RU2819564C1 - Dynamic pressure sensor testing device - Google Patents

Abstract

FIELD: control and measuring equipment.

SUBSTANCE: invention relates to instrumentation, namely to devices for evaluation of efficiency and testing of high pulse pressure sensors. Device for testing dynamic pressure sensors is made with a housing in the form of a shock tube containing an expanding measuring cavity having a free outlet into the atmosphere, communicating with its narrow part through a hollow channel a high-pressure source – shock wave generator in the form of a chamber with an explosive charge placed therein, and sockets for installation of pressure sensors of shock wave, located on walls of cavity at selected distance from specified charge. Measuring cavity is made in the form of a straight quadrangular prism with bases in the form of isosceles trapezoids, having a free outlet into the atmosphere from the side of large bases of the trapezoids. Shock wave generator used is an initiating waveguide installed in a charging chamber placed along the horizontal axis of symmetry of the measuring cavity on the side of its smaller face. Cavity of the charging chamber is cylindrical with a diameter equal to the diameter of the waveguide, and is connected to the measuring cavity by a channel of cylindrical section with a diameter equal to the diameter of the waveguide channel. Sockets for installation of sensors are made in the form of holes equipped with the corresponding fixation elements, and are placed along the axes of the trapezium-bases of the prism opposite each other, the upper one – for the reference sensor, the lower one – for the tested sensor.

EFFECT: providing the possibility of testing sensors without their dismantling from test sites, increasing the level of safety of the measurement process.

1 cl, 2 dwg

Description

The invention relates to instrumentation equipment, specifically to devices for assessing the performance and testing without dismantling high pulse pressure sensors from test sites, and can be used for metrological support when conducting field tests of various explosive materials and products based on them - prototypes and production samples artillery and engineering ammunition, as well as missile warheads.

A device for calibrating high-pressure sensors /1/ is known, made in the form of a shock tube of constant quadrangular cross-section, containing, respectively, high and low pressure chambers filled with working gas and separated by a burst diaphragm. The low-pressure chamber, having no outlet to the atmosphere, is limited by an end wall made of two plates forming a concave dihedral angle. The socket (hole) for placing the reference sensor is located on the wall of the low-pressure chamber, and for the one being calibrated - on the dihedral angle plate. It is proposed to calibrate the sensor under test according to a theoretical dependence, taking into account the pressure value recorded by the reference sensor, as well as the geometric characteristics of the end wall of the chamber and the locations of the sensors.

The proposed design, as well as its method of measuring the pressure of the generated shock wave with a calibrated sensor, have a number of disadvantages:

1) The relative complexity of design and operation, determined by the need for a high-pressure chamber and a burst diaphragm, as well as the need for a high-pressure source.

2) Due to design features, it is necessary to remove the controlled sensor from the measuring beam of the test site, and hence the possibility of using the device only in stationary laboratory conditions.

3) Loading the reference and test sensors with shock waves of varying intensities, which requires additional mathematical calculations that do not take into account diffraction and interference effects determined by the relative position of the sensors and the design of the end wall of the low-pressure chamber.

The closest to the proposed invention in terms of technical essence and the achieved result is a device /2/, structurally suitable for testing shock wave pressure sensors, made in the form of a shock tube containing an expanding cavity having a free exit to the atmosphere, communicating with its narrow part through hollow channels source high pressure - a shock wave generator in the form of a chamber with an explosive charge placed in it, and a socket for installing a shock wave pressure sensor, located on the wall of the cavity at a selected distance from the specified charge.

However, this device design is also not without certain disadvantages:

1) The conical design of the device cavity increases its dimensions and also complicates the possibility of docking with the pressure sensor under test, located on the measuring beam of the test site.

2) The design does not provide for the placement of nests on the walls of the cavity for simultaneous placement of the reference and tested sensors.

3) The use of a high-explosive charge as a high-pressure source - a shock wave generator - carries an increased risk of using the device.

The technical objective of the proposed invention is to eliminate the above-mentioned disadvantages of the prototype device, first of all, to ensure the possibility of testing high pulse pressure sensors without dismantling them from the test sites, while simultaneously increasing the level of safety of the measurement process.

