An analysis method and system for laminar diffusion jet flame stability

Abstract

This invention discloses a method and system for analyzing the steady-state of a laminar diffusion jet flame, relating to the field of gas turbine combustion technology. The method includes: obtaining the instantaneous propagation velocity of the laminar jet diffusion flame when the flame root reaches its final stable position during propagation towards the nozzle. S d and the local airflow velocity at that location U G ;according to S d and U G Determine the instantaneous combustion rate; compare the instantaneous combustion rate with... U G If the difference between the two is within a preset range, it indicates that the combustion rate and the local airflow velocity are in dynamic equilibrium, and it is determined to be a pusher flame; if the instantaneous combustion rate is greater than 1, it indicates that the combustion rate and the local airflow velocity are in dynamic equilibrium, and it is determined to be a pusher flame. U G If the difference exceeds a preset range, it indicates that the flame propagation and the extinction caused by heat loss are in equilibrium, and the flame is identified as an attached flame. This invention achieves precise identification of the flame's stable state by quantifying the comparison between combustion rate and airflow rate, providing a quantitative basis for combustion adjustment and significantly reducing operational blindness and time costs. A corresponding analysis system is also provided.

Description

Technical Field

[0001] This invention relates to the field of gas turbine combustion technology, specifically to a method and system for analyzing the steady state of laminar diffusion jet flames. Background Technology

[0002] Jet-diffused flames are widely used in the energy and power sector, such as in gas turbines and industrial boilers. The stability characteristics of the flame are one of the core issues in diffusion flame research, and understanding the stable behavior of jet-diffused flames is of great significance for guiding the design of combustion equipment and fire safety control.

[0003] Based on the stable position of the flame root, jet flames typically exhibit two basic stable states: when the flame root stabilizes in a certain area upstream of the burner nozzle, it is called an attached flame; when the jet velocity or environmental conditions change, the flame root detaches from the nozzle and stabilizes in a certain position downstream, forming a lifter flame. Currently, there is a consensus in academia regarding the stabilization mechanism of laminar lifter flames, which is considered to be based on the dynamic balance between laminar combustion velocity and local airflow velocity. However, there are still differing opinions in academia regarding the stabilization mechanism of laminar attached flames: some scholars believe that the stabilization mechanism of attached flames is similar to that of lifter flames; others point out that the fuel / oxidizer mixing layer near the root of the attached flame is extremely narrow, making it difficult to form a typical premixed flame structure, thus the theory of lifter flames cannot be directly applied.

[0004] In actual combustion equipment operation, the flame state needs to be adjusted according to operating conditions to switch between attached and lifted flames. Existing adjustment methods mainly involve changing the jet velocity, wake velocity, or dilution level. However, the prerequisite for adjustment is accurate judgment of the current flame state: generally, when the flame root is attached to a certain position upstream of the burner nozzle, it is an attached flame; when the flame root is located a certain position downstream of the nozzle, it is a lifted flame. However, in actual observation, when the flame root is exactly near the nozzle, or maintains a very small distance from the nozzle, its state characteristics are ambiguous, making it difficult to clearly determine whether the flame belongs to an attached or lifted flame. This ambiguity in state judgment directly leads to a lack of clear basis for subsequent adjustment strategy selection. Operators often rely on experience and repeated trial and error, making the combustion adjustment process highly unpredictable and significantly increasing the time cost of adjustment. Summary of the Invention

[0005] To address the problem in existing technologies where the lack of understanding of the stabilization mechanism of laminar attached flames leads to difficulties in accurately determining the state of the flame root near the nozzle and resulting in blind combustion adjustments, this invention provides a method and system for analyzing the stabilization state of laminar diffusion jet flames. Based on a quantitative analysis of the propagation process of a portion of the premixed flame in the mixing layer at the root of a laminar attached jet diffusion flame, a dynamic stabilization mechanism is proposed, involving the balance between flame propagation and the extinguishing phase caused by heat loss. This enables precise analysis of the stabilization behavior of the attached flame.

