A flame speed and quenching distance testing device and testing method

Abstract

The application provides a flame speed and quenching distance testing device and testing method, and belongs to the technical field of combustion testing. The testing device comprises an annular sleeve, a fuel delivery assembly, a central fixed shaft and a plurality of circular ring pieces. The first end of the annular sleeve and the output end of the fuel delivery assembly are in communication. The plurality of circular ring pieces are sequentially mounted on the central fixed shaft along the axial direction of the central fixed shaft. The outer diameters of the plurality of circular ring pieces increase sequentially from the first end to the second end. A first micro-hole for placing a sensor is arranged on the inner ring surface of the circular ring piece. A through hole extending along the axial direction is arranged in the central fixed shaft, and the through hole is used for penetrating the sensor wire harness and for introducing cooling water. A second micro-hole corresponding to the first micro-hole is arranged on the central fixed shaft. The fuel delivery assembly is connected to the annular sleeve and the central fixed shaft for delivering fuel therebetween. The application can simultaneously measure the laminar flame propagation speed and quenching distance of a given mixed gas in one experiment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of combustion test, in particular to a flame speed and quenching distance test device and test method. BACKGROUND

[0002] Laminar flame propagation speed refers to the speed of laminar adiabatic premixed plane flame relative to the combustion movement of stationary unburned mixed gas, which is controlled by the thermodynamic, transport and reaction properties of components at the same time, and can comprehensively represent the reaction activity of fuel mixed gas, which is a core parameter of premixed combustion. Quenching distance refers to the minimum size that can just maintain flame propagation. These parameters are directly related to the safety of fuel use, and are of great significance to guide the safe use of fuel and the design of combustor.

[0003] In the measurement of laminar flame propagation speed, complex test equipment needs to be used and many assumptions need to be considered to eliminate the influence of heat loss or flame stretching effect on flame speed, resulting in reduced accuracy of flame speed measurement. In addition, traditional laminar flame propagation speed and quenching distance measurement need to be measured separately using different experimental equipment, which is difficult to obtain at one time and time-consuming and laborious in the test process. SUMMARY

[0004] Therefore, the present application provides a flame speed and quenching distance test device and test method, which solves the problems in the prior art and measures the laminar flame propagation speed and quenching distance of a given mixed gas at one time.

[0005] In one aspect, the flame speed and quenching distance test device provided by the present application adopts the following technical scheme:

[0006] A flame speed and quenching distance test device, comprising a ring sleeve, a fuel delivery assembly, a central fixed shaft and a plurality of circular ring pieces, the ring sleeve comprising a first end and a second end, the first end of the ring sleeve being in communication with the output end of the fuel delivery assembly, the plurality of circular ring pieces being installed on the central fixed shaft in the axial direction of the central fixed shaft, the circular ring pieces, the central fixed shaft and the ring sleeve being coaxially arranged, the outer diameters of the plurality of circular ring pieces increasing in turn from the first end to the second end, a first micro-hole for placing a sensor being formed on the inner ring surface of the circular ring piece, a through hole extending in the axial direction of the ring sleeve being formed in the central fixed shaft, the through hole being used for passing through the sensor wire harness and for introducing cooling water, a second micro-hole corresponding to the first micro-hole being formed on the central fixed shaft, the second micro-hole being used for passing through the sensor, the fuel delivery assembly being in communication with the ring sleeve and the central fixed shaft for delivering fuel therebetween, and the second end being in communication with the external space.

[0007] Optionally, the fuel delivery assembly comprises a ring-shaped premixing cavity, one end of the ring-shaped premixing cavity is fixedly connected with the first end, the ring-shaped premixing cavity is in communication with the ring-shaped sleeve, the other end of the ring-shaped premixing cavity is provided with an air inlet hole and an inner cavity of the ring-shaped premixing cavity is in communication, and the central fixed shaft penetrates the inner ring of the ring-shaped premixing cavity.

[0008] Optionally, one end of the ring-shaped premixing cavity close to the first end is provided with a porous medium partition, the ring-shaped premixing cavity is in communication with the ring-shaped sleeve through the porous medium partition, and the porous medium partition is provided with an opening through which the central fixed shaft penetrates.

