JP2008281314A - Method and device for controlling flame of jet type coombustor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method and a device therefor, capable of precisely controlling the direction and the size of a flame by a simple technique on a floating jet diffusing flame. <P>SOLUTION: This flame control method of a jet type combustor controls combustion in the jet type combustor 1 by changing a floating jet flame by exciting vibration in a flame flowing field. Thus, optimal combustion operation can be realized for improving stability in the flame such as the expansion of a blowing-off limit, in addition to a change in the floating height of a floating flame, by adjusting vibration exciting strength and a position of the flame flowing field for exciting the vibration. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control method capable of accurately controlling the direction and size of a flame in a jet-type combustor and an apparatus therefor.

  Over the years, various technological developments such as exhaust heat regeneration for improving the efficiency of heat engines, development of new materials for increasing combustion temperature, and post-treatment technology for reducing harmful emissions have been carried out. On the other hand, in terms of improving the combustion itself, there is a trade-off relationship between combustion efficiency and harmful emissions, and it is a very complicated phenomenon. Was difficult. In recent years, with the aim of optimizing this combustor, academic combustion phenomena have also been elucidated. Combustion simulation technology by remarkably improving computer performance, as well as new materials and electronic control technology, will lead to new technologies. Attempts have been made to develop combustion systems. Examples include next-generation combustion technologies such as HiCOT, distributed power systems such as micro gas turbines, and next-generation diesel engine combustion technologies using piezo injectors. In order to develop such an ideal next-generation combustor, it is necessary to elucidate basic combustion phenomena and to develop various technologies that can be applied to actual combustors. It is important to let them.

  The combustion state of a flame is classified into two types, a premixed flame and a diffusion flame, depending on the mixed state of fuel and oxidant before combustion. The premixed flame is a flame that burns in a state where the fuel and the oxidant are mixed in advance, and has a propagating property. On the other hand, a diffusion flame (non-premixed flame) is a flame in which fuel and oxidant are separately supplied to a burner, and mixing thereof is performed by a diffusion process and burns. The progress of combustion is governed by the diffusion rate of fuel and oxidant, and does not have the propagating properties of premixed flames.

Therefore, since diffusion flames do not cause dangerous phenomena such as flashback and explosion, jet diffusion flames are widely used in actual combustors, and there are many research examples. This jet diffusion flame is expected to reduce NO _x by raising the flame from the burner. Fujimori, etc. is facilitated mixing of fuel and oxidant upstream of the flame base (most upstream portion of the flame that standing in a state of floating from Banarimu) floating, it is reported to be effective in NO _x reduction. This floating jet flame has an advantage that the flame is lifted from the jet burner to avoid contact with the burner rim and to prevent damage to materials such as metal constituting the burner rim. On the other hand, the flame is inferior in stability and easily blown off as compared with a flame adhered to a burner rim or a flame held by a pilot burner or the like.

Conventionally, in low-NO _x combustion apparatus, techniques such as to ensure and combustion amount varying achieving further lower NO _x reduction by further thinning the concentration of dilute flame has been proposed. Specifically, a lean flame port that communicates with the lean chamber and supplies a lean mixture, a first flame port that communicates with the first mixture chamber adjacent to the lean chamber and is close to the lean flame port, and the first A second flame port provided in close proximity to the first flame port in communication with the second gas mixture chamber adjacent to the gas mixture chamber, wherein the concentration of the first gas mixture chamber is higher than the concentration of the second gas mixture chamber; At the same time, the flow rates of the lean mixture, the first mixture, and the second mixture are increased or decreased at the same rate, and even when the combustion amount is increased or decreased, Because the flow pattern of the rich mixed gas ejected from the flow is similar and the flow concentration difference is maintained, material diffusion from the rich mixed gas is stably maintained, and the concentration of the lean mixed gas is reduced to a very low level. it is intended to reduce the NO _x reduction (e.g., see Patent Document 1).

JP 2002-48337 A (page 6, FIG. 1)

  However, the control of the rising jet diffusion flame by controlling the concentration of the lean air-fuel mixture as in Patent Document 1 is advantageous for improving the efficiency of the actual combustor and reducing the environmental load. However, it is not yet sufficient as a stability control, and it is not possible to achieve both a reduction in harmful emissions such as nitrogen oxides in the exhaust gas and a combustion state in which the combustion temperature is increased as much as possible.

  In the present invention, the stability of the rising jet diffusion flame depends on the characteristics of the flame base, particularly at the most upstream end of the flame. This is because there is a region where the fuel and oxidant are partially premixed from the burner outlet to the flame base, and depending on the degree of premixing, the flame base has propagating properties and flows into it. In consideration of the fact that it is fixed at a height that matches the flow velocity, aiming at optimization of the actual combustor, focusing on the flow field and mixing field upstream of the flame as factors that influence the combustion state of the rising jet flame, It is an object of the present invention to provide a control method and an apparatus therefor capable of accurately controlling the direction and size of a flame by a method of actively controlling a floating jet diffusion flame by a simple method.

In order to solve the above problem, a flame control method for a jet-type combustor according to claim 1 of the present invention provides:
It is characterized by controlling the combustion in a jet-type combustor by changing the jet flame by raising vibration excitation in the flow field of the flame.
According to this feature, by adjusting the strength of vibration excitation, the position of the flow field of the flame that gives vibration excitation, etc., in addition to changes in the lift height of the rising flame, etc. This makes it possible to achieve optimal combustion operation for improving stability.

A flame control method for a jet type combustor according to claim 2 of the present invention is the flame control method for a jet type combustor according to claim 1,
The flow field of the flame to which the vibration excitation is applied is a flow field or a mixing field upstream of the flame.
According to this feature, it was found that the factor that determines the combustion state of the rising jet flame is the flow field or mixing field upstream of the flame, and optimal control is possible by controlling this part with vibration excitation. Become.

The flame control method for a jet type combustor according to claim 3 of the present invention is the flame control method for a jet type combustor according to claim 1 or 2,
When deflecting the deflection direction of the flame to the ventral side of the pressure in the standing wave as the control of the deflection direction of the flame, the density of the fuel system is selected to be smaller than the surrounding gas and the deflection direction of the flame is set to the standing wave. In the case of deflecting to the node side of the pressure, the density of the fuel system is selected to be larger than the surrounding gas.
According to this feature, the deflection direction of the flame can be easily controlled by selecting the density of the fuel system.

A flame control device for a jet-type combustor according to claim 4 of the present invention,
A vibration excitation means is arranged in the vicinity of the flame flow field, and the vibration control is performed by applying vibration excitation to the flame flow field by the vibration excitation means to change the floating jet flame.
According to this feature, by adjusting the strength of vibration excitation, the position of the flow field of the flame that gives vibration excitation, etc., in addition to changes in the lift height of the rising flame, etc. This makes it possible to achieve optimal combustion operation for improving stability.

