RU2285131C1 - Steam-turbine engine - Google Patents

Abstract

FIELD: aero-engine manufacturing.

SUBSTANCE: proposed steam-turbine engine is made on base of turboprop engine operating on liquid hydrogen with use of steam-gas technologies. Water is used as additional working medium in steam-turbine engine, water being liberated from combustion products by means of freezing chamber installed in engine output device. Cold-retaining capacity of fuel (liquid hydrogen) is used for cooling exhaust gases to freezing temperature (condensing of water) and at boosting of engine, also cold-retaining capacity of atmosphere.

EFFECT: increased efficiency of engine in flight and at boosting.

5 cl, 4 dwg

Description

The invention relates to aircraft engine manufacturing.

Recently, in Russia and abroad, the STIG technology of gas turbine engines (steam injection into the combustion chamber) has been developed, which have already found practical application in stationary and ship gas turbines (Emin O.N. Use of aircraft gas turbine engines to create combined gas turbine units for stationary and transport purposes. Textbook.M.: MAI, 1998, 80 pp.). The effective efficiency of combined cycle plants today reaches 58–60%, which is significantly higher than the efficiency of aircraft engines. One of the main problems hindering the introduction of STIG gas turbine technology in aviation is the need to place enough water on board an aircraft to operate the engine in flight. The use of hydrogen as an aviation fuel allows us to solve this problem: the output of water vapor (water) during the combustion of hydrogen in air is ~ 9 kg per kilogram of hydrogen, which is significantly greater than other known fuels. The technical solution in this case is reduced to two main tasks: the allocation of water from the combustion products and its effective use.

Known gas turbine engines (Theory, calculation and design of aircraft engines and power plants: Textbook edited by V. A. Sosunov, V. M. Chepkin. M: Publishing House of the Moscow Aviation Institute, 2003, Fig. 19-10, p. 567 ) in which a heat exchanger is installed in the output device (behind the turbine), the refrigerant of which is fuel (liquid hydrogen).

A known method of forcing a gas turbine engine by injecting a liquid (Theory and calculation of jet engines. Edited by S.M.Shlyakhtenko. M.: Engineering, 1987, p. 374).

Known liquid-air rocket engines (Theory, calculation and design of aircraft engines and power plants: a Textbook edited by V. A. Sosunov, V. M. Chepkin. M: Publishing House of the Moscow Aviation Institute, 2003, Fig. 19-21, p.576), which use freezers to release oxygen from the air.

Known air-fuel heat exchanger (Patent RU No. 2241937, MPK7 F 28 D 11/02, 2004), allowing to cool the air in the gas-air duct of the axial compressor. The heat exchanger is designed for gas turbine engines using cryogenic fuels.

The essence of the invention lies in the fact that in a gas turbine engine using liquid hydrogen as fuel, a freezer is located in the output device (behind the turbine), which consists of a heat exchanger whose coolant is fuel (liquid hydrogen) and a centrifugal separator located at the outlet of specified chamber and heated by exhaust gases. In the freezer, water is released (frozen) from the combustion products and removed (in the form of ice and condensate) in a special container. In gas turbine engines, water is used as an additional working fluid, which is supplied to the internal cavity of the drum of the axial compressor or to the mixing chamber in front of the engine turbine.

Figure 1 shows a diagram of a steam turbine engine (PDD);

Figure 2 shows the dependence of the effective efficiency and specific power of the PDD on the parameters of the working process;

Figure 3 shows the dependence of the effective efficiency and specific power of the PDD on the parameters of the working process;

Figure 4 shows a diagram of a steam turbine engine.

The PTD is based on a turboprop engine and consists of an input device, a compressor 1, a combustion chamber 2, a turbine 3, a freezer 4, which includes a heat exchanger 5 and a separator 6, water storage tanks 7, an output device, pumps (n). In this case, the refrigerant in the heat exchanger 5 is a fuel - liquid hydrogen.

The engine is as follows. Air through the inlet device enters the compressor 1 for compression (compression ratio of at least 30).

Water from the tank 7 under the action of the high-pressure pump is fed into the inner cavity of the compressor drum 1, where it is sawn and mixed with wet steam inside the drum. Part of the water also evaporates in the form of dry steam, which, due to the action of centrifugal forces, is located in the central part of the drum and is removed (through special channels) into the gas-air duct of the engine. Unevaporated water in the form of a thin film is located on the inner surface of the drum. Under the action of centrifugal forces, the film moves towards the warmer part of the drum. During its movement, the film heats up from the side of the drum surface and from the side of the steam surface, which leads to its intense evaporation. The unevaporated part of the film under the action of centrifugal forces and vapor pressure is squeezed out through the perforated holes made in the drum casing into the flow part of the compressor, where it evaporates. Evaporation of water both inside the drum and in the compressor duct reduces the air temperature in the compressor duct, which, firstly, reduces the work required to compress the air, and secondly, it allows (from the condition of the compressor blades strength) to increase the degree of compression the compressor itself.