[0006] This invention is achieved through the following technical solution: A method for analyzing the steady state of a laminar diffusion jet flame includes the following steps: Obtain the instantaneous propagation velocity of the laminar jet diffused flame when the flame root reaches its final stable position during propagation towards the nozzle. S d and the local airflow velocity at the final stable position. U G ; According to the instantaneous propagation speed S d With local airflow velocity U G Determine the instantaneous combustion rate at the final stable position; Compare the instantaneous combustion rate with the local airflow rate. U G ; If the instantaneous combustion speed is greater than the local airflow speed U G If the difference is within a preset range, it indicates that the combustion rate and the local airflow rate are in dynamic equilibrium, and the laminar jet diffusion flame is determined to be a push flame. If the instantaneous combustion speed is greater than the local airflow speed U G If the difference between the two exceeds the preset range, it indicates that the flame propagation and the extinguishing caused by heat loss are in balance, and the laminar jet diffusion flame is determined to be an attached flame.

[0007] Preferably, the acquisition of instantaneous propagation speed S d The steps include: Ignite at a certain distance downstream of the nozzle outlet and record images of the flame propagating towards the nozzle. Based on the process image, obtain the evolution curve of the flame root position over time; Differentiating the evolution curve yields the instantaneous propagation velocity along the flame root. The instantaneous propagation velocity at the final stable position of the attached flame is then taken as... S d .

[0008] Preferably, the local airflow velocity U G It is obtained through particle image velocimetry or through velocity similarity equations in laminar jet theory.

[0009] Preferably, the instantaneous combustion speed is the same as the instantaneous propagation speed. S d With the local airflow velocity U G sum.

[0010] Preferably, it also includes a combustion adjustment step: When it is necessary to convert the push flame into an attached flame, reduce the local airflow velocity at the root of the flame so that the flame can propagate upstream until it reattaches to the nozzle. Preferably, when it is necessary to convert the attached flame into a pusher flame, the local airflow velocity at the flame root is increased, or the combustion velocity at the flame root is decreased, so that the flame is pushed downstream to the target position.

[0011] Preferably, the method of reducing the local airflow velocity at the flame root includes: gradually reducing the fuel supply or air supply; The methods for increasing the local airflow velocity at the root of the flame include: gradually increasing the fuel supply or air supply. The methods for reducing the combustion rate at the flame root include: gradually increasing the dilution level on the fuel side or the air side.

[0012] A system for analyzing the steady state of a laminar diffusion jet flame includes: The acquisition module is used to obtain the instantaneous propagation velocity of the laminar jet diffused flame when the flame root reaches the final stable position during its propagation towards the nozzle. S d and the local airflow velocity at the final stable position. U G ; The speed measurement module is used to measure the instantaneous propagation speed. S d With local airflow velocity U G Determine the instantaneous combustion rate at the final stable position; The judgment module is used to compare the instantaneous combustion speed with the local airflow speed. U G ; If the instantaneous combustion speed is greater than the local airflow speed U GIf the difference is within a preset range, it indicates that the combustion rate and the local airflow rate are in dynamic equilibrium, and the laminar jet diffusion flame is determined to be a push flame. If the instantaneous combustion speed is greater than the local airflow speed U G If the difference between the two exceeds the preset range, it indicates that the flame propagation and the extinguishing caused by heat loss are in balance, and the laminar jet diffusion flame is determined to be an attached flame.

[0013] A computer device includes: a processor and a computer-readable storage medium; The processor is adapted to execute computer programs; The computer-readable storage medium stores a computer program, which, when executed by the processor, implements the method for analyzing the stable state of a laminar diffusion jet flame as described above.

[0014] A computer-readable storage medium storing a computer program adapted to be loaded by a processor and executed as described in the method for analyzing the steady state of a laminar diffusion jet flame.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This application provides a method for analyzing the steady state of a laminar diffusion jet flame, the core of which lies in obtaining the instantaneous propagation velocity from the flame root to the nozzle. S d Local airflow velocity at the final stable position U G This allows for the determination of instantaneous combustion speed and, based on this, the flame type. The principle behind this technical solution lies in its novel differentiation of the different stabilization mechanisms of push flames and attached flames: for push flames, the difference between the instantaneous combustion speed and the local airflow speed is within a preset range, indicating a dynamic equilibrium; for attached flames, the instantaneous combustion speed is greater than the local airflow speed, and the difference exceeds the preset range, indicating that flame propagation is not balanced by the airflow speed, and its stability depends on the balance between flame propagation and the extinguishing phase caused by heat loss. The technical advantage of this solution is that it overcomes the limitations of traditional methods that rely solely on the flame root position for fuzzy discrimination. By quantifying the comparison between combustion speed and airflow speed, it achieves precise discrimination of the flame's stable state, providing a clear quantitative basis for combustion adjustment, significantly reducing operational blindness and time costs, and offering important guidance for the optimized design and operational control of combustion equipment such as gas turbines and industrial boilers.