[0009] Optionally, a heat insulation gasket is arranged between two adjacent circular ring members, the distance between two adjacent first micropores is equal to the axial thickness of the heat insulation gasket and the circular ring member, an annular boss is fixedly arranged on the outer periphery of the central fixed shaft close to the second end, and the circular ring member and the heat insulation gasket are movably sleeved on the outer periphery of the central fixed shaft.

[0010] Optionally, the ring-shaped sleeve is made of quartz glass.

[0011] In another aspect, the application provides a method for testing flame speed and quenching distance

[0012] A method for testing flame speed and quenching distance, the testing method is performed by using the testing device, and the testing method comprises the following steps:

[0013] Step 1: selecting the diameter D1 of the smallest circular ring member according to the estimated laminar flame propagation speed value, selecting the diameter Dn of the largest circular ring member according to the estimated quenching distance, and selecting the inner diameter D of the ring-shaped sleeve in The difference between the inner diameter D of the ring-shaped sleeve and the outer diameter Di of the largest circular ring member is less than the quenching distance of the flame, and the ring-shaped sleeve is made of transparent material;

[0014] Step 2: inputting fuel into the fuel input assembly, the fuel is input into the ring-shaped sleeve from the first end through the fuel input assembly, and the flame is ignited at the second end to form flame propagation;

[0015] Step 3: gradually reducing the fuel flow rate input into the ring-shaped sleeve, the flame will continuously move towards the larger circular ring member, and the positions of the flame at the stable flow rate are recorded until the flame cannot be maintained and is extinguished;

[0016] Step 4: calculating the flame speed, forming the relationship between the length scale and the flame speed, and analyzing to obtain the laminar flame propagation speed and the quenching distance of the flame.

[0017] Optionally, the positions of the flame at the stable flow rate in step 3 are recorded by using a high-speed camera or a temperature sensor / ion sensor in the first micropore.

[0018] Optionally, the length scale at the flame stable position is the difference between the outer diameter Di of the circular ring at the flame stable position and the inner diameter D of the annular sleeve. in

[0019] At a given flow rate Vm of the fuel input assembly, the flame area without wrinkles is A f = π(Di n 2 -Di 2 , and the flame speed is Vm / A f = π(D in 2 -Di 2 , a graph of the fuel flow rate and the flame speed is drawn, and the critical speed at which the flame speed remains relatively constant within a certain flow rate range is the laminar flame propagation speed.

[0020] Optionally, the difference between the outer diameter of the circular ring at the flame extinguishing position and the inner diameter of the annular sleeve is the quenching distance of the flame.

[0021] Optionally, a flowmeter is arranged on the pipeline for conveying fuel to the fuel input assembly, and the flow rate of the fuel conveyed to the fuel input assembly is obtained through the flowmeter.

[0022] In summary, the present application has the following beneficial technical effects:

[0023] The present application utilizes the characteristic that the flame burning speed is affected by the characteristic length scale, utilizes the stacked annular flow channel to realize the change of the characteristic length scale in a single experiment, adjusts the fuel gas flow rate at the inlet, so that the flame is automatically stabilized at the characteristic length scale suitable therefor, obtains the critical burning speed not affected by the characteristic length scale, i.e., the laminar flame propagation speed. Further reducing the flow rate, the minimum annular flow channel size at which the flame can maintain combustion is the quenching distance of the flame. Therefore, the laminar flame propagation speed and the quenching distance of a given mixed gas can be measured simultaneously in one experiment. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0025] Figure 1 It is a schematic diagram of the overall structure of the test device for the flame speed and quenching distance of the present application.

[0026] Figure 2 It is a graph of the relationship between the fuel flow rate and the size of the circular ring where the stable flame is located.

[0027] ​Explanation of reference numerals in the attached drawings: 1. Annular sleeve; 11. First end; 12. Second end; 2. Central fixed shaft; 21. Through hole; 22. Second micro-hole; 23. Annular boss; 3. Circular ring; 31. First micro-hole; 4. Annular premixing chamber; 41. Air inlet; 5. Porous medium barrier; 6. Heat insulation gasket. Detailed Implementation

[0028] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0029] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0031] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0032] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0033] This application provides a testing device for flame velocity and quenching distance.