Compressed to a predetermined pressure air (a mixture of air and water vapor) is supplied in a continuous stream to combustion chamber 2, where at the same time a high-pressure pump pumps gaseous fuel heated in heat exchanger 5. As a result of fuel combustion, the gas temperature rises to an allowable strength of the turbine blades 3 In this case, the enthalpy of hot gases due to the increase in heat capacity of the vapor-air mixture is higher than the enthalpy of gases during combustion of the air-fuel mixture. In turbine 3, part of the potential energy of the gases is converted into mechanical work on the motor shaft, which is transmitted to the compressor and screw.

After passing through the turbine 3, the exhaust gases are divided into two streams.

The first stream through the output device is removed to the atmosphere.

The second stream is sent to the freezer 4, in which there is a liquid-air heat exchanger 5, the refrigerant of which is liquid hydrogen. When the gas moves inside the freezer, its temperature drops to a temperature below the freezing point of water, which causes icing of the heat exchanger 5 and, as a result, increases its thermal resistance. The process of icing continues until thermal equilibrium sets in, at which the gas temperature in the freezer is equal to the freezing temperature of water. To remove condensate, including ice, which actively forms at the indicated temperature, a centrifugal separator 6 is installed at the end of the freezer. In the impeller of the separator, water and ice particles are discarded by centrifugal forces into an annular collector located on the periphery of the separator (to prevent icing, the collector is heated by an external stream ) Water is removed from the collector into a container 7, from where it is supplied under pressure to the internal cavity of the compressor drum 1. The gas cooled in the freezer is removed to the atmosphere. The operating mode of the freezer is controlled by changing the area of the outlet cross section of the external nozzle: when the fuel (hydrogen) consumption increases, the external nozzle “clamps”, which leads to an increase in gas flow through the freezer and, accordingly, an increase in water output.

Figure 2 shows the dependences of the effective efficiency η _e and the specific power N _beats (effective power per kilogram of air flow) of a steam turbine engine on the parameters of the working process: the degree of air compression by the compressor PC and the relative water flow m (water flow per kilogram of flow air). The characteristics are calculated for the takeoff mode of the PDD. In the calculation, the gas temperature in front of the turbine was taken equal to 2000 K, the losses were taken into account by the corresponding coefficients: compressor efficiency - 0.83; Turbine efficiency - 0.94; pressure loss: in the input device - 1%; in the combustion chamber - 4%; in the output device - 4%. The separator was modeled by a separation coefficient Kc (the proportion of released water). Figure 2 presents the dependence for the four values of Ks: 0; 0.5; 0.75; 1,0. At Ks = 0, the PTD degenerates into a high-temperature fuel recovery with heat recovery, the characteristics of which are used as the starting point for evaluating (by comparison) the effectiveness of the PTD.

An analysis of the dependences shown in Fig. 2 shows that the liquid hydrogen coolant is sufficient to provide a water flow rate of 4% of the air flow rate, which makes it possible to increase the effective engine efficiency by 5–6%. A certain increase in engine mass (within 20%) due to the appearance of a freezer and an increase in the compression ratio of the compressor is compensated by an increase in the specific power of the engine by 15–30% and, accordingly, does not lead to a deterioration in the weight characteristics of the engine, rather the opposite.

In flight conditions, the effect of using the freezer increases. Figure 3 shows the dependences of the effective efficiency and specific power of the PTD obtained for the cruise flight conditions of the aircraft (H = 8 km, M = 0.8). It can be seen that the effective efficiency increases by 7–8%, and the specific power by 20–45%. The increase in the gap in the characteristics of the compared engines (PTD and TVD) is explained by the fact that, along with traditionally acting factors, such as: a decrease in air temperature and an increase in the total compression ratio, the efficiency of the freezer increases in the PDD with an increase in flight height. The latter is due to the fact that the relative fuel consumption increases, and, consequently, the water yield.

When using the liquid hydrogen coolant placed on board an aircraft, the theoretical capabilities of the PDD to extract water from the combustion products are realized by less than 20% (gas flow through the freezer does not exceed 25% of its total flow). Forcing the PDD (increase in water consumption) is possible due to the use of the atmospheric cold resource, which, unlike the fuel cold resource, is not limited. Technically, this means placing an additional heat exchanger 8 in the freezer 4 (Fig. 4), which will transfer part of the thermal energy to the atmosphere, which will allow, for example, with a relative water flow rate of ~ 10%, an effective efficiency of more than 70%. However, the solution to this problem, apparently, is associated with the possibility of creating highly efficient and lightweight heat transfer devices using easily volatile liquids, such as ammonia, as a working fluid.

Water from the tank 7 can also be fed into the mixing chamber located in front of the engine turbine. However, in this case, a positive effect (an increase in effective efficiency) will be manifested when the relative water flows are greater than when the water is supplied to the internal cavity of the compressor.

Thus, the use of combined-cycle technologies in aircraft engine manufacturing, which is made possible by the use of a freezer, allows one to obtain effective efficiency of aircraft engines using liquid hydrogen at a level of 65% or more.

Claims (5)

1. A steam turbine engine containing an input device, a compressor, a combustion chamber (mixing chamber), