JPS58200910A - Pulse burner - Google Patents

Abstract

PURPOSE:To simplify a structure and reduce the generation of a noise, by a method wherein a device has a sufficient length to allow the resonance of an air column of a tail tube of a cushion chamber by means of a wave being n-fold as many as a fundamental frequency of a combustion sound. CONSTITUTION:A tail tube 10 of a cushion chamber 3 is sized to have a sufficient length to allow the resonance of an air column by means of a wave being n-fold as many as a fundamental frequency of a combustion sound to reduce the production of a low frequency component of a combustion sound having a fundamental frequency or wave 2-3 times as many as the fundamental frequency. With regard to a sound of a frequency amplified by the resonance of the air column, a plurality of holes 12 are machined in the tail tube 10 to surround the holes 12 with a resonance chamber 11, and this forms a resonance chamber resonating at the frequency at which the air column resonates. Through the working of the resonance chamber, a sound amplified by the resonance of the air column is decreased. This provides a silencing effect through a simple structure.

Description

[Detailed description of the invention] The present invention relates to a pulse combustor.

Conventionally, a Hals combustor, as shown in Figure 1, has a furnace chamber 1,
Exhaust pipe 2, Kutsunyeon chamber 3, pulp device 4,
It consists of a spark plug 5, a starting blower 6, an air supply pipe 7, a fuel supply pipe 8, a cushion chamber 9, and a tail pipe 10.

At the time of starting, the spark plug 5 is operated and the starting blower 6 supplies combustion air to the combustion chamber 1, thereby forcing combustion to occur. Once the system is stable and a stable firing cycle is formed, the spark plug and starting blower are stopped, combustion air is automatically sucked through the air supply pipe 7 and the pulp device 4, and self-ignition is started. This continues pulse combustion at a constant frequency. On the other hand, when a muffler is installed to reduce combustion noise, the fundamental frequency of the combustion cycle may change because the acoustic impedance changes. For this reason, it often happens that even the best silencers are not as effective as expected. Therefore, a cushion chamber 3 is provided on the downstream side of the exhaust pipe 2 so that pulse combustion can be maintained at a predetermined frequency even when a muffler is attached.

Such a pulse combustor can smoke under high loads, has good heat transfer characteristics, and has advantages such as automatic suction of combustion air and self-ignition except during startup.

Furthermore, the combustor has a simple structure and can be manufactured at relatively low cost. However, because pulse combustors generate excessive noise during combustion, when used as a heat source such as a domestic water heater, the noise will be too great for practical use unless a silencer is used as a noise reduction measure. Gui.

Therefore, it costs money to reduce noise by incorporating a silencer into all equipment, but
Pulse combustor differs from the combustion sound of other combustors, with 1o o
There is a lot of noise in the low frequency range below Hz. In general, it is difficult to reduce @ sounds in the low frequency range with a muffler.
<4' method had the disadvantage of requiring a thick muffler with a large plate thickness.

The present invention has been devised in view of these drawbacks, and it is an object of the present invention to provide a low-noise pulse combustor with a simple structure.

Hereinafter, one embodiment of the present invention will be described with reference to all the drawings.

The pulse furnace of the present invention has a combustion chamber 1, as shown in FIG.
, exhaust pipe 2, cushion chamber 3, pulp device 4
, a spark plug 5, a starting blower 6, an air supply pipe 7, a furnace supply pipe 8, a cushion chamber 9, a tail pipe 10, and a resonance chamber 11.

The operating principle of combustion has been described in the conventional example, so a description thereof will be omitted.

Next, noise reduction according to the present invention will be explained.

The combustion sound of the pulse combustor is produced by the combustion chamber 1 as shown in Figure 3a.
and the fundamental frequency f determined by the shape of the exhaust vibe 2
. It has harmonic components consisting of sounds that are integral multiples of the fundamental frequency. 1. The length of the tail pipe 10 based on the present invention is 2f0
Figure 3 and Figure 3C show the results of investigating the effect on combustion noise when the length is set so that the air column resonates at a frequency of 4fo, and when the length is set so that the air column resonates at a frequency of 4fo.

