JPH10132210A - Combustion device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent vibration combustion from being generated by a combustion device by preventing a combustion gas and/or an air for combustion from passing through by substantially closing the upstream side of a space being created between the outer-periphery surface and the inner-periphery surface of a pipe part and opening a downstream side. SOLUTION: A motor case room 7, a mixer, a flame hole 16, a combustion room 17, a combustion cylinder 22, and a ceiling buffer room 24 are arranged nearly axisymmetrically and on a concentric shaft 32, a rectifying plate 30 that is nearly axisymmetrical and has a number of openings 31 is arranged on the shaft 32 inside the combustion cylinder 22, a middle reflection plate 33 that is nearly axisymmetrical and has a number of openings is arranged on the shaft 32 at the front part of the flame hole 16, and a reflection plate A37 is arranged nearly at right angle to the shaft 32 inside the ceiling buffer room 24. Further, by providing a space 39 between the combustion room 17 and the combustion cylinder 22, acoustic resonance conditions are changed and further the blow-off direction of a primary flame is set nearly at right angle to the concentric shaft 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus and a method for manufacturing the same, which can be used for, for example, household / industrial hot water supply / heating combustion apparatuses.

[0002]

2. Description of the Related Art Oscillation combustion has been observed in the design stage of a household or industrial combustion apparatus.

[0003] When such oscillating combustion occurs, the combustion device may be accompanied by loud noise, or combustion may be unstable, and normal combustion may not be performed. Therefore, when commercializing a combustion device, at the design stage,
With due consideration, such oscillating combustion must be prevented. Conventionally, this preventive measure has been performed by trial and error.

[0004]

However, the above-described trial and error method has a problem that it takes a long time to study for suppressing the oscillating combustion.

An object of the present invention is to provide a combustion apparatus and a method of manufacturing the same, which can suppress the oscillating combustion more efficiently than in the past, in consideration of such conventional problems.

[0006]

According to a first aspect of the present invention, there is provided a combustion blower for supplying combustion air, a mixer for mixing vaporized fuel and the combustion air, and A burner portion provided with a flame hole for forming a flame by the fuel, a combustion cylinder provided between a combustion gas outlet portion and the burner portion, and a combustion air inlet portion to an outlet portion. A pipe portion provided along the inner peripheral surface of the combustion cylinder on the downstream side from the position of the flame with respect to the direction toward the flame, formed between the outer peripheral surface of the pipe portion and the inner peripheral surface. The space is a combustion device having a structure in which combustion gas and / or combustion air cannot pass through because the space is closed on the upstream side and substantially opened on the downstream side.

According to a second aspect of the present invention, the inlet portion and the outlet portion are acoustically closed ends, and a structure other than the tube portion generates an oscillating combustion without the tube portion. It is.

According to a third aspect of the present invention, an acoustic characteristic determined from the structure of the combustion device is analyzed, and when it is determined from the analysis result that the oscillating combustion occurs, a direction from the inlet to the outlet of the combustion device. On the basis of, a pipe portion is provided along the inner peripheral surface of the combustion cylinder on the downstream side from the position of the flame of the combustion device, and a space formed between the outer peripheral surface of the pipe portion and the inner peripheral surface is: This is a method for manufacturing a combustion device in which combustion gas and / or combustion air cannot pass through because the upstream side of the space is closed and the downstream side is substantially open.

According to a fourth aspect of the present invention, there is provided a combustion blower for supplying combustion air, a vaporizer for vaporizing a liquid fuel,
A mixer that mixes the combustion air with the vaporized fuel to generate an air-fuel mixture, a flame hole having a number of openings through which the air-fuel mixture is jetted, And a combustion cylinder through which the combustion gas flows,
A combustion gas outlet connected to a downstream side of the combustion gas, wherein the vaporizer and the mixer have an integral structure, the vaporizer, the mixer, the flame hole, the combustion chamber, and the combustion chamber; The cylinder is arranged substantially coaxially and has a substantially axially symmetric structure, and a ring-shaped or cylindrical acoustic characteristic changing means closed at one end and opened at the other end in the vicinity of the combustion chamber and the combustion cylinder. And a combustion device having a structure in which combustion air and / or combustion gas does not pass through the inside of the acoustic characteristic changing means.

According to a fifth aspect of the present invention, there is provided a combustion apparatus in which a structure other than the acoustic characteristic changing means generates oscillating combustion without the acoustic characteristic changing means.

