A system for measuring the flame extension extinction limit and flame speed

Abstract

The present application discloses a counter-flame stretch extinction limit and flame speed measurement system, including: a gas tank group, a PIV device, a CCD camera group, a computer and two counter-flame devices arranged relatively up and down; the counter-flame device includes a shell and a non-coplanar coaxial annular nozzle counter-flame system; the non-coplanar coaxial annular nozzle counter-flame system is installed on the shell; the shell is connected to the gas tank group through a pipeline system; the PIV device and the CCD camera group are both facing the area between the two counter-flame device nozzles; the PIV device is electrically connected to the computer; the non-coplanar coaxial annular nozzle counter-flame system includes an inner nozzle and an outer nozzle; the inner nozzle and the outer nozzle are both arc-edge nozzles; there is a preset first height difference between the inner nozzle and the outer nozzle. The present invention fits the flow direction of the gas to the greatest extent, reduces the possibility of cross turbulence generated by the airflow of the inner and outer nozzles, can form a more stable flow field in the measurement area, and thus improves the measurement accuracy.

Description

Technical Field

[0001] The present application relates to the technical field of opposed flame measurement, and in particular to an opposed flame stretch extinction limit and flame speed measurement system. Background Art

[0002] Flame propagation velocity and flame stretch extinction limit are very important parameters in combustion theory, and have great practical significance and broad application prospects. The study of flame propagation velocity can be used to improve combustion efficiency and reduce the production of incomplete combustion products; the study of flame stretch extinction limit can control the combustion process, and by controlling the injection rate of a specific fuel, the required flame temperature and length can be obtained to meet the special requirements of the process, thereby improving the understanding of combustion technology and promoting the development of combustion technology.

[0003] At present, the counter-flame method is commonly used to measure parameters such as flame propagation speed and flame stretch extinction limit, but the existing measurement system has poor measurement accuracy. Therefore, the present invention proposes a counter-flame stretch extinction limit and flame speed measurement system. Summary of the invention

[0004] The embodiment of the present application provides a system for measuring the flame stretch extinction limit and flame speed, which effectively improves the stability of the flow field and thus improves the measurement accuracy.

[0005] In view of this, the present application provides a counter-flame stretch extinction limit and flame speed measurement system, including: a gas tank group, a PIV device, a CCD camera group, a computer and two counter-flame devices arranged opposite to each other up and down;

[0006] The counter-impact device comprises a shell and a non-coplanar coaxial annular nozzle counter-impact system;

[0007] The non-coplanar coaxial annular nozzle countermeasure system is installed on the housing;

[0008] The shell is connected to the gas tank group through a pipeline system;

[0009] The PIV device and the CCD camera group are both facing the area between the two nozzles of the hedging device;

[0010] The PIV device is electrically connected to the computer;

[0011] The non-coplanar coaxial annular nozzle countermeasure system includes an inner nozzle and an outer nozzle;

[0012] The inner nozzle and the outer nozzle are both arc-edge nozzles;

[0013] There is a preset first height difference between the inner nozzle and the outer nozzle.

[0014] Optionally, the pipeline system is provided with a tracer particle addition system and an MFC mass flow meter.

[0015] Optionally, the tracer particle addition system is provided with a regulating valve capable of changing the volume of the pressurization chamber.

[0016] Optionally, the shell includes a lower shell, a middle outer shell and a middle inner shell;

[0017] The middle outer shell and the middle inner shell are both connected to the lower shell;

[0018] The middle outer shell has no direct connection with the middle inner shell;

[0019] The inner nozzle is installed on the top of the middle inner shell;

[0020] The outer nozzle is installed on the top of the middle outer shell;

[0021] The bottom of the lower shell is provided with a pipeline connection port for connecting with the pipeline system.

[0022] Optionally, a hedging distance adjustment device for adjusting the distance between the nozzles of the two hedging devices is provided between the two hedging devices;

[0023] The middle outer shell is provided with a connection port;

[0024] The middle outer shell is connected to the hedging spacing adjustment device through the connecting port.