The flame control device for a jet combustor according to claim 5 of the present invention is the flame control device for a jet combustor according to claim 4,
The vibration excitation means is high-frequency vibration that forms a standing wave between a pair of vibration surfaces and a reflection surface.
According to this feature, the jet center is located near the center of the standing wave pressure node and the antinode, so that the jet can be deflected, and the turbulence of the jet can be promoted by vibration excitation. Compared with the case where the fuel is not performed, the effect of promptly mixing the fuel and the oxidant can be effectively obtained.

  Examples of the present invention will be described below.

  An embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 is an overall view of a fuel and oxidant supply system supplied to a jet-type combustor. FIG. 2 is a photograph of a floating jet flame formed on the burner and a partial cross-sectional view of the burner. FIG. 3 is a diagram showing the basic characteristics of a jet flame depending on the fuel flow rate and air flow rate conditions. FIG. 4 is a photograph of a typical flame. FIG. 5 is a conceptual diagram of the entire vibration excitation system. FIG. 6 is a photograph of the burner adhesion flame at the time of high frequency vibration excitation. FIG. 7 is a diagram illustrating a standing wave between the vibration surface and the reflection surface. FIG. 8 is a diagram showing the definition of the lift height of the flame and the definition of the deviation of the flame from the burner. FIG. 9 is a diagram showing flow rate setting conditions in each measurement. FIG. 10A is a diagram showing a change in the flame standing position in case A, and FIG. 10B is a photograph similar to FIG. FIG. 11A is a diagram showing a change in the flame standing position in case B, and FIG. 11B is a photograph similar to FIG. FIG. 12 is a table in which measurement conditions are classified for changes in the floating height due to vibration excitation. FIG. 13 is a diagram showing the lifting height at Vf = 0.7 m / s. FIG. 14 is a diagram showing the lifting height at Vf = 1.4 m / s. FIG. 15 is a diagram showing the lifting height at Vf = 2.1 m / s. FIG. 16 is a diagram showing the lifting height at Vf = 2.8 m / s. FIG. 17 is a diagram showing the lifting height at Vf = 4.2 m / s. FIG. 18 is a diagram showing the lifting height at Vf = 5.6 m / s. FIG. 19 is a diagram showing the lifting height at Vf = 7.0 m / s. FIG. 20 is a table in which measurement conditions are classified for the acetone PLIF method. FIG. 21 is a diagram illustrating the arrangement of the vibration excitation system and the irradiation direction of the laser sheet light. FIG. 22 is a diagram illustrating a measurement result in case 2-i. FIG. 23 is a diagram illustrating a measurement result in case 2-ii. FIG. 24 is a diagram illustrating a measurement result in case 5-iii. FIG. 25 is a diagram illustrating a measurement result in case 5-iv. FIG. 26 is a diagram illustrating measurement results in case 5-iii and case 5-iv. FIG. 27 is a diagram illustrating a measurement result in case 6-v. FIG. 28 is a diagram showing a measurement result in case 6-vi. FIG. 29 is a diagram illustrating measurement results in case 6-v and case 6-vi. FIG. 30 is a diagram showing the result of visualizing a jet using methane and argon.

  FIG. 1 shows an overall view of a fuel and oxidant supply system supplied to a coaxial jet burner 1 as a jet combustor. Methane is used as fuel and dry air is used as oxidant. Methane is adjusted to a predetermined pressure (0.24 MPa in this embodiment) by a pressure regulator 3 attached to the gas cylinder 2, and then the flow rate is adjusted by a flow rate regulator 5. The volume flow rate is displayed by an electronic flow meter 4. Is done. The flow-adjusted methane passes through the on-off valve 15 and is connected to the first flow path ((a) in the figure) directly introduced into the burner 1 through the on-off valve 6a through the on-off valve 6b. It branches to the 2nd flow path ((b) in a figure) introduced into the burner 1 via the acetone addition part 16 which adds acetone. When one channel is used, the on-off valve 6a or 6b interposed in the other channel is closed.

  Similarly, the dry air is adjusted to a predetermined pressure (0.26 Mpa in this embodiment) by a pressure regulator 8 attached to the gas cylinder 7, and then the volume flow rate is adjusted by the flow controller 18 and the electronic flow meter 9, It passes through the on-off valve 17 and is guided to the burner 1. The fuel and the oxidant adjusted to the volume flow rate corresponding to the set conditions are introduced into the burner 1 as a main flow and an ambient flow, respectively.

  FIG. 2 shows details of the burner 1 main body. The burner 1 has a high standing height and uses a coaxial jet type in order to form a stable floating jet flame. The fuel and oxidant flow introduced into the burner 1 by the supply system described above were sufficiently rectified by passing through a layer filled with silica beads having a diameter of 2 mm inside the burner 1. After passing through the inner rectification unit 1a, the mainstream fuel flow is sufficiently disturbed by the metal mesh 1b and ejected into the surrounding flow through the inner nozzle 1c. Similarly, the oxidant, which is the ambient flow, is suppressed from being disturbed by the outer rectifying unit 1d and the metal mesh 1b, and then ejected from the outer nozzle 1e into the stationary atmosphere.

  In this example, with the aim of active combustion control of the rising jet flame, an experiment was performed in which the flow field and the mixing field were changed by excitation by high-frequency vibration in the rising region. In order to clarify the influence of vibration excitation, it is necessary to reduce the influence of disturbance of the surrounding atmosphere as much as possible, and the coaxial jet burner 1 suitable for this is used.

  FIG. 2 shows a photograph of an example of a rising jet flame formed on the burner 1 and a coordinate system used on the burner. By appropriately setting the outlet flow velocities of the inner nozzle 1c and the outer nozzle 1e, a floating jet flame as shown in the photograph is formed. The coordinate system is an orthogonal coordinate system (x, y, z) with the burner exit center as the origin. Note that the x-axis and y-axis directions are defined as shown in the figure, and the z-axis is defined as a direction extending forward along the right-handed coordinate system.

  FIG. 3 shows the results of examining various setting conditions in order to clarify the basic characteristics of the jet flame formed on the burner 1. The flame conditions observed when the fuel flow rate and air flow rate are changed are classified into four types: (a) burner attachment, (b) stable lift, (c) vibration lift, and (d) blow-off. This corresponds to the areas (a) to (d) shown in FIG.

