RU2354924C1 - Device for definition of characteristics of energetic materials destruction by jet cavitation - Google Patents

Abstract

FIELD: weapons.

SUBSTANCE: invention is related to the field of ammunition recycling. Device is arranged in the form of test cuvette filled with water with cavitating nozzle and sample of energetic material installed along normal line to nozzle axis. Sample is arranged in the form of rotary disc, rotation axis of which is displaced from axis of cavitating nozzle. In process of cavitating nozzle operation, circular trace appears on sample surface from jet traversing with preset circular speed. Trace radius is changed by means of regulation of value of circular disc rotation axis shift relative to axis of cavitating nozzle. Device that also includes closed circuit of power water, makes it possible to set power characteristics of cavitating jet, distance from nozzle to sample and traversing speed.

EFFECT: provision of possibility to define speed of mass loss, fractional composition of destruction products, geometric parametres of surface destruction, specific energy of destruction and specific water consumption for destruction.

2 cl, 2 dwg

Description

The invention relates to the field of disposal of military equipment and ammunition by means of stocking and disposal of components of artillery shells using hydrocavitational destruction of an array of energy material, and in particular, to methods and devices for determining the mechanical resistance of such materials to the eroding and power effects of a flooded cavitating jet. When developing installations for the removal or leaching of explosive substances (explosives) and mixed solid rocket fuels (STRT) from rockets and solid propellant rocket engines using jet cavitation with the required performance and economy, it is necessary to know the characteristics of the mechanical resistance of explosives and STRT to the effects of such a jet in order to reasonably choose modes of jet destruction by a cavitating jet.

For this, devices are needed to determine the mechanical resistance characteristics on small samples of energy materials (explosives and STRT) under conditions that should be close to those planned to be in washing units for real products equipped with energy materials.

Known devices for testing materials under the influence of a flooded cavitating jet of liquid in the form of a chamber with channels for supplying and discharging a medium, a nozzle installed in a channel for supplying a medium, and a holder for a cylindrical sample [1]. During operation, the distance between the nozzle exit and the sample surface is set, the working medium is supplied under pressure to the inlet pipe, and the surface of the sample is sprayed from the nozzle. During the test, the specified ratio between the hydrostatic pressure in the chamber and the pressure at the nozzle exit is maintained. After the test, the chamber is opened, a sample is taken and the erosion of the material is determined by weighing and measuring the erosion zone [2].

In addition to the chamber itself, autonomous test devices usually include a container for the working fluid, usually water, a high-pressure water supply system with a high-pressure pump, a system for draining water from the chamber after filtering back into the working fluid tank in a closed cycle, and measuring instruments.

The disadvantage of using known test devices is that the main test materials are usually metals, i.e. materials with high erosion resistance. Energy materials have low mechanical properties, and this feature allows them to carry out cavitation erosion destruction in ammunition shells and flushing explosive fragments from the shells safely with a fairly high performance. Known devices can determine the static characteristics of erosion, for example, local wear, while in the practical implementation of the leaching method, a cavitating jet is moved (traversed) over the surface at a sufficiently high peripheral speed. Thus, we need data on the erosion characteristics of materials under jet traverse conditions with the determination of the relationships between erosion performance, traverse speed, water supply pressure, nozzle diameter and the distance between the nozzle and the surface of the material. These conditions also include erosion by a flooded stream with a supply pressure of 10 ... 50 MPa at a pressure in the wash chamber of 0.1 ... 0.3 MPa.

Known laboratory mock devices for determining the erosion characteristics of inert materials that simulate real energy materials containing a system for supplying a working fluid (water) under high pressure, an open container with water as a washing chamber, a jet nozzle immersed in water on a tripod, and a plate of the material to be studied, fixed under the nozzle. Common disadvantages of such devices are low productivity, low accuracy of setting the distance between the nozzle exit and the sample surface, the inability to control the pressure in the washout chamber, the large volume of water in the container, which after testing is contaminated with abrasive destruction products [3].

The closest and accepted as a prototype technical solution is a device made in accordance with the standardized method of testing materials for resistance to jet cavitation erosion ASTM G134-95 (2001) [4].

The test device contains a test cuvette filled with water, in which a sample of the test material is placed and a cavitating nozzle, the axis of which is directed normal to the surface of the sample. The test cuvette is equipped with windows for visual observation of the process of sample erosion. The distance between the nozzle and the sample surface is established by moving along the axis of the sample holder. The sample has a diameter of 12 mm, and to replace it, remove the sample holder from the housing together with a sealed sleeve or separately from it and then perform the reverse operation of installing the holder with a new sample at the end. In addition to the cuvette, the device includes a closed loop of water circulation, including a high-pressure water supply system, a water drainage and purification system, and measuring instruments. Using a micrometer screw, establish the distance between the nozzle and the sample, fill the cuvette with water and turn on the supply of high pressure water for a given time. After that, water is removed from the cuvette, a sample is removed from the cuvette and measurements, weighing and other studies are performed.