[0016] This application also proposes an analysis system for the steady state of laminar diffusion jet flames, an electronic device, and a computer storage medium, which possess all the advantages of the aforementioned analysis methods for the steady state of laminar diffusion jet flames. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 These are color photographs and schlieren images showing the flame propagation process in embodiments of the present invention, wherein (a1, a2) represent attached flames and (b1, b2) represent pushed flames; Figure 2 The diagrams show the analysis of conduction and convection heat loss at the flame root under different conditions in the embodiments of the present invention, where (a) is the result under different wall thermal conditions, (b) is the result under different jet velocities, and (c) is the result under different jet velocities.

[0019] Figure 3 This is a flowchart illustrating the analysis of the stable state of the laminar diffusion jet flame according to the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0022] See Figure 3 A method for analyzing the steady state of a laminar diffusion jet flame includes the following steps: Step 1: Conduct a laminar flow attached jet diffusion flame experiment. Ignite the flame at a distance downstream of the nozzle outlet and record images of the flame propagation process towards the nozzle. Step 2: Based on the flame propagation process image, obtain the evolution curve of the flame root position over time. Differentiating this curve yields the instantaneous propagation velocity along the flame root. The instantaneous flame propagation velocity at the final stable position of the attached flame is taken as the instantaneous propagation velocity. S d ; Step 3: Measure the local airflow velocity in the region where the attached flame finally stabilizes using particle image velocimetry. U G ; Step 4: Instantaneous flame propagation speed S d With local airflow velocity U G Add them together to obtain the instantaneous combustion rate of the laminar attached jet diffusion flame in the stable point region; The instantaneous combustion rate is compared with the local airflow velocity of the fuel / air mixture; 1) If the difference between the two is within the preset range, it means that the stability of the laminar flow attached jet diffusion flame is based on the balance between the combustion rate and the local airflow rate, and the jet diffusion flame is a push flame. 2) If the instantaneous combustion velocity is greater than the local airflow velocity and exceeds the preset range, it should be noted that for laminar attached jet diffusion flames, the local airflow velocity... U G The propagation of the premixed flame in the fuel / air mixture layer is not balanced by the instantaneous combustion rate at the flame root. The propagation of the premixed flame is eventually terminated due to the adhesion of the flame. Therefore, the jet diffusion flame is an adhered flame. Step 5: Adjust the combustion parameters to stabilize the flame.

[0023] Based on the analysis of flame stabilization mechanisms, rapid and precise control of flame conditions can be achieved. The specific methods are as follows: 1. The push flame is converted into an attached flame; After ignition, a stable pusher flame is formed downstream of the burner nozzle. When the target state is an attached flame, the flame is gradually propagated upstream until it reattaches to the nozzle by reducing the local airflow velocity at the flame root. Specifically, this involves gradually reducing the fuel supply or air supply.

[0024] 2. The attached flame transforms into a lifting flame; After ignition, a stable attached flame is formed near the burner nozzle. If the target state is a pushed flame, the flame is gradually pushed downstream to the target position by increasing the local airflow velocity at the flame root or decreasing the combustion velocity at the flame root. Specific implementation methods include, but are not limited to, any one or more combinations of the following: Gradually increase the supply of fuel or air; Gradually increase the dilution level on the fuel side or air side, such as by adding inert gases like nitrogen.

[0025] To verify the accuracy of the above-mentioned method for analyzing the stable behavior of laminar attached diffused jet flames, this invention analyzes the heat loss characteristics near the flame root through numerical simulation. The specific process is as follows: 1. Numerical Model Construction Studies have shown that cold-wall flameout in laminar premixed flames is caused by localized extinction due to heat loss. For laminar attached diffusion flames, this type of localized extinction may also be the cause of partial premixed flame propagation termination within the mixing layer at the flame root. To verify this hypothesis, a two-dimensional axisymmetric numerical model was constructed to simulate a laminar fuel / air jet diffusion flame.

