JP2007131119A - Wide area heat protection technology by air flow transpiration cooling using inclining porous ceramic composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple and light air flow transpiration cooling system with high heat-resistance, having extremely high heat flux and atmosphere gas with an oxidization/reduction property, and capable of materializing suitable gas blow-out even under an environment where atmosphere gas pressure and the heat flux are spatially changed, in a heat-resisting system of a method making gas uniformly blow out from a surface of heatproof material made from porous ceramic. <P>SOLUTION: In the air flow transpiration wide area heat protecting system using the inclining porous ceramic composite material 1, a fiber reinforcing porous ceramic composite material incliningly adjusted in porosity and/or thickness is joined with base material to structure a heatproof wall corresponding to outside air flow pressure and a heat flux distribution. Pressurizing coolant is supplied from a back surface to ooze from the heatproof wall into the outside air, thereby forming a cooling system element. Fiber material improving the toughness if the porous ceramic by fiber reinforcement is combined by tilting a fiber containing rate in a wall thickness direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat-resistant material and a heat-resistant system in general, and more particularly to a heat-resistant, thermal protection element technology and a thermal protection system in the aerospace field.

  As a technology to protect the walls of structures that reach high temperatures from high enthalpygas, the idea of performing air flow blowout from the walls is not new, and even today, gas turbines are used for film cooling and leaching (translation) cooling. It is being considered as cooling of the blades and side walls of the combustor. However, these conventional techniques are intended for applications where the gas temperature is up to about 4,000 K, and the wall surface is not significantly exposed to an oxidizing or reducing atmosphere except for a special combustion gas. Therefore, technically, the heat flux blocking is purely assumed by the air flow. On the other hand, for example, in a high heat load environment where the gas temperature around the aircraft is 8,000 to 12,000K, such as the flight environment of a hypersonic aircraft, oxygen atoms in the atmosphere are almost completely dissociated, and the walls are in a significantly oxidizing atmosphere. Will be exposed. In such a situation, the wall surface is not only melted by a thermal load but also strongly oxidized, and a heat protection technique having both heat resistance and oxidation resistance must be used. At present, there is no heat-resistant material and heat-protection technology that completely satisfy this requirement. For example, space shuttle heat-resistant tiles are a major obstacle in terms of reusability and reliability.

When airflow blowing cooling is performed, it is desirable to suppress as much as possible the turbulence of the main flow associated with the airflow blowing, and a method of blowing gas uniformly using porous ceramics having a high porosity as a heat resistant material is effective. The heat protection technology used (see, for example, Patent Document 1) is being proposed. In general, porous ceramics are formed by sintering a ceramic having a small particle diameter of several microns to several tens of microns, and are ceramic materials having a microcavity as an internal structure. Materials having high heat resistance such as alumina, silicon nitride, zirconia, and silicon carbide can be developed, and are generally used as filters. However, with this conventional technology that uses this porous ceramic as a heat-resistant material and blows gas uniformly from the surface, the distribution of external wall pressure and heat flux is locally distributed, for example, around the nose cone of a hypersonic machine and the leading edge of the blade. When changing, it is difficult to perform efficient cooling. This is because the part where the external pressure is high (at the same time the heat flux is large) blocks the gas blowout, and conversely the excess gas leaks out at the part where the external pressure is low (heat flux is small). Will result in unevenness. In order to overcome this, there is an idea to adjust the pressure on the back surface of the porous ceramics according to the external pressure, but this is not practical because it is complicated and increases in weight as a thermal protection system.
A problem when using ceramics as a heat-resistant material is that ceramics have low toughness and are vulnerable to thermal shock, which is particularly problematic with porous ceramics having a high porosity. In order to overcome this, it is considered effective to use fiber reinforced ceramics (FRC), and glass fiber reinforced ceramics are used in heat-resistant tiles of the Space Shuttle. A manufacturing method has not been established.
JP 2005-42721 A "Method for cooling equipment having surface with cooling medium and porous member, leaching cooling device, and method for cooling structure" Published February 17, 2005

  An object of the present invention is to provide a heat protection system in which gas is uniformly blown from the surface of a heat-resistant material made of porous ceramics. The heat flux is extremely high, the atmospheric gas has oxidizing / reducing properties, and the atmospheric gas pressure and the heat flow. An object of the present invention is to provide a highly heat-resistant, simple and lightweight airflow leaching cooling system capable of realizing proper gas blowing even in an environment where the bundle changes spatially.