[0025] Optionally, an internal flow stabilizing device for stabilizing the airflow is provided at the connection between the middle internal shell and the lower shell.

[0026] Optionally, the relative position of the inner nozzle is higher than the relative position of the outer nozzle.

[0027] Optionally, the first height difference is 3-5 mm.

[0028] Optionally, both the outer nozzle and the inner nozzle are funnel-shaped structures that gradually narrow along the flame spraying direction.

[0029] Optionally, the radius of the top of the outer nozzle is 30 mm;

[0030] The radius of the bottom end of the outer nozzle is 80 mm;

[0031] The radius of the top of the inner nozzle is 10 mm;

[0032] The radius of the bottom end of the inner nozzle is 40 mm.

[0033] It can be seen from the above technical scheme that the embodiment of the present application has the following advantages: it includes a gas cylinder group, a PIV device, a CCD camera group, a computer and two hedging devices arranged relatively up and down, the hedging device includes a shell and a non-coplanar coaxial circular annular nozzle hedging system, the non-coplanar coaxial circular annular nozzle hedging system is installed on the shell, the shell is connected to the gas cylinder group through a pipeline system, the PIV device and the CCD camera group are both facing the area between the nozzles of the two hedging devices, and the PIV device is electrically connected to the computer; the non-coplanar coaxial circular annular nozzle hedging system includes an inner nozzle and an outer nozzle, the inner nozzle and the outer nozzle are both arc-edge nozzles, and there is a preset first height difference between the inner nozzle and the outer nozzle. By adopting an inner and outer double nozzle model, and the nozzle adopts an arc-edge nozzle configuration design, there is a certain height difference between the inner and outer nozzles, which can maximize the flow direction of the gas, reduce the possibility of cross turbulence of the airflow of the inner and outer nozzles, and form a more stable flow field in the measurement area, which has the potential to improve measurement accuracy and flow field stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the structure of the hedge flame stretch extinction limit and flame speed measurement system in an embodiment of the present application;

[0035] Figure 2 It is a cross-sectional view of the hedging device in the embodiment of the present application;

[0036] Figure 3 This is a cross-sectional view of a tracer particle adding system in an embodiment of the present application;

[0037] Wherein, the accompanying drawings are marked as follows:

[0038] 1-shell, 2-non-coplanar coaxial annular nozzle hedging system, 3-hedging spacing adjustment device, 4-PIV device, 5-computer, 6-CCD camera group, 7-pipeline system, 8-tracer particle addition system, 9-MFC mass flowmeter, 10-gas tank group, 11-middle inner shell, 12-middle outer shell, 13-sealing ring, 14-lower shell, 15-protective gas pipeline connection port, 16-fuel or oxidant pipeline connection port, 17-stabilizing plate, 18-connection port, 21-inner nozzle, 22-outer nozzle, 81-pressurization chamber, 82-regulating valve. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0040] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0041] Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0042] The inventor found that the counter-jet nozzle used by scholars in the 1960s was a single-layer annular nozzle, lacking a shunted protective gas nozzle, and failing to wrap the protective gas outside the flame to protect the flame from external interference. In this case, the stability of the flame was worse than that of the double-jet model, resulting in a decrease in the stability of the counter-jet flame. Compared with the latest non-coplanar coaxial annular double-jet model, the coplanar coaxial annular nozzle model has a slight difference in the stability and area of ​​the central flow field because the protective gas and fuel are ejected at the same height, compressing the central combustion flow field.

[0043] When measuring the velocity using the counter-flame method, the two nozzles are arranged opposite to each other at a certain distance on the center line of the nozzles. The combustible gas is ejected symmetrically through the two nozzles at a certain distance at the same time. The flame will form a stagnation surface in the middle of the distance. In order to keep the flame stable between the two nozzles and prevent the outside world such as air from mixing with the fuel and oxidant in the internal space and the influence of air flow, nitrogen is introduced into the shell to protect the combustion area. At this time, the flame state is steady, laminar, quasi-adiabatic, without external flow field effects, ideal and can be simply quantitatively described. Combined with the PIV experimental device, the velocity distribution on the central axis of the flow field can be measured.