[0026] The finite volume method was used to discretize the mass, momentum, energy, and component transport equations, and the SIMPLEC algorithm was applied to handle the pressure-velocity coupling problem. Since the radiant heat from the flame root has no direct and significant impact on the burner wall temperature, flame stability behavior, and the structure of small-sized laminar jet diffusion flames, the effect of thermal radiation was neglected in the numerical model.

[0027] 2. Definition of heat loss parameters A small region at the root of a laminar attached diffusion flame is selected as the object of analysis, and the temperature of this region is assumed to be... T f The heat flow rate caused by heat conduction. q cond Heat flow rate caused by heat convection q conv They are represented as follows: (1) (2) In the formula, K Thermal conductivity, T wall Indicates the wall temperature. T u This indicates the temperature of the local incoming gas. l This is the distance between the flame root and the nozzle edge. ρ f For the mixed gas at a temperature of T f Density at time C p This indicates the specific heat capacity of the fuel at constant pressure.

[0028] 3. Analysis of heat loss characteristics Based on the above numerical model, and combining equations (1) and (2), the thermal conductivity of the flame root under different wall thermal boundary conditions and different fuel jet velocities is obtained.q cond ) and convective heat flow rate ( q conv By comparing and analyzing the thermal conductivity and convective heat loss characteristics of the flame root under different conditions, and combining this with the stable behavior of the flame, a dynamic stabilization mechanism for the balance between flame propagation and the extinction phase caused by heat loss is proposed.

[0029] The numerical simulation results and theoretical analysis corroborate each other, verifying the accuracy of the laminar attached diffusion jet flame stability behavior analysis method proposed in this invention.

[0030] Example 1 A method for analyzing the steady state of a laminar diffusion jet flame includes the following steps: Step 1: Conduct a laminar flow attached jet diffusion flame experiment and record images of the flame propagation process. Ignition is performed at a point relatively downstream of the nozzle. A clear laminar flame front will propagate along the fuel-air mixture, which gradually narrows as the axial distance decreases. Images of the flame propagation process towards the nozzle are recorded.

[0031] like Figure 1 The image shown is a color photograph and schlieren image illustrating the flame propagation process, where (a1) and (a2) represent the flame in its final attached state, (U j = 1.05 m / s, Xf = 0.40, Uair = 0 m / s); (b1) and (b2) represent the flame in the final push state, (U j = 1.10 m / s, Xf = 0.40, Uair = 0.32 m / s); the flame propagation speed can be obtained through this process. When the flame root is far from the nozzle, a very clear three-pronged flame structure is observed ( Figure 1 (a1) and (b1)). However, during flame propagation, the radial distance between the RPF (rich premixed flame) and DF (diffusion flame) branches continuously decreases, while the LPF (lean premixed flame) branches gradually disappear. These changes in the flame root structure are mainly caused by changes in the mixing layer between fuel and air (the mixing layer narrows as the axial height of the flame root decreases).

[0032] Step 2: Obtain the propagation speed at the base of the flame Based on the flame propagation process image, the evolution curve of the flame root position over time is obtained. Differentiating this curve yields the instantaneous propagation velocity along the flame root path. The instantaneous flame propagation velocity at the final stable position of the attached flame is taken as the instantaneous propagation velocity. S d .

[0033] Step 3: Measure the local airflow velocity The local airflow velocity in the region of the final stabilization point of the attached flame is measured using particle image velocimetry. U G Within a reasonable margin of error, this velocity can be successfully predicted by the velocity similarity equation in laminar jet theory.

[0034] Step 4: Compare the combustion rate with the local airflow rate. The instantaneous flame propagation speed S d With local airflow velocity U G The values ​​are added together to obtain the instantaneous combustion rate of the laminar attached jet diffuser flame in the steady-state region. This instantaneous combustion rate is then compared with the local airflow velocity of the fuel / air mixture.

[0035] Studies have found that the cold wall extinction phenomenon of laminar premixed flames is caused by local extinction due to heat loss. For laminar attached diffusion flames, this type of local extinction may also be the reason why the propagation of some premixed flames in the mixing layer at the flame root is terminated.

[0036] Step 5: Numerical simulation analysis of heat loss characteristics To verify the above conjecture, a two-dimensional axisymmetric model was used to simulate a laminar fuel / air jet diffusion flame, further analyzing the heat loss characteristics near the flame root. The finite volume method was employed to discretize the mass, momentum, energy, and component transport equations, and the SIMPLEC algorithm was applied to handle the pressure-velocity coupling. Since the heat radiated from the flame root has no direct and significant impact on the burner wall temperature, flame stability, or the structure of small-sized laminar jet diffusion flames, the effect of thermal radiation was neglected in the numerical simulation model.

