JPH04206399A - Plasma torch - Google Patents

Abstract

PURPOSE:To enhance the holding power of plasma and form stable plasma by providing cooling gas ports which are open at required twist angles to form a protective shield embracing plasma jetted from a nozzle port. CONSTITUTION:A jet nozzle 8 has the axial center portion provided with an insertion hole for a cathode rod 5 and a nozzle port 10 and the upper outer periphery provided with a ring groove 18 and also a spiral groove 20 to form a spiral passage 19 twisted in the same direction as the twist direction of a slope passage 14 in a space to an anode block 15. Cooling gas passing through the spiral passage 19 in the jet nozzle 8 is tuned around, continuously held in turning force by a twist angle when passing through cooling gas ports 22 and jetted in a wide-spreading state to form a protective shield embracing plasma 28. It is thus possible to enhance the holding power of plasma 28 and greatly improve the ignitability.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is particularly applicable to aircraft applications in which plasma-formed working fluid is injected into a combustor through which a fluid to be combusted passes at supersonic speed to promote ignition and combustion. The present invention relates to a plasma torch for ignition of an engine or an automatic engine, or for cutting, welding, thermal spraying, etc.

[Prior Art] Generally, the technique shown in FIG. 5 is known as a technique for igniting a fluid to be combusted that flows at a supersonic velocity, which is said to be difficult to ignite because the flow velocity is too high.

As shown in the figure, a plasma torch b is provided which faces into the combustor a where air flows at supersonic speed and ejects a working fluid to promote combustion. Inside this plasma torch b, there is a tank stainless steel cathode Wc as an arc generating means and a copper anode d.
Or is provided. Further, the part of the plasma torch b facing the combustor a is provided with an injection hole C for injecting the working fluid into the combustor a, and the part not facing the combustor a is provided with an injection hole C for injecting the working fluid into the combustor a. A working fluid inlet is provided, and cooling water inlets g, h and outlets j, J are provided for respectively cooling the cathode C and anode d heated by arc discharge. The cooling water passing from the inlet g to the outlet i exerts a thermal pinch effect that narrows the arc column at the anode d forming the nozzle part.In addition, the cooling water flows at supersonic speed into the combustor a facing the plasma torch b. A fuel injection nozzle k is provided upstream of the air flow path to inject hydrogen as fuel into the supersonic air flow.

When igniting the supersonic combustion fluid flowing in the combustor a, first, hydrogen as a fuel is injected into the supersonic air stream from the combustion injection nozzle k, and the hydrogen is mixed with the supersonic air stream. to create a supersonic mixed fluid. Then, argon, hydrogen, nitrogen, etc. (not shown) are used as a working fluid, either alone or in a mixed state, and flowed into the working fluid inlet r provided in the plasma torch b, and the working fluid in the plasma torch b is A required voltage is applied to the cathode c and the anode d to generate an arc, and the working fluid is heated to an extremely high temperature to form a plasma state, resulting in plasma!
is injected into the combustor a through which the supersonic to-be-combusted fluid flows.

When the plasma-formed working fluid is injected into the combustor a where the mixed fluid flows at supersonic speed, the injected plasma!
Due to its thermal and kinetic energy and the chemical reaction promoting effect accompanying the generation of active groups, combustion of the mixed fluid flowing at supersonic speed can be promoted and spontaneous ignition can be achieved.

Among the argon, hydrogen, and nitrogen used alone or as a mixture thereof, which have been tried as the above-mentioned working fluid, a mixture of argon and hydrogen is said to be effective and has been used. The problem is that this will increase the weight of the aircraft.

In this regard, if oxygen or air itself, which is abundant in the atmosphere, could be used as the working fluid, there would be no need to mount a cylinder for storing working fluid, which would increase the weight of the aircraft. The combustion promotion effect of oxygen plasma or air plasma is almost the same as the combustion promotion effect of the argon and hydrogen mixture plasma mentioned above, and oxygen or air can generate a stable arc with a relatively low capacity power source. It is known that it can be maintained.

However, in conventional plasma torches, as shown in Figure 5, a tank stencil electrode is used for the cathode C that constitutes the arc generating means for turning the working fluid into plasma, so the working fluid contains oxygen. If a fluid that is Therefore, in recent years, metals that have a high melting temperature and promote the formation of oxide films have been used for the cathode.

[Invention or Problem to be Solved] When a plasma torch such as the one described in 42 is actually applied to an aircraft engine, diesel engine, etc., it is necessary to constantly generate plasma stably and reliably without causing the plasma to blow out. It is desired that the device be able to be formed into a large size, and it is also desired that the structure can be made simple and compact, and that the peripheral devices can also be simplified.