  Here, (a) burner adhesion means a state in which the flame end is adhered to the burner rim. In the fuel flow velocity setting range in the burner 1 used in this example, all the flames were in the state of (a) burner adhesion when air was not passed through the surrounding flow. When the fuel flow rate is set to a certain value and the air flow rate is increased, the flame end is separated from the burner rim from a certain point, and a flame that is stably lifted is formed. When the air flow rate is decreased from that state, the flame reattaches to the burner 1, but the value becomes lower than the air flow rate at which the lift occurred, and the state change between the lift and the burner attachment has a response with hysteresis. . (B) When the air flow rate is further increased from the stable floating state, the standing height of the flame fluctuates with time due to the disturbance of the surrounding atmosphere or the influence of buoyancy on the flame. (C) Vibration Transition to the floating state. The state includes two states, a periodic vibration of a laminar flame and a vibration due to a transition to a turbulent flame. When the air flow rate is increased, the flame eventually blows away (d).

  Based on the above, in order to float on the burner 1 and form a jet flame, the flow rate setting conditions of methane and air corresponding to the regions (b) and (c) may be used.

  FIG. 4 shows a photograph of typical flames in each region excluding (d) blowing away. (A) The burner adhesion region is shown in FIG. Also in the regions (b) and (c), as shown in FIGS. 4 (2), (3), (4) and (5), (6), the flame length and flame shape are various. It is possible to change.

  In this example, the acetone PLIF method was used to visualize the mainstream jet. The acetone PLIF method was excited by adding acetone vapor as a flow field tracer and irradiating it with laser sheet light. This is a technique for measuring the fluorescence emission emitted from acetone molecules. In this embodiment, acetone vapor is added to methane as a fuel.

  Next, the influence of high-frequency vibration on the combustion characteristics of the jet field and the lifted jet diffusion flame by irradiating the high-frequency vibration directly on the outlet of the burner 1 in the axial direction will be described below.

  FIG. 5 shows a conceptual diagram of the entire vibration excitation system. This system is composed of a burner 1 and a flame control device 20 that controls a rising jet flame on the burner 1. The flame control device 20 will be described in detail. The transmission horn 11 is connected to the vibrator 10, and a sine wave voltage is applied between the electrodes of the vibrator 10 by the drive power supply 12, thereby transmitting the horn 11. The vibration is generated from the vibration surface 11a formed on the end face of the head. In this embodiment, the entire vibration system is driven by a sine wave whose speed change of the vibration surface is gentle. The drive power supply 12 is a bipolar power supply that can flexibly support driving of a capacitive load. Further, the function generator 13 is used to generate the drive waveform, and the amplitude and offset of the waveform are monitored and adjusted with an oscilloscope (not shown).

  As a method for generating high-frequency vibration, a method using a vibrator utilizing a piezoelectric phenomenon or magnetostriction phenomenon of a material is mainly used. In this embodiment, a bolt-clamped Langevin type vibrator widely used for generating strong high-frequency vibration is adopted.

  The vibration surface 11a has a circular shape with a predetermined diameter (15 mm in this embodiment). Moreover, the reflector 14 is installed so that the reflective surface 14a may be arrange | positioned facing the vibration surface 11a. The diameter of the reflection surface 14a is a circle having the same diameter as that of the vibration surface 11a and is made of aluminum. The vibration surface 11a and the reflection surface 14a are arranged so that the central axes thereof coincide with each other, and the reflector 14 is arranged so as to be slidable in the direction of the central axis, and the vibration surface 11a and the reflection surface 14a are arranged. The interval can be arbitrarily adjusted. Further, the central axis (y axis) of the burner 1 and the central axes of the vibration surface 11a and the reflection surface 14a are installed so as to be orthogonal to each other. A predetermined height directly above (in this embodiment, the center of the vibration surface is y = 7.5 mm). By these mechanisms, a high-frequency vibration excitation system as a vibration excitation means that can finely adjust the distance between the vibration surface 11a and the reflection surface 14a and can change in the radial direction of the burner coordinate system while maintaining the distance therebetween. Has been built.

  In the high-frequency vibration excitation system, it is considered that an acoustic flow from the vibration surface 11a is generated to act on the flow field. In FIG. 6, the photograph of the burner adhesion flame at the time of high frequency vibration excitation is shown. When high-frequency vibration is not excited, the flame is formed vertically on the central axis of the burner 1. However, when high-frequency vibration is generated, a phenomenon occurs in which the flame tilts so as to be pushed away from the vibration surface 11a side. In addition, the flame surface on the vibration surface 11a side was in a depressed shape. Moreover, since this tendency did not change so much in time, it can be considered that a steady flow field from the vibration surface 11a, that is, an acoustic flow from the vibration surface 11a is generated.

  Next, as shown in FIG. 7, the vibration wave used in the present embodiment will be described. It is assumed that a standing wave is formed between the pair of vibration surfaces 11a and the reflection surface 14a. Since the vibration surface 11a is a free end and the reflection surface 14a is a fixed end, in order to form a standing wave, an odd multiple (2n−1) · λ / 4 of a quarter wavelength shown in FIG. The interval is necessary. However, n is an arbitrary positive integer. Further, the amplitude of the standing wave shown in FIG. 7 indicates the velocity amplitude in the longitudinal wave of the sound wave. In the case of pressure, the amplitude is opposite to the velocity.

  In this embodiment, in order to change the positional relationship between the burner and the jet and examine the influence on the flow field, a standing wave corresponding to a half wavelength is secured at least at a position not including the vibration surface and the reflection surface. For that purpose, a standing wave of at least 5λ / 4 or more is required. Here, the wavelength λ [m] of the sound wave is expressed by Equation 1 using the sound speed a [m / s] and the frequency f [Hz].

The speed of sound a [m / s] depends on the medium through which the sound wave is transmitted, and is expressed by Equation 2 using the specific heat ratio γ [J / mol · K], the pressure p [Pa], and the density ρ [kg / m ³ ]. It is represented by Furthermore, using the gas constant R [J / (kg · K)] and the absolute temperature T [K] from the equation of state of the ideal gas,

  In this embodiment, since the laboratory temperature is kept at about 20 ° C., if the medium is air at 20 ° C., the sound velocity at that time is a = 343.1 m / s. Here, since the burner diameter d used in the present embodiment is 20 mm, it is necessary to make the interval larger than that in order for the vibration surface and the reflection surface not to interfere with the jet. In addition, in order to change the positional relationship between the formed standing wave and the jet, it is necessary to move the half wavelength, which is one cycle of the standing wave antinode and node. Therefore, the following Equation 3 is obtained.

  Therefore, considering the case where the standing wave is 5λ / 4 (n = 3) and 7λ / 4 (n = 4), the frequency constraint conditions are expressed by the following equations 4 and 5 using equations 1 and 2, respectively. It becomes like this.

  Thus, in order to form the standing wave of each wavelength, the upper limit of the vibration frequency can be determined. Further, when n is large, a higher frequency is required, and it is considered that the attenuation in the air becomes severe, and a frequency higher than that is excluded from selection.

