RU2626033C1 - Installation for determination of solid fuel burning velocity - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: installation for determining solid fuel burning velocity contains a gas pressure source, a combustion chamber, a pressure sensor, a bolt with a reinforced fuel sample, a fuse and a hermetic outlet. The combustion chamber is made of several identical chambers radially installed in the horizontal plane. In each of the chambers there is a control sample in the form of a cylindrical channelless stick, equipped with afterburning channel stick on the side of the igniting torch and put onto the channelless srick with an interference of 1…2 mm by elastic tube connecting the stick with the measuring insert. The length of the elastic tube exceeds the length of the stick by an amount equal to 0.7…1.4 of the inside diameter of the elastic tube. In the central part of the insert there is a light guide and a photosensor. In the body cavity water is placed, filling about 90% of this cavity, and a replaceable nozzle bush with a delivery outlet, which diameter is selected for each type of fuel, is installed.

EFFECT: invention allows to perform direct measurement of the solid fuel burning velocity at high pressure, and exclude the use of an external source of gas pressure.

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Description

The invention relates to measuring equipment, namely, devices designed to determine the burning rate of solid fuel at high pressures: from twenty to several hundred megapascals.

The relevance of the task due to the need to measure the burning rate of solid fuels (TT, hereinafter referred to as “samples”) used for products for various purposes:

- oil deep wells;

- receiver systems for various purposes;

- solid fuel devices for deep-sea systems;

- powder pressure accumulators,

operating at high pressures.

A device for determining the burning rate of gunpowder at high variable pressure: a manometric vessel (chamber), described in the book M.E. Serebryakova - Internal ballistics. M .: Oborongiz, 1949, pp. 43-46, 105-113.

The manometer vessel is a thick-walled steel casing with two threaded holes, muffled by the ignition and measuring bushings with O-rings. A pressure sensor is installed in the measuring sleeve. To create a given pressure, a small-sized fine-arched (about 1 ... 3 mm) powder cylindrical sample with a channel and an ignitor are placed in the cavity of the vessel.

For gunpowder with a linear law, where the burning rate at high pressure is equal to the product of the conditional unit speed and pressure, with the integrated processing method, the unit speed is found in the ratio of the burning set of the sample to the pressure pulse obtained from the processing of the measured pressure-time relationship.

The disadvantages of this method are:

- not a direct measurement of the burning rate, but the calculation of the unit velocity (for the linear form of the law of combustion of the form U = U ₁ ⋅ P, where U ₁ is the unit speed, P is the pressure) under certain assumptions;

- variable (increasing to a given level) high pressure;

- a relatively small value of the burning arch.

These shortcomings lead to a significant (about 8%) error in determining the burning rate.

The known method described in the article by Aksenov B.C., Leonova G.N., Lyubimova A.V., Parfenova A.K., Chikova V.M. The differential method of measuring the burning rate of condensed systems in a manometric chamber - Sat. The physics of combustion and explosion. NSB ,. "Science" SB, 1979, 15, No. 2, p. 103-107 and device Kostochko A.A., Aleksandrova V.N., Dinovetsky B.D., Kostochko A.V. RF patent No. 2236003 published on 09/10/2004

This method of determining the burning rate is based on the experimental recording of changes in pressure and its derivative in the combustion process.

The pressure signal amplifier is made on the basis of an integrated circuit according to the scale amplifier circuit. It has two outputs, one of which is used to record pressure, and the other to supply a signal to a differentiating amplifier.

Consistent use of characteristic ratios for a certain shape of the powder element allows using the known value of the burnt arch to a given point in time to determine the pressure in the chamber and calculate the burning rate at this pressure. The proposed manometric vessel using the differential method of calculating the burning rate allowed to reduce the error to 4%, which is positive compared to the previous analogue.

However, a serious drawback of this analogue is the difficulty of its application in industrial production while maintaining the main disadvantages of the pressure chamber with an integrated method of processing measurements.

The known design of the installation for determining the burning rate of solid fuel according to the patent of the Russian Federation for invention No. 2406864 dated 12/27/2010, authors Milekhin Yu.M., Kondakov MA, Gusev SA, Kononov VB, Zavyalov AT ., Kalashnikov V.I. The installation contains an external source of gas pressure, a combustion chamber, a pressure sensor and a shutter, on which solid fuel samples with an ignition conductor and a gas outlet for this conductor are installed. The TT specimen is made integral and includes an armored cylindrical ignition specimen with an ignition conductor mounted on one of its end faces and one or more consecutive control armored specimens docked to its opposite end. At the joints of the samples and at the end of the last control sample, samples of smoky gunpowder or solid fuel with a high level of gas formation are placed. The joints are covered with a heat-insulating tape. The length of the firing sample TT exceeds its diameter. An intracameral gas pressure source in the form of an unarmored TT sample is attached to the end face of the ignition sample on the side of the ignition conductor, intended for additional boost of the combustion chamber. It cannot be used for a significant increase in pressure (tens of times higher than achieved) and the burning time due to insufficient gas inlet and burning arch not exceeding the burning set of the ignition sample.

