due to the presence of its drain edge. Reper 3 is mounted on the rack with the up-down movement mechanism and has a readout device5

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This allows you to change the height of the drain edge of the reference frame, and hence the reference plane of the reference frame relative to the free surface of the model's watercourse. The constructive solution allows to expand the working range of the linear section of the differential pressure gauge with significant changes in the levels of the free surface of the model at its different flow rates. Separate flushing of the hydraulic system in two modes is provided to improve the reliability of the device, prevent damage to the membrane 5 of the differential pressure gauge and is caused by the fact that the hydraulic circuits of the taps 7, 8 are chambers 9-1, 4-2 of the differential pressure gauge 9 and taps 7.8 - interrogation switch 6 — pipelines 2-1 and pressure receivers 1-1 ... 1-p have different hydraulic resistances.

The hydraulic resistance of the pressure receiver circuits 1-1 ... 1-p is much larger than the chains of chambers 4-1, 4-2 of the differential pressure gauge, since the length of pipelines 2 can be significant (receivers are spaced apart on the spatial model), therefore, to flush these circuits you need sufficient head The washing of the chains of the differential pressure gauge chamber is carried out with a considerably smaller pressure (this is ensured by the small through-passage opening of the outlets of the taps 7, 8 to the chambers 4-1, 4-2), which prevents damage to the sensitive membrane 5 of the differential pressure gauge. Flushing the hydraulic system of the device is carried out with clean water from the water mains.

In the third mode of operation is measured and set to zero. Valves 7, 8 and 9 are installed in this position, while the cranes handle is rotated 120 ° counterclockwise relative to the position of the second mode (see Fig. 2, mode 3), when pressure receivers 1-1 ... 1-n through Interrogation switch 6, pipelines 2-1 and valve 7 are connected to the working chamber 4-1 of the differential pressure gauge. Reverse 3 is connected to another working chamber 4-2 through crane 8 and pipeline 2-1. At the same time, the outlets of chambers 4-1 and 4-2 are blocked by crane 9.

The pressure receivers 1-1 ... ί-p are alternately connected to the working chamber of the differential pressure gauge 4-1 using the interrogation switch 6 (multi-way plug valve with one direction).

It is known that any electrical measuring circuit of high sensitivity has a time drift. To ensure measurement accuracy, such schemes are necessary to set to zero during measurements after some period of time. This device uses a highly sensitive electrical measuring circuit, providing the sensitivity of the device up to 0.01 mm water column. To ensure high measurement accuracy, the device provides for setting the zero of the measuring circuit. This is achieved in the measurement mode by setting the interrogation switch 6 to the position "0", while the same pressure is supplied to both chambers 4-1 and 4-2 of the pressure gauge from reference frame 3 through the reference device 3 interrogation switch 6 - valve 7, chamber 4-1 and reference device 3 crane 8 - camera 4-2. Differential pressure is set to zero in differential pressure gauge.

Compared with known devices of similar purpose and principle of operation, the device has greater reliability of operation, measurement accuracy due to constructive solutions for separate flushing of the system, installation of zero differential pressure in the differential pressure gauge. Switching using a complex crane 7, 8 and 9 of the hydraulic system during its withdrawal to different modes of operation eliminates the failure of the device in case of operator errors during switching. Reference device 3 improves the accuracy of the reference piezometric height and expands the working range of measurement levels on hydraulic spatial models, with their different fillings with the same absolute measurement error in the entire working range. The device provides high accuracy of measurement with sensitivity up to 0.01 mm of water column, and remote measurement at many points of the model with documentary registration, along with great convenience in the work, provide extensive information and allow to mechanize data processing on the computer as averaging and analysis of surface pulsation parameters relief.

Claims (1)

Claim A device for measuring levels and slopes, containing pressure receivers connected to the working chambers of a differential pressure gauge, a recorder, characterized in that, in order to increase reliability, enhance functionality and improve measurement accuracy, as well as remote measurement at several points introduced a reference device, three cranes with a common handle for three directions each, a interrogation switch, to the inputs of which pressure receivers and a reference device are connected, with the first crane oedinen yield interrogator with an operating switch and 7 757850 eight the camera of the differential pressure gauge, the second valve is connected to a reference device and the second working chamber of the differential pressure meter, the third crane is connected to both working chambers of the differential pressure gauge, and all three cranes and the interrogation switch are also connected to the water mains pipeline.