  Next, in performing vibration excitation, the optimum positional relationship between the burner 1 and the vibration excitation system, that is, in which position of the standing wave to be formed is optimum is described below. First, the vibration excitation system is moved in the x-axis direction immediately above the outlet of the burner 1 to show how the standing position of the rising flame changes. As parameters for evaluating the standing position of the flame, the lifting height (H) and the deviation (Δxc) between the burner 1 central axis and the flame central axis were measured.

  FIG. 8 shows the definition of the lifting height in the rising jet diffusion flame. The burner 1 is disposed so that the outlet of the burner 1 is opened vertically upward, the center point of the outlet surface of the burner 1 is the origin O, and the direction orthogonal to the vibration surface 11a and the reflection surface 14a disposed substantially parallel to each other Is the x-axis, and the burner central axis is the y-axis. The lift height (H) is the distance in the y-axis direction from the burner 1 outlet to the bottom of the flame. If the flame has an asymmetrical structure due to vibration excitation, the maximum height on both sides of the flame when viewed from the center axis of the flame and the front. The position of the intersection of the straight lines connecting the upstream ends is defined as the height. FIG. 8 shows the definition of the deviation between the burner 1 central axis and the flame central axis. The center axis of the flame was determined from the photograph of the flame and measured. The x-axis is positive on the vibration surface 11a side, and the y-axis is positive vertically upward.

  FIG. 9 shows flow rate setting conditions in each measurement described later. These are two conditions: a case where the flame remains laminar flame due to vibration excitation (case A) and a case where the flame transitions to a turbulent flame (case B). In both cases, the set flow velocity is within the laminar flow range for both fuel and air. In this embodiment, the distance between the vibration surface 11a and the reflection surface 14a is 30 mm, and the drive frequency of the vibrator 10 is 20.27 kHz. The amplitude of the vibrator 10 applied voltage was 105V. The position of the vibration excitation system was changed in a range where the vibration surface 11a and the reflection surface 14a did not interfere with the burner 1 exit surface.

  FIG. 10A shows the result of examining the change in the flame standing position in case A. FIG. H and Δxc are made dimensionless by the burner center nozzle diameter d (2 mm in this embodiment). The horizontal axis of FIG. 10A is the distance L from the vibration surface 11a to the burner 1 central axis. The dotted line in the vertical direction of FIG. 10A is the position of the pressure node in the standing wave. Further, the solid line in the horizontal direction is the height of the flame rising when vibration excitation is not performed.

  From this result, it can be seen that the standing position of the flame greatly changes with the position of the node and the position of the belly considered to be positioned between the nodes. H / d takes a sharp maximum near the position of the node of λ and the position of the antinode of 3λ / 4. This height substantially coincides with the floating height when vibration excitation is not performed. On the other hand, in the region between the node and the belly, it was found that the floating height was lowered. And it has a local minimum near the center of the node and belly. Δxc / d becomes 0 near the position of the node of λ and the position of the antinode of 3λ / 4. When vibration is not excited, an axially symmetric floating flame is formed on the burner central axis, so that no change due to vibration excitation is observed near the position of the node of λ and the position of the antinode of 3λ / 4.

  On the other hand, in the region between the node and the belly, a result was obtained in which the flame shifted from the burner central axis in the x-axis direction. The tendency of showing the minimum value and the maximum value near the center is the same as in the case of H / d. It was found that the horizontal position of the flame surface changes in the direction toward the vibration surface side in the range of 3λ / 4 to λ, and changes in the direction in which the flame is moved away from the vibration surface in the range of λ to 5λ / 4. That is, the flame has moved in a direction approaching the stomach.

  From the flame image of the photograph shown in FIG. 10B, at positions (a) and (c) where H / d takes the minimum value, the flame tends to be inclined asymmetrically, and the position of the node (b It can be seen that the direction of tilting at the boundary changes. Based on the results of the evaluation of H / d and Δxc / d in the above flame, the positional relationship between the vibration excitation system and the burner, which is considered to have a large effect due to vibration excitation, shows that the center axis of the burner is just This is considered to be the case where the center is located.

  Next, FIG. 11A shows the result of examining the change in the flame standing position in case B. FIG. FIG. 11B also shows a photograph of the flame. From this result, it can be seen that Δxc / d has the same tendency as in Case A. As for H / d, since a transition to a turbulent flame by vibration excitation was observed, a photograph of a flame in a state where vibration excitation is not performed is shown in FIG. There is no temporal change in the shape of the flame edge or the height of the rise, and it can be classified as a laminar flame.

  On the other hand, when vibration excitation is applied, as shown in (a) and (c) of FIG. However, it became a laminar flame about (b). That is, although there is a difference in the floating height, it is close to the flame shape when vibration excitation is not applied. (B) is a condition that the burner central axis is located near the node of λ, and when the burner central axis is located near the node, the influence on the flame due to vibration excitation is reduced as in the case A. It is. The laminar flame and turbulent flame are considered to have very different determinants of lift height, and it is considered impossible to simply compare the two. Therefore, except for (b), which was a laminar flame, only the conditions for transition to a turbulent flame were compared. Comparing these conditions, H / d is minimized under the condition (a) where the burner central axis is closest to the vibration surface. Here, the energy density of the sound wave on the central axis of the burner is considered to be the highest in the condition (a) because the sound wave spreads away from the vibration surface. As a result, it is considered that the effect of promoting the turbulence of the jet becomes the highest, and it is considered that the energy density of the sound wave is greatly involved in the effect of promoting the turbulence.

  From the above, as a result of examining the change in the flame standing position by vibration excitation in Case A and Case B, it was found that there are three effects. The first is that the flame is displaced from the central axis of the burner by vibration excitation, and this shows the same tendency regardless of the flow velocity setting conditions, both of which are the pressure antinodes (nodes of amplitude) in the standing wave. The result was moving in the direction. However, under the condition that the jet center is located near the node and the abdomen, a flame was formed at a position almost unchanged from the case where vibration was not excited. Secondly, in case A, the jet center takes a local minimum just near the center of the node and the belly, and it has been found that the change in the floating height due to vibration excitation is large. Third, in Case B, a phenomenon was observed in which laminar flame transitioned to turbulent flame due to vibration excitation, and under these conditions, the change in lift height tended to be greater the closer to the vibration surface. However, under the condition that the jet center is located in the vicinity of the center of the node of λ or the vibration surface and the reflection surface, the transition to the turbulent flame was not observed.