The airflow leaching wide area thermal protection system using the inclined porous ceramic composite material of the present invention is based on a fiber reinforced porous ceramic composite material in which the porosity and / or thickness is adjusted to be inclined corresponding to the external airflow pressure and the heat flux distribution. A heat-resistant wall was constructed by joining with a soot material, and a cooling system element was formed by supplying pressurized refrigerant from the back and leaching out of the heat-resistant wall into the outside air. And the fiber material which improves the toughness of porous ceramics by fiber reinforcement was made to mix | blend the fiber content rate in the wall thickness direction.
In the wide-area thermal protection system using the inclined porous ceramic composite material of the present invention, the heat-resistant wall back surface is coupled to the pressure partition via the honeycomb structure, and a pressure chamber is formed on the pressure partition side of the honeycomb structure, The pressure partition was provided with a supply port for supplying a refrigerant.
The wide area thermal protection system using the inclined porous ceramic composite material according to the present invention has a wide area heat-resistant wall divided into a plurality of segments in the wide area thermal protection system according to the present invention using the inclined porous ceramic composite material as one form. Thus, the supply pipe for supplying the refrigerant to the supply port is arranged so as to go around the segment surface.

The manufacturing method for obtaining a tilted porous ceramic composite material for a wide area thermal protection system according to the present invention includes a matrix in which Si powder and phenol resin are tilted in-plane when silicon carbide fiber fibers are woven, and after drying and molding It was manufactured by reactive sintering.
As another manufacturing method, in a PIP method in which a fiber preform is impregnated and thermally decomposed with an organosilicon polymer of a SiC precursor, the in-plane porosity distribution is adjusted by adjusting the number of impregnation steps for each region. A method to obtain graded porous ceramic composites for wide area thermal protection system was presented.
As a method of using the wide-area thermal protection system according to the present invention, an inert and low heat conduction gas up to 3,000 K is adopted as a refrigerant for the purpose of improving the oxidation / reduction property of the heat-resistant wall surface in an oxidation / reduction atmosphere. Presented to leach. More specifically, liquid nitrogen is used as a refrigerant, the specific volume during storage is suppressed, and the use of a wide-area thermal protection system that promotes cooling and gas vaporization of structural panels by piping to each heat-resistant segment did.

