RU2739416C1 - Device for testing dynamic pressure sensors - Google Patents

Abstract

FIELD: instrument engineering.

SUBSTANCE: proposed invention relates to instrument making and testing equipment, in particular, to devices for dynamic testing (calibration) of pressure sensors used to determine characteristics of an air shock wave when testing real charges of high-energy condensed systems (ES) and articles based thereon, arranged on measuring beams of test sites. Device for calibration of dynamic pressure sensors consists of separate parallel installed tube modules for arrangement of charges of explosive substance, interconnected and arranged in common shell. Each module is an initiating waveguide. Initiating waveguides arranged in a common shell have the same length, with arrangement of open (output) ends of the waveguides in one plane. Total area of the open ends of the initiating waveguides is commensurate with the area of the membrane element of the tested pressure sensor.

EFFECT: applicability of a device for testing pressure sensors located directly in conditions of use thereof on measuring beams of a test site, and high accuracy of measurements while reducing risk of use.

1 cl, 5 dwg

Description

The proposed invention relates to the field of instrumentation and testing equipment, in particular to devices for dynamic testing (calibration and verification of measuring transducers) - pressure sensors used to determine the characteristics of an air shock wave when testing real charges of high-energy condensed systems (HE) and products based on them located on the measuring beams of test sites.

At present, shock tubes are widely used for testing (during verification and calibration) of air blast wave (SW) pressure sensors.

A number of devices are known for loading objects with air hydrocarbons. For example, the device / 1 / contains a shock tube with open and closed ends to accommodate the test object, and an HC source in the form of a detonating explosive charge placed inside it near the closed end. The device / 2 / consists of an explosion chamber, an explosive charge placed inside it and located on the chamber wall of the tested and exemplary pulse pressure sensors. Testing is carried out by acting on the sensing element of the sensor with an HC generated by the explosion of a small explosive charge or an electric explosion of the wire.

A common disadvantage of devices of this type is their inapplicability for testing pressure sensors located directly in the conditions of use at the test site, due to the following factors:

1) The operation of these devices involves removing the sensor under test from the actual installation site and placing it in the shock tube channel - thus, the testing does not take into account the electrical characteristics of the communication lines (ohmic resistance, capacitance, inductance) of the sensor with the recording equipment, which introduce some system distortions into the measurement result.

2) Also, the operation of these devices assumes, when testing a specific sensor taken from the measuring beam, at the same time the use of an exemplary sensor, the constancy of the characteristics of which is not unlimited - the more working sensors are tested, the more likely it is to change the characteristics of the exemplary sensor and it itself will need calibration , which promises additional material and financial costs.

3) Structurally, these devices initially have significant mass and size characteristics, which makes it almost impossible to transport and place them directly on the test site near specific sensors on measuring beams, ensuring the use of existing communication lines and recording equipment.

Closest to the proposed invention in terms of technical essence - design features, and the achieved result is a device for testing (calibration) pressure sensors / 3 /, consisting of separate parallel installed tube modules for placing explosive charges, interconnected and placed in a common shell.

Each tube module in this design is coaxial tubes installed with a gap between the ends facing each other to accommodate a flat explosive charge.

Despite a number of advantages of this design, along with the aforementioned disadvantages inherent in analog devices / 1, 2 /, this device has a number of specific disadvantages:

1) The initiation of flat explosive charges placed between the ends of the pipes requires the presence of an appropriate number of electric detonators - hence the additional financial costs, plus additional labor costs for the installation of the explosive network.

2) Increased danger of use due to the use of a relatively large number of initiation means - electric detonators, as well as concentrated explosive charges.

3) There are no structural elements in the device that prevent the propagation of a shock wave along the annular space, as well as along the gap between the tube bundle and the common shell, which can lead to distortion of the accuracy of the measurements.

The technical problem of the present invention is to ensure the applicability of the device for testing pressure sensors located directly in the conditions of their use on the measuring beams of the test site, and to increase the accuracy of measurements while reducing the risk of use.

The solution to the problem is achieved by the fact that in the known device for testing pressure sensors / 3 /, consisting of separate parallel installed tube modules for placing explosive charges, connected to each other and placed in a common shell, in accordance with the invention, each module is an initiating waveguide.

The necessity and sufficiency of the distinctive feature of the proposed technical solution can be explained as follows.

An initiating waveguide, for example, of the type described in the patent / 4 /, is a tubular sheath made of a flexible polymer material, for example, polyethylene, polyvinyl chloride, etc., with a thin layer of energy-saturated material applied to the inner surface of the sheath, which does not take up more than 10% of the channel cross-sectional area, and the rest of it forms a gas channel that is continuous in the longitudinal direction.