A significant increase in pressure level (tens to hundreds of megapascals) in such an installation is associated with the development - manufacture (as well as operation) of a unique external gas pressure source in the form of a complex ultra-high pressure compressor.

Consistently installed solid fuel control samples are burned alternately at relatively low pressures, the burning time of each is measured by pressure surges on the pressure-time waveform. As signaling devices for determining the moments of passage of the flame front in the above patent, add dusting gun powder between the control samples.

The installation of the above patent is taken as a prototype.

The disadvantages of the installation of the prototype include the following:

- in conditions of a significant unchanged free volume of the installation and a relatively small gas intake during the sequential combustion of each control sample, it is very difficult to create increased pressure without using an external source of gas pressure;

- due to the smoothed nature of the pressure surge during the operation of the powder alarm, an increased error in measuring the time and burning rate appears;

- since compressed air is injected into the combustion chamber by the compressor and nitrogen is supplied from the cylinder, air oxygen, being in the combustion zone and participating in the combustion of the fuel control sample, leads to a distortion of the result of the measured burning rate;

- increased danger in the case of using an external source of gas pressure in an installation similar to the prototype, when servicing cylinders, compressors and high-pressure lines.

Therefore, the measurement of the burning rate at pressures from twenty to several hundred megapascals in this installation seems to be very problematic.

The technical problem to which the invention is directed is to create a simpler, more convenient to maintain, economical installation that allows direct measurement of the fuel burning rate at elevated (from 20 to 200 MPa) pressures and a significant increase in productivity, reliability, and test safety.

The technical result is achieved by the fact that in the installation for determining the burning rate of solid fuel containing a gas pressure source, a combustion chamber, a pressure sensor and a shutter, on which a sample with a fuse and a gas outlet are mounted, the combustion chamber is made of several identical chambers radially mounted in the horizontal plane with placed in each control sample in the form of a cylindrical channelless checker, equipped on the fuse side with afterburner channel checkers and worn on a channelless checker with an interference fit of 1 2mm elastic tube connecting to the measuring insert checker. The length of this tube exceeds the length of the checker by the amount of attachment to the insert L _mount. = (0.7 ... 1.4) d, where L is _fastened . - the additional length of the tube for attaching the sample to the measuring insert, d is the inner diameter of the elastic tube of various sizes, and in the central part of the insert there is a light guide and a photosensor. Water is filled into the body cavity, filling about 90% of this cavity; in the lower part of the body there is a replaceable nozzle sleeve with a flow hole, the diameter of which is selected for each type of fuel.

The invention is illustrated by figures 1, 2 and 3.

In FIG. 1 schematically shows an apparatus for determining the burning rate of solid fuel at high pressure.

In FIG. 2 is a top view of the installation.

In FIG. Figure 3 shows a typical oscillogram of testing a sample of a CT assembled from four control and afterburners in an installation.

1 - igniter; 2 - ignition insert; 3 - shutter; 4 - afterburners; 5 - control sample; 6 - combustion chamber; 7 - an elastic tube; 8 - powder alarm; 9 - light guide; 10 - measuring insert; 11 - photosensor; 12 - clamp; 13 - case; 14 - water; 15 - nozzle sleeve; 16 - pressure sensor; 17 - kick plug.

In FIG. 3 - the following notation: P is the pressure curve record, τ is the burning time of the samples; a, b, c, d - light pulses at the end of combustion of each sample.

Installation for determining the burning rate of solid fuel at high pressure (ATC) consists of a housing 13 and several combustion chambers 6.

Above, in the neck of the housing 13, an ignition sleeve 2 and an igniter 1 are fixed.

Opposite the igniter 1, identical combustion chambers 6 are placed in a horizontal plane, each of which contains a control sample 5 in the form of a cylindrical channelless checker assembled with an elastic compression tube 7 with an interference fit of 1 ... 2 mm. The length of the tube is made larger by the amount of fastening L _fastened. = (0.7 ... 1.4) ⋅d, where L was _fastened. - the additional length of the tube for attaching the sample 5 to the measuring insert 10, d is the inner diameter of the tube. Channel unarmoured afterburners 4 are docked to the ignition end of each control sample, the control sample is attached with the other end with an elastic tube 7 to the measuring insert 10, in the central part of which there is a conical light guide 9 and a photo sensor 11. Between the end end of each sample and the inner end of each measuring insert detector 8 spherical fine powder.