According to a sixth aspect of the present invention, there is provided a combustion blower for supplying combustion air, a mixer for mixing vaporized fuel and the combustion air, and a mixer provided inside the mixer. An intermediate reflector having a plurality of apertures, a burner provided with a flame hole for forming a flame by the mixed fuel, and a combustion provided between a combustion gas outlet and the burner; A combustion device comprising a tube, wherein the intermediate reflector and the outlet are acoustically closed ends.

According to the first aspect of the present invention, the combustion blower supplies combustion air, the mixer mixes the vaporized fuel with the combustion air, and the burner section is provided with a flame hole. Forms a flame by the mixed fuel, a combustion cylinder is provided between an outlet portion of the combustion gas and the burner portion, and a pipe portion extends from an inlet portion of the combustion air toward the outlet portion. On the basis of the direction, on the downstream side from the position of the flame, provided along the inner peripheral surface of the combustion cylinder, a space formed between the outer peripheral surface of the pipe and the inner peripheral surface is Since the upstream side of the space is closed and the downstream side is substantially open, the combustion gas and / or combustion air cannot pass through.

[0013] Thereby, the oscillating combustion can be suppressed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a semi-enclosed heater using kerosene fuel according to an embodiment of the present invention. The configuration and operation of the embodiment will be described with reference to FIG. . The connection between the controller and each component is not shown because the drawing becomes complicated.

As shown in FIG.
Is supplied to the blower 3 through the intake port 2, pressurized by the blower 3, and sent to the branch valve 4. At the branch valve 4, the combustion air 1 is branched into primary air 5 and secondary air 106, and the primary air 5 is sent to the motor case chamber 7 through the primary air passage 6.
A throttle A8 is provided in the primary air passage 6. A carburetor motor 9 is provided in the motor case chamber 7.
The fin 11 and the fin cup 12 inside the vaporizer 10 are rotated. The kerosene 107 sent by the fuel supply device 13 collides with the fin cup 12, travels along the fins 11 by centrifugal force and reaches the tip, and is atomized by centrifugal force to be vaporized.
Collide with The vaporizer 10 is heated by the heater 14 or the combustion heat at the time of combustion, and the colliding kerosene 107 is vaporized here, mixed with the primary air 5 and sufficiently stirred by the fins 11 to become the premixed gas 15, It is sent to the flame hole 16. The premixed gas 15 blown out from the primary flame hole 16 burns in the combustion chamber 17 to form a primary flame 18. Further, secondary air 106 is blown out from the secondary flame holes 19, and a sufficient amount of air for complete combustion is supplied.
After the combustion is completed, the gas becomes combustion gas 21 and is sent to the combustion tube 22. The secondary air 106 is supplied to the branch valve 4
From the secondary air passage 23.

The combustion gas 21 is sent from the combustion cylinder 22 to the ceiling buffer chamber 24, sent to the radiator 26 through the throttle B 25, and further exhausted from the exhaust port 28 to the atmosphere through the exhaust pipe 27 as exhaust gas 29. . A flow straightening plate 30 is provided inside the combustion tube 22, and a large number of holes 31 are drilled.

At this time, the motor case chamber 7, the carburetor motor 9, the fin 11, the fin cup 12, the carburetor 10, the primary flame hole 16, the combustion chamber 17, the secondary flame hole 19, the combustion cylinder 22, the rectifying plate 30, The ceiling buffer chamber 24 is made substantially symmetrical (axially symmetrical or point symmetrical), and these symmetrical axes are arranged substantially on the same axis 32.

An intermediate reflector 33 is disposed on the same axis 32 between the primary flame hole 16 and the vaporizer 10.

Ignition is controlled by a controller 34. An igniter 35
It is performed by

The combustion control is performed by a signal from a frame rod 36 sent to a controller 34.

The control of the blower 3 is performed by a controller 34.

The control of the carburetor motor 9 is performed by a controller 34.

The control of the heater 14 of the vaporizer is performed by a controller 34.
It is performed by

Oscillation combustion is generally of the acoustic resonance type.
The Rayleigh oscillation conditions (Rayleigh-Putnu) shown in (Equation 1)
m oscillation conditions)

[0026]

(Equation 1)

It is said that this occurs when the condition is satisfied. Here, p is a pressure, h is a calorific value, and T is a cycle of vibration. At the acoustic resonance frequency f of the space inside the combustor, p and h fluctuate. Means to occur.

Here, since the relation between p and h is unknown, a particle velocity fluctuation u is introduced to decompose the relation into p and u, and h and u.