[0037] While the one-step turnbuffered reaction mechanism cannot yield detailed flame structure results, it can provide reasonable results for the temperature and velocity fields. Furthermore, the laminar combustion rate of the equivalence mixture under different conditions, the changes in the stable position of the flame root, and heat losses due to conduction and convection can be reasonably predicted.

[0038] Three sets of numerical simulations were conducted for a fixed type of fuel (methane mass fraction, Xf = 0.34): Group 1: Fixed-center fuel jet velocity and accompanying air velocity (U j = 4.0 m / s, Uair = 0.05 m / s), by applying different thermal conditions (adiabatic, 273 K, 373 K, 473 K, 573 K, 673 K and 773 K) to the burner wall, this study focuses on the effect of heat loss caused by heat conduction from the flame root to the wall on the stability of the attached flame.

[0039] Group 2: Change the central fuel jet velocity (0.5 m / s - 5.0 m / s, Uair = 0.05 m / s, wall temperature 273 K) to focus on the effect of thermal convection between the flame root and the local incoming flow on the stability of the attached flame.

[0040] Group 3: Change the wake air velocity (0.05 m / s - 0.25 m / s, U j = 0.5 m / s, wall temperature 273K), focusing on the effect of thermal convection between the flame root and the local incoming flow on the stability of the attached flame.

[0041] Step 6: Analyze heat loss characteristics Numerical simulations were used, combined with equation (1-2), to obtain the heat conduction at the flame root under different wall thermal boundary conditions and different fuel jet velocities. q cond ) and convection ( q conv By comparing and analyzing the heat conduction and convective heat loss characteristics of the flame root under different conditions and combining them with the stable behavior of the flame, a dynamic stabilization mechanism for the balance between flame propagation and extinction caused by heat loss is proposed.

[0042] Figure 2 (ac) represent the heat conduction at the flame root under different wall thermal boundary conditions, different fuel jet velocities, and different flow velocities, respectively. q cond ) and convection ( q conv ) Flow rate.

[0043] For insulated walls, heat loss near the flame root is primarily controlled by thermal convection. For example... Figure 2 As shown in Figure a, the wall temperature increases, leading to greater heat loss from the flame root to the nozzle edge. According to formula (1). q cond and( T f – T wall )and l -1 If they are directly proportional, then the competition between these two factors is crucial to the changing trend of heat conduction and heat loss. T wall Linear effect ( T f – T wall The size of ) but for l -1 The effect is nonlinear (due to the characteristic time of the chemical reaction), because l -1 forq cond The influence outweighed ( T f – T wall ),lead to q cond Follow T wall It increases with the increase of wall temperature. T wall At K = 773 K, the axial height of the flame root attachment point is relatively low, resulting in significant thermal loss (see...). Figure 2 a), but it seems so small l The value actually promotes the propagation of some premixed flames at the flame root into a narrower mixing layer.

[0044] Local heat loss near the flame root under different fuel jet velocities, such as Figure 2 As shown in b, convective heat loss can be observed. q conv With the jet velocity U j The flame height increases with the increase of the flame, thus requiring a thicker mixing layer to maintain the local partial premixed flame, which in turn causes the flame stability height to increase.

[0045] Figure 2 c represents the local heat loss under different current velocities, where q conv The trend and Figure 2 The results in b are similar, but the slope is greater, which makes the flame stabilize at a higher position, consistent with the results of experiments and numerical simulations. U air Enlargement, causing Figure 2 c q cond The reduction is mainly due to l The increase and T f The reduction in [something] is likely the main reason for the sustained stability of the flame under these conditions. Note q conv right U air Extremely sensitive, even exceeding [a certain threshold] at certain traverse velocities. q cond This indicates that the stability of the attached diffusion flame is more sensitive to the wake and is more easily controlled by the wake.

