CN105548184A - Pipe system for quantizing detonation instability degree of premixed gas and method thereof - Google Patents

Abstract

The invention relates to a pipeline system and method for quantifying the detonation instability of premixed gas. The pipeline system includes a detonator, a first pipeline, a second pipeline, a smoke film and a measuring device; one end of the detonator passes through the first A flange is sealed to one end of the first pipeline, the other end of the first pipeline is sealed to one end of the second pipeline through the second flange, and the other end of the detonator is connected to the other end of the second pipeline respectively through Flange head seal with rubber sealing ring, the measuring device is set on the first pipeline and the second pipeline, the smoke film is set inside the second pipeline on the side of the flange head with rubber sealing ring . The invention reliably and flexibly obtains the smoke film results under different initial pressures of various premixed gases quickly, and provides a technical method for digitally processing the smoke film images. The system has improved the method of quantifying the detonation instability of premixed gas, which can be widely used in the analysis of smoke film trajectory of premixed gas, which is beneficial for quantitative comparison.

Description

A pipeline system and method for quantifying detonation instability of premixed gas

technical field

The invention relates to a research method of detonation mechanism, in particular to a pipeline system and method for quantifying the detonation instability of premixed gas for the research of detonation instability and detonation structure.

Background technique

Document 1 (Lee, J.H.S.Dynamicsofexothermicity.1995:321-335.GordonandBreach.) points out that stable and unstable detonation mechanisms are different. The quantitative study of the cellular structure formed by the shear wave trajectory is very important in detonation propagation. The trajectory recorded on the smoke film obtained in the experiment does not move in a straight line. In order to explain and describe the reason for this phenomenon, it is necessary to study the degree of instability of different gases. The classification of "regular trajectories" and "irregular trajectories" described by smoke film trajectories has been qualitative and subjective. It is difficult to clarify the structural properties of the highly irregular shear-wave trajectories recorded on the smoke film. Therefore, quantitative analysis of the detonation instability of premixed gas is of great significance for perfecting the detonation mechanism. Here, the detonation instability of the premixed gas is described by the irregularity of the smoke film trajectory.

It is very difficult to directly scan the smoke film to obtain the trajectory. Adjusting the "grey scale" is necessary because of "grey scale unevenness", "errors" caused by non-uniform soot deposits.文献2（J.J.Lee,FrostD,LeeJHS,KnystautasR(1993)Digitalsignalprocessinganalysisofsoot-foils.ProgressinAstronauticsandAeronautics,AIAAPress,Washington,153:182-202.）和文献3（J.J.Lee,D.Garinis,Two-dimensionalautocorrelationfunctionanalysisofsmokedfoilpatterns,ShockWaves,1995, 5:169-174.) Point out the method of hand-drawn recording and scanning of cigarette film trajectory to obtain trajectory pictures that can be processed digitally. In the past few decades, although the stability theory of knock has been studied, there is still no systematic quantitative method.

Contents of the invention

In order to solve the above problems, the object of the present invention is to provide a simple structure, easy to use, can obtain the smoke film of various premixed gases under different initial pressure conditions, and can quantitatively describe the degree of detonation instability of different premixed gases Piping systems and methods for quantifying detonation instability of premixed gases.

The technical solution of the present invention is: a pipeline system for quantifying the detonation instability of premixed gas, the system comprising a detonator, a first pipeline, a second pipeline, a smoke film and a measuring device;

One end of the detonating tube is sealingly connected to one end of the first pipeline through a first flange, and the other end of the first pipeline is sealingly connected to one end of the second pipeline through a second flange, so The other end of the detonating tube and the other end of the second pipeline are respectively sealed by a flange head with a rubber sealing ring, the measuring device is arranged on the first pipeline and the second pipeline, and the The smoke film is arranged inside the second pipeline on one side of the flange head with the rubber sealing ring.

Further, the measurement device includes an optical fiber and an optical fiber fixing ring, and the optical fiber is respectively fixed on the outer walls of the first pipeline and the second pipeline through the optical fiber fixing ring.

Further, the detonating tube is a metal tube, the length of the detonating tube is 0.8-1.2m, and the inner diameter is 50.8mm-63.5mm.

Further, the first pipeline and the second pipeline are both high-strength PC pipes with an inner diameter of 50.8mm-63.5mm.

Further, the thickness of the smoke film is more than 0.04mm.

