JPH1041567A - Combustion type gas dynamic laser oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive combustion type of gas dynamic laser oscillator which can oscillate a CO2 laser beam with high output, in spite of such a condition that the pressure inside a combustor is relatively low, using combustible gas as fuel. SOLUTION: This oscillator has a combustor 2 for generating high- temperature gas containing CO2 by combusting combustible gas, and also has a laser oscillator 10 comprising a supersonic nozzle 3 for discharging the high- temperature gas at supersonic speed, a laser cavity 4 for generating a CO2 laser by heat-insulatingly expanding the discharged high-temperature gas, and a diffuser 5 for smoothing the flow of high-temperature gas. Besides, the pressure inside the combustor 2 at laser oscillation is 0.1-1.5MPa, and also the input of combustible gas is 1-15kW.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion type gas dynamic laser oscillation device using a combustible gas as fuel.

[0002]

2. Description of the Related Art Conventionally, there is a combustion type gas dynamic laser oscillation device as one of devices for oscillating laser light. This combustion type gas dynamic laser oscillation device oscillates laser light from CO ₂ in the combustion gas by adiabatically expanding the combustion gas containing CO ₂ obtained by burning the fuel.

[0003] The principle of the oscillation of a CO ₂ laser beam is that, as is conventionally known, by rapidly changing a high energy level of CO ₂ to a low energy level, a change in the energy level is converted into a laser beam. It oscillates. The change in the energy level in the combustion type gas dynamic laser oscillation device is realized in the process of adiabatic expansion of the combustion gas.

Under such a principle, conventionally, a solid fuel or a liquid fuel is used as a fuel for generating a combustion gas containing high-energy level CO ₂ , and this is mixed with an oxidizing agent according to the type. It was burning. Specifically, for example, there is a rocket propellant as a solid fuel,
As the liquid fuel, there is, for example, benzene. Examples of the oxidizing agent include ammonium perchlorate and liquefied nitrous oxide.

[0005]

However, the above-mentioned solid fuel and liquid fuel and the oxidizing agent used therefor are not very easy to handle. In addition, since it is not easy to obtain them, equipment such as a tank for securing and storing a necessary amount in advance is required. In contrast, combustible gases such as city gas are examples of fuels that can be easily handled.

[0006] This combustible gas is generally widely used in a form utilizing combustion heat, but has not reached practical use as a fuel for generating combustion gas in a combustion type gas dynamic laser oscillation device. It can be said that. In other words, although several gas dynamic laser oscillators using flammable gas have been proposed so far, high-performance laser oscillators capable of oscillating laser light with high output have not yet been developed. .

Further, in the conventional combustion type gas dynamic laser, when the pressure in the apparatus immediately before driving is set to about the atmospheric pressure, the pressure in the combustor is set to a high pressure of several tens MPa or the pressure immediately before driving is increased. The pressure in the apparatus was reduced to reduce the combustor pressure to several MPa. That is, in the related art, the internal pressure of the combustor needs to be set to an extremely high pressure of several MPa or more regardless of the internal pressure of the apparatus immediately before driving. Therefore, an expensive combustor with high pressure resistance was required, and the entire laser oscillation device was very expensive.

The present invention has been made in view of the above-mentioned conventional problems, and uses a combustible gas as a fuel and oscillates a CO ₂ laser beam at a high output while the pressure in the combustor is relatively low. It is an object of the present invention to provide an inexpensive combustion-type gas dynamic laser oscillating device that can be used.

[0009]

According to a first aspect of the present invention, there is provided a combustor for burning a combustible gas to generate a high-temperature gas containing CO ₂ , and a supersonic speed for discharging the high-temperature gas at a supersonic speed. A laser having a nozzle, a laser cavity for adiabatically expanding the emitted high-temperature gas to generate a CO ₂ laser, and a laser oscillation unit including a diffuser for smoothing the flow of the high-temperature gas; The pressure in the combustor during oscillation is 0.1 to 1.5M
The combustion type gas dynamic laser oscillator is characterized in that the pressure is within the range of Pa and the input of the combustible gas is within the range of 1 to 15 kW.