A disadvantage of the known device is the inability to determine the characteristics of erosion under conditions of traversing the surface of the sample with a cavitating jet, in which erosion is affected not only by the pressure of the liquid at the exit of the nozzle and the distance between the nozzle and the sample, but also by the speed of movement (traverse) of the jet above the surface. It is known from experiments that this influence is nonlinear and has a maximum. It is advisable to remove explosives from shells at the maximum erosion rate to increase the productivity of the installation. When studying the erosion characteristics of metals, the test time reaches several hours to obtain sufficient for weighing the erosion entrainment of the test material. The slowness of the process allows the use of manual control when setting the test mode. When studying the erosion characteristics of energetic materials, the test time is several seconds to obtain a hole in a material with a depth of 10 ... 15 mm, which requires preliminary adjustment of the test mode and automation of the test, which is also necessary under safety conditions.

The technical problem solved by the present invention is to give the device the ability to measure the characteristics of erosive ablation of the material of the sample when traversing at various speeds of the surface of the sample with a cavitating jet with specified parameters, subject to the requirements of working with energy materials.

The solution of the technical problem is achieved by the fact that in the device for determining the characteristics of the destruction of energy materials by jet cavitation, made on the basis of a water filled test cuvette in the form of a body with parallel transparent windows interconnected by the location of the cavitating nozzle and the sample, with the sample holder displaced along the axis and means measuring conditions inside the housing and at the entrance to it, and connected through a hydraulic inlet and outlet to a closed loop of working water from the means and discharge water pressure and water flow regulation, water purification. In the test cuvette, the sample holder is made in the form of a rotary shaft, on the free end of which inside the body there is a supporting disk with a circular sample. The shaft axis has several steps of vertical displacement relative to the axis of the cavitating nozzle. The shaft is kinematically connected to measuring and fixing the distance from the cavitating nozzle to the surface of the sample and an external adjustable drive of rotational motion. In the lower part of the casing, a removable sump of fragments of energy material is made. Means of measuring and fixing the distance from the cavitating nozzle to the surface of the sample include a measuring ruler fastened to the body of the test cell with front and rear latches of the axial position of the disk positioner mounted on the shaft.

A comparative analysis of the essential features of the prototype and the proposed device shows that the distinguishing features of the proposal are those in accordance with which:

- the axis of the rotary shaft is installed with a vertical offset relative to the axis of the nozzle;

- the sample is made in the form of a rotating circle;

- the sample through a rotary shaft is connected to an adjustable drive of rotational motion;

- in the bottom part of the cuvette body, a removable settler of fragments of energetic material is made.

The essence of the present invention will be more clear from a consideration of the drawings, where:

- FIG. 1 is a general hydraulic diagram of a device for determining the destruction characteristics of energy materials by jet cavitation;

- FIG. 2 gives a schematic view of a test cell for determining the fracture characteristics of energetic materials under the influence of a single jet from a cavitating nozzle and describing an example embodiment of the device of the present invention.

As can be seen in figure 1, the closed loop of the working water contains a water tank 1 connected by a pipeline to a high pressure pump 2. Next, a damper 3 is installed downstream to smooth out pressure fluctuations, a filter 4 for cleaning impurities from the water, a pressure control throttle valve 5 water supply, an electric three-way valve 6 for directing high-pressure water either through a bypass line back to the water tank 1 or to the test cell 7. At the outlet of the test cell, a customizable anti-theft valve is installed water supply 8, the output of which is connected to the filter unit 9 and further with a drain supporting throttle valve 10. Instrumentation of a closed circuit includes a pressure sensor or pressure gauge at the inlet 11, a pressure sensor or manometer 12 in front of the cavitating nozzle, a pressure sensor or manometer 13 in the test cell , temperature sensor 14 in the test cell, measuring line 15. The closed loop of the working water also includes a water filling line for the test cell 7 with a manual valve 16, a manual valve 17 for draining water from the test hydrochloric cuvette and drainage valve 18 of the test cell during discharge.