Another object of the present invention is to provide a method for analyzing using the above pipeline system, which specifically includes the following steps:

Step 1. First assemble the pipeline system, check the tightness, pass the test gas into the pipeline system, use the equal volume condition to calculate the partial pressure of the test gas in the blasting tube, obtain an accurate initial pressure value of the experiment, and then detonate the test gas, After detonation, vacuumize the detonating tube and then slowly put it into the atmosphere to ensure that no scour marks will be formed on the smoke film. Open the flange of the head, take out the smoke film with the trajectory map, and spray transparent protective paint evenly. The smoke film is scanned to obtain a scanned image;

Step 2. Carry out quantitative instability analysis to the scanned image obtained through step 1, make a vertical line on the trajectory map with the true height of the smoke film, determine the number n of pixel discrete points of the vertical line, when a vertical line touches the trajectory Record the position of the sudden change pixel on the line, record the value as '1', and record the value of other pixels as '0', each pixel is discretely numericalized, and the trajectory map is transformed into a discrete function , record the discrete function as a sequence function x(n), which contains discrete signals of 1 and 0, n is the number of discrete points, x is the value of discrete points, composed of '1' and '0';

Calculate the autocorrelation function φ _xx (m) according to the following formula, which is as follows:

(Formula 1)

In the formula, yes and y The cross-correlation function, M is the number of units; y(n) is the zero-fill sequence translation function of x(n), n is the number of discrete points obtained by all vertical lines, m is the translation value, and x is the value of discrete points ;

Step 3: After the calculation, the spectrogram form of the autocorrelation function result can be visually given. The proportion of the first highest peak in the figure is Φ ^1st _max , which is the corresponding ordinate value, and the multiple of the proportion higher than other peaks Φ ^1st _max /Φ ^2ed _max gives the detonation instability of the premixed gas.

When the trajectory is completely regular, the discrete function will still repeat the original function after a certain distance of translation; only when the translation distance is a multiple of the trajectory distance, the discrete function and the discrete function after translation are completely repeated, then the first autocorrelation function ACF The translation distance corresponding to the highest peak is the main track spacing, and the other peaks correspond to less track spacing and multiples. Even for irregular trajectories, the first peak of the autocorrelation function represents the most frequently occurring trajectories spacing. Therefore, the proportion of the first highest peak of the autocorrelation function result and the multiples higher than other peaks give the detonation instability of the premixed gas.

Advantages and positive effects of the present invention: Due to the adoption of the above-mentioned technical scheme, the present invention can reliably and flexibly obtain the smoke film results under different initial pressures of various premixed gases quickly, and provides a technical method for digitally processing smoke film images. The system has improved the method of quantifying the detonation instability of premixed gas, which can be widely used in the analysis of smoke film trajectory of premixed gas, which is beneficial for quantitative comparison.

Description of drawings

Fig. 1 is a structural schematic diagram of the pipeline system for quantifying the detonation instability of premixed gas according to the present invention.

Fig. 2 is the detonation smoke film trajectory diagram of CH ₄ +2O ₂ premixed gas with an initial pressure of 7.25kPa.

Fig. 3 is a left-handed trajectory diagram of the CH ₄ +2O ₂ premixed gas smoke film with an initial pressure of 7.25kPa.

Figure 4 shows the unbiased autocorrelation function of the left-handed trajectory of the smoke film with the initial pressure of CH ₄ +2O ₂ premixed gas at 7.25kPa.

Figure 5 shows the biased autocorrelation function of the left-handed trajectory of the smoke film with the initial pressure of CH ₄ +2O ₂ premixed gas at 7.25kPa.

In the picture:

1. Detonation tube; 2. First flange, 3. First pipeline, 4. Second flange, 5. Second pipeline; 6. Smoke film, 7. Head flange, 8. Optical fiber fixing ring , 9, optical fiber.

detailed description

The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

As shown in Figure 1, it is a structural schematic diagram of a pipeline system for quantifying the detonation instability of premixed gas according to the present invention. The system includes a detonator, a first pipeline, a second pipeline, a smoke film and a measuring device;

The measuring device includes an optical fiber and an optical fiber fixing ring;

Wherein, one end of the detonating tube is sealingly connected to one end of the first pipeline through a first flange, and the other end of the first pipeline is sealingly connected to one end of the second pipeline through a second flange. , the other end of the detonating tube and the other end of the second pipeline are respectively sealed by a flange head with a rubber sealing ring, and the measuring device is arranged on the first pipeline and the second pipeline, The smoke film is arranged inside the second pipeline on one side of the flange head with a rubber sealing ring, and the optical fiber is respectively fixed on the outside of the first pipeline and the second pipeline through an optical fiber fixing ring on the wall. The detonating tube is a metal tube, the length of the detonating tube is 0.8-1.2m, and the inner diameter is 50.8mm-63.5mm. Both the first pipeline and the second pipeline are high-strength PC pipes with an inner diameter of 50.8mm-63.5mm. The thickness of the smoke film is above 0.04mm.