The airflow leaching wide area thermal protection system using the inclined porous ceramic composite material of the present invention is based on a fiber reinforced porous ceramic composite material in which the porosity and / or thickness is adjusted to be inclined corresponding to the external airflow pressure and the heat flux distribution. Since a heat-resistant wall is constructed by joining with a soot material, a cooling system element is formed by supplying pressurized refrigerant from the back and leaching out of the heat-resistant wall into the outside air. Without providing a system for adjusting the pressure, only by supplying a pressurized refrigerant having a constant pressure from the back surface, leaching of the cooling gas corresponding to the external air flow pressure and the heat flux distribution can be realized, and a suitable cooling system can be provided. And the fiber material which improves the toughness of the porous ceramics by fiber reinforcement is made by adding the fiber content rate in the wall thickness direction, thereby improving the thermal shock resistance and increasing the porosity in the surface direction. However, the air leaching wide area thermal protection system that does not disturb near the outer surface could be realized.
In the wide-area thermal protection system using the inclined porous ceramic composite material of the present invention, the heat-resistant wall back surface is coupled to the pressure partition via the honeycomb structure, and a pressure chamber is formed on the pressure partition side of the honeycomb structure, Since the supply port for supplying the refrigerant is arranged in the pressure partition wall, the refrigerant is supplied to the inclined porous ceramic composite material with the honeycomb structure as a flow path, and the flow of the cooling gas is directed so as to be leached from the outer surface. be able to.
Moreover, in the wide-area thermal protection system according to the present invention using the inclined porous ceramic composite material as one embodiment of the present invention, the wide-area heat-resistant wall is divided and formed in a plurality of segments, so that a complicated curved surface shape that is not a simple structure is formed. Even with this structure, a panel can be formed for each divided region. In addition, when the supply pipe for supplying the refrigerant to the supply port is provided so as to go around the segment surface, the structure brings about the effect of promoting the cooling of the structural panel and the gas evaporation.
The global thermal protection technology by airflow leaching cooling using the tilted porous ceramic composite of the present invention uses the tilted porous ceramics to minimize the disturbance to the external airflow and against the external airflow pressure and heat flux distribution. It is possible to provide an appropriate gas leaching distribution, and it is possible to heat-protect a wide-area wall surface with a single thermal barrier wall and a single pressure hermetic chamber. Thereby, a system can be constructed simply and lightly.

The manufacturing method for obtaining a tilted porous ceramic composite material for a wide area thermal protection system according to the present invention can realize an arbitrary gas leaching distribution by a manufacturing method for tilting the porosity of ceramic as a matrix in the in-plane direction. Is possible. And when manufacturing the inclination porous ceramics composite material of the said specification by reaction sintering method, shrinkage | contraction of a molded object can be restrained small compared with another method, and a manufacturing process is also simplified. Further, in the method of adjusting the impregnation step by the PIP method, it is difficult to incline the fiber content rate in the direction perpendicular to the plane, but it is possible to adjust the porosity gradient in the in-plane direction more finely and accurately. .
The use method of the wide-area thermal protection system according to the present invention, which employs an inert and low heat conduction gas up to 3,000 K as a refrigerant and is leached out in an oxidizing / reducing atmosphere, Since stable inert gas leaching was achieved, the oxidation resistance / reduction property of the heat resistant wall surface could be improved. In addition, liquid nitrogen is used as a refrigerant, the specific volume during storage is suppressed, and the piping to each heat-resistant segment also promotes cooling and gas vaporization of structural panels. The specific volume is suppressed, and there are also secondary effects such as the piping to each heat-resistant segment can cool the structural panel.

  The airflow leaching cooling system using the tilted porous ceramic composite material of the present invention obtains the external airflow pressure and heat flux distribution characteristics of the target structure, and an appropriate amount of gas with a constant back pressure in an environment showing the distribution characteristics. The refrigerant represented by (1) is purged. One form for realizing this is shown in FIG. In this method, the fiber-reinforced porous ceramic composite material 1 whose porosity is adjusted to be inclined so as to obtain a desired gas outflow is joined to the base material 2 in order to provide mechanical strength, thereby constructing a heat-resistant wall. Since the base material 2 needs to allow the refrigerant to pass through the fiber-reinforced porous ceramic composite material 1, a net-like structure is used instead of a plate-like body. In addition, a honeycomb structure that allows the refrigerant to move in the lateral direction between the pressure partition walls 4 that also serve as the heat-resistant wall and the structural wall so that an appropriate gas leaching distribution is given to the external air flow pressure and the heat flux distribution. 3 connect to form a cooling system element. The honeycomb structure that enables the lateral movement of the refrigerant can be designed such that a through-hole is provided in the wall forming the honeycomb, or the honeycomb structure 3 and the pressure partition 4 are bridge-connected at important points. is there. In addition, as a derivative form thereof, a method of changing the refrigerant permeability distribution by adjusting the thickness of the porous ceramics 1 instead of adjusting the porosity in an inclined manner is presented. This is what is shown in FIG. Further, a method of giving gas leaching distribution by using the above two forms together can be adopted in the present invention. By using porous ceramics with gradient characteristics in refrigerant permeability, a wide range of walls with varying external air pressure and heat flux distribution are protected by a single thermal barrier and single pressure hermetic chamber. Therefore, the system can be constructed simply and lightly.

