JPS58160711A - Pulse burner - Google Patents

Abstract

PURPOSE:To contrive the reducing of burning noise of the titled device by a method wherein two discharging pipes from a burner are connected each other, and said pipes different in each length are arranged to invert the sound wave phases passing through each pipe at the connecting part of two discharging pipes. CONSTITUTION:A sound wave 14 passing through the inside of a discharging pipe 2 and a sound wave 15 passing through the inside of a discharging pipe 3 are collided at the connecting part 16 where two discharging pipes are connected. The two discharging pipes 2, 3 are formed to be different in length for inverting said two sound wave phases. Thereby, a pulse burner producing low burning noise can be obtained, and especially successive effect at low frequency sound range can be achieved. Further, the excellent burning characteristic can be maintained without disturbance of the flowing by providing, at said connecting part, the sound permeable wall 10 having the property which intercepts the flow of fluid and permeates only the sound.

Description

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

Conventionally, pulse combustors have the advantage of being able to burn at high loads, have good heat transfer characteristics, and are capable of 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, due to the excessive noise generated during combustion, when used as a heat source such as a domestic water heater, it is difficult to make noise that can withstand practical use unless a silencer is used. Furthermore, unlike the combustion noise of a general combustor, the noise in the low frequency range is large, and when this noise is reduced by a muffler,
This had the disadvantage of requiring a large muffler.

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

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

In the figure, the pulse combustor has a combustion chamber, two exhaust pipes 2 and 3, a valve device 4, a spark plug 6, a starting blower 6, an air supply pipe 7, a fuel supply/squive 8, a mixing chamber 9, an acoustic It is composed of a transparent wall 10.

At the time of starting, the spark plug 6 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 self-exciting cycle is formed, combustion air 11 is automatically sucked in through the air intake valve 7 and valve device 4, even if the spark plug and starting blower are stopped, and self-ignition is started. The combustion continues. The combustion gas 13 passes through the exhaust pipe 2 and is exhausted to the outside.

At this time, the combustion sound 14 is also emitted to the outside through the exhaust pipe 2 together with the combustion gas 13. On the other hand, the sound-transmitting wall 10 located at at least one of the connecting portion between the furnace chamber 1 and the exhaust pipe 3 or the connecting portion between the exhaust pipe 2 and the exhaust pipe 3 has the characteristic of blocking the flow of fluid and allowing only sound pressure to pass through. Because of this, only the sound waves 16 pass through the exhaust pipe 3. If we consider that the sound waves passing through the exhaust pipe are sine waves with a phase as shown in Figure 2a, then if the sound waves passing through the exhaust pipe 2゜3 are out of phase, the two sound waves will be superimposed. In this case, the sound becomes stronger or weaker due to the phase shift, as shown in Figure 2C. Therefore, a silencing effect can be obtained by colliding two sound waves having opposite phases.

Therefore, in this device, the sound waves 14 passing through the exhaust pipe 2 are
The two exhaust pipes 2 and 3 are provided with lengths so that when the sound waves 15 passing through the exhaust pipes 3 collide at the joint 16 of the two exhaust pipes, the phases of the sound waves become opposite. It is important to be different. Therefore, by adding a simple structure to the exhaust pipe, this device can achieve a significant noise reduction effect compared to conventional pulse combustors. The effect is particularly great on low frequency sounds. Furthermore, if both the sound waves and the combustion gas collide at the joint of the exhaust pipe, the flow will be disturbed and the combustion mechanism may be damaged. Therefore, as shown in Fig. 1, an acoustically transparent wall has a property of blocking the flow of fluid and allowing only sound pressure to pass through at least one of the joints between the combustion chamber 1 and the exhaust pipes 2 and 3, or the joints between the two exhaust pipes. 1o, the combustion gases do not collide at the exhaust pipe connecting portion 16, so that the flow field is not affected.

Therefore, noise can be reduced without impairing the furnace firing characteristics.

A third embodiment of a pulse combustor in which the present invention is also applied to the air supply side is shown in FIG. It consists of a blower 22, two air supply pipes 23 and 24, a fuel supply pipe 25, a mixing chamber 26, and an acoustically transparent wall 2.

When a self-exciting cycle is formed and combustion continues after startup, combustion air 28 is supplied to the combustion chamber through the air supply pipe 23 and the pulp device 2o. At this time, the combustion sound 30 is also emitted to the outside through the air supply pipe 23.

As mentioned above for the exhaust side, this device
The two air supply pipes are connected so that when the sound waves 30 passing through the air supply pipe 3 and the sound waves 31 passing through the air supply pipe 24 collide at the joint 32 of the two air supply pipes, the phases of the sound waves become opposite to each other. Since the air supply pipes 23 and 24 have different lengths, a significant noise reduction effect can be obtained compared to conventional pulse combustion. The effect is particularly great on low frequency sounds. Furthermore, if there are two air supply squibs, the flow of combustion air in the air supply system will be complicated, and there is a risk that the suction capacity of the pulse combustor will be reduced. Therefore, by providing an acoustically transparent wall 27 having a characteristic of blocking the fluid flow and allowing only sound pressure to pass through at least one of the connection portion between the mixing chamber and the air supply pipe or the connection portion between two air supply pipes, the flow can be improved. Noise can be reduced without affecting the field or deteriorating the combustion characteristics.

As described above, in the present invention, one or both of the exhaust pipe and the air supply pipe is configured by connecting two pipes, and the phases of the sound waves passing through the respective pipes are opposite to each other at the connecting part. A low-noise pulse combustor can be achieved by providing a difference in length between the two pipes so that The effect is particularly great on low frequency sounds. Furthermore, by providing a sound-transmitting wall having a characteristic of blocking the flow of fluid and allowing only sound pressure to pass through the connecting portion, there is an effect that good furnace firing characteristics can be maintained without disturbing the flow field. Therefore, even when used as a heat source for a domestic water heater, a relatively simple and small muffler only needs to be attached to provide a small-sized domestic water heater.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a pulse combustor demand increase which is one embodiment of the present invention, a second characteristic diagram of combustion noise, and Fig. 3 is a block diagram of a pulse combustor which is another embodiment of the present invention. It is. 1.17... Combustion chamber, 2, 3, 18.19...
...Exhaust pipe, 4,20...Valve device, 7 23.24...Air supply vibe, 9,26
......Mixing room, 10.27...Sound-transmitting wall.

Claims (4)

[Claims] (1) a combustion chamber, an exhaust pipe connected to the combustion chamber, a mixing chamber located upstream of the combustion chamber for mixing gas and air, a gas pipe and an air supply pipe connected to the mixing chamber; a valve device located upstream in the mixing chamber, the exhaust pipe is configured by connecting two pipes, and the phase of the sound wave passing through each pipe is adjusted at the connecting portion of the pipes. A pulse combustor that has two pipes with different lengths so that they have opposite phases. (2) A patent claim in which a sound-transmitting wall having a characteristic of blocking fluid flow and allowing only sound pressure to pass is provided at each connecting portion of the exhaust pipe and the combustion chamber or at least one of the connecting portions of the two pipes. The pulse combustor according to the range 1 above. (3) The air supply pipe is constructed by connecting two pipes, and the lengths of the two pipes are set so that the phases of the sound waves passing through each pipe are in opposite phases at the connecting part of the pipes. A pulse combustor according to claim j, which is configured to provide a difference. (4) A patent for a configuration in which an acoustically transparent wall having the property of blocking fluid flow and allowing only sound pressure to pass is provided at each connection between the intake pipe and the combustion chamber or at least one of the connection between the two pipes. A pulse combustor according to claim 3.