  Based on the above results, the positional relationship between the vibration excitation system and the burner 1 considered to have the greatest effect of vibration excitation is examined. In the result of evaluating Δxc and Case A in two conditions, the influence of vibration excitation is large when the jet center is located in the region between the antinode and the node in the standing wave. Therefore, it is more effective when the jet center is located either between the 3λ / 4 antinode and the λ node or between the λ node and the 5λ / 4 antinode. Moreover, based on the result of evaluating H of Case B, the effect of promoting turbulence is higher when the jet center is located near the vibration surface 11a. Therefore, it is effective to bring the jet center closer to the vibration surface 11a. In addition, the range in which the vibration system can be moved is limited by interference with the burner 1 outlet. Further, in order to prevent the vibration surface 11a and the reflection surface 14a from obstructing the flow field, it is preferable to install both at a position as far from the burner 1 as possible. Considering the above in total, the one closer to the vibration surface 11a should be selected from the two ranges described above. Therefore, L = 14 mm near the center of the 3λ / 4 antinode and λ node is considered to be the position where the vibration excitation effect is maximized.

  Next, the results of examining the change in the lift height due to vibration excitation under a wider flow rate setting condition than described above will be described. The change in the floating height is also important in examining the stability of the flame, such as ease of blowing. As an experimental procedure, first, the flow rates of fuel and air were set. The fuel outlet flow velocity Vf (center flow) was kept constant, the air outlet flow velocity Va (ambient flow) was increased, and the flame was lifted. In this way, the flame was allowed to stand without vibration excitation, and the floating height at that time was measured. Thereafter, vibration excitation was started, and the lifting height at the time of vibration excitation was measured. At this time, the passage of a certain time (2 to 3 seconds in this embodiment) was waited until the flame became a steady state. Depending on the setting conditions, re-attachment to the burner and blowing out of the flame may occur. At that time, the floating height was set to 0 and no data, respectively. Eventually, the flow rate was increased to the level at which the flame was blown, and the range up to the floating height at the blow-off limit was set as the experimental range. The blow-off limit at the time of vibration excitation was measured by increasing the air outlet flow velocity until the flame blows off in a state where vibration excitation was continuously applied.

  As shown in FIG. 12, measurement was performed for each condition of Vf = 0.7, 1.4, 2.1, 2.8, 4.2, 5.6, 7.0 m / s. At this time, the distance between the vibration surface and the reflection surface is set to 30 mm, and the drive frequency and the applied voltage are set to 20.27 kHz and 105 V, respectively. In addition, the relative positional relationship between the vibration system and the burner 1 is determined to be the optimum position as a result of the above examination, and the center of the λ node and the center of the 3λ / 4 antinode in the standing wave with a 7λ / 4 jet center are determined. The setting is made to be close.

  All seven conditions measured are roughly classified into three, focusing on changes in the flame state. The first group is a case where the flame becomes a laminar flame regardless of the presence or absence of vibration excitation under three conditions of Vf = 0.7, 1.4, and 2.1 m / s. The second group is a case where a laminar flame is changed to a turbulent flame by vibration excitation, which was observed under two conditions of Vf = 2.8 and 4.2 m / s. The third group is a case where the flame becomes a turbulent flame regardless of the presence or absence of vibration excitation under two conditions of Vf = 5.6, 7.0 m / s.

  In the following, for the cases of groups a to c in FIG. 12 in which the measurement conditions are classified, results and consideration are shown for changes in the lift height and blow-off limit due to vibration excitation, respectively.

  First, the result of the condition of group a classified in FIG. 12 will be described. This is a condition in which a laminar flame is formed regardless of the presence or absence of vibration excitation, and includes three conditions of cases 1 to 3. FIGS. 13 to 15 show the results of examining the changes in the lift height and the blow-off limit due to vibration excitation in Case 1, Case 2, and Case 3, respectively. The floating height H is made dimensionless by the inner nozzle outlet diameter d, and the blow-off limit (B.O.) is shown in the drawing together with an arrow. In each condition, two pairs of flame photos were shown. The photograph at the top of the figure is a flame in a normal state where vibration excitation is not applied, and the photograph shown at the bottom is a flame after vibration excitation.

  What is common to the three conditions is that the floating height is generally reduced by vibration excitation. At this time, it is understood from the flame photograph that when the vibration excitation is performed, the flame end is inclined asymmetrically. When attention is paid to the condition where the set air flow velocity is lower than the arrow (a) shown in each figure, it can be seen that the flame is reattached to the burner 1 by vibration excitation. Whether or not re-adhesion occurs varies depending on the H / d = 7.5 vicinity, which is the height of the upper end of the vibration surface 11a (diameter 15 mm) when the vibration excitation is not performed.

  That is, it can be seen that the flame reattaches when the flame base is within the vibration excitation range. When the set air flow velocity is higher than that of the arrow (a) and the lift height when vibration excitation is not performed is H / d> 7.5, the lift height is slightly increased by vibration excitation. Thereafter, the relationship between the heights of the lifts due to the presence / absence of vibration excitation is reversed, and the decrease in the lift heights due to vibration excitations becomes significant as Va increases. Finally, the blow-off limit has also been greatly improved, and it can be seen that a flame state in which blow-off is difficult to occur due to vibration excitation is found. Therefore, it was found that the rising flames in cases 1 to 3 were stabilized by vibration excitation. However, it should be noted that flame reattachment may occur depending on conditions.

  Next, the result of the condition of group b classified in FIG. 12 will be described. This is a condition in which a transition from laminar flame to turbulent flame is observed due to vibration excitation, and includes two conditions, Case 4 and Case 5. FIGS. 16 and 17 show the results of examining changes in the lift height and blow-off limit due to vibration excitation in Case 4 and Case 5, respectively. The maximum and minimum values of the conditions where the floating height was changed were shown as error bars.

  The state of increase in the floating height when vibration excitation is not performed in group b is generally consistent with the result of group a, although the rate of increase is different. This is considered to be because there is no big difference in the determinant of the lift height because both are results in laminar flame. Further, the point that the floating height is lowered by vibration excitation is the same as in the case of group a. However, when the vibration excitation is performed in group b, the state of increase in the floating height is different from that of the laminar flame. When the air outlet flow velocity increased, it was confirmed that transition to a turbulent flame occurred at the flow velocity indicated by arrows (b) in the figure.

  It can be seen from the photograph of the vibrationally excited flame shown on the right side of FIGS. 16 and 17 that the flame surface is disturbed at the flame end. During the experiment, it was also confirmed that the shape and length of the flame fluctuated unsteadyly and that combustion noise was generated. This is presumed to be the result of the instability of the flow field being promoted by vibration excitation and the flame becoming turbulent in response to the disturbance of the flow field. As the turbulent transition of the flame, a phenomenon was observed in which the floating height increased discontinuously. This rapid increase in the floating height is particularly noticeable in the case 5 result.