However, conventional plasma torches have a weak holding power to stabilize and form plasma, and when trying to form plasma in the supersonic flow of air in the combustor, the problem is that it becomes unstable or blows out. Therefore, there were problems such as narrow restrictions on the conditions under which the plasma torch could be used (such as the altitude of the aircraft).

In addition, conventional plasma torches have a complicated cooling tank structure, making it difficult to downsize them. However, especially in systems that use water for cooling, complicated equipment is required around the water circulation tank. There were problems such as:

The present invention was made by focusing on the conventional problems mentioned above.
It is an object of the present invention to provide a plasma torch that can increase the plasma retention force, enable stable plasma formation, and achieve the above-mentioned effects with a simple configuration.

[Means for Solving the Problems] The present invention includes a cathode rod provided in a nozzle casing, and an injection nozzle that faces the tip of the cathode rod via an ejection passage, and the injection nozzle a nozzle opening for injecting plasma on the axis of the rod; a spiral groove forming a spiral passage for cooling waste concentric with the nozzle opening on the outer periphery; - the nozzle is connected to the spiral passage, is formed with a required wide angle toward the tip and has a required wide angle with respect to the nozzle opening, and has a plurality of openings with a required twist angle in the same direction as the twist direction of the spiral passage; - the nozzle; The present invention relates to a plasma torch characterized in that it has a cooling gas injection port that forms a protective tunnel that surrounds the plasma that is ejected from the mouth.

[Function] When cooling gas flows in from the cooling sludge inlet passage, the cooling gas is swirled by passing through the spiral passage of the injection nozzle, and when passing through the plurality of cooling sludge injection ports, the swirling force continues due to the twist angle. At the same time, the plasma is ejected in a spread state due to the wide angle, and a protective tunnel is formed to surround the plasma ejected from the nozzle orifice.

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

FIG. 1 shows an embodiment of the present invention, and as shown in the figure, a nozzle body l constituting a plasma torch is defined by a cylindrical nozzle casing 4 installed facing a passage 3 of a combustor 2. ing. Inside this nozzle casing 4, a predetermined length is extended in the axial direction at the shaft center, and the arc
A cylindrical cathode rod 5 constituting a single electrode is provided. At the tip of the second cathode rod 5, a cathode 6 made of a metal that promotes the formation of a high melting point oxide film, such as hafnium, is formed on its surface. The cathode 6 may be formed using zirconium, rhenium, yttrium, or the like, which have properties similar to hafnium, alone or in a composite material.

An injection nozzle 8 forming an anode 7 of the arc generating electrode is provided on the cathode 6 with a predetermined gap therebetween. A jet passage 9 through which the working fluid passes is formed in the gap between the cathode 6 and the anode 7 constituting the arc generating electrode. It is connected to the downstream nozzle port IO formed in the.

A link-shaped supply passage 11 is formed on the outer periphery of the upstream side of the cathode 6 so as to surround the cathode 6, and a working fluid supply pipe 1 is connected to the upstream side of the supply passage 11 via a passage 11'.
A supply port 13 communicating with the ejection passage 9 and an inclined passage 14 for giving a swirl to the plasma 28 are formed at the lower end of the supply passage 11 extending to near the tip of the cathode 6. There is.

The injection nozzle 8 constituting the anode 7 is connected to the anode block 15
When the injection nozzle 8 and anode block 15 are combined, a ring-shaped cooling groove 16 is formed between them.

The injection nozzle 8 has an insertion hole 17 for the cathode rod 5 and a nozzle opening IO at its axial center, as shown in FIGS. 2-4.

A link groove 18 is formed on the upper outer periphery of the injection nozzle 8, and a spiral passage 19 twisted in the same direction as the twisting direction of the inclined passage 14 is formed between the injection nozzle and the anode block 15 on the outer periphery of the injection nozzle. The upstream end of the spiral groove 20 communicates with the link groove 18, and the tip communicates with the cooling groove 16.

Further, a plurality of cooling gas injection ports 22 are formed between the tip surface 21 of the injection nozzle 8 and the inner deep part of the cooling groove 16 so as to surround the nozzle port 10.

The cooling gas injection port 22 is connected to the nozzle row 1 as shown in FIG.
It is formed with a required twist angle α in the same direction as the twist direction of the sharp turning groove 20 with respect to the axis of the nozzle roller 10, as shown in FIG. It is formed with a bevel angle β.

The widening angle β is 18° to 2 from the viewpoint of the coercive force of the plasma 28.
In experiments, the best results were shown when the angle was around 0° or 19''.