Figure 2 schematically shows a test cuvette 7 of the device containing a rectangular casing of sheet material 19 with two circular windows 20 on the front and rear sides of the casing. The windows are closed with organic glass plates 21, which are pressed against the housing 19 by means of flanges 22 with fixing bolts (not shown). A threaded sleeve 23 is fixed on one of the sides for screwing a cavitating nozzle (not shown), the output section of which extends into the housing. The other side 24 of the housing is equipped with a hatch closed by a removable cover 25, bolted to the housing 19. The sealing of the cover 25 is carried out using gaskets (not shown). The axis of the manhole cover 25 and the threaded sleeve 23 are in the same plane parallel to the planes of the front and rear walls of the housing 19. The manhole cover 25 contains a vertical row of bushings 26 or threaded sockets for bushings of passage into the housing 19 of the shaft 27 of the rotation of the carrier disk 28 with a sample mounted on it 29 energy material. A disk positioner 30 is mounted on the outer part of the rotary shaft 27, which enters the gap between the front 31 and rear 32 latches on the measuring line 15. The free end of the shaft 27 is connected via an detachable sleeve 33 to an adjustable rotary drive 34, for example, performing 1 shaft revolution 5 ... 100 s. The axis of the upper sleeve 26 is shifted downward in a vertical plane from the axis of the threaded sleeve 23 by 10 ... 15 mm.

The test cuvette is equipped with a settling tank 35. It is made in the form of a pipe 36 in the bottom of the casing of the test cuvette 19 and is closed by a threaded cover 37, into which a glass 38 for collecting fragments is installed. After draining the water from the test cuvette through the valve 17, the threaded cover 37 is opened and the beaker 38 is removed with a mass of destroyed energy material. The bottom of the cell for better collection of fragments is made of inclined sections converging to the nozzle.

During operation, samples of 29 energetic materials are prepared and secured to bearing disks 28 with glue or clamping devices. The thickness of the samples is taken depending on the mechanical characteristics of the energy materials from 5 to 30 mm from the condition that the expected depth of the cut groove does not exceed the thickness of the sample. The diameter of the samples is taken depending on the traverse speed and the required representative length of the slotted groove. In the case of studies of energy materials with low solubility of the components of the energy material in water, samples of the energy material are used according to the size of the carrier disk 28 with consecutive tests when traversing at different radii without changing the sample.

When testing with samples of energetic materials containing components with high solubility in water, disposable samples of minimum diameter are used to provide the required representative length of the groove to be cut.

Representative length is the circumference of the wake of a cavitating jet along the circumference, minimum and sufficient to determine all the erosion characteristics of the energy material. For samples with increased erosion resistance and low erosion of the material, the representative length is taken longer than for materials with low erosion resistance, to obtain a sample of eroded material, the weighing of which will give mass within the permissible error.

Open the side hatch by removing the cover 25. Pass the rotary shaft 27 through the sleeve 26 with O-rings and fix the carrier disk 28 with the sample 29 at its end. Close the side hatch with a cover 25. Connect the shaft 27 and the rotational drive 34 with the help of the coupling 33, install drive shaft to zero position. The rotary shaft 27 is shifted along the axis to a predetermined position along x / d, where x is the specified linear distance along the axis from the nozzle exit section to the outer surface of the sample of energetic material 29 with thickness h, d is the minimum nozzle diameter. If the outer surface of the sample is uneven, then the average value for measuring roughness using a profilometer is taken as the thickness of the sample. The value x = x ₀ -h is taken as the value x, and the distance x ₀ is determined by the position of positioner 30 on the measuring line 15. The position of the positioner 30 x ₀ = 0 on measuring line 15 will be when the carrier disc 28 is in the output section of the cavitating nozzle fixed in the threaded sleeve 23. The shaft 27 is fixed at a predetermined position along the longitudinal movement using the front 31 and rear 32 latches on the measuring ruler, between which the disk positioner 30 of the rotary shaft is placed.

To configure the test cell to obtain a larger radius of the cut groove, the shaft 27 is passed through the sleeve 26 located below.

They include a closed loop of working water. Using the pump and throttle valve 5 set the desired high supply pressure with a given flow rate for operation through the bypass circuit. Fill the test cuvette with water taken from the circuit. Set the backpressure valve 8 at the outlet of the test cell to a predetermined pressure value in the test cell. They include lighting devices for visual observation and video shooting through windows. Three-way valve 6 is switched to supply high-pressure water through a cavitating nozzle. When a jet arises at the inlet from the cavitating nozzle in the threaded sleeve 23, an adjustable drive 34 for the rotational movement of the carrier disk 28 with a sample of energy material 29 fixed on it is turned on. The arrival of water through the nozzle into the test cell causes an increase in pressure in it, the excess pressure overcomes the compression force of the spring of the backpressure valve 8, and water is discharged through filters 9 back into the water tank 1.

Heavy and large fragments of destroyed material under the influence of gravity sink into the sump. After each test, they are removed from the sump for control weighing, morphology analysis and fracture mechanism. Tests on hydrocavitation leaching of hexogenous explosives A-IX-2 from shells showed that the granulometric composition of the destruction products depends on the working pressure, and with increasing pressure, the fraction of large fractions, such as 3 ... 10 mm and more than 10 mm, increases.

