CN102562827A - High-speed bearing cooling system of turbine/compressor for aviation and method and application thereof - Google Patents

Abstract

The invention discloses a cooling system for a high-speed bearing of a turbine/compressor used in aviation, and belongs to the technical field of aircraft environment control. It mainly includes air supply (1), air compressor (2), air radiator (3), turbine (4), heat pipe condensation end (5), heat pipe evaporation end (6), heat exchanger (7), air outlet (8 ). The cooling working method has outstanding advantages such as high efficiency and simple structure. This cooling working method utilizes the extremely high thermal conductivity of the heat pipe, and introduces the heat pipe into the two-wheel system of the turbine/compressor to cool the bearing.

Description

Cooling system, method and application of aviation turbine/compressor high-speed bearing

the

technical field

The invention relates to a cooling system, method and application of a high-speed bearing of a turbine/compressor used in aviation, and belongs to the technical field of aircraft environment control.

Background technique

With the development of air cycle machines (ACM), the requirements for bearings in the aviation industry are getting higher and higher. The speed of bearings in the United States can generally reach more than 1 x 10 ⁵ r/min, but the speed of domestic bearings can only reach about 3 to 4 x 10 ⁴ r/min, which may be lower in actual production applications. The reason is that the bearing lubrication in the United States mostly uses air lubrication, while in our country due to technical reasons, only grease lubrication can be used. The air lubrication technology is unique to the United States, and it is difficult to break through the technical barriers of air lubrication in the short term. Therefore, how to seek a breakthrough on the basis of the existing grease lubrication and further improve it, so as to improve the lubrication ability, has become the key to improving the performance of the bearing. There is a positive correlation between the temperature of the bearing and the speed of the bearing. The increase of the speed will lead to the increase of the temperature of the bearing, and the working temperature of the bearing generally cannot exceed 70 ℃. So how to effectively cool the bearing is the key issue of research. At present, for applications on the ground or with sufficient space, a refrigeration cooling system can be added, and a pump or fan can be used to transport liquid or gas to cool the bearing. It is obviously not possible for the very compact space of the aeronautical system.

Contents of the invention

The object of the present invention is to provide a high-efficiency, simple-structure cooling system, method and application of the high-speed bearing of the turbine/compressor used in aviation.

A cooling system for a turbine/compressor high-speed bearing, characterized in that: the system is composed of an air supply end, an air compressor, an air radiator, a turbine, a heat pipe, a heat exchanger, and an air outlet; Both ends; the air supply end is connected to the compressor, air radiator, turbine, heat exchanger, and outlet in turn; the heat pipe condensation end of the heat pipe is connected to the heat exchanger, and the heat pipe evaporation end is connected to the outer ring of the bearing. The above-mentioned heat pipe may be a single-pipe heat pipe or a loop heat pipe.

The cooling method utilizing the cooling system of the turbine/compressor high-speed bearing is characterized in that it includes the following process: the air supply is first compressed by the compressor, and then the temperature is further reduced by the air radiator, which can improve the cooling effect; the gas continues to After cooling down through the expansion of the turbine, it is used as a cold source to connect the condensing end of the heat pipe; the high-speed rotation of the bearing generates a large amount of heat, and the heat is transmitted from the outer end of the bearing to the evaporating end of the heat pipe. When the evaporating end of the heat pipe is heated, the liquid in the heat pipe evaporates rapidly, and the steam Under a small pressure difference, it flows to the condensing end of the heat pipe, releases heat, and condenses into a liquid again. The liquid then flows back to the evaporating end of the heat pipe along the porous material by capillary force, and the cycle continues. The heat is transferred from the evaporating end of the heat pipe to the condensing end of the heat pipe . In this way, the bearing is cooled and conditions are provided for the further improvement of the bearing speed.

The cooling method of the turbine/compressor high-speed bearing is characterized in that it is applied to a two-wheel system composed of a compressor/turbine, or to a three-wheel system composed of a fan/compressor/turbine, or to a fan/compressor Four-wheel system composed of engine/turbine/turbine.

Most aviation bearings use rolling bearings, and the lubrication method is grease lubrication. When the bearing reaches a certain speed, a large amount of heat will be generated, which limits the further increase of the bearing speed.

Utilizing the extremely high thermal conductivity of the heat pipe, the heat pipe is introduced into the turbine/compressor two-wheel system to cool the bearing.

Compared with ordinary cooling devices, heat pipe heat exchange equipment is safer and more reliable than conventional equipment, can run continuously for a long time, has high efficiency, and has remarkable energy-saving effects. Materials with good thermal conductivity include aluminum [(λ=202W/m·℃)], wood copper [λ=385W/m·℃], and silver: λ=410W/m·℃)], but their thermal conductivity is only It can reach the order of 10 ² W/m·℃, which is far from meeting the needs of rapid heat dissipation and heat transfer in aeronautical engineering, and the use of heat pipes solves this problem. The equivalent thermal conductivity of the heat pipe can reach an order of magnitude of 10 ⁵ W/m·°C. It is hundreds or even thousands of times that of ordinary metal materials. Therefore, the heat pipe can achieve the effect of a large metal section with a small cross-sectional area, and it can transmit a large amount of heat through a small cross-sectional area for a long distance without external power.

The heat pipe is an artificial component with excellent heat transfer. The commonly used heat pipe consists of three parts: the main body is a closed metal tube (tube shell), and there is a small amount of working medium (working fluid) and capillary structure ( tube core), the air and other impurities in the tube must be excluded. The heat pipe uses three physical principles when working: 1) Under low pressure, the boiling point of the liquid decreases; 2) The latent heat of vaporization of the same substance is much higher than the sensible heat; 3) The suction force of the porous capillary structure on the liquid can be Make the liquid flow. From the perspective of heat transfer, the heat pipe can be divided into three parts: the evaporation section, the adiabatic section and the condensation section along the axial direction.