[0044] This application provides an embodiment of a system for measuring the flame stretch extinction limit and flame speed. Figure 1 and Figure 2 .

[0045] The counter-flame stretch extinction limit and flame speed measurement system in this embodiment includes: a gas cylinder group 10, a PIV device 4, a CCD camera group 6, a computer 5 and two counter-flame devices arranged opposite to each other in an upper and lower direction, the counter-flame device includes a shell 1 and a non-coplanar coaxial annular nozzle counter-flame system 2, the non-coplanar coaxial annular nozzle counter-flame system 2 is installed on the shell 1, the shell 1 is connected to the gas cylinder group 10 through a pipeline system 7, the PIV device 4 and the CCD camera group 6 are both facing the area between the nozzles of the two counter-flame devices, and the PIV device 4 is electrically connected to the computer 5; the non-coplanar coaxial annular nozzle counter-flame system 2 includes an inner nozzle 21 and an outer nozzle 22, the outer nozzle 22 and the inner nozzle 21 together constitute the non-coplanar coaxial annular nozzle counter-flame system 2; the inner nozzle 21 and the outer nozzle 22 are both arc-edge nozzles, and there is a preset first height difference between the inner nozzle 21 and the outer nozzle 22.

[0046] It should be noted that: by adopting the inner and outer double nozzle model and the arc-edge nozzle configuration design, there is a certain height difference between the inner and outer nozzles, which can maximize the flow direction of the gas and reduce the possibility of cross turbulence in the airflow of the inner and outer nozzles. A more stable flow field can be formed in the measurement area, which has the potential to improve measurement accuracy and flow field stability.

[0047] The above is a first embodiment of a system for measuring the flame extension extinction limit and flame speed provided by the embodiment of the present application. The following is a second embodiment of a system for measuring the flame extension extinction limit and flame speed provided by the embodiment of the present application. For details, please refer to Figures 1 to 3 .

[0048] The counter-flame stretch extinction limit and flame speed measurement system in this embodiment includes: a gas tank group 10, a PIV device 4, a CCD camera group 6, a computer 5 and two counter-flame devices arranged opposite to each other in an upper and lower direction, the counter-flame device includes a shell 1 and a non-coplanar coaxial annular nozzle counter-flame system 2, the non-coplanar coaxial annular nozzle counter-flame system 2 is installed on the shell 1, the shell 1 is connected to the gas tank group 10 through a pipeline system 7, the PIV device 4 and the CCD camera group 6 are both facing the area between the nozzles of the two counter-flame devices, the PIV device 4 is electrically connected to the computer 5, and the CCD camera group 6 can also be electrically connected to the computer 5, the PIV device 4 emits a laser, and the tracer particles in the counter-flame flow field emit light of a certain frequency under the irradiation of the laser, and the CCD camera group 6 records this moment intuitively and accurately, and through data processing by the computer 5 and based on the data recorded by the CCD camera group 6, the original appearance of the counter-flame flow field can be more accurately analyzed.

[0049] The non-coplanar coaxial circular nozzle countermeasure system 2 includes an inner nozzle 21 and an outer nozzle 22, and the outer nozzle 22 and the inner nozzle 21 together constitute the non-coplanar coaxial circular nozzle countermeasure system 2; the inner nozzle 21 and the outer nozzle 22 are both arc-edge nozzles, and the arc-edge nozzles are composed of an arc edge with a specific radius and angle and a straight line segment tangent to the two; there is a preset first height difference between the inner nozzle 21 and the outer nozzle 22.