  However, a material called porous ceramics has a weak point that it is vulnerable to mechanical strain. Therefore, in order to reinforce the toughness of the porous ceramics, a fiber reinforced ceramic composite material is used in the present invention. In order to reduce the disturbance of the leach gas distribution on the external wall surface, as shown in FIG. 3, the fiber content is formed to be inclined so as to gradually decrease as it approaches the outer surface. To be. The inclination distribution in the direction perpendicular to the surface also has an effect of suppressing breakage due to a rapid change in the thermal stress distribution. As a manufacturing method of the inclined porous ceramic composite material 1, the first presented method uses a SiC / SiC composite material using a SiC matrix. In this case, as shown schematically in FIG. Sometimes, a matrix in which the composition of Si powder 6 and phenol resin 7 is inclined in the plane is arranged, dried and molded to prepare prepreg 8. Similarly, by changing the density of the SiC fibers 5, a matrix in which the composition of the Si powder 6 and the phenol resin 7 is inclined in the plane is arranged, dried and molded. These steps are sequentially laminated to form a material having a SiC fiber density gradient in the thickness direction. By sintering this by a reactive sintering method, the porosity was inclined in the plane as shown in FIG. 3 and the fiber content was inclined so as to gradually decrease as it approached the outer surface. A porous matrix composite 1 can be obtained.

  As a second production method, an application of a polymer infiltration and pyrolysis (PIP) method in which a fiber preform is impregnated with a silicon precursor organosilicon polymer and thermally decomposed is presented. In this manufacturing method, as schematically shown in FIG. 5, a phenol resin is applied to a fiber preform formed of SiC fibers 5 and heated to first form a porous carbon matrix. This material is impregnated with the SiC precursor organosilicon polymer 9 and thermally decomposed to form silicon carbide. In the part where the porosity is to be kept low, the organosilicon polymer is impregnated compared to the part where the porosity is to be raised. By increasing the number of times, the density of SiC is increased, and as a result, the prepreg 8 in which the in-plane porosity is adjusted to an arbitrary distribution is generated. A woven fabric in which the density of the SiC fiber 5 is changed is stacked on this material, and a prepreg 8 in which the in-plane porosity is adjusted to an arbitrary distribution is formed by the same method. Rough prepregs 8 are sequentially laminated, and the heating process is applied to incline the porosity in the plane as shown in FIG. 3, and incline so that the fiber content gradually decreases as it approaches the outer surface. The porous matrix composite material 1 formed as described above can be obtained.

  In order to improve the oxidation / reduction properties of the heat-resistant wall of the structure exposed to an oxidation / reduction atmosphere, it is necessary to use a gas with low thermal conductivity and inert properties up to about 3,000K as the leaching gas. is there. The refrigerant may be a gas in the storage state, but is preferably a liquid in consideration of the specific volume during storage. For example, as shown in FIG. 6, the refrigerant thermal barrier wall is divided into segments, and the supply pipe 11 that supplies the refrigerant from the supply source to the supply port 10 provided in each segment is provided so as to go around the segment surface. By piping in this way, the structural panel is cooled and the effect of promoting vaporization of the refrigerant is achieved. Nitrogen is used as a typical refrigerant.

An example of the cooling system for the entire single blade is shown in FIG. 7 as the first embodiment. This can be applied to the one that cools the entire small blade, such as a gas turbine cascade or a hypersonic canard. In the case of the small wing 12, the structure can be formed by the hollow inclined porous ceramic composite material 1. By making the hollow portion a refrigerant flow path or an airtight chamber, the above-described pressure partition 4 or the like is not required, and the system can be simplified and reduced in weight. However, in this case, since the ceramic composite material 1 bears the structural strength, care must be taken in the strength design.
When it is impossible to construct a wing structure with a ceramic composite material 1 alone, such as a slightly medium-scale wing, as a derived type, a porous reinforcing plate 13 is used as a hollow inner surface as shown in FIG. A method of increasing the structural strength by providing a beam 14 between the reinforcing plates is proposed.