In initiating waveguides of modern designs, pentaerythritol tetranitrate (PETN) is mainly used as an energy-saturated material, but cyclotrimethylenetetrinitramine (Hexogen), cyclotetramethylenetetranitramine (Octogen) and similar substances with a high detonation ability, and in addition - aluminum powder, salts, smoky powder can also be used. -oxidants NaNO ₃ , NH ₄ NO ₃ , ammonium perchlorate, etc.

When such a waveguide is initiated, the reaction propagates through it in the form of a gas SW supported by an energy-saturated material at a speed of 1700 to 2700 m / s, and a corresponding high pressure at the front. Moreover, due to the fact that the weight of the energy-saturated material in the waveguide channel is small, - from 10 milligrams to 0.2 grams per 1 running meter, the waveguide is triggered without destroying the tubular shell and does not lead to the initiation of adjacent waveguides in contact with its surface, but also other means of initiation or explosive charges, which ensures the safety and reliability of the system both during loading and during their use. Experiments have established that with an outer diameter of the waveguide of about 5 mm, the diameter of the inner channel of the waveguide, which ensures the safety of the shell during operation, is about 3 mm.

Due to the fact that the channel diameter of a single waveguide is less than the linear dimensions of the membrane surface of the sensor, it is advisable to use an assembly of parallel-mounted waveguides of the same length in a common shell, with the arrangement of open ( output) ends of waveguides in one plane.

The number of waveguides over the exit area of the open ends is set so that the total area of the open ends is proportional to the area of the membrane element of the pressure sensor under test. The geometric arrangement of the open ends of the waveguides in the common plane must correspond to the shape of the membrane surface of the sensor.

This will make it possible, firstly, with the simultaneous initiation of the waveguides, to provide also the simultaneous exit of individual shock waves from the channels, and secondly, at a small distance from the plane of the exit ends, to obtain a combined shock wave with an almost flat front, which will increase the accuracy of the measurement results.

Simultaneous initiation of such an assembly of waveguides can be carried out, for example, using a specially designed wiring unit / 5 /.

The practice of using initiating waveguides in the mining industry has shown that the pressure of a shock wave in the channel of a waveguide with a weighed amount of the order of 20 ... 40 mg is sufficient at end contact to initiate detonator caps for industrial applications.

For example, in the case of using aluminum, oxidizing salts, etc. to equip a waveguide. active materials in its channel, the HC pressure can be estimated as follows:

P _max = P ₀ ⋅Т _Г ⋅n _к / T ₀ ⋅n _n

Where

T ₀ is the initial pressure at which the air suspension of material particles is in the waveguide channel, kPa;

T ₀ - initial temperature of the initial mixture, K;

T _G - adiabatic temperature of combustion of a stoichiometric mixture with air at a constant volume, K;

n _n - the number of moles of the original gas mixture;

n _to - the number of moles of gaseous combustion products.

Thus, due to the fact that the dimensions of the membrane elements of the shock wave pressure sensors, as noted above, are small, the device can be made with weight and size characteristics that allow it to be manually transported and placed directly on the test site near specific sensors on the measuring beams, allowing use of existing communication lines and recording equipment.

The invention is illustrated by the following graphic information:

FIG. 1 shows a schematic diagram of a device for testing pressure sensors as an example.

FIG. 2 to explain the principle of operation, a longitudinal section of the initiating waveguide is shown at the time of the passage of the gas shock wave.

FIG. 3 schematically shows the design of the wiring block of the initiating waveguides / 5 /.

FIG. 4 and 5 show possible schemes of installation and application of the device when testing pressure sensors directly on the measuring beams of the test site. To simplify the images, the wired communication lines of the pressure sensor with the recording equipment are conventionally not shown.

The device for testing pressure sensors consists of separate parallel-installed initiating waveguides 1 connected to each other and placed in a common shell 2. Open (output) ends of the waveguides are located in the same plane 3. The total area of the open ends of the initiating waveguides is proportional to the area of the membrane element of the pressure sensor under test, and the geometrical arrangement of the open ends of the waveguides in the common plane corresponds to its shape.

The initiating waveguide (Fig. 2) has a tubular shell 1 made of a flexible polymer material, with a thin layer of energy-saturated material deposited on the inner surface of the shell 4. When the waveguide is initiated, the reaction propagates through it in the form of a supersonic gas SW supported by the energy-saturated material 4 (its direction is shown arrow) and the corresponding high pressure at the front, and this process is carried out without destruction of shell 1.