Water 14 is placed in the cavity of the housing 13, filling about 90% of this cavity.

In the lower part of the housing 13 there is a pressure sensor 16, a nozzle sleeve 15 with a replaceable insert and a knockout plug 17.

Before the fire tests to measure the burning rate of a solid fuel sample at a given high pressure, a pressure sensor 16 is installed in the lower opening of the housing 13, a nozzle sleeve 15 of a given size, selected for each type of test fuel, is attached. Knockout plug 17 is inserted into the nozzle sleeve.

The body cavity is filled with water 14 to a level 1 ... 1.5 cm below the edge of the holes connecting the internal cavity with the attached combustion chambers 6. This is about 90% of the volume of the cavity.

Each control channelless checker 5 is assembled with an interference fit of 1 ... 2 mm with an elastic tube 7 into which a powder _{detector 8 is placed. At} this end, the elastic tube due to the additional length L of the _fastener. attached to measuring insert 10.

Fastening of the prepared assemblies with control samples in the combustion chambers is done by clamps 12, into which photosensors 11 are inserted.

An ignition insert 2 with an igniter 1 and a shutter 3 connected to it is installed in the neck of the housing.

Installation works as follows. When power is supplied through the ignition insert 2 using the igniter 1, ignition of the unarmored afterburners 4 (with a relatively small burning dome) and control channelless samples 5 located in the combustion chambers 6 are ignited. All fuel samples are ignited simultaneously due to the gas connection between the combustion chambers.

The constant high pressure in the installation of the proposed design is ensured by the use of water (instead of high-temperature products of fuel combustion, containing a certain amount of condensed particles in the form, for example, metal oxides and hydrochloric acid for certain types of fuels) during the measurement of the burning rate, as a result of which the nozzle sleeve consumes aperture their sizes.

When the combustion front reaches the powder detector 8, the detector rapidly (due to the small burning arch and high burning speed at high pressure) burns out, and the light pulse through the optical fiber 9 of the measuring insert enters the photosensor 11 and the recording equipment in the form of an autonomous clear peak for each control sample .

The burning time of each control sample, τ _k, is found as τ _k = τ _kon- τ _nach , where τ _nach is the beginning of combustion at the time of reaching 0.75⋅P _cp (P _cf is the average _integral pressure), τ _kon is the end of combustion, is determined by the time of exposure of the photosensor.

When conducting fire tests, the intra-chamber pressure is monitored on a computer monitor. After the combustion of control samples and the expiration of combustion products from the installation, a decrease in pressure to atmospheric is observed.

Constructive solutions of the proposed installation can eliminate the drawbacks noted for analogues and prototype.

Using the proposed ATC, a direct measurement of the burning rate of a wide range of solid fuels burning under various laws at high constant pressure is provided.

The use of several identical channelless control samples (with afterburner channel blocks) located radially in the same plane allows you to create high pressure (from 20 to 200 MPa or more) without using an external gas pressure source.

The indicated design solutions along with the measurement of the burning time with the help of photosensors allow measuring the burning rate with a given error (no more than 2%).

At the same time, the danger arising from the maintenance of high-pressure devices is reduced as a result of eliminating the use of an external gas pressure source.

Constant pressure during increasing gas supply is maintained by increasing the volume of the cavity when water flows out of it through a replaceable nozzle sleeve with a flow hole, the diameter of which is selected for each type of fuel. It is the use of water that allows you to save the diameter of the nozzle bore during testing.

This ensures reliable measurement of the burning rate of control TT samples at high constant pressure, while reducing the risk of disassembling the ATC due to the lack of chamber pressure after the test and in connection with the removal of an external gas pressure source.

Tests of the proposed installation in a pilot semi-factory production of JSC "NIIPM" confirmed its effectiveness.

Claims (1)

Installation for determining the burning rate of solid fuel (TT), containing a gas pressure source, a combustion chamber, a pressure sensor and a shutter, on which a TT sample with a fuse and a pressure relief are mounted, characterized in that the combustion chamber is made of several identical chambers radially mounted in the horizontal plane with a control cylinder placed in each control sample in the form of a cylindrical channelless checker equipped with afterburner channel checkers and worn on a channelless checker with an interference fit of 1 ... 2 mm elastic deckhouse connecting checker with the measuring insert, wherein the tube is longer than a length of the magnitude checkers fastening to insert L _mountable. = (0.7 ... 1.4) ⋅d, where L was _fastened. - the additional length of the tube for attaching the sample to the measuring insert, d is the inner diameter of the elastic tube of various sizes, in the central part of the insert are a light guide and a photosensor; at the same time, water is placed in the body cavity, filling about 90% of this cavity, and in the lower part of the body there is a replaceable nozzle sleeve with a flow hole, the diameter of which is selected for each type of fuel.

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