[0034] like Figure 1 As shown, a testing device for flame velocity and quenching distance includes an annular sleeve 1, a fuel delivery assembly, a central fixed shaft 2, and several annular components 3. The annular sleeve 1 includes a first end 11 and a second end 12. The first end 11 of the annular sleeve 1 is connected to the output end of the fuel delivery assembly. Several annular components 3 are sequentially mounted on the central fixed shaft 2 along the axial direction of the central fixed shaft 2. The annular components 3, the central fixed shaft 2, and the annular sleeve 1 are coaxially arranged. The outer diameter of the several annular components 3 increases sequentially from the first end 11 to the second end 12. The outer diameter of a single annular component 3 is consistent at different axial positions. The inner ring surface of the annular component 3 is provided with a first micro-hole 31 for placing a sensor. The central fixed shaft 2 is provided with a through hole 21 extending along the axial direction of the annular sleeve 1. The through hole 21 is used for passing through the sensor wiring harness and for introducing cooling water. The central fixed shaft 2 is provided with a second micro-hole 22 corresponding to the first micro-hole 31. The second micro-hole 22 is for the sensor to pass through. The fuel delivery assembly is used to deliver fuel between the annular sleeve 1 and the central fixed shaft 2. The second end 12 is connected to the external space.

[0035] In this embodiment, the fuel delivery assembly is connected to the fuel source through a pipeline. The fuel delivered by the fuel delivery assembly to the annular sleeve 1 is a mixed gas, specifically a mixed gas of oxidant gas and reducing agent gas. In one embodiment, the oxidant gas can be air or oxygen, and the reducing agent is a combustible gas such as hydrogen, methane, etc.

[0036] This application utilizes the characteristic that flame combustion velocity is affected by a characteristic length scale. It employs a stacked annular flow channel to achieve modification of this characteristic length scale in a single experiment. By adjusting the fuel gas flow rate at the inlet, the flame automatically stabilizes at a corresponding characteristic length, obtaining a critical combustion velocity unaffected by the characteristic length scale, i.e., the laminar flame propagation velocity. Further reducing the flow rate, the minimum annular flow channel size at which the flame can maintain combustion is the flame quenching distance. Therefore, the laminar flame propagation velocity and quenching distance of a given gas mixture can be measured simultaneously in a single experiment.

[0037] The thickness of the ring 3 in the axial direction can maintain flame stability. Multiple rings with different outer diameters and the same inner diameter are made of high-temperature resistant material, and each ring 3 has the same thickness.

[0038] Sensors include temperature sensors and ion sensors.

[0039] The fuel delivery assembly comprises a ring-shaped premixing cavity 4, one end of which is fixedly connected with the first end 11, the ring-shaped premixing cavity 4 communicates with the ring-shaped sleeve 1, and the other end of the ring-shaped premixing cavity 4 is provided with an inner communication hole 41 and an air inlet hole 41, through which the ring-shaped premixing cavity 4 delivers fuel to the inner ring of the ring-shaped premixing cavity 4 passing through the center fixed shaft 2.

[0040] The ring-shaped premixing cavity 4 is provided with a porous medium partition 5 at one end close to the first end 11, the ring-shaped premixing cavity 4 communicates with the ring-shaped sleeve 1 through the porous medium partition 5, and the porous medium partition 5 is provided with an opening through which the center fixed shaft 2 passes. The porous medium partition 5 is fixed on the ring-shaped premixing cavity 4.

[0041] The heat insulation gasket 6 is arranged between the two adjacent circular ring members 3, the distance between the two adjacent first micro-holes 31 is equal to the axial thickness of the heat insulation gasket 6 and the circular ring member 3, the outer periphery of the center fixed shaft 2 close to the second end 12 is fixed with a ring-shaped boss 23, and the circular ring member 3 and the heat insulation gasket 6 are movably sleeved on the outer periphery of the center fixed shaft 2.

[0042] The ring-shaped sleeve 1 is made of quartz glass.