It is most remarkable in the present invention that the pressure in the combustor is 0.1 to 1.5 MPa even if the pressure in the apparatus immediately before the driving is about atmospheric pressure, and the flammable gas Input is 1 to 15 kW.

The pressure in the combustor is 0.1 MPa
If the pressure is lower than the predetermined value, high-power laser light cannot be oscillated, and for convenience of operation, the pressure is about atmospheric pressure (0.1
There is a problem that it is not preferable to make the pressure lower than (MPa). Therefore, the pressure is more preferably 0.2 MPa or more. On the other hand, the higher the pressure in the combustor, the higher the laser output can be obtained. However, if the pressure exceeds 2.0 MPa, there is a problem in the pressure resistance design of the combustor. Therefore, it is further preferable to reduce the internal pressure of the combustor to 0.9 MPa or less by reducing the internal pressure of the apparatus immediately before driving to about 0.01 MPa.

The input of the combustible gas is 15 k.
If it exceeds W, there is a problem in the heat resistance of the device. On the other hand, when the power is less than 1 kW, there is a problem that high-power laser light cannot be oscillated. here,
The input refers to the calorific value per unit time of the combustible gas supplied to the combustor.

As the combustible gas, for example, various combustion gases such as city gas containing methane gas as a main component, propane gas, butane air gas and the like can be used. Further, as the above-mentioned combustor, a combustor of a type used in a conventionally known gas turbine, a flame propagation combustor described later, or the like can be used.

Further, as described above, the laser oscillation section has a supersonic nozzle, a laser cavity, and a diffuser sequentially, and the supersonic nozzle side is connected to the combustor. This supersonic nozzle is a so-called nozzle in which the cross-sectional area of the combustion gas supplied from the combustor is narrowed narrowly, and the combustion gas is accelerated to supersonic speed by the change of the cross-sectional area and is emitted into the laser cavity. Play a role.

The laser cavity has an opening cross-sectional area sufficiently larger than the opening area of the supersonic nozzle, and is maintained in a low pressure state below the atmospheric pressure. The diffuser is a portion where the cross-sectional area of the opening is slightly narrowed near the exit of the laser cavity, and is for smoothing the flow of the combustion gas discharged into the laser cavity.

Next, the operation of the present invention will be described. In the combustion type gas dynamic laser oscillation device of the present invention, the pressure in the combustor is set to 0.1 to 1.5.
MPa and the input of combustible gas is within a range of 1 to 15 kW. Therefore, high-power laser light suitable for practical use can be oscillated by an inexpensive device.

That is, the pressure in the combustor is 0.1 to 1.5 MPa, which is a relatively low pressure, and the input of the combustible gas supplied at this time is 1 to 15 kW, which is high energy. Therefore, the CO _{2 in} the combustion gas immediately before passing through the supersonic nozzle becomes a high energy level relatively easily at a high ratio.

The combustion gas containing CO ₂ at a high energy level is discharged from the supersonic nozzle into the laser cavity at high speed. The discharge speed at this time becomes supersonic due to the action of the supersonic nozzle. for that reason,
The combustion gas released into the laser cavity in the low pressure state is adiabatically expanded in a very short time, and the energy level changes from high to low in a very short time.

Therefore, the laser light is reliably oscillated by the rapid change of the energy level, and the high output C
O ₂ laser light is obtained. Therefore, in the present invention,
This can greatly contribute to the practical use of a combustion type gas dynamic laser oscillator using a combustible gas. On the other hand, when the pressure in the combustor is less than 0.1 MPa, or when the input of the combustible gas is less than 1 kW, a laser beam having a very high output cannot be obtained, and practical application is difficult. It is.

In the present invention, as described above,
A high-power laser can be oscillated without setting the internal pressure of the combustor to a high pressure as in the related art. So the combustor,
Consequently, the entire apparatus can be made inexpensive. Therefore,
This can greatly contribute to the practical use of a combustion type gas dynamic laser oscillation device using combustible gas.

Next, the opening ratio (C / N) of the cross-sectional area C of the laser cavity to the opening area N of the supersonic nozzle is preferably 19 to 60. If the aperture ratio (C / N) is less than 19, there is a problem that the emission speed of the combustion gas into the laser cavity cannot be increased so much. It is necessary to increase the ratio to the pressure, and the pressure in the combustor must be several M
There is a problem that laser oscillation is not performed unless the pressure is set to a pressure higher than Pa.