Comparing Figure 3 a, b, and c, the air column resonance frequency, 2f0 in the case of b and 4fo in the case of C, has increased compared to the original sound of a, but the other sounds are It can be seen that it is decreasing. In particular, the sound in the low frequency range, which is difficult to reduce with a muffler, has been significantly reduced. Therefore, as a sound reduction measure, it is only necessary to take measures for the sound of the air column resonance frequency, and a simple muffler is sufficient.

Therefore, the present invention takes full advantage of this fact.
By making the 10 tail pipes of the cushion chamber 3 long enough to resonate with the air column at the n-th harmonic of the fundamental frequency of the combustion sound, in other words, for the combustion sound as shown in Fig. 3d, the tail pipe 10 is set to 4fo with a low sound pressure level. By making the length so that the air column resonates with
Low frequency components of combustion sound such as the fundamental frequency and 2nd to 3rd harmonics of the fundamental frequency are significantly reduced. Furthermore, for the sound of the frequency t'' amplified by air column resonance, a plurality of holes 12 are made in the tail pipe 10 and these holes are surrounded by a resonance chamber 11, so that a resonance chamber that resonates at the frequency of air column resonance is created. formed,
The function of this resonance chamber is to reduce the sound amplified by air column resonance.Therefore, this device is designed to replace conventional pulse combustion by adding a simple structure to the tail pipe of the cushion chamber. It is possible to obtain a remarkable sound deadening effect compared to other instruments, and the effect is particularly great in the low frequency range. Similar effects can be obtained even when the above is used for the air supply pipe 7.

Therefore, both the noise emitted from the exhaust system and the noise emitted from the air supply system can be reduced, and a pulse furnace with low noise level can be obtained.

As described above, the present invention provides a structure in which the tail pipe connected to the cushion chamber has a length that causes the air column to resonate at a frequency that is an integral multiple of the reference frequency of combustion sound, and furthermore, the tail pipe has a length that resonates at the frequency of the air column resonance. By providing the chamber, it is possible to obtain a low-noise pulse combustor with a particularly effective noise reduction effect in the low-frequency sound range.

Further effects can be obtained if used in combination with a conventional expansion type muffler. Therefore, even when used as a heat source for a domestic water heater, it is sufficient to use a relatively simple and small muffler in combination, making it possible to provide a complete compact domestic water heater.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional Noculus combustor.
...Smoking chamber, 2...Exhaust, C-eve, 3.
...Kunonyo/Chan/ζ, 4.../<Luff device, 7...Air supply pipe, 8...
Gas no Ku Eve, 9...Mixing room, 10...
・Tail tube, 11...Resonance chamber. Name of agent: Patent attorney Toshio Nakao 1! , or 1
Name 3 figure ^) N skin [, 7 skin number・) 6゛671

Claims (2)

[Claims] (1) a combustion chamber, an exhaust pipe connected to the combustion chamber, a cushion chamber connected to the other end of the exhaust pipe, a tail pipe connected to the cushion chamber, and a cushion chamber located upstream of the combustion chamber; A furnace material supply pipe and an air supply pipe connected to the cushion chamber and a pulp device located upstream of the Kusonyo/cha/ba are provided, and the tail pipe is configured to generate air at one frequency having a harmonic component of the combustion sound. A pulse combustor having a length that causes column resonance, and further comprising a plurality of holes and a resonance chamber in the tail pipe that cause Helmholtz resonance at a frequency of air column resonance. (2) The air supply pipe has a length that causes the air column to resonate at a certain frequency of the harmonic component of the combustion sound, and the air supply pipe further includes a plurality of holes and a resonance chamber that causes Helmholtz resonance at the frequency of the air column resonance. Claims with [! 14. The pulse combustor according to item 1.