[0043] Before testing, the diameter D1 of the smallest circular ring member 3 P1 is selected according to the estimated laminar flame propagation speed value, and the diameter Dn of the largest circular ring member 3 Pn is selected according to the estimated quenching distance, and the difference between the inner diameter Di n of the transparent ring-shaped sleeve and the outer diameter Di of the largest circular ring member 3 is less than the quenching distance of the flame. The selected circular ring members 3 are sequentially sleeved on the center fixed shaft 2 in descending order, each circular ring member 3 is separated by a high-temperature-resistant heat insulation gasket 6 to prevent heat transfer between the circular ring members 3, and the first micro-hole 31 is aligned with the second micro-hole 22, a sensor is inserted into the center through hole 21 of the center fixed shaft 2, the sensor passes through the second micro-hole 22 first and then enters the first micro-hole 31, and the sensor is fixed in the first micro-hole, and the second upper micro-hole is sealed by a plug. Then, the fixed circular ring member 3 and the center fixed shaft 2 are placed inside the quartz glass cover, the center fixed shaft 2 is connected with the installed gas premixing cavity on the quartz glass cover, so that fuel can be introduced into the annular flow passage formed by the circular ring member 3 and the inner wall of the quartz glass.

[0044] A test method for flame speed and quenching distance, using the test device described above to perform the test method, the test method comprising:

[0045] Step 1, according to the estimated laminar flame propagation speed value, the diameter D1 of the smallest circular ring member 3 is selected, and the diameter Dn of the largest circular ring member 3 is selected according to the estimated quenching distance, the difference between the inner diameter Di n of the ring-shaped sleeve 1 and the outer diameter Di of the largest circular ring member 3 is less than the quenching distance of the flame, and the ring-shaped sleeve 1 is made of transparent material.

[0046] Step 2, fuel is input into the fuel input assembly, and the fuel is input into the annular sleeve 1 from the first end 11 through the fuel input assembly, and is ignited at the second end 12 to form flame propagation.

[0047] Step 3, gradually reduce the fuel flow rate input into the annular sleeve 1, the flame will continue to move to the larger outer diameter ring 3, and record the position of the flame at the current flow rate until the flame cannot be maintained and is extinguished.

[0048] Step 4, calculate the flame speed, form the length scale and the relationship of the flame speed, and analyze the laminar flame propagation speed and the quenching distance of the flame.

[0049] The position of the stable flame at the current flow rate is recorded in step 3 by using a high-speed camera or a temperature sensor / ion sensor in the first micro-hole 31.

[0050] The length scale at the position of the stable flame is the difference between the outer diameter Di of the ring 3 at the position of the stable flame and the inner diameter Di n of the annular sleeve 1.

[0051] At a given flow rate Vm of the fuel input assembly, the flame area without folding is Af=π(Di n2-Di2), and the flame speed is Vm / Af=π(Di n2-Di2). As shown in Figure 2 By plotting the fuel flow rate and the corresponding stable flame ring size, it can be observed that the critical speed at which the flame speed remains relatively constant within a certain flow rate range is the laminar flame propagation speed, Figure 2 The flame speed curve under different working conditions is shown in FIG. 2, and different symbols represent different working conditions. Figure 2 In FIG. 2, a represents the critical speed at which the flame speed remains relatively constant within a certain flow rate range, which is the laminar flame propagation speed.

[0052] The difference between the outer diameter of the ring 3 at the position of the extinguished flame and the inner diameter of the annular sleeve 1 is the quenching distance of the flame. Figure 2 In FIG. 2, b represents the size of the ring 3 at the position of the extinguished flame.

[0053] A flow meter is arranged on the pipeline for conveying fuel to the fuel input assembly, and the flow rate of the fuel conveyed to the fuel input assembly is obtained by the flow meter.