  Then, it can be seen that the state of the rising height also changes at the transition point of the arrow (b). The increase rate of the lift height with respect to the air outlet flow velocity is smaller than the increase rate in the laminar flame when vibration excitation is not performed. In addition, the air outlet flow velocity at the blow-off limit is the same as or slightly reduced when vibration excitation is performed. This tendency is different from the case of group a in which the blow-off limit is increased. However, it is conceivable that the factors that determine the lift height and the factors that lead to blow-off differ between laminar and turbulent flames, and they cannot be compared in general. In addition, in each condition immediately before the blow-off limit indicated by a dotted line in the figure, it was also confirmed that a flame was blown out by vibration excitation. In group b, the rising height is so high that such a flame is considered to be very sensitive to upstream flow field fluctuations. In particular, since voltage application was started stepwise this time, it can be estimated that a rapid fluctuation of the flow field occurred.

  Next, the results of group c conditions classified in FIG. 12 will be described. This is a condition in which the state of the turbulent flame is confirmed regardless of the presence or absence of vibration excitation, and includes two conditions of Case 6 and Case 7. 18 and 19 show the results of examining changes in the lift height and the blow-off limit due to vibration excitation in Case 6 and Case 7, respectively. The maximum and minimum values of the conditions where the floating height was changed were shown as error bars.

  The transition to the turbulent flame described above occurred regardless of the presence or absence of vibration excitation. In the range where the air outlet flow velocity is larger than the arrow (b) in the figure, a turbulent floating flame was observed. In Case 6, the transition to the turbulent flame at the time of vibration excitation occurs under the condition of a low air outlet flow velocity as compared with the case where vibration excitation is not performed. On the other hand, in case 7, the transition point occurs at the same air flow velocity. In the range where the air outlet flow velocity is larger than the transition point indicated by the arrow (b), it exists as a turbulent flame regardless of the presence or absence of vibration excitation. There is no. The change in the lift height caused by the vibration excitation is almost unchanged in the case 7 while the lift height is lowered by the vibration excitation in the case 6.

  Furthermore, even when compared with the conditions of group a and group b, the effect of raising the height due to vibration excitation is small. However, each flame photograph shown on the right side of the figure shows that the width of the flame base is enlarged. Thereby, even if the change in the floating height is small, it is considered that the range in which the air-fuel mixture reaching the mixing ratio in the combustible range at the position of the flame end is increased. From this, it is considered that mixing was promoted by vibration excitation. On the other hand, with regard to the blow-off limit, it can be seen that there is no significant difference in the floating height at which blow-off occurs and the air outlet flow velocity at the time of blow-off.

  Based on the above, we found three points as a result of investigating the effects of vibration excitation on the rising flame under various flow rate setting conditions. First, in laminar flames, a drop in the lift height of the flame and an increase in the blow-off limit are confirmed by vibration excitation, and the stability of the lift flame is improved. Second, the turbulence of the flame is promoted by vibration excitation. This is due to the turbulence of the flame and the increase in the flame end width in the turbulent flame. It is considered that the turbulence of the jet can be promoted by vibration excitation. Thirdly, depending on the state of the flame, there is an effect of preventing stable combustion, for example, a phenomenon such as redeposition to the burner or blow-off occurs due to vibration excitation.

Next, in order to visualize the state of the flow field in the floating region, the results of jet flow visualization using the acetone PLIF method, which is a non-contact laser measurement technique, are described.
This time, six measurement conditions were set for visualizing the jet. These are two conditions selected from each of the groups a, b, and c shown in FIG. 12, and the details are shown in FIG. The lift height under these conditions is shown by corresponding data points in FIG. 14, FIG. 17, and FIG.

  FIG. 21 shows the arrangement of the burner and the vibration excitation system and the irradiation direction of the laser sheet light. The direction of the vibration surface 11a was set on the left side of the image, that is, in the negative direction of the x-axis direction in the burner coordinate system. In addition, the measurement was performed with the axis connecting the centers of the vibration surface 11a and the reflection surface 14a aligned with the irradiation direction of the laser sheet light.

  First, the results of Case 2-i and Case 2-ii in which a steady laminar flame is formed will be described. 22 and 23 show the measurement results under the conditions of Case 2-i and Case 2-ii. Based on the image of the jet only without vibration excitation (a in the figure), the image of the jet only with vibration excitation (b in the figure) and the image with the flame formed (c in the figure) I will show you one. Under these conditions, a nearly steady flow field and flame were formed, so only the average image is shown. In both conditions, when vibration excitation is not performed, a symmetric jet is formed on the burner central axis. On the other hand, when vibration excitation is performed, it can be seen that the flow direction is bent so that the jet is drawn toward the vibration surface. Further, the flame end is deformed asymmetrically in accordance with the flame. Such a change in the flow direction is considered to be a factor of the phenomenon that the flame described above is attracted to the vibration surface side. Moreover, when the two conditions are compared, there is a difference in the floating height of the flame, but the degree of jet deflection does not change much. Therefore, it is considered that the change in the floating height is mainly caused by the difference in the flow velocity of the outer nozzle.

  Next, the results of Case 5-iii and Case 5-iv in which a transition from laminar flame to turbulent flame was observed are shown. First, FIGS. 24 and 25 show the measurement results of only the jet under the conditions of Case 5-iii and Case 5-iv. Average image without vibration excitation (a in the figure), average image with vibration excitation (b in the figure), instantaneous image without vibration excitation (c in the figure), vibration excitation This is an instantaneous image (d in the figure). Comparing the average images of “a” and “b” in the figure, it can be seen that when the vibration excitation is performed, the jet width is broadened compared to the case where the vibration excitation is not performed. Further, when the fluorescence luminance at the center of the jet is compared, there is a tendency for the vibration excitation to decrease significantly downstream. In the present embodiment, since the intensity correction in the height direction of the laser sheet is not performed, only the luminance at the same height can be quantitatively compared. Comparing the luminance at the same height with and without vibration excitation, the luminance is smaller when vibration excitation is performed.

  From this, it is considered that the fuel and air are rapidly mixed by vibration excitation. This is considered to be a result of promoting the mixing by the vortex because a vortex structure not seen in c in the figure where vibration excitation is not performed is confirmed in the instantaneous image of d in the figure. The phenomenon that the jets confirmed in Case 2-i and Case 2-ii are bent toward the vibrating surface is that the jet is slightly bent toward the vibrating surface (in the negative x-axis direction) from the average image b in the figure. I understand. However, the deviation between the jet center and the burner center axis at the same height is much smaller than in the case of the above two conditions. This is because the fuel outlet flow velocity is larger in Case 5-iii and Case 5-iv, the residence time of the methane jet in the vibration excitation region (up to y = 15mm) is small, and the initial momentum of methane is large. And so on. When the degree of mixing in case 5-iii and case 5-iv is compared, the fluorescence intensity is almost the same at the same height, and there is no significant difference between the two.