The solution to the problem is achieved by the fact that in the known device for testing dynamic pressure sensors, made with a housing in the form of a shock tube containing an expanding measuring cavity having a free exit to the atmosphere, communicating with its narrow part through a hollow channel, a high-pressure source - a shock wave generator in in the form of a chamber with an explosive charge placed in it, and sockets for installing shock wave pressure sensors, located on the walls of the cavity at a selected distance from the specified charge, in accordance with the invention, the measuring cavity is made in the form of a straight 4-gonal prism with bases in the form of isosceles trapezium, which has free access to the atmosphere from the side of the large bases of the trapezoids, an initiating waveguide is used as a shock wave generator, installed in a charging chamber located along the horizontal axis of symmetry of the measuring cavity from the side of its smaller edge, the cavity of the charging chamber is made cylindrical with a diameter equal to the diameter of the waveguide , and connected to the measuring cavity by a cylindrical cross-section channel with a diameter equal to the diameter of the waveguide channel, and the sockets for installing sensors are made in the form of holes equipped with appropriate fixation elements, and are placed along the axes of the trapezoidal bases of the prism opposite each other, the upper one is for the reference one, the lower one is for test taker.

The presented main distinctive features of the proposed device provide a solution to the problem as follows:

- making the measuring cavity in the form of a straight 4-gonal prism with bases in the form of isosceles trapezoids, which has free access to the atmosphere from the large bases of the trapezoids, allows you to significantly reduce the overall dimensions of the device, and due to the presence of flat surfaces, ensure its fairly simple pairing with the sensor under test , without dismantling the latter from the measuring beam of the test site;

- the use of an initiating waveguide as a shock wave generator, containing a small amount of explosive (milligrams per meter), and ensuring the transmission of an initiating impulse - a shock wave - through its channel without destroying the shell, significantly reduces the danger of using the device;

- the design of the charging chamber cavity is cylindrical with a diameter equal to the diameter of the waveguide, and its connection to the measuring cavity by a cylindrical cross-section channel with a diameter equal to the diameter of the waveguide channel ensures (along with a structurally possible additional retainer) the elimination of “leakage” of products of explosive transformation of the waveguide charge and reliable transmission of the shock wave into measuring cavity;

- making sockets for installing sensors in the form of holes, with corresponding fixing elements, and their placement along the axes of the trapezoidal prism bases opposite each other, the upper one for the reference, the lower one for the test one, ensures both ease of “interfacing” of the measuring cavity with the sensors, and equal loading of them by the shock wave.

By way of example, the invention is illustrated by graphical information:

In fig. Figure 1 schematically simplifies the main design elements of the device (without elements for fixing the sensors and the initiating waveguide).

In fig. Figure 2 shows a longitudinal section of the device installed on the measuring beam of the test site before testing an individual sensor.

To simplify the images, the recording equipment is not shown in the illustrations.

Numerical positions in the accompanying illustrations indicate:

1 - device body in the form of a shock tube;

2 - expanding cavity;

3 - channel connecting the charging chamber to the cavity;

4 - charging chamber;

5 - initiating waveguide;

6 - socket for installing a reference pressure sensor;

7 - socket for docking with the pressure sensor being tested;

8 - threaded bushing;

9 - ring made of elastic material;

10 - reference pressure sensor;

11 - threaded bushing;

12 - union nut;

13 - sleeve made of elastic material;

14 - pressure ring;

15 - pressure sensor under test;

16 - mounting cup of the sensor under test;

17 - soil of the test site;

18, 19 - cable lines to recording equipment;

20 - initiating device.

The device for testing dynamic pressure sensors (Fig. 1) is made with a housing in the form of a shock tube 1 containing an expanding measuring cavity 2 in the form of a straight 4-gonal prism with bases in the form of isosceles trapezoids, which has free access to the atmosphere. Through channel 3, located in the narrow part of the cavity, the latter communicates with the shock wave generator in the form of chamber 4 with an explosive charge placed in it - initiating waveguide 5. The diameter of channel 3 is equal to the internal diameter of the waveguide channel.

The sockets for installing the sensors are made in the form of holes equipped with corresponding fixing elements (Fig. 2), and are placed along the axes of the trapezoidal bases of the prism opposite each other, the upper 6 for the reference, the lower 7 for the test.

The device operates as follows (Fig. 2).

When testing pressure sensors without dismantling them from the test sites, a reference pressure sensor 10 is screwed into slot 6 of the body of the shock tube 1 using a torque wrench, which is connected to the recording equipment using cable line 19.

One end of a section of waveguide 5 is inserted into the cavity of the charging chamber 4 until its channel mates with channel 3, and is fixed in it by means of a threaded bushing 8 and a ring made of elastic material (rubber) 9.