The particle velocity fluctuation u can be expressed as u = | u | exp (jωt). Further, assuming that θ ₁ and θ ₂ are a phase delay of p with respect to θ ₁ : u and a phase delay of h with respect to θ ₂ : u (see FIGS. 3A and 3B), p = | p | exp {j (ωt−θ ₁ )} and h = | h | exp {j (ωt−θ ₂ )}.

These are expressed by Rayleigh's oscillation condition (Equation 1).
Into (2), the following (Equation 2) is obtained.

[0031]

(Equation 2)

(Equation 2) is a formula for determining the energy. Generally, attention is paid to the real part, and the determination is made based on the sign of cos (-θ ₁ + θ ₂ ).
(Since complex numbers have no magnitude, jsin (-θ ₁ + θ ₂ ) is irrelevant to the decision.) Here, FIG. 3A shows cos (−θ ₁
+ θ ₂ ) is a positive value, and FIG.
This shows a case where the value of (−θ ₁ + θ ₂ ) is negative.

In our domestic combustor, θ ₂ is 0
> Θ ₂ > −π, and θ ₁ = π / 2: cos (−θ ₁ + θ ₂ ) = cos (−π / 2 + θ ₂ ) = s
in θ ₂ <0, which does not satisfy the vibration condition, but θ ₁ = −π / 2: cos (−θ ₁ + θ ₂ ) = cos (π / 2 + θ ₂ ) = − s
inθ ₂ > 0, which satisfies the vibration condition.

Therefore, it can be determined whether or not oscillation occurs based on the value of θ ₁ .

Here, when a standing wave exists in the space inside the combustor at the closed end on the inlet side and the closed end on the outlet side, the acoustic resonance frequency f must be f = nc / 2l. here,
n: mode, c: sound speed, l: length of acoustic system. FIG. 4 shows the relationship between p and θ ₁ at this time. n = 1 is the primary mode and n = 2 is the secondary mode.

When the inlet is closed and the outlet is closed, as shown in FIG.
In the case of the first-order mode, the distribution of p is such that the entrance and the exit are antinodes of p, and one node of p exists between them. Also, the phase difference between p and u between the antinode and the node is θ ₁ = π / 2 from the entrance to the exit, and θ ₁ = −π / 2 between the node and the antinode.

As shown in FIG. 4, in the case of the secondary mode, the entrance and the exit are the antinodes of p, and the nodes, antinodes, and nodes of p exist in order. Also in the case of the second-order mode, the phase difference θ ₁ = π / 2 between p and u between the antinode and the node from the entrance to the exit, and θ ₁ = −π / 2 between the node and the antinode.

As described above, in a domestic combustor in which the phase delay θ _{2 of} h with respect to u is in the range of 0> θ ₂ > −π, the Rayleigh oscillation condition is defined as θ ₁ = π / 2 is not satisfied, but θ ₁ = −π / 2 is satisfied. Therefore,
If a flame exists between the arrows shown in FIG. 4, oscillating combustion occurs.

When the entrance is closed and the exit is closed, the number of nodes matches the number of modes, and the number of antinodes is one more than the number of modes.

In the case where the intermediate reflector 33 is not provided, in the combustor of this configuration, the reflector A37 disposed inside the motor case chamber 7 and the reflector B38 disposed inside the ceiling buffer chamber 24 are disposed. Constitutes an acoustic resonance device, and the reflector A37
And the reflection plate B38 becomes an antinode of pressure. Then, oscillating combustion using the energy of the primary flame 18 as a driving source occurs, and the resonance frequency becomes 180 Hz ± 20%. In the case of vibration combustion at such a frequency, if the reflector A37 or the reflector B
Even if the sound absorbing material is arranged at the position 38, the sound absorbing material does not exhibit a sound absorbing effect, and vibration combustion cannot be prevented.

In such a case, when the intermediate reflecting plate 33 is inserted, this surface becomes an acoustic reflecting plate and becomes an antinode of pressure, and the acoustic resonance device and the reflecting plate disposed inside the ceiling buffer chamber with the intermediate reflecting plate 33 are arranged. It is constituted between the plate B38. At this time, the resonance frequency becomes 400 Hz ± 20%. However, since the intermediate reflector 33 and the primary flame 18 approach each other, a flame surface exists between the antinode of pressure and a node, and the energy of the primary flame 18 is increased. Oscillation combustion driven by does not satisfy the generation conditions. Therefore, oscillating combustion is prevented.