  Next, the Example which applied this invention to the combustor throat and the cooling system of a nozzle wall surface is shown. In this case, the surface exposed to the high-temperature gas is not the outer peripheral surface of the structure but the inner peripheral surface. FIG. 9 shows an example of a system for cooling the combustor throat and the nozzle wall surface, and the coolant is supplied to the back surface of the inclined porous ceramic composite material 1 by the external grooves 15 and the longitudinal grooves 16 formed by the partition structure. . In the case of a large-scale nozzle, it is difficult to integrally form and sinter the inclined porous ceramic composite material. In the case of leaching cooling, the internal combustion gas pressure distribution balances with the leaching pressure distribution or is slightly lower than the latter, so that the porous ceramic surface is not subjected to the combustion pressure, and the structural strength is borne by the external pressure partition 15. For this reason, compared with the passive heat-resistant system which receives a combustion pressure directly on a wall surface, the stress of wall surface ceramics is reduced.

  Next, an embodiment in which the present invention is applied to a cooling system for a blade leading edge of a hypersonic aircraft will be described. FIG. 10 shows an example of a slightly large blade leading edge cooling system such as a hypersonic machine. In this case, since the cooling site is wide and large, several inclined porous ceramic composite materials 1 are divided into cooling segments to constitute one cooling system as a whole. In this example, the blade leading edge is divided into a plurality of blocks in the longitudinal direction, and each divided block is divided into upper, middle and lower segments. The blade as a whole is designed and manufactured so that the gas permeability of each segment is connected so that the optimum gas leaching is continuously connected to the external flow pressure and heat flow rate distribution. By appropriately tilting the porosity or gas permeability in each segment, the amount of leached gas is made to correspond to the pressure and heat flux of each part of the blade, so that a constant refrigerant pressure is supplied to the supply port 10 into which the refrigerant flows. The supply pipe 11 may be simply connected to connect the supply source and the supply port 10 in the partition wall. When adjusting the partition internal pressure of each segment individually, the refrigerant needs to be supplied to each segment through the respective pressure regulation systems, but when the same internal partition pressure is used in all the segments as in this embodiment. The pressure regulating system may be single (except for the redundant system), and the piping may be common. Thus, unlike conventional approaches, it is not necessary to prepare many pressure regulation systems to provide the leach gas distribution, and the system is simplified and weight is reduced.

  Finally, an embodiment in which the present invention is applied to the nose portion of a hypersonic aircraft will be described. FIG. 11 shows an example of a cooling system for the nose portion of a hypersonic aircraft. The basic design philosophy is divided into several inclined porous ceramic composite cooling segments according to the case of a large blade leading edge. As a whole, one cooling system is configured, and each segment is supplied with a constant refrigerant pressure. By the way, in the example shown here, the nose part of the hypersonic aircraft is divided into a plurality of blocks in the aircraft axis direction, the nose tip is divided into one segment, and the next block is divided into a plurality of segments in the circumferential direction. It is composed. Each segment becomes the inclined porous ceramic composite material 1 in which the porosity of the portion is inclined corresponding to the pressure and heat flux distribution of the outer wall of the nose portion during hypersonic flight.

Heat resistance and thermal protection system in the aerospace field-Naturally, it can be used as a general application, and other specific applications include gas turbine blades, combustion chamber wall surface, combustor throat wall surface, nozzle wall surface, external wall surface of hypersonic aircraft, etc. Can be assumed.