A general heat pipe consists of a shell, a liquid-absorbing core and an end cap. The inside of the heat pipe is pumped into a negative pressure state and filled with a suitable liquid, which has a low boiling point and is easy to volatilize. The tube wall has a liquid-absorbing core, which is made of capillary porous material. One end of the heat pipe is connected to the outer ring of the bearing. This section is used as the evaporation end of the heat pipe, and the other end is connected to the radiator. The radiator is used to dissipate heat from the air cooled by the cooling turbine. This section is used as the condensation end.

The high-speed rotation of the bearing generates a large amount of heat. The heat is transferred from the outer end of the bearing to the evaporation end of the heat pipe. The liquid in the capillary evaporates rapidly, and the steam flows to the condensation end under a small pressure difference, and releases heat. The porous material flows back to the evaporating section by the action of capillary force, and the cycle is endless, and the heat is transferred from one end of the heat pipe to the other end.

This cycle is rapid, and heat can be continuously conducted away. Thereby, the bearing can be effectively dissipated heat, the temperature of the bearing can be reduced, and the purpose of further increasing the rotational speed of the bearing can be achieved.

Description of drawings

Figure 1 is a schematic diagram of the cooling system of the high-speed bearing of the turbine/compressor used in aviation;

Label names in Fig. 1: 1, air supply, 2, compressor, 3, air radiator, 4, turbine, 5, heat pipe condensing end, 6, heat pipe evaporating end, 7, heat exchanger, 8, air outlet.

Detailed ways

According to shown in Fig. 1, the cooling system of the high-speed bearing of turbine/compressor for aviation of the present invention mainly comprises air supply air supply 1, compressor 2, air radiator 3, turbine 4, heat pipe condensation end 5, heat pipe evaporation end 6, Heat exchanger 7, air outlet 8. The compressor 2 and the turbine 4 form a two-wheel system.

The working process of the system is described in conjunction with Figure 1: the air supply 1 is first compressed by the compressor 2, and then the temperature is further lowered by the air radiator 3 to prevent the gas from absorbing heat at the condensing end 5 of the heat pipe and returning to temperature, resulting in a decline in refrigeration performance. Next, the gas passes through the cooling action of the turbine 4 and serves as the condensation end 5 of the heat pipe. The other end of the heat pipe is connected to the outer ring of the bearing, and this section is used as the evaporation end 6 of the heat pipe. The high-speed rotation of the bearing generates a large amount of heat. The heat is transferred from the outer end of the bearing to the evaporation end 6 of the heat pipe. The liquid in the heat pipe evaporates rapidly. Flow back to the evaporating section along the porous material by the action of capillary force, so that the cycle continues, and the heat is transferred from the evaporating end 6 of the heat pipe to the condensing end 5 of the heat pipe. Therefore, cooling the bearing can provide conditions for the continuous improvement of the bearing speed.

The above-mentioned cooling method for high-speed bearings of turbine/compressors used in aviation can also be applied to aviation or ground high-speed rotating bearing systems. Such as engines, generators, motors, etc. Its cold source can come from other places, such as external air, refrigeration system, fuel oil, PCM (phase change material), etc.

Claims (4)

1. A cooling system for aviation turbine/compressor high-speed bearings, characterized in that: The system consists of air supply end (1), air compressor (2), air radiator (3), turbine (4), heat pipe, heat exchanger (7), and air outlet end (8); Wherein the compressor (2) and the turbine (4) are located at both ends of the rotating shaft; The air supply end (1) is sequentially connected with the compressor (2), the air radiator (3), the turbine (4), the heat exchanger (7), and the outlet end (8); Wherein the heat pipe condensation end (5) of the heat pipe is connected with the heat exchanger, and the heat pipe evaporation end (6) is connected with the outer ring of the bearing. 2. The cooling system for aviation turbine/compressor high-speed bearings according to claim 1, wherein the heat pipe is a single-pipe heat pipe or a loop heat pipe. 3. according to the cooling method of the cooling system of the said aviation turbine/compressor high-speed bearing of claim 1, it is characterized in that comprising the following process: The air supply (1) is first compressed by the compressor (2), and then the temperature is further reduced by the air radiator (3), which can improve the cooling effect; the gas continues to cool down through the expansion of the turbine (4), and then acts as a cooling source Connect the condensation end of the heat pipe (5); The high-speed rotation of the bearing generates a large amount of heat, and the heat is transferred from the outer end of the bearing to the evaporating end (6) of the heat pipe. When the evaporating end (6) of the heat pipe is heated, the liquid in the heat pipe evaporates rapidly, and the steam flows to the condensing end of the heat pipe under a small pressure difference ( 5), and release heat, re-condensed into a liquid, and the liquid flows back to the heat pipe evaporation end (6) along the porous material by capillary force, so that the cycle continues, and the heat is transferred from the heat pipe evaporation end (6) to the heat pipe condensation end ( 5), so as to cool the bearing and provide conditions for the further increase of the bearing speed. 4. The cooling method for aviation turbine/compressor high-speed bearings according to claim 3, characterized in that: it is applied to a two-wheel system composed of a compressor/turbine, or to a three-wheel system composed of a fan/compressor/turbine system, or applied to a four-wheel system consisting of fan/compressor/turbine/turbine.

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