  FIG. 26 shows the measurement results when a floating flame is formed in case 5-iii and case 5-iv. All are instantaneous images, and the flame surface at the uppermost stream of the floating flame is shown by a black line. However, when vibration excitation of case 5-iv is not performed (c in the figure), the flame surface is not displayed because the flame exists at a position higher than the measurement region. From this result, it is possible to confirm changes in the flame shape and the floating height due to the turbulent flow field by vibration excitation and the accompanying mixing promotion.

  The results of case 6-v and case 6-vi in which a turbulent flame is formed regardless of the presence or absence of vibration will be described. 27 and 28 show the measurement results under the conditions of case 6-v and case 6-vi. Average image without vibration excitation (a in the figure), average image with vibration excitation (b in the figure), instantaneous image without vibration excitation (c in the figure), and vibration excitation This is an instantaneous image (d in the figure). From the instantaneous images under each condition, it can be seen that a vortex structure is generated in the methane jet regardless of the presence or absence of vibration excitation. On the other hand, comparing the average images, it can be seen that the jet width is larger when vibration excitation is performed. Moreover, even when the fluorescence brightness at the jet height at the same height is compared, the case of vibration excitation is smaller, and it is considered that mixing is promoted by vibration excitation. The phenomenon in which the jet generated when vibration excitation is performed is bent to the vibration surface side is not clearly identifiable.

  FIG. 29 shows a comparison of instantaneous images when flames are formed in case 6-v and case 6-vi. The results with and without vibration excitation are shown. On each image, the flame surface at the flame end is shown by a black line. It can be seen that mixing is promoted by vibration excitation and the flame is moving further upstream. Moreover, it can be seen that the width of the flame base is increased as the jet width increases.

  In the above description, the phenomenon that the jet is bent by vibration excitation has been confirmed. This phenomenon occurs when the center of the jet is located in the region between the node and the belly in the standing wave, and the jet is bent toward the ventral side of the pressure. Next, what factors determine the direction in which the jet is bent will be described below.

In an experimental example of ultrasonic floating of an object, a solid such as a droplet of water or oil and a styrene foam sphere is suspended in the air. In this case, the object is generally held in a pressure node. However, in the present embodiment, the jet flow is deflected toward the pressure side of the pressure, so that a phenomenon opposite to these results occurs. Here, the gas density of methane is 0.717 kg / m ³ and the specific gravity with respect to air is 0.555. In many cases, liquids and solids used in floating an object are considered to have a higher density than the surrounding gas (air), and the density relationship in this embodiment is reversed. Therefore, it is considered that the jet flow is deflected depending on the density difference between the ambient flow and the central flow, and the results of the demonstration experiment are shown below.

In this experiment, argon is used as a gas having a different density. The gas density of argon is 1.784 kg / m ³ and the specific gravity with respect to air is 1.38. As usual, we tried to visualize the jet flow using methane, and using argon instead of methane for the central jet in the same way. As the experimental conditions, the conditions of case 2-i described above are adopted, and other setting conditions are also matched.
FIG. 30 shows the result of visualizing the jet using methane and argon. All four images are average values of 100 images. From FIGS. 30 (b) and 30 (d), which are the results of vibration excitation, it can be seen that the flow deflection direction due to vibration excitation is reversed. That is, the methane jet is deflected toward the vibrating surface, and the argon jet is deflected toward the reflecting surface. In the positional relationship between the burner and the vibration excitation system in this experiment, the vibration surface side corresponds to the pressure side of the pressure, and the reflection surface side corresponds to the direction of the pressure node. In other words, it was found that a gas having a lower density than the surrounding gas has an effect of being drawn to the ventral side and a gas having a higher density to the node side. The result of argon shows a tendency similar to the result that an object having a higher density than the surrounding gas in the experimental example of ultrasonic levitation is held at a pressure node in the ultrasonic standing wave.

  From the above, it was found that the flow deflection is caused by the density difference between the gas in the central jet and the surrounding gas, and the direction depends on the density of the surrounding gas.

  In laminar uplifting flames, effects such as lowering the lifting height and improving the blow-off limit were observed. Under this condition, the effect of deflecting the methane jet was confirmed by visualization of the jet. This is an effect obtained by installing the jet center near the center of the antinode and node in the standing wave. It was confirmed from the visualization results of the jets using gases with different densities that the deflection direction is caused by the difference in density with the surrounding gas and is drawn to the ventral side of the standing wave pressure. It was confirmed that the flow can be changed even in a gas fluid by such a completely non-contact method.

  It was also confirmed that the jet flame rises from laminar flame to turbulent flame due to vibration excitation. It was found that the visualization of the jet stream promoted the turbulence of the flow field by vibration excitation, and as a result, the flame changed to a turbulent flame according to the turbulence of the flow. Furthermore, even in a flame that was turbulent without vibration excitation, it was confirmed that the lifted height decreased and the flame base width expanded due to vibration excitation. It was confirmed from the visualization results that this is because the turbulent flow of the jet is promoted by vibration excitation, and the mixing of the fuel and the oxidant is further promoted.

  It was confirmed by visualization of the jet by the acetone PLIF method that two effects can be obtained by vibration excitation to the flow field at the outlet of the jet burner. The first action is an action in which the jet is deflected by positioning the jet center near the node of the standing wave pressure and the center of the belly. The second action is an action that promotes the turbulent flow of the jet by vibration excitation and promotes quick mixing of the fuel and the oxidant as compared with the case where vibration excitation is not performed.

  Due to the first action and the second action described above, the standing position of the flame and the change of the flame shape occurred in the floating jet diffusion flame. Laminar floating flames have the effect of improving the stability of the flame and reducing the luminous flame, such as lowering the floating height and increasing the blow-off limit. In addition, with the effect of promoting turbulence in the flow field, the transition from laminar flame to turbulent flame and the accompanying change in flame shape, and the rise in the turbulent flame and the width of the flame base increase. The effect was seen.

  It was found that the flow deflection effect was caused by the difference in density between the surrounding jet and the central jet. It was found that the direction of deflection is determined to the ventral side of the pressure in the standing wave when the gas has a lower density than the surrounding gas, and to the node side of the pressure when the gas has a higher density than the surrounding gas. Further, the degree of bending of the jet is determined by the influence of the residence time in the vibration excitation region, the momentum of the jet, and the like, since a larger deflection was observed under the condition that the initial flow velocity of the central jet is small.

  The features and effects of the flame control method and flame control apparatus for the jet-type combustor obtained by the experiment in the above-described embodiment will be described below.