The other end of the waveguide 5 is mounted on the spark gap needle of the initiating device 20 immediately before testing.

Socket 7 of the body of device 1 with a threaded sleeve 11 installed in it mates with the body of the mounting sleeve 16, located in the ground of the test site 17, with the pressure sensor 15 under test placed in it. The device is fixed to the mounting sleeve by means of a union nut 12, a sleeve made of elastic material (rubber) 13 and pressure ring 14. The sensor under test 15 is connected to the recording equipment by cable line 18.

Sockets 6 and 7 and the accompanying structures of the fixing elements of the reference 10 and tested 15 sensors ensure the location of their sensitive elements in the planes of parallel faces of the internal cavity 2 at the same distance from the outlet hole of channel 3 into it (in fact, a continuation of the outlet hole of the waveguide channel 5).

When the initiation device 20 is activated, an electric discharge occurs in the channel of the waveguide 5, exciting the explosive transformation of the pyrotechnic composition with the formation of highly compressed and heated gaseous explosion products. The energy released during the explosive transformation goes to the formation of a shock wave propagating along the waveguide channel 5 with constant amplitude and speed of the order of 1900 m/s.

Upon completion of the explosive transformation in waveguide 5, the shock wave propagates through channel 3 inside the expanding internal cavity 2. In this case, as it moves away from the outlet of the channel (the end of waveguide 5), its amplitude decreases due to irreversible losses in the shock front and the divergence of the gas flow behind it . Thus, in the experimental sample of the device, the location of the mounting sockets 6 and 7 for the reference and tested sensors 10 and 15 was chosen from the condition of ensuring a maximum excess pressure at the shock wave front in their action zone equal to 0.1 MPa.

Due to the symmetry of the internal cavity of device 2, the air medium moving in the shock wave exerts simultaneous and equally time-varying pressure on the sensitive elements of both sensors 10 and 15, electrical signals from which are transmitted via cable lines 18, 19 and recorded by recording means. The recorded signals are compared with each other, and on the basis of this comparison the sensitivity coefficient of the tested pressure sensor 15 is determined, conclusions are drawn about its serviceability or metrological failure.

When reproducing the shock wave effect on the sensors, sections of the waveguide of the domestic non-electric initiation system “Korshun-M” (TU 7287-002-79853272-2013) and the IV-2AM waveguide initiation device can be used.

For testing using the comparison method, a pressure sensor of the PCB Piezotronics ICP 102B18 type can be used as a reference, and for measuring the output signals from the sensors, recording means of test sites, in particular, cable lines, measuring and computing complexes of the type MIC-553, MIC-503, oscilloscope portable digital type R&S RTH1002 or digital mixed signal type Tektronix MSO64B 6-BW-4000, as well as other recording equipment to support the test conditions.

Thus, the proposed device design has small dimensions and weight, ensures testing of high pulse pressure sensors located in protective housings without dismantling them from the test sites, while simultaneously increasing the level of safety of the measurement process.

Sources of information taken into account when describing the application:

1) A.s. USSR No. 1520371, G01L 27/00, Device for calibrating high pressure sensors, 1989.

2) US Patent US 3184955A Explosive driven conical shock tube, F42B 3/22, 1965 - prototype.

Claims (1)

A device for testing dynamic pressure sensors, made with a housing in the form of a shock tube containing an expanding measuring cavity having a free exit to the atmosphere, communicating with its narrow part through a hollow channel, a high-pressure source - a shock wave generator in the form of a chamber with an explosive charge placed in it substances and sockets for installing shock wave pressure sensors, located on the walls of the cavity at a selected distance from the specified charge, characterized in that the measuring cavity is made in the form of a straight 4-gonal prism with bases in the form of isosceles trapezoids, having free access to the atmosphere from the large bases of trapezoids, an initiating waveguide is used as a shock wave generator, installed in a charging chamber located along the horizontal axis of symmetry of the measuring cavity on the side of its smaller edge, the cavity of the charging chamber is made cylindrical with a diameter equal to the diameter of the waveguide, and is connected to the measuring cavity by a channel of cylindrical cross-section with a diameter equal to the diameter of the waveguide channel, and the sockets for installing sensors are made in the form of holes equipped with appropriate fixation elements, and are placed along the axes of the trapezoidal bases of the prism opposite each other, the upper one is for the reference sensor, the lower one is for the sensor under test.