[0046] like Figure 2 As shown, except U air Except for a few cases ≥ 0.15 m / s, q cond All are greater than those under the corresponding conditionsq conv .and, q cond The share of total heat loss (defined as) q cond / ( q cond + q conv The finite element value (olive-colored solid dots) is mainly in the range of 0.50-0.60, reaching 0.37 or 0.70 in some extreme cases. Therefore, the heat loss through conduction to the wall plays a relatively important role in the stability of the attached diffusion flame without a faucet (or with a small amount of faucet). As the faucet velocity increases, the convective heat loss between the flame root and the local incoming flow gradually becomes the key factor for flame stability.

[0047] In summary, the stability of laminar attached flames is due to the extinguishing of some premixed flames in the mixing layer near the root caused by heat loss due to conduction and local convection. This is different from the stability mechanism of laminar push flames, which is based on the balance between the local airflow velocity at the flame root and the maximum laminar combustion velocity.

[0048] Step 7: Adjust the combustion parameters to achieve the mutual conversion between the push flame and the attached flame. Based on the analysis of flame stabilization mechanisms, rapid and precise control of flame conditions can be achieved. The specific methods are as follows: Conversion of push flame to attached flame After ignition, a stable pusher flame is formed downstream of the burner nozzle. When the target state is an attached flame, the flame is gradually propagated upstream until it reattaches to the nozzle by reducing the local airflow velocity at the flame root. Specifically, this involves gradually reducing the fuel supply or air supply.

[0049] Conversion from attached flame to lifting flame After ignition, a stable attached flame is formed near the burner nozzle. If the target state is a pushed flame, the flame is gradually pushed downstream to the target position by increasing the local airflow velocity at the flame root or decreasing the combustion velocity at the flame root. Specific implementation methods include, but are not limited to, any one or more combinations of the following: Gradually increase the supply of fuel or air; Gradually increase the dilution level on the fuel side or air side, such as by adding inert gases like nitrogen.

[0050] Example 2 A system for analyzing the steady state of a laminar diffusion jet flame includes: The acquisition module is used to obtain the instantaneous propagation velocity of the laminar jet diffused flame when the flame root reaches the final stable position during its propagation towards the nozzle. S dand the local airflow velocity at the final stable position. U G ; The speed measurement module is used to measure the instantaneous propagation speed. S d With local airflow velocity U G Determine the instantaneous combustion rate at the final stable position; The judgment module is used to compare the instantaneous combustion speed with the local airflow speed. U G ; If the instantaneous combustion speed is greater than the local airflow speed U G If the difference is within a preset range, it indicates that the combustion rate and the local airflow rate are in dynamic equilibrium, and the laminar jet diffusion flame is determined to be a push flame. If the instantaneous combustion speed is greater than the local airflow speed U G If the difference between the two exceeds the preset range, it indicates that the flame propagation and the extinguishing caused by heat loss are in balance, and the laminar jet diffusion flame is determined to be an attached flame.

[0051] It should be noted that, in the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules may be combined or integrated into another device, or some features may be ignored or not executed. The modules described as separate components may or may not be physically separated. The components shown as modules may be one or more physical units, that is, they may be located in one place or distributed in multiple different places. Some or all of the modules can be selected to achieve the purpose of the solution in this embodiment according to actual needs.

[0052] Furthermore, in the various embodiments of the present invention, the modules can be integrated into one processing unit, or each module can exist physically separately, or two or more modules can be integrated into one unit. The integrated unit described above can be implemented in hardware or as a software functional unit.

[0053] An electronic device provided in this application includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the steps of the analysis method for the stable state of laminar diffusion jet flame as described in any of the above embodiments.

[0054] Another electronic device provided in this application embodiment may further include: an input port connected to a processor for transmitting multimodal data collected by an external acquisition device to the processor; a display unit connected to the processor for displaying the processor's processing results to the outside world; and a communication module connected to the processor for enabling communication between the electronic device and the outside world. The display unit may be a display panel, a laser scanning display, etc.; the communication method adopted by the communication module includes, but is not limited to, Mobile High Definition Link (HML), Universal Serial Bus (USB), High Definition Multimedia Interface (HDMI), and wireless connection (including Wi-Fi, Bluetooth, Bluetooth Low Energy, and IEEE 802.11s-based communication technology).

[0055] This application provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the steps of the analysis method for the stable state of laminar diffusion jet flame as described in any of the above embodiments.