The wiring unit / 5 / (Fig. 3) is designed for the simultaneous initiation of several waveguides by joint placement and fixing in a common housing of a detonator cap with a primary waveguide section and several wired waveguide sections and, thus, obtaining their connection of standard quality that does not change from external conditions and not depending on the qualifications of the blaster.

Divided sections of waveguides 1, equipped with protective caps 5 at the ends, are passed through the holes in the bottom and flange parts of the cylindrical glass 6 of the block with a 180 ° bend and subsequent tightening. A protective shield 7 is installed on the flange part of the glass 6. In the central opening of the glass 6, simultaneously with the divorced sections of the waveguides 1, a detonator cap 8 is placed, initiated, for example, by means of a separate waveguide 9.

In the examples shown in FIG. 4 and 5 of possible installation and application schemes, a device of parallel assembled waveguides 1, in a common shell 2, equipped with a set of initiation elements 6 ... 9, is oriented downward with the plane of open ends 3 by means of an installation support 10 and is fixed with the required small gap h relative to the membrane element under test pressure sensor 11, fixed in a massive glass 12 located in the ground on the measuring beam of the test site.

The difference in the diagrams in FIG. 4 and 5 is determined by the number of used initiating waveguides 1 supplied and enclosed in a common shell 2. In the case of a relatively small number of them, the scheme of FIG. 4, and in the case of relatively large, the diagram of FIG. 5, which ensures better stability and positioning of the mounting support 10. In principle, both the design of the mounting support and the arrangement and initiation of the device by examples in FIG. 4, 5 are not limited to.

Installation and operation of the device (Fig. 4, 5) is carried out as follows. The assembly of the required number of parallel waveguides of the same length 1 in a common shell 2 with the placement of open (output) ends in one plane 3 (Fig. 1), opposite ends of the waveguides equipped with protective caps 5, is connected to the body 6 of the wiring unit equipped with a protective screen 7 ( fig 3). A detonator cap 8 is installed in the central opening of the housing 6, which is pre-connected to the primary (supply) initiating waveguide 9.

With the help of the mounting support 10, the shell 2 with the waveguides 1 placed in it is oriented by the plane of the open ends of the waveguides 3 in parallel and with a predetermined small gap h from the membrane element of the pressure sensor under test And, which is installed in a massive glass 12 immersed in the ground on the measuring beam of the test site.

From any starting device, for example from a piercing capsule of the "Zhevelo" type, the gas shock wave (Fig. 2) along the primary (supply) section of the waveguide 9 reaches the detonator cap 8, which detonates (instantly or with a given deceleration interval) and, in turn initiates the ends of waveguides 1 located in the housing of the wiring block 6. Gas shock waves propagate along parallel waveguides up to the exit through their open ends 3 located in the same plane, thus forming an aggregate shock wave with an almost flat front, which acts on the membrane element of the pressure sensor under test 10, which is recorded by the recording equipment via the corresponding communication lines.

The above operations are naturally pre-performed with an exemplary pressure sensor.

Thus, the proposed design of the device enables its transportation and placement near specific sensors, i.e. applicability for testing pressure sensors located directly in the conditions of their use on the measuring beams of the test site, ensuring the possibility of using existing communication lines and recording equipment, increasing the accuracy of measurements, and simultaneously reducing the risk of use.

Sources of information taken into account when completing the application:

1) RF Patent No. 2217723, Device for loading objects with an air shock wave, G01M 9/00, G01M 7/08, 2003

2) Fedyakov E.M., Koltakov V.K., Bogdat'ev E.E. Measurement of variable pressures. - M .: Publishing house of standards, 1982, 216 p., Ill.

3) RF patent No. 2185623, Cellular explosion chamber, G01N 33/22, G01N 3/313, 2002

4) USSR Patent No. 373967 A1 Detonating cord, C06C 5/04, F42B 3/10, 1973

5) RF patent №2113426, Wiring unit for low-power detonating cords, С06С 5/06, 1998

Claims (1)

A device for calibrating dynamic pressure sensors, consisting of separate parallel installed tube modules for placing explosive charges, interconnected and placed in a common shell, characterized in that each module is an initiating waveguide of the same length with the arrangement of open output ends of the waveguides in the same plane , while the total area of the open ends of the initiating waveguides is proportional to the area of the membrane element of the pressure sensor being calibrated.

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