Also, as in the third aspect of the present invention, it is preferable that the aperture ratio (C / D) of the sectional area C of the laser cavity to the sectional area D of the diffuser is 1-2. If the throttling ratio (C / D) is less than 1, there is a problem that the effect of smoothing the flow of the combustion gas is small. Problem.

Further, as in the fourth aspect of the present invention, the supersonic nozzle, the laser cavity, and the diffuser are all rectangular in cross section, and are preferably formed continuously by a smooth inner wall. . As a result, the flow of the combustion gas can be further smoothed, which can contribute to the reliable oscillation of the laser beam. Further, by making the cross-sectional shape of the opening rectangular, it is possible to easily manufacture the laser oscillation section.

Further, as in the invention of claim 5, it is preferable that the combustor is a flame propagation combustor. This flame-propagating combustor is of a type that burns fuel while constantly moving the flame position (see the embodiment). Therefore, the temperature rise of the combustor itself can be suppressed as much as possible.
Does not require very high heat resistance. Therefore, for example, the cost can be further reduced as compared to a gas turbine combustor having both high heat resistance and high pressure resistance.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 A combustion-type gas dynamic laser oscillation device according to an embodiment of the present invention will be described with reference to FIGS. The combustion type gas dynamic laser oscillating device 1 of the present embodiment is shown in FIG.
As shown in Fig. 1, city gas containing methane gas as a main component was used as combustible gas.

That is, the combustion type gas dynamic laser oscillation device 1 has a combustor ₂ for burning the city gas F to generate a high temperature gas containing CO ₂ and for discharging the high temperature gas at a supersonic speed. A laser cavity 4 including a supersonic nozzle 3, a laser cavity 4 for adiabatically expanding the emitted high-temperature gas to generate a CO ₂ laser, and a diffuser 5 for smoothing the flow of the high-temperature gas. Having. The pressure in the combustor 2 is about 1.15 MPa, and the input of the combustible gas is about 15 kW. The details are described below.

Combustor 2 for generating the above combustible gas
As shown in FIG. 1, a flame spread combustor is used. The flame-propagating combustor includes a fuel supply unit 21 for supplying city gas F and air A while mixing them, a combustion tube 22 for moving a flame during combustion, and an ignition unit 23 for igniting the air-fuel mixture. Become. The tip of the supersonic nozzle 3 of the laser oscillation unit 10 is disposed at the rear end of the ignition unit 23. Reference numeral 221 denotes a thermocouple for measuring temperature, and reference numeral 23 denotes a thermocouple.
2 is a pressure sensor.

Next, the combustion characteristics of the flame spread combustor will be briefly described. First, a mixture of city gas F and air A is continuously supplied from the fuel supply unit 21 into the combustion pipe 22. In the combustion tube 22, the air-fuel mixture is ignited by an igniter 231 provided in the ignition section 23, and a flame is generated. This flame moves toward the upstream side against the flow of the air-fuel mixture and is extinguished when reaching the fuel supply unit 21 by the blowing pressure of the air-fuel mixture.

Next, the igniter 231 re-ignites the air-fuel mixture filled in the combustion tube 22 again. As a result, the above-described series of combustion proceeds again. The most characteristic feature of the flame-propagating combustor is that the combustion gas is generated while repeating the ignition, flame movement, and fire extinguishing cycle.

In this embodiment, the city gas F and the air A are supplied at a mixing ratio of 1.0 so that the input reaches about 15 kW. Thereby, the flame propagation combustor can generate a combustion gas having a pressure of about 1.15 MPa.

Next, as shown in FIGS. 1 and 2, the laser oscillating section 10 is provided with the supersonic nozzle 3, laser cavity 4, and diffuser 5 in this order. , These are smooth inner walls 18
Are formed continuously. In the maximum expansion portion of the combustion gas in the laser cavity 4, transmission windows 15 through which laser light can pass are provided on the left and right.