[0056] For descriptions of relevant parts in the laminar diffusion jet flame stability analysis system, electronic device, and computer-readable storage medium provided in this application's embodiments, please refer to the detailed descriptions of the corresponding parts in the laminar diffusion jet flame stability analysis method provided in this application's embodiments; they will not be repeated here. Furthermore, parts of the technical solutions provided in this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0057] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for analyzing the steady state of a laminar diffusion jet flame, characterized in that, Includes the following steps: Obtain the instantaneous propagation velocity of the laminar jet diffused flame when the flame root reaches its final stable position during propagation towards the nozzle. S d and the local airflow velocity at the final stable position. U G ; According to the instantaneous propagation speed S d With local airflow velocity U G Determine the instantaneous combustion rate at the final stable position; Compare the instantaneous combustion rate with the local airflow rate. U G ; If the instantaneous combustion speed is greater than the local airflow speed U G If the difference is within a preset range, it indicates that the combustion rate and the local airflow rate are in dynamic equilibrium, and the laminar jet diffusion flame is determined to be a push flame. If the instantaneous combustion speed is greater than the local airflow speed U G If the difference between the two exceeds the preset range, it indicates that the flame propagation and the extinguishing caused by heat loss are in balance, and the laminar jet diffusion flame is determined to be an attached flame.

2. The method for analyzing the steady state of a laminar diffusion jet flame according to claim 1, characterized in that, The acquisition of instantaneous propagation speed S d The steps include: Ignite at a certain distance downstream of the nozzle outlet and record images of the flame propagating towards the nozzle. Based on the process image, obtain the evolution curve of the flame root position over time; Differentiating the evolution curve yields the instantaneous propagation velocity along the flame root. The instantaneous propagation velocity at the final stable position of the attached flame is then taken as... S d .

3. The method for analyzing the steady state of a laminar diffusion jet flame according to claim 1, characterized in that, The local airflow velocity U G It is obtained through particle image velocimetry or through velocity similarity equations in laminar jet theory.

4. The method for analyzing the steady state of a laminar diffusion jet flame according to claim 1, characterized in that, The instantaneous combustion speed is the instantaneous propagation speed. S d With the local airflow velocity U G sum.

5. The method for analyzing the steady state of a laminar diffusion jet flame according to claim 1, characterized in that, It also includes combustion adjustment steps: When it is necessary to convert the push flame into an attached flame, the local airflow velocity at the flame root is reduced, allowing the flame to propagate upstream until it reattaches to the nozzle orifice.

6. The method for analyzing the steady state of a laminar diffusion jet flame according to claim 5, characterized in that, When it is necessary to convert the attached flame into a pusher flame, increase the local airflow velocity at the flame root or decrease the combustion velocity at the flame root to push the flame downstream to the target location.

7. The method for analyzing the steady state of a laminar diffusion jet flame according to claim 1, characterized in that, The methods for reducing the local airflow velocity at the flame root include: gradually reducing the fuel supply or air supply. The methods for increasing the local airflow velocity at the root of the flame include: gradually increasing the fuel supply or air supply. The methods for reducing the combustion rate at the flame root include: gradually increasing the dilution level on the fuel side or the air side.

8. A system for analyzing the steady state of a laminar diffusion jet flame, characterized in that, include: The acquisition module is used to obtain the instantaneous propagation velocity of the laminar jet diffused flame when the flame root reaches the final stable position during its propagation towards the nozzle. S d and the local airflow velocity at the final stable position. U G ; The speed measurement module is used to measure the instantaneous propagation speed. S d With local airflow velocity U G Determine the instantaneous combustion rate at the final stable position; The judgment module is used to compare the instantaneous combustion speed with the local airflow speed. U G ; If the instantaneous combustion speed is greater than the local airflow speed U G If the difference is within a preset range, it indicates that the combustion rate and the local airflow rate are in dynamic equilibrium, and the laminar jet diffusion flame is determined to be a push flame. If the instantaneous combustion speed is greater than the local airflow speed U G If the difference between the two exceeds the preset range, it indicates that the flame propagation and the extinguishing caused by heat loss are in balance, and the laminar jet diffusion flame is determined to be an attached flame.

9. A computer device, characterized in that, include: Processor and computer-readable storage media; The processor is adapted to execute computer programs; The computer-readable storage medium stores a computer program, which, when executed by the processor, implements the method for analyzing the stable state of a laminar diffusion jet flame as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program adapted to be loaded by a processor and executed by the method for analyzing the steady state of a laminar diffusion jet flame as described in any one of claims 1-7.

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