Further, as shown in FIG. 1, a space 39 is provided between the combustion chamber 17 and the combustion tube 22 by using an outer frame B40 and a heat shield plate 41. In this space 39, the upstream side of the space 39 is closed and the downstream side is open based on the direction from the entrance side to the exit side of the combustion device. still,
Not limited to such a structure, for example, a ring-shaped space protruding further outward from the outer peripheral surface of the combustion cylinder may be formed around the connection between the combustion chamber and the combustion cylinder. This ring-shaped space has a predetermined thickness in the axial direction of the combustion cylinder, one end in the radial direction of the combustion cylinder is open to the inside of the combustion cylinder, and the other end and other parts are all It is closed.

The presence of the space 39 acoustically creates a situation in which the dimensions of the portion where the combustion cylinder 22 contacts the space 39 are as if they were long.

In order to explain this more concretely, in the combustion device shown in FIG. 1, the pressure amplitude between the upstream closed end face corresponding to the inlet side and the downstream closed end face corresponding to the outlet side inside the combustion apparatus is described. Was simulated. The results are shown in FIGS. FIG.
6 is a simulation result of a pressure distribution in the combustion device before the space 39 is provided, and FIG. 6 is a diagram of a simulation result of a pressure distribution in the combustion device after the space 39 is provided. 5 and 6, the horizontal axis represents the dimension from the upstream closed end face to the downstream closed end face of the combustion device, and the vertical axis represents the pressure amplitude. In FIG. 5, the position of the antinode 51a of the pressure amplitude 51 in the primary mode is upstream of the flame position 52.

Before the space 39 is inserted, the vibration frequency is 178.
Hz. The downstream end of the space 39 is located on the horizontal axis at 211.
When the space 39 is inserted so as to come to the position 63 of 0 mm,
The situation is as if the length of the combustion cylinder 22 at the insertion portion was increased. That is, apparently, the flame position 52 (on the horizontal axis, 14
A pressure amplitude similar to that when the size of the combustion cylinder 22 downstream of 1.0 mm) is increased. Since the pressure amplitude ratio 61 in the first mode shown in FIG. However, the position of the node is on the upstream side of the space insertion, and this part has no change in shape before and after insertion of the space, so the wavelength decreases due to the decrease in frequency, and the position of the node is located downstream. Moving. That is, in this simulation, as shown in FIG.
This shows that the antinode 61a of the pressure amplitude ratio 61 in the primary mode moves downstream from the flame position 52. In the actual combustion device, it was confirmed that by inserting the space 39 at a place corresponding to the simulation, the acoustic condition deviated from the vibration condition, and the vibration combustion could be prevented. The dimensions of each part of the combustion device used in the simulation are shown in Tables 1 and 2.

[0046]

[Table 1]

[0047]

[Table 2]

Tables 1 and 2 show dimensions of the combustor broken down into acoustic elements. Element numbers are assigned from the entrance to the exit of the combustor. Among the element types, C is a closed end element, P is a pipe element, and E is a symbol indicating a branch pipe element.
The cross-sectional area and length are given based on the direction from the inlet to the outlet of the combustor. Temperature is the average temperature of the acoustic element. Table 1 shows the data before the space 39 is inserted, and Table 2 shows the data after the space 39 is inserted.

However, even with such a configuration,
For example, when the combustion load is increased, another mode of oscillating combustion may occur. This is because a large number of acoustic resonance frequencies generally exist for one acoustic system, and any one of them always corresponds to the condition for generating vibration combustion. However, even if they match, the oscillating combustion does not necessarily occur, but occurs only when the driving energy by the flame is larger than the damping energy of the acoustic system. Then, since the higher the frequency, the greater the damping energy, the lower the frequency, the lower the frequency of the oscillating combustion when the frequencies match. Therefore, the oscillating combustion is more likely to occur as the combustion load increases. In this device, the combustion load (flame hole load) is not so large, so that even if the primary mode or the secondary mode is out of the vibration condition, the vibration combustion does not occur.

In order to prevent oscillating combustion with this mechanism, a one-dimensional acoustic system, that is, an acoustic system, is interposed between the intermediate reflector 33 and the reflector B38 disposed inside the ceiling buffer chamber 24. An acoustic system in the same direction as the coaxial 32 of the vessel must be formed. When a three-dimensional three-dimensional acoustic system is formed, the conditions for generating vibration combustion increase, and the conditions for generating vibration combustion are easily satisfied, and vibration combustion is easily generated. In order to prevent this, a flow straightening plate 30 (see FIGS. 2A to 2C) is provided inside the combustion cylinder 22. FIG. 2 (a) to (c)
As shown in (1), a large number of holes 31 are arranged in the current plate 30 in an axially symmetric manner. For this reason, even if a radial vibration mode occurs, resistance is applied to the hole 31 so that the vibration mode hardly exists, and only one-way vibration combustion on the coaxial 32 exists. Circumferential vibration modes are less likely to exist due to the axially symmetrical arrangement of the components, and therefore only unidirectional vibration combustion on the coaxial 32 exists. 2A is a plan view of the rectifying plate 30, FIG. 2B is a side view including a partially schematic cross section of the rectifying plate 30, and FIG.
It is AA sectional drawing in (b).