As shown in FIGS. 2 and 3, the opening ratio (C / N) of the sectional area C of the laser cavity 4 to the opening area N of the supersonic nozzle 3 is set to 20. The aperture ratio (C / D) of the sectional area C of the laser cavity 4 to the sectional area D of the diffuser 5 is set to 1.5.

In producing the laser oscillation section 10, the upper and lower portions are formed by cutting stainless steel square bars, and then butted and welded. Thereby, the laser oscillation unit 10 having the smooth inner wall 18 and having high pressure resistance is provided.
Can be easily produced.

Next, in this embodiment, the laser oscillation unit 10
A gain measuring device 6 for measuring the output (gain) of the CO ₂ laser light is provided outside the transmission window 15. As shown in FIG.
_It has an external laser device 61 for projecting the _two probe laser from the transmission window 15 into the laser cavity 4.
On the side opposite to the CO ₂ laser device 61 via the two transmission windows 15, there is provided a reflection mirror 62 for receiving CO ₂ laser light oscillated from the laser cavity 4 together with the CO ₂ probe laser.

An MCT for measuring the light intensity of the reflected CO ₂ laser light is provided in the reflection direction of the reflection mirror 62.
A detector 63 and an oscilloscope 64 for displaying a measurement result are provided. Reference numeral 65 denotes the above CO ₂
H emitting visible laser light for setting the optical path of the probe laser
An e-Ne laser 66 is a reflection mirror that reflects visible laser light into the laser cavity 4.

Next, the operation of this embodiment will be described.
In the combustion type gas dynamic laser oscillation device 1 of this embodiment, the city gas of about 15 kW is input into the combustor 2 as described above, and the combustion gas of about 1.15 MPa high pressure is generated. In other words, the combustion gas has a relatively low pressure, but has a sufficiently high energy. Therefore, the combustion gas immediately before passing through the supersonic nozzle 3 is in a very high energy state, and the CO ₂ therein has a high energy level at a high ratio.

Next, the CO _{2 having} a high energy level
Is discharged from the supersonic nozzle 3 into the laser cavity 4 at high speed. The release rate at this time is
The supersonic speed of the Mach number is about 5 by the action of the supersonic nozzle 3. Therefore, the combustion gas discharged into the laser cavity 4 in the low pressure state is adiabatically expanded in a very short time, and the energy level changes from a high level to a low level in a very short time. Therefore, the laser beam is reliably oscillated by the rapid change of the energy level, and the high output CO ₂
Laser light is obtained.

Next, in this example, the oscillated CO ₂
The intensity of the laser light was measured by the gain measuring device 6.
The measurement results were obtained from the CO ₂ emitted from the external laser device 61.
The incident intensity of the probe laser on the transmission window 15 is defined as I ₀ ,
The intensity of the CO ₂ laser light oscillated together with the CO ₂ probe laser from the transmission window 15 is evaluated as I and the gain G calculated by the following formula. G = (1 / L) × ln (I / I ₀ ) [m ⁻¹ ] Here, L is the optical path length of the probe laser, and is 10 mm in the case of the present test apparatus.

As a result of the evaluation, the gain G in this example is
It reached 0.6 m ^-1 , indicating that a very high output CO ₂ laser beam was oscillated. This corresponds to about 85 W in terms of laser output. Of the commercially available CO ₂ lasers that are already commercially available, the ones used for cutting and processing have an output of about 500 W to 1,500 W, and the optical path length is set to about 0.17 m with this tester. This means that the same high output of 1,500 W can be obtained, which can be put to practical use.

Embodiment 2 In this embodiment, the relationship between the pressure of the combustion gas in the combustor and the gain G was investigated using the combustion type gas dynamic laser oscillation device 1 of the embodiment 1. The pressure of the combustion gas was changed in the range of about 0.9 to 1.2 MPa.
The configuration of the gain measuring device 6 and the method of calculating the gain G are the same as those in the first embodiment.

FIG. 4 shows the measurement results of the gain. FIG.
The horizontal axis indicates the pressure of the combustion gas, and the vertical axis indicates the gain G. As can be seen from FIG. 4, the gain G reached 0.2 to 0.7 m ^-1 over the entire range of the measured combustion gas pressure, and a very high output was obtained. It was also found that in the above measurement range, a higher gain was obtained as the pressure of the combustion gas was higher.