On the -1-stream side of the link groove 18, as shown in FIG.
He and N are connected to each other from the cooling gas inflow pipe 23.
A flammable or non-flammable cooling gas 25 such as 2,02, N2 or the like is supplied.

Further, the outer periphery of the anode float 15 is surrounded by an insulating sleeve 726 made of porous alumina or the like, and the tip is protected by a heat-resistant material 27 such as silicon nitride.

Reference numeral 29 indicates a protective shield formed by the cooling scum 25 that is injected from the cooling scum injection port 22 so as to surround the plasma 28, and 30 indicates a working fluid.

In the above configuration, the working fluid 3 is supplied from the working fluid supply pipe 12.
At the same time, cooling gas 2 is supplied from the inflow pipe 23 at high pressure.
5 is supplied at high pressure.

High pressure working fluid 25 supplied from the working fluid supply pipe 12
The cathode rod 5 is cooled while passing through the link-shaped supply passage 11 from the passage 11', and is then given a turning force by the inclined passage 14 to further cool the cathode rod 5 while being guided to the ejection passage 9, where it is guided into the ejection passage 9. The generated plasma 28 is turned into plasma after passing through the generation electrodes 6 and 7, and is accelerated by the nozzle 10 and injected deep into the combustor 2.

Further, the cooling gas 25 supplied from the cooling gas inflow pipe 23 is introduced into the link groove 18 of the injection nozzle 8 constituting the anode 7 via the cooling gas inflow passage 24, and then into the spiral passage 1.
9. It passes through the cooling groove 16 and is injected to the outside from the waste ejection port 22.

] As mentioned above, the cooling gas 25 is twisted in the same direction as the swirling direction of the plasma 28 through the spiral passage [9], and is further provided with a cooling gas injection port having a twist angle α and a widening angle β. 22 is injected with a twist in the same direction as the plasma 28, so that a substantially truncated conical cylinder surrounds the outer periphery of the plasma 28 with a required wide angle β toward the tip side. A protective shield 29 is formed.

Therefore, the plasma 28 is protected by the protective shield 29, thereby increasing the holding power of the plasma 28, preventing the plasma 28 from being succumbed to high-speed airflow, and improving ignitability.

Furthermore, as described above, since the injection nozzle 8 is cooled by passing the cooling gas 25 through the spiral passage 19 and the inclined passage I4, the cooling efficiency of the injection nozzle 8 can be increased, and therefore the entire plasma torch is cooled. Can be made smaller. Furthermore, since the cooling gas 25 is injected onto the outer periphery of the plasma 28 without being circulated, the internal structure can be further simplified and downsized.

It should be noted that the plus 71.
- It goes without saying that various changes can be made within the scope.

[Effects of the Invention] As explained above, the plasma torch of the present invention has a feature that after cooling the plasma torch, the cooling residue is injected around the plasma to form a gas protection shield surrounding the plasma. As a result, the retention power of the plasma is increased and the ignitability can be significantly improved.

In addition, since the injection nozzle is cooled by passing the cooling gas through the spiral passage and not swirling it, the injection nozzle can be effectively cooled, and the cooling residue after cooling can be injected to the outside. By doing so, the internal structure can be simplified, and excellent effects such as miniaturization of the device can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of one embodiment of the present invention, FIG. 2 is a front view showing the injection nozzle shown in FIG. 1 taken out, and FIG.
FIG. 4 is a vertical cross-sectional view of the figure, FIG. 4 is a view taken along the line IV--IV of the third stage, and FIG. 5 is a partial cross-sectional view showing an example of a conventional plasma torch. 4 is a nozzle casing, 5 is a cathode rod, 8 is an injection nozzle, 9 is an injection flow path, 19 is a spiral passage, 20 is a spiral groove, 2
2 is a cooling gas injection port, 24 is a cooling gas inflow passage, 28 is a plasma, 29 is a protective shield, α is a twist angle, and β is a widening angle.

Claims (1)

[Claims] 1) A cathode rod provided in a nozzle casing, and an injection nozzle facing the tip of the cathode rod via an ejection passage, the injection nozzle being a nozzle that injects plasma onto the axis of the cathode rod. a spiral groove forming a spiral passage for cooling gas concentric with the nozzle opening on the outer periphery; It is formed with a required spread angle with respect to the nozzle opening, and has a plurality of openings with a required twist angle in the same direction as the twisting direction of the spiral passage, forming a protective shield that surrounds the plasma injected from the nozzle opening. A plasma torch characterized by having a cooling gas injection port.