After reaching a representative traverse length, turn off the high-pressure water supply (switch to bypass operation) and rotate the shaft 27 and reconfigure the operating mode, for example, reduce x / d by changing the position x ₀ along the longitudinal movement. After fixing the shaft 27 in a new position, turn on the high-pressure water supply through the cavitating nozzle and, after the jet appears at the nozzle exit, turn on an adjustable drive for the rotational movement of the carrier disk with a sample of energetic material, if it has enough space on the circumference of the fracture of the material to obtain another representative traverse length .

In automatic operation, at the same time, the three-way valve 7 is switched to work in the test cuvette and the adjustable drive 34 is started for a given operating time.

If the energy material does not contain components with high solubility in water, then in order to further use the material of the test sample, disconnect the test chamber from the closed loop, drain water from it, remove the manhole cover, move shaft 27 to another sleeve 26, and close the test cell again, then put the shaft 27 in the zero position in rotation. Fill the test cell with water and continue testing.

Initial processing of the results includes:

- calculation of the initial data (power of the cavitating jet N = P ₀ Q, cavitation parameter

, x/d),

, x / d),

where P ₀ - water supply pressure cavitating nozzle, Q - volumetric flow rate through the cavitating nozzle; P _K is the pressure in the test cell; ρ is the density of water; V is the flow rate from the cavitating nozzle; d is the minimum diameter of the flow path of the cavitating nozzle;

- determining the length of the arc groove on the sample and calculating the traverse speed using the test time;

- determination of the ablation mass per unit time (by the mass of sludge);

- determination of the surface area of erosion destruction (measurement);

- determination of the surface area of cracking (measurement);

- determination of the depth of destruction (measurement);

- determination of the fractional composition of ablation (sieving sludge mass).

The generalized output data on destructible energy material are the energy of cavitation destruction in MJ / kg, the specific consumption of water kg / kg, the dependence of the energy of cavitation destruction on the traverse speed.

The use of a device for preliminary determination of the characteristics of destructible energy materials will allow for a given installation performance to determine design data on energy consumption, hydraulic characteristics of a closed water circuit, the number of cavitating nozzles. As a result, the time of designing and manufacturing the installation will be reduced, as well as the time to refine the characteristics of the installation to design parameters will be reduced.

In the transition to the destruction of new energy materials, the use of basic data on these materials will reduce the period of adaptation to a new material, since its behavior under the influence of a cavitating jet is already known.

The device is preferably placed in a special box with a lightweight roof and armored doors, equipped with an alarm and locking lock. Outside the box, the control panel displays the gauges for initial pressure, pressure in the test cuvette, a high-pressure adjustment throttle valve handwheel, a discharge pressure throttle valve flywheel, a three-way valve toggle switch, a pump batch switch, an adjustable rotary drive toggle switch, camcorder triggers and a monitor.

As samples can be used sections of shells obtained by cutting using saws or abrasive-jet cutting.

Information sources

1. SU 1620913, 1991 (Glazkov N.M. et al.).

2. SU 1652883, 1991 (Rodionov V.P., V.A. Maslov, A.Yu. Schulte).

3. Yanaida K., Nakaya M. et al. Waterjet Cavitation Performance of Submerged Horn Shaped Nozzles // Proceedings of the 3-rd US Water Jet Conference, May 1985, p. 266-280.

4. Soyama H., Kumano H. The Fundamental Threshold Level - a New Parameter for Predicting Cavitation Erosion Resistance // Journal of Testing and Evaluation, 2002, Vol.30, No. 5, p. 421-431.

Claims (2)

1. A device for determining the characteristics of the destruction of energy materials by jet cavitation, made in the form of a water-filled test cell containing a case with parallel transparent windows interconnected by the location of the cavitating nozzle and the sample, with a sample holder displaced along the axis and means of measuring conditions inside the case and at the entrance into it, and connected through a hydraulic inlet and outlet to a closed loop of working water with means of pumping water, regulating the pressure and flow rate of water, och water drain, characterized in that the sample holder of the test cuvette is made in the form of a rotary shaft, on the free end of which a supporting disk for the sample is fixed in the form of a circle, the axis of the rotary shaft being made with vertical displacement steps relative to the axis of the cavitating nozzle, the rotary shaft kinematically connected to measuring and fixing the distance from the cavitating nozzle to the surface of the sample and an external adjustable drive of rotational movement, and a removable is made in the lower part of the housing sedimentation tank for collecting fragments of energy material. 2. The device according to claim 1, characterized in that the means of measuring and fixing the distance from the cavitating nozzle to the surface of the sample are made in the form of a measuring ruler fastened to the body of the test cell with front and rear latches of the disk positioner mounted on the shaft.

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