Embodiment 3 In this embodiment, an example in which the combustion type gas dynamic laser oscillation device 1 of Embodiment 1 is put to practical use will be described. That is, as shown in FIGS. 5 and 6, the transmission window 15 of the laser oscillation unit 10 is provided.
The resonator 7 for extracting the CO ₂ laser light is disposed on both sides of the optical fiber, and the optical fiber 73 for transferring the laser light is disposed.

As shown in FIGS. 5 and 6, the resonator 7 includes a reflector 71 that totally reflects the laser beam and a semi-reflector 72 that reflects half the laser beam and transmits half the laser beam. The optical fiber 73 is disposed outside the semi-reflective plate 72. The CO ₂ laser light oscillated in the laser cavity 4 by the resonator 7 having such a configuration is amplified while being repeatedly reflected between the reflection plate 71 and the semi-reflection plate 72 and sent to the optical fiber 73.

Therefore, in the combustion type gas dynamic laser oscillation device having the resonator 7 of the present embodiment, for example, the laser beam sent out from the optical fiber 73 is used.
It can be used for cutting, processing, etc. Further, the laser light obtained at this time has a high output as shown in the above embodiment, so that it can be used very effectively.

[0045]

As described above, in the present embodiment, a combustible gas is used as fuel, and a CO ₂ laser beam can be oscillated at a high output while the pressure in the combustor is relatively low. It is possible to provide a simple combustion type gas dynamic laser oscillation device.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a combustion-type gas dynamic laser oscillation device according to a first embodiment.

FIG. 2A illustrates a laser oscillation unit according to the first embodiment.
A longitudinal section, (b) a transverse section.

FIGS. 3A and 3B show a supersonic nozzle (in the direction of arrows in FIG. 2B-B) and a laser cavity in FIG.
Explanatory drawing which shows the cross-sectional shape of EE (as seen from the arrow of line E) and (c) the diffuser (as seen from the arrow of line HH in FIG. 2).

FIG. 4 is an explanatory diagram showing a relationship between a combustor internal pressure and a gain in a second embodiment.

FIG. 5 is an explanatory diagram showing a configuration of a combustion-type gas dynamic laser oscillation device according to a third embodiment.

FIG. 6 is an explanatory diagram showing a configuration of a resonator according to a third embodiment.

[Explanation of symbols]

 1. . . 9. Combustion type gas dynamic laser oscillation device, . . Laser oscillation section, 15. . . 1. transmission window; . . 2. combustor, . . 3. supersonic nozzle, . . Laser cavity, 5. . . Diffuser, 6. . . 6. Gain measuring device, . . Resonator,

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takayuki Kobayashi 2367 No. 483 Hachiryu, Omori Omori, Moriyama-ku, Nagoya-shi, Aichi

Claims (5)

[Claims] 1. A supersonic nozzle having a combustor for burning a combustible gas to generate a hot gas containing CO ₂ , and a supersonic nozzle for discharging the hot gas at a supersonic speed.
It has a laser cavity for adiabatic expansion of the released high-temperature gas to generate a CO ₂ laser, and a laser oscillating unit consisting of a diffuser for smoothing the flow of the high-temperature gas. A combustion type gas dynamic laser oscillation device, wherein a pressure in the combustor is in a range of 0.1 to 1.5 MPa, and an input of the combustible gas is in a range of 1 to 15 kW. 2. The combustion type gas dynamic laser oscillation according to claim 1, wherein an opening ratio (C / N) of a sectional area C of the laser cavity to an opening area N of the supersonic nozzle is 19 to 60. apparatus. 3. A combustion-type gas dynamic laser according to claim 1, wherein the aperture ratio (C / D) of the sectional area C of the laser cavity to the sectional area D of the diffuser is 1 to 2. Oscillator. 4. The method according to claim 1, wherein:
The combustion type gas dynamic laser oscillation device, wherein the supersonic nozzle, the laser cavity, and the diffuser are all rectangular in cross-sectional shape, and are continuously formed by smooth inner walls. 5. The method according to claim 1, wherein:
The combustion type gas dynamic laser oscillation device, wherein the combustor is a flame propagation combustor.