  In the flame control method of a jet-type combustor, the vibration flow is given to the flame flow field to change the floating jet flame, and the combustion control in the jet-type combustor is performed to increase the strength of vibration excitation and vibration excitation. By adjusting the position of the flow field of the applied flame, it is possible to realize an optimal combustion operation for improving the stability of the flame, such as the expansion of the blow-off limit, in addition to the change in the lift height of the lifted flame.

  Further, in the flame control method of the jet-type combustor, the flow field of the flame to which vibration excitation is applied is the flow field or the mixing field upstream of the flame, and the factor that determines the combustion state of the rising jet flame is the upstream of the flame. It becomes clear that this is a flow field or a mixing field, and optimal control is possible by controlling this part by vibration excitation.

  Furthermore, in the flame control method of a jet-type combustor, when the deflection direction of the flame is deflected to the ventral side of the pressure in the standing wave as a flame deflection direction control, the density of the fuel system is made smaller than the surrounding gas. When selecting and deflecting the deflection direction of the flame to the nodal side of the pressure in the standing wave, by selecting the fuel system density to be larger than the surrounding gas, it is easy to select the fuel system density. The deflection direction can be controlled.

  In a flame control device for a jet-type combustor, a vibration excitation means is arranged in the vicinity of the flame flow field, and vibration excitation is applied to the flame flow field by the vibration excitation means, and the combustion control is performed by changing the rising jet flame. By adjusting the strength of vibration excitation and the position of the flow field of the flame that gives vibration excitation, the stability of the flame, such as the expansion of the blow-off limit, in addition to changes in the lift height of the lifted flame, etc. Combustion operation that is optimal for improvement can be realized.

  In addition, in the flame control device of a jet-type combustor, the center of the jet is located near the node of the pressure of the standing wave and the center of the belly by high-frequency vibration that forms a standing wave between the pair of vibrating surfaces and the reflecting surface By positioning it, it is excellent in the action of deflecting the jet, and it can promote the turbulence of the jet by vibration excitation, and it is effective in promoting prompt mixing of fuel and oxidant compared to the case without vibration excitation Can be obtained.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments, and modifications and additions within the scope of the present invention are included in the present invention. It is.

  For example, in the above embodiment, as a vibration excitation system applied to the flame flow field, a vibration surface and a reflection surface connected to the vibrator are arranged, and a predetermined frequency excited by the vibrator is set to the flame flow field. However, the vibration excitation system is not necessarily limited to this embodiment, and the vibration control is applied to the flow field of the flame to change the floating jet flame and control the combustion in the jet type combustor. In this case, for example, the frequency to be excited may be a low frequency instead of a high frequency, or only the excitation surface or the excitation unit may be provided without particularly providing the reflection surface.

  In the above embodiment, methane is used as the fuel and dry air is used as the oxidizer. However, the type of the fuel or oxidizer is not necessarily limited to this embodiment, and a known alternative material may be used.

It is a general view of the supply system of the fuel and oxidant supplied to a jet type combustor. It is the photograph of the floating jet flame formed on a burner, and the partial cross section figure of a burner. It is a figure which shows the basic characteristic of the jet flame by the conditions of a fuel flow velocity and an air flow velocity. It is a photograph about a typical flame. It is a conceptual diagram of the whole vibration excitation system. It is a photograph of the burner adhesion flame at the time of high frequency vibration excitation. It is a figure which shows the standing wave between a vibration surface and a reflective surface. It is a figure which shows the definition of the floating height of a flame, and the definition of the deviation | shift of the flame from a burner. It is a figure which shows the flow-rate setting conditions in each measurement. (A) is a figure which shows the change of the flame stationary position in case A, (b) is a photograph similarly to (a). (A) is a figure which shows the change of the flame stationary position in case B, (b) is a photograph similarly to (a). It is the table | surface which classified measurement conditions about the change of the floating height by vibration excitation. It is a figure shown about the floating height in Vf = 0.7m / s. It is a figure shown about the floating height in Vf = 1.4m / s. It is a figure shown about the floating height in Vf = 2.1m / s. It is a figure shown about the floating height in Vf = 2.8m / s. It is a figure shown about the floating height in Vf = 4.2m / s. It is a figure shown about the floating height in Vf = 5.6m / s. It is a figure shown about the floating height in Vf = 7.0m / s. It is the table | surface which classified the measurement conditions about the acetone PLIF method. It is a figure which shows arrangement | positioning of a vibration excitation system, and the irradiation direction of a laser sheet light. It is a figure which shows the measurement result in case 2-i. It is a figure which shows the measurement result in case 2-ii. It is a figure which shows the measurement result in case 5-iii. It is a figure which shows the measurement result in case 5-iv. It is a figure which shows the measurement result in case 5-iii and case 5-iv. It is a figure which shows the measurement result in case 6-v. It is a figure which shows the measurement result in case 6-vi. It is a figure which shows the measurement result in case 6-v and case 6-vi. It is a figure which shows the result of having visualized a jet flow using methane and argon.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Burner 1a Inner rectification | straightening part 1b Metal mesh 1c Inner nozzle 1d Outer rectification | straightening part 1e Outer nozzle 2 Gas cylinder 3 Pressure regulator 4 Electronic flow meter 5 Flow regulator 6a, 6b On-off valve 7 Gas cylinder 8 Pressure regulator 9 Electronic flow meter 10 Vibration Child 11 Transmission horn 11a Vibrating surface 12 Drive power supply 13 Function generator 14 Reflector 14a Reflecting surface 15 On-off valve 16 Acetone addition unit 17 On-off valve 18 Flow rate regulator 20 Flame control device

Claims (5)

  A method of controlling a flame of a jet-type combustor, characterized in that a combustion flow in a jet-type combustor is controlled by changing an up-flowing jet flame by applying vibration excitation to a flow field of the flame.   The flame control method for a jet-type combustor according to claim 1, wherein the flow field of the flame to which the vibration excitation is applied is a flow field or a mixing field upstream of the flame.   When deflecting the deflection direction of the flame to the ventral side of the pressure in the standing wave as the control of the deflection direction of the flame, the density of the fuel system is selected to be smaller than the surrounding gas and the deflection direction of the flame is set to the standing wave. 3. The flame control method for a jet-type combustor according to claim 1, wherein the density of the fuel system is selected to be larger than the surrounding gas when the pressure is deflected to the node side of the pressure.   A jet-type combustor characterized in that a vibration excitation means is disposed in the vicinity of a flame flow field, and combustion control is performed by applying vibration excitation to the flame flow field by the vibration excitation means and changing the floating jet flame. Flame control device.   The flame control device for a jet-type combustor according to claim 4, wherein the vibration excitation means is high-frequency vibration that forms a standing wave between a pair of vibration surfaces and a reflection surface.