It is a conceptual diagram of the thermal defense wall by the inclination porous ceramics which concern on this invention. It is a conceptual diagram of the thermal protection wall by the other inclination porous ceramics of this invention. It is a conceptual diagram of the fiber-reinforced gradient porous ceramic composite. It is a figure explaining the inclination porous ceramics composite manufacturing method by the reaction sintering method. It is a figure explaining the inclination porous ceramics composite manufacturing method using PIP method. It is a figure explaining the structural panel cooling form by regeneration cooling of a piping system. It is a figure which shows the Example which integrally molded the small wing | blade with the inclination porous ceramic composite_body | complex of this invention. It is a figure explaining the Example which gave the intensity | strength reinforcement of the small-medium-sized wing | blade. It is a figure which shows the Example which comprised the throat and the small scale nozzle with the inclination porous ceramic composite_body | complex of this invention. It is a figure which shows the Example which comprised the large-scale blade front edge with the inclination porous ceramic composite_body | complex of this invention. It is a figure which shows the Example which comprised the hypersonic machine nose part with the inclination porous ceramic composite_body | complex of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inclined porous ceramic composite 2 Base material 3 Honeycomb structure 4 Pressure partition 5 SiC fiber 6 Si powder 7 Phenolic resin 8 Prepreg 9 Organosilicon polymer 10 Supply port 11 Supply pipe 12 Small blade 13 Reinforcement plate 14 Beam 15 External pressure partition 16 Vertical groove

Claims (10)

  A heat-resistant wall is constructed by joining a fiber-reinforced porous ceramics composite with a porosity and / or thickness adjusted in an inclined manner corresponding to the external air pressure and heat flux distribution to the base material, and pressurized refrigerant is applied from the back. A wide-area thermal protection system in which a cooling system element is formed by supplying and leaching from the heat-resistant wall into the outside air.   The fiber material that improves the toughness of the porous ceramics by reinforcing the fiber is blended by inclining the fiber content in the wall thickness direction, thereby improving the thermal shock resistance and increasing the porosity in the surface direction. The wide area thermal protection system according to claim 1, wherein the material is not disturbed near the outer surface.   The rear surface of the heat-resistant wall is coupled to a pressure partition via a honeycomb structure, a pressure chamber is formed on the pressure partition side of the honeycomb structure, and a supply port for supplying a refrigerant is disposed on the pressure partition. The wide-area thermal protection system according to claim 1 or 2, wherein the honeycomb structure is formed so that the supplied refrigerant moves in the heat-resistant wall thickness direction.   The wide-area heat protection system according to claim 1 or 2, wherein the hollow structure is integrally formed of an inclined porous ceramic composite material, and the surface thereof serves as a heat protection wall.   The wide-area heat protection system according to any one of claims 1 to 3, wherein the wide-area heat-resistant wall using the inclined porous ceramic composite material is formed by being divided into a plurality of segments.   6. The wide area thermal protection system according to claim 5, wherein the supply pipe for supplying the refrigerant to the supply port is provided so as to go around the segment surface.   Manufacture of tilted porous ceramic composites for wide-area thermal protection systems by placing a matrix in which Si powder and phenol resin are tilted in-plane when weaving silicon carbide fiber fibers, drying, molding, and reaction sintering Method.   Inclined porous for wide-area thermal protection system that adjusts in-plane porosity distribution by adjusting the number of impregnation steps for each region in PIP method of impregnating and thermally decomposing SiC precursor organosilicon polymer into fiber preform A manufacturing method for obtaining a ceramic composite material.   7. The refrigeration gas according to claim 1, wherein an inert and low thermal conductivity gas is used and leached up to 3,000 K for the purpose of improving the oxidation / reduction property of the heat-resistant wall surface in an oxidation / reduction atmosphere. How to use a wide area thermal protection system.   7. The wide-area thermal protection according to claim 6, wherein liquid nitrogen is used as a refrigerant, a specific volume during storage is suppressed, and cooling and gas vaporization are promoted by piping to each heat-resistant segment. How to use the system.

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