Another object of the present invention is to provide the test method of above-mentioned system, specifically comprises the following steps:

Step 1. First assemble the pipeline system, check the tightness, pass the test gas into the pipeline system, use the equal volume condition to calculate the partial pressure of the test gas in the blasting tube, obtain an accurate initial pressure value of the experiment, and then detonate the test gas, After detonation, vacuumize the detonating tube and then slowly put it into the atmosphere to ensure that no scour marks will be formed on the smoke film. Open the flange of the head, take out the smoke film with the trajectory map, and spray transparent protective paint evenly. The smoke film is scanned to obtain a scanned image;

Step 2. Carry out quantitative instability analysis to the scanned image obtained through step 1, make a vertical line on the trajectory map with the true height of the smoke film, determine the number n of pixel discrete points of the vertical line, when a vertical line touches the trajectory Record the position of the sudden change pixel on the line, record the value as '1', and record the value of other pixels as '0', each pixel is discretely numericalized, and the trajectory map is transformed into a discrete function , record the discrete function as a sequence function x(n), which contains discrete signals of 1 and 0, n is the number of discrete points, x is the value of discrete points, composed of '1' and '0';

Calculate the autocorrelation function φ _xx (m) according to the following formula, which is as follows:

(Formula 1)

In the formula, yes and y The cross-correlation function, M is the number of units; y(n) is the zero-fill sequence translation function of x(n), n is the number of discrete points obtained by all vertical lines, m is the translation value, and x is the value of discrete points ;

Step 3: After the calculation, the spectrogram form of the autocorrelation function result can be visually given. The proportion of the first highest peak in the figure is Φ ^1st _max , which is the corresponding ordinate value, and the multiple of the proportion higher than other peaks Φ ^1st _max /Φ ^2ed _max gives the detonation instability of the premixed gas.

Example 1

In order to show that the detonation instability calculation method is universally applicable to all kinds of cigarette film trajectories, the following takes CH ₄ +2O ₂ which is not easy to ignite but is sensitive and has very irregular trajectories as an example, and further explains the present invention in conjunction with the accompanying drawings and examples:

The detonation experiment used a detonator with an inner diameter of 50.8 mm. The length of the front detonation tube is about 1m, and the back-end experiment part adopts the first tube body and the second tube body of two single-length 2m transparent high-strength plastic tubes. In order to facilitate data collection and consider stability, the plastic tube is composed of two parts , the middle is sealed by the rubber ring inside the flange. A very sensitive small volume of C ₂ H ₂ +O ₂ (stoichiometric ratio) is used to fill the metal detonator to promote the initiation of detonation in the test part, and the part that is not easy to detonate after detonation in a short distance CH ₄ +2O ₂ premixed gas. Calculate the partial pressure of C ₂ H ₂ +O ₂ premixed gas and CH ₄ +2O ₂ premixed gas to obtain accurate experimental pressure by using isovolumic conditions.

Open the head flange, wipe the inner wall of the pipe clean, put a 1m-long evenly smoked diaphragm at the rear end of the pipe in the experimental section, called a smoke film, even if C ₂ H ₂ +O ₂ is used to detonate, CH ₄ + The ultimate detonation (detonation) pressure of 2O ₂ premixed gas is also about 5kPa, so it is necessary to use a smoke film with a thickness of more than 0.04mm. Install the head flange. The outer wall of the tube in the experimental section is fixed with an optical fiber. When the detonation surface propagates to a certain place, because the material on the detonation surface is still undergoing chemical reactions, light will be generated. After being sensed by the optical fiber, the signal is transmitted to the data box, and the detonation surface is obtained. The detonation velocity is calculated by the formula for the propagation time of the bombardment surface and the distance from the optical fiber. All explosive mixtures have been pre-prepared in the high-pressure bottle by the method of partial pressure, and different gases are safely input into the pre-mixed high-pressure bottle through the control panel. After filling the tank, the pre-mixed gas can be used after more than 24 hours to ensure The different gases in the tank are evenly mixed. After detonation, the tube is evacuated and slowly released to atmosphere to ensure that no scour marks are formed on the smoke film. Open the flange of the head, take out the smoke film and evenly spray transparent protective paint, and then scan.

Because the thickness of the brush in the drawing of the smoke film trajectory is greater than 1 pixel, the pixels are continuous, and there will be continuous '1' during discretization. When optimizing, the connected '1' in the discrete function can be optimized. The initial pressure of the improved CH ₄ +2O ₂ premixed gas is 7.25kPa. The left-handed trajectory of the smoke film is biased. The autocorrelation calculation results are shown in Figure 4. The initial pressure of the improved CH ₄ +2O ₂ premixed gas is 7.25kPa. Autocorrelation calculation results are shown in Figure 5. The autocorrelation results can be significantly changed, and the improved results show the peak more clearly.

Calculate the autocorrelation function φ _xx (m) according to the following formula, which is as follows:

(Formula 1)

In the formula, yes and y The cross-correlation function, M is the number of units; y(n) is the zero-fill sequence translation function of x(n), n is the number of discrete points obtained by all vertical lines, m is the translation value, and x is the value of discrete points ;

Obviously, the higher the proportion of the first highest peak, the more concentrated the data, that is, the more regular the trajectory, the more stable the detonation of the premixed gas. Therefore, the ordinate value corresponding to the first highest peak of the autocorrelation function result of the smoke film trajectory is the proportion of the peak to the total data Φ ^1st _max =2.7×10 ^-4 , which is very small. The first highest peak is higher than other peaks by a multiple of Φ ^1st _max /Φ ^2ed _max =1.42, which is also very small.

Claims (6)

1. quantize a piping system for premix gas explosion Hong instability, be characterised in that: this system comprises powder squib, the first pipeline, the second pipeline, cigarette film and measurement mechanism;

One end of described powder squib is tightly connected by one end of the first flange and described first pipeline, the other end of described first pipeline is tightly connected by one end of the second flange and described second pipeline, the other end of described powder squib and the other end of described second pipeline seal respectively by the flange end socket with rubber seal, described measurement mechanism is arranged on described first pipeline and the second pipeline, and the inside that described cigarette film is arranged on the second pipeline is positioned at the side of the flange end socket with rubber seal.

2. system according to claim 1, is characterized in that, described measurement mechanism comprises optical fiber, optical fiber retainer plate, and described optical fiber is separately fixed on the lateral wall of described first pipeline and the second pipeline by optical fiber retainer plate.

3. system according to claim 1 and 2, is characterized in that, described powder squib is metal tube, and described powder squib length is 0.8-1.2m, and internal diameter is 50.8mm-63.5mm.

4. system according to claim 1 and 2, is characterized in that, described first pipeline and the second pipeline are high-strength PC pipe, and internal diameter is 50.8mm-63.5mm.

5. system according to claim 1 and 2, is characterized in that, the thickness of described cigarette film is more than 0.04mm.

6. what use the piping system as described in claim 1-5 any one carries out an analytical approach, it is characterized in that, specifically comprises the following steps:

First piping system has assembled by step 1., detect sealing, test gas is passed in piping system, the appearance conditions such as utilization calculate the gas dividing potential drop of blasting cartridge build-in test gas, obtain and test initial pressure value accurately, then test gas is ignited, after detonating, then slowly air is put into by vacuumizing in powder squib, wash away vestige to ensure not formed on cigarette film, open cover flange, take out the protective paint that after the cigarette film with trajectory diagram, evenly spray is transparent, described cigarette film is scanned, obtains scan image;

Step 2. carries out quantitatively unstable analysis to obtaining scan image through step 1, be on trajectory diagram with the true altitude of cigarette film and make a perpendicular line, determine the quantity n of the pixel discrete point of perpendicular line, the position of the pixel that this line suddenlys change is recorded when a perpendicular line encounters trajectory, value is designated as ' 1 ', other pixel point value is designated as ' 0 ', each pixel is by dispersion number value, just trajectory diagram is transformed and obtain a discrete function, discrete function is recorded with ordinal function x (n), containing the discrete signal of 1 and 0, n is the quantity of discrete point, x is the value of discrete point, form by ' 1 ' and ' 0 ',

According to following formulae discovery autocorrelation function φ _xx(m), formula is as follows:

(formula 1)

In formula, be and y cross correlation function, M is a unit number; Y (n) is the zero padding sequence translation function of x (n), and n is the quantity that all perpendicular line obtain discrete point, and m is shift value, and x is the value of discrete point;

Step 3: calculate the spectrogram form that intuitively can provide autocorrelation function result after terminating, first peak-peak proportion Φ in figure ^1st _max, namely corresponding Y value, and exceed the multiple Φ of other peak value proportion ^1st _max/ Φ ^2ed _maxnamely premix gas explosion Hong instability is provided.