Further, the blowing direction of the primary flame hole 16
When the coaxial 32 is oriented at right angles, the acoustic system is one-dimensional (coaxial 3).
2).

This is because if the blowing direction of the primary flame hole 16 and the coaxial 32 are made the same, the turbulent direction of the primary flame 18 matches the direction of the acoustic system, and the energy of the flame is easily transmitted to the acoustic system. Therefore, vibration combustion in the direction of the coaxial 32 is likely to occur. To prevent this, the blowout direction of the primary flame hole 16 and the coaxial 32 are perpendicular to each other.

Further, since it is difficult to make the shapes of the primary flame holes 16 the same, irregularities are inevitably generated in the primary flame 18. This unevenness causes turbulence, and blowing in the same direction induces circumferential and radial vibration combustion. However, when the air blows in the right angle direction, the turbulence direction and the axial direction intersect, so that it is difficult for the turbulence of the flame to be transmitted to the acoustic system parallel to the axis. This has the effect of preventing oscillating combustion.

In this embodiment, a semi-closed heater using kerosene 107 is shown. However, the effect of the present invention is not impaired by a closed heater.

Further, even if a gaseous fuel is used, the effect of the present invention is not impaired. In that case, a vaporizer and a heater become unnecessary.

As described above, one of the reasons why it is difficult to efficiently prevent the oscillating combustion is that the mechanism of the oscillating combustion is unknown as described above. The purpose of the present invention is to analyze the acoustic characteristics determined from the structure of the combustion device, and adjust the acoustic characteristics to design the combustor under conditions that do not cause oscillating combustion.

That is, as a method of manufacturing and designing a combustion device, acoustic characteristics determined from the structure of the combustion device are analyzed, and when it is determined from the analysis result that oscillating combustion occurs, an inlet to an outlet of the combustion device is used. A pipe is provided along the inner peripheral surface of the combustion cylinder on the downstream side from the position of the flame of the combustion device with respect to the direction toward the space, and a space formed between the outer peripheral surface of the pipe and the inner peripheral surface The part is much more efficient than in the past, using a method that is designed so that the combustion gas and / or combustion air cannot pass through because the upstream side of the space is closed and the downstream side is substantially open. It is possible to manufacture and design a combustion device that does not generate oscillating combustion.

According to the above embodiment, the following effects can be obtained.

The front buffer chamber, the mixer, the flame hole, the combustion chamber, the combustion cylinder, and the rear buffer chamber are disposed substantially coaxially and substantially coaxially, and a number of openings having a substantially axial symmetry inside the combustion cylinder. A rectifying plate having a substantially coaxial arrangement is disposed substantially coaxially at the front of the flame hole, and an intermediate reflector having a large number of apertures is disposed substantially coaxially at the front of the flame hole, and substantially coaxially disposed within the front buffer chamber. By arranging the entrance reflector at a substantially right angle and arranging the exit reflector at a substantially right angle and substantially coaxially inside the rear buffer chamber, there is an effect of preventing oscillating combustion.

Further, the provision of the air gap between the combustion chamber and the combustion cylinder changes the acoustic resonance conditions, and has the effect of preventing oscillating combustion.

Further, by making the blowing direction of the flame holes substantially coaxial with the coaxial direction, acoustic resonance conditions are generated substantially coaxially, which has the effect of preventing vibration combustion.

[0062]

As is apparent from the above description, the present invention has an advantage that oscillation combustion can be more efficiently suppressed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a semi-enclosed oil heater (combustion device) according to an embodiment of the present invention.

2A is a plan view of a current plate of the present embodiment. FIG. 2B is a side view including a partially schematic cross section of the current plate. FIG. 2C is a cross-sectional view taken along line AA in FIG. 2B.