[0050] The pipeline system 7 is provided with a tracer particle addition system 8 and an MFC mass flow meter 9. Specifically, Figure 3 As shown, the tracer particle addition system 8 is provided with a regulating valve 82 which can change the volume of the boost chamber 81 , and the output of the tracer particles can be controlled by controlling the turbulent state of the airflow in the boost chamber 81 , thereby achieving control over the amount of tracer particles added.

[0051] It should be noted that the tracer particle addition system 8 is provided with a regulating valve 82, which can change the internal volume and pressure of the tracer particle addition system 8 to control the concentration of the tracer particles in the flame flow field, ensure that there are enough tracer particles in the shooting window, avoid analysis errors caused by too few or too many tracer particles, and thus ensure the accuracy of the analysis results.

[0052] like Figure 2 As shown, the shell 1 includes a lower shell 14, a middle outer shell 12 and a middle inner shell 11. The middle outer shell 12 and the middle inner shell 11 are both connected to the lower shell 14. The middle outer shell 12 has no direct connection with the middle inner shell 11. The inner nozzle 21 is installed on the top of the middle inner shell 11, and the outer nozzle 22 is installed on the top of the middle outer shell 12. A pipeline connection port for connecting to the pipeline system 7 is provided at the bottom of the lower shell 14. Specifically, the pipeline connection port includes a protective gas pipeline connection port 15 and a fuel or oxidant pipeline connection port 16.

[0053] A counter-hedging spacing adjustment device 3 for adjusting the distance between the nozzles of the two counter-hedging devices is provided between the two counter-hedging devices. The middle-layer external shell 12 is provided with a connecting port 18. The middle-layer external shell 12 is connected to the counter-hedging spacing adjustment device 3 through the connecting port 18. Specifically, the connecting port 18 is provided with a thread, which can adjust the distance between the nozzles of the two counter-hedging devices. By adding the counter-hedging spacing adjustment device 3, the distance between the counter-hedging devices can be adjusted and fixed, which is convenient for studying the changing phenomena and laws of the parameters related to the counter-hedging flames at different distances.

[0054] An internal flow stabilizing device for stabilizing the airflow is provided at the connection between the middle internal shell 11 and the lower shell 14. Specifically, the internal flow stabilizing device can adopt a flow stabilizing plate 17. The flow stabilizing plate 17 is made of a ceramic honeycomb body. The ceramic honeycomb body adopts a square porous channel structure. When the gas passes through the flow stabilizing plate 17, it can be rectified into a vertical upward laminar flow, making the flow field more stable, thereby improving the success rate of the experiment.

[0055] Sealing rings 13 are provided at the connections between the lower shell 14 and the middle outer shell 12 and the middle inner shell 11 to ensure that there is no air leakage at the connection of the shell 1. Specifically, the sealing ring 13 can be made of rubber.

[0056] The relative position of the inner nozzle 21 is higher than the relative position of the outer nozzle 22. Specifically, the first height difference is 3-5 mm. Preferably, the first height difference is 3 mm.

[0057] The outer nozzle 22 and the inner nozzle 21 are both funnel-shaped structures that gradually narrow along the flame spraying direction.

[0058] Specifically, the radius of the top end of the outer nozzle 22 is 30 mm, the radius of the bottom end of the outer nozzle 22 is 80 mm, and the radius of the outer nozzle 22 gradually decreases from 80 mm to 30 mm; the radius of the top end of the inner nozzle 21 is 10 mm, the radius of the bottom end of the inner nozzle 21 is 40 mm, and the radius of the inner nozzle 21 gradually decreases from 40 mm to 10 mm.