[0054] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements within the technical scope disclosed in the present application can be easily thought of by those skilled in the art, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A test apparatus for flame speed and quenching distance, characterised in that, The application relates to a test device for testing the quenching distance of a laminar flame, which comprises a ring sleeve (1), a fuel delivery assembly, a central fixed shaft (2) and a plurality of circular ring pieces (3), the ring sleeve (1) comprises a first end (11) and a second end (12), the first end (11) of the ring sleeve (1) is communicated with the output end of the fuel delivery assembly, the plurality of circular ring pieces (3) are sequentially arranged on the central fixed shaft (2) along the axial direction of the central fixed shaft (2), the circular ring piece (3), the central fixed shaft (2) and the ring sleeve (1) are coaxially arranged, the outer diameters of the plurality of circular ring pieces (3) are sequentially increased from the first end (11) to the second end (12), a first micropore (31) for placing a sensor is formed in the inner ring surface of the circular ring piece (3), the central fixed shaft (2) is internally provided with a through hole (21) extending along the axial direction of the ring sleeve (1), the through hole (21) is used for penetrating a sensor wire harness and for introducing cooling water, the central fixed shaft (2) is provided with a second micropore (22) corresponding to the first micropore (31), the second micropore (22) is used for penetrating the sensor, the fuel delivery assembly is communicated with the ring sleeve (1) and the central fixed shaft (2) and is used for delivering fuel, and the second end (12) is communicated with an external space. The fuel delivery assembly comprises a ring-shaped premixing cavity (4), one end of the ring-shaped premixing cavity (4) is fixedly connected with the second end (12), the ring-shaped premixing cavity (4) is communicated with the ring sleeve (1), the other end of the ring-shaped premixing cavity (4) is provided with an air inlet hole (41) and is internally communicated with the ring-shaped premixing cavity (4), and the central fixed shaft (2) penetrates the inner ring of the ring-shaped premixing cavity (4). The ring-shaped premixing cavity (4) is provided with a porous medium partition (5) at one end close to the second end (12), the ring-shaped premixing cavity (4) is communicated with the ring sleeve (1) through the porous medium partition (5), and the porous medium partition (5) is provided with an opening for the central fixed shaft (2) to penetrate.

2. The test apparatus for flame speed and quenching distance according to claim 1, characterized in that, Heat insulation gaskets (6) are arranged between two adjacent circular ring pieces (3), the distance between two adjacent first micropores (31) is equal to the axial thickness of the heat insulation gasket (6) and the circular ring piece (3), and an annular boss (23) is fixedly arranged on the outer periphery of the central fixed shaft (2) close to the second end (12), and the circular ring piece (3) and the heat insulation gasket (6) are movably sleeved on the outer periphery of the central fixed shaft (2).

3. The flame velocity and quenching distance testing apparatus of claim 1, wherein The ring sleeve (1) is made of quartz glass.

4. A method of testing flame speed and quenching distance, characterised in that, The test method is performed by using the test device in any one of claims 1-3, and the test method comprises the following steps: Step 1: the diameter D1 of the minimum circular ring piece (3) is selected according to the estimated laminar flame propagation speed value, the diameter Dn of the maximum circular ring piece (3) is selected according to the estimated quenching distance, the difference between the inner diameter Din of the ring sleeve (1) and the outer diameter Di of the maximum circular ring piece (3) is less than the quenching distance of the flame, and the ring sleeve (1) is made of transparent material; Step 2: fuel is input into the fuel input assembly, the fuel is input into the ring sleeve (1) from the first end (11) through the fuel input assembly, and the second end (12) is ignited to form flame propagation. Step 3, gradually reduce the fuel flow rate into the annular sleeve (1), the flame will continue to move to the larger ring (3), record the flow rate at which the flame is stable, until the flame can not be maintained and extinguished; Step 4, calculate the flame speed, form the length scale and the relationship of the flame speed, and analyze the laminar flame propagation speed and the quenching distance of the flame.

5. The test method for flame speed and quenching distance according to claim 4, wherein the position of the stable flame at the current flow rate is recorded by using a high-speed camera or a temperature sensor / ion sensor in the first micro-hole (31) in step 3.

6. The method of testing the flame speed and quenching distance according to claim 4, wherein, The length scale at the position of the stable flame is the difference between the outer diameter Di of the ring (3) at the position of the stable flame and the inner diameter Din of the annular sleeve (1); Under the flow rate Vm of the fuel input assembly, the flame area without folding is Af=π(Din2-Di2), and the flame speed is Vm / Af=π(Din2-Di2). Draw the relationship between the fuel flow rate and the flame speed, and the critical speed at which the flame speed remains relatively constant within a certain flow rate range is the laminar flame propagation speed.

7. The method of testing the flame speed and quenching distance according to claim 4, wherein The difference between the outer diameter of the ring (3) at the position where the flame is extinguished and the inner diameter of the annular sleeve (1) is the quenching distance of the flame.

8. The method of testing the flame speed and quenching distance according to claim 4, wherein, A flow meter is arranged on the pipeline for conveying fuel to the fuel input assembly to obtain the flow rate of the fuel conveyed to the fuel input assembly.

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