FIG. 3 (a): Particle velocity u, in the present embodiment
FIG. 4B is a diagram showing the relationship between the pressure p and the heat generation fluctuation h. FIG.
Diagram showing the relationship between heat generation fluctuation h

FIG. 4 is a diagram showing a relationship between a distribution of p and a phase difference between p and u in the present embodiment.

FIG. 5 is a diagram of a simulation result in a state where a space is not inserted in the present embodiment.

FIG. 6 is a diagram illustrating a simulation result in a state where a space is inserted according to the present embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Combustion air 2 ... Intake port 3 ... Blower 4 ... Branch valve 5 ... Primary air 6 ... Secondary air 7 ... Motor case room 8 ... Restrictor A9 ... Vaporizer motor 10 ... Vaporizer 11 ... Fin 12 ... Fin cup 13 ... Fuel supply device 14 ... Heater 15 ... Premixed air 16 ... Primary flame hole 17 ... combustion chamber 18 ... primary flame 19 ... secondary flame hole 20 ... secondary flame 21 ... combustion gas 22 ... combustion cylinder 23 ... secondary air passage 24 ... Ceiling buffer chamber 25 ・ ・ ・ Aperture B 26 ・ ・ ・ Heat radiator 27 ・ ・ ・ Exhaust tube 28 ・ ・ ・ Exhaust port 29 ・ ・ ・ Exhaust gas 30 ・ ・ ・ Rectifier plate 31 ・ ・ ・ Hole 32 ・ ・ ・ Coaxial 33 ・..Intermediate reflector 34 ・ ・ ・ Controller 35 ・ ・ ・ Ignition device 36 ・ ・ ・ Frame rod 37 ・ ・ ・ Reflector A 38 ・..Reflecting plate B 39 air gap 40 outer frame B 41 heat shield plate 42 outer frame A 43 motor case

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shuji Sano 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Satoru Nitta 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A combustion blower for supplying combustion air, a mixer for mixing vaporized fuel and the combustion air, and a flame hole for forming a flame by the mixed fuel. A burner portion, a combustion tube provided between the combustion gas outlet portion and the burner portion, and a downstream side from the flame position with reference to a direction from the combustion air inlet portion to the outlet portion. A pipe provided along the inner peripheral surface of the combustion cylinder, a space formed between the outer peripheral surface and the inner peripheral surface of the tube is closed on the upstream side of the space and downstream. A combustion device having a structure in which combustion gas and / or combustion air cannot pass through when the side is substantially open. 2. The apparatus according to claim 1, wherein the inlet and the outlet are acoustically closed ends, and a structure other than the tube causes oscillating combustion without the tube. Combustion equipment. 3. An acoustic characteristic determined from the structure of the combustion device, and when it is determined from the result of the analysis that oscillating combustion occurs, the combustion device is determined based on a direction from an inlet to an outlet of the combustion device. A pipe is provided along the inner peripheral surface of the combustion cylinder downstream of the flame position, and a space formed between the outer peripheral surface of the tube and the inner peripheral surface is closed on the upstream side of the space. A method for manufacturing a combustion apparatus, characterized in that the combustion gas and / or combustion air cannot pass through because the downstream side is substantially open. 4. A combustion blower for supplying combustion air,
A vaporizer for vaporizing a liquid fuel, a mixer for mixing the combustion air and the vaporized fuel to produce a mixture, a flame hole having a number of openings for ejecting the mixture, and the ejection A combustion chamber in which the mixed gas is burned to produce combustion gas, a combustion cylinder through which the combustion gas flows, and a combustion gas outlet connected to a downstream side of the combustion gas, wherein the vaporizer and the mixer are An integral structure, wherein the vaporizer, the mixer, the flame hole, the combustion chamber, and the combustion cylinder are substantially coaxially arranged and have a substantially axially symmetric structure, and the combustion chamber and the combustion cylinder A ring-shaped or cylindrical acoustic characteristic changing means having one end closed and the other end opened is provided in the vicinity of the acoustic characteristic changing means, and the inside of the acoustic characteristic changing means has a structure through which combustion air and / or combustion gas do not pass. Features combustion equipment. 5. The combustion apparatus according to claim 4, wherein a structure other than said acoustic characteristic changing means generates vibration combustion without said acoustic characteristic changing means. 6. A combustion blower for supplying combustion air, a mixer for mixing vaporized fuel with the combustion air, and a plurality of apertures provided inside the mixer. An intermediate reflector, a burner portion provided with a flame hole for forming a flame by the mixed fuel, and a combustion cylinder provided between a burner gas outlet portion and the burner portion; A combustion device wherein the reflector and the outlet are acoustically closed ends.