[0059] During the specific implementation, the distance between the two hedging device nozzles is adjusted, the gas tank group 10 connected to the pipeline system 7 is opened, the fuel, oxidant and protective gas are connected, and the tracer particle addition system 8 connected to the pipeline system 7 is opened to add an appropriate amount of tracer particles into the pipeline system 7, and the MFC mass flowmeter 9 installed in the pipeline system 7 is opened to adjust the flow rates of the three gases respectively; the computer 5, CCD camera group 6 and PIV device 4 of the matching measurement and control part are turned on, the laser is adjusted to hit the measurement area, and the lens direction and focal length of the CCD camera group 6 are initially adjusted so that the photographed hedging nozzle is in the middle of the measurement window and is clearly visible; the fuel between the hedging device nozzles is ignited using an electronic ignition device, the flame shape is observed, and the focal length of the CCD camera group 6 is fine-tuned so that the photographed flame picture is clear and full; the CCD camera group 6 is used to photograph the experimental phenomena. After the experiment, the data recorded by the CCD camera group 6 is imported into the computer 5 of the matching measurement and control part for data processing.

[0060] The counter-attack flame stretching extinction limit and flame speed measurement system improves the existing counter-attack device and adopts an inner and outer double nozzle model. At the same time, the nozzle adopts an arc-edge nozzle configuration design. There is a certain height difference between the inner and outer nozzles, which can maximize the fit of the gas flow direction and reduce the possibility of cross turbulence of the airflow of the inner and outer nozzles. A more stable flow field can be formed in the measurement area, which has the potential to improve measurement accuracy and flow field stability.

[0061] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A system for measuring the flame stretch extinction limit and flame speed, characterized in that: include: Gas tank set, PIV device, CCD camera set, computer and two hedging devices arranged opposite to each other; The counter-impact device comprises a shell and a non-coplanar coaxial annular nozzle counter-impact system; The non-coplanar coaxial annular nozzle countermeasure system is installed on the housing; The shell is connected to the gas tank group through a pipeline system; The PIV device and the CCD camera group are both facing the area between the two nozzles of the hedging device; The PIV device is electrically connected to the computer; The non-coplanar coaxial annular nozzle countermeasure system includes an inner nozzle and an outer nozzle; The inner nozzle and the outer nozzle are both arc-edge nozzles; There is a preset first height difference between the inner nozzle and the outer nozzle; The shell comprises a lower shell, a middle outer shell and a middle inner shell; The middle outer shell and the middle inner shell are both connected to the lower shell; The middle outer shell has no direct connection with the middle inner shell; The inner nozzle is installed on the top of the middle inner shell; The outer nozzle is installed on the top of the middle outer shell; The bottom of the lower shell is provided with a pipeline connection port for connecting with the pipeline system; The relative position of the inner nozzle is higher than the relative position of the outer nozzle.

2. The counter-flame stretch extinction limit and flame speed measurement system according to claim 1, characterized in that: The pipeline system is provided with a tracer particle adding system and an MFC mass flow meter.

3. The counter-flame stretch extinction limit and flame speed measurement system according to claim 2, characterized in that: The tracer particle adding system is provided with a regulating valve which can change the volume of the pressurization chamber.

4. The counter-flame stretch extinction limit and flame speed measurement system according to claim 1, characterized in that: A hedging distance adjustment device for adjusting the distance between the nozzles of the two hedging devices is provided between the two hedging devices; The middle outer shell is provided with a connection port; The middle outer shell is connected to the hedging spacing adjustment device through the connecting port.

5. The counter-flame stretch extinction limit and flame speed measurement system according to claim 1, characterized in that: An internal flow stabilizing device for stabilizing airflow is provided at the connection between the middle layer internal shell and the lower layer shell.

6. The counter-flame stretch extinction limit and flame speed measurement system according to claim 1, characterized in that: The first height difference is 3-5 mm.

7. The counter-flame stretch extinction limit and flame speed measurement system according to claim 1, characterized in that: The outer nozzle and the inner nozzle are both funnel-shaped structures that gradually narrow along the flame spraying direction.

8. The counter-flame stretch extinction limit and flame speed measurement system according to claim 7, characterized in that: The radius of the top of the outer nozzle is 30 mm; The radius of the bottom end of the outer nozzle is 80 mm; The radius of the top of the inner nozzle is 10 mm; The radius of the bottom end of the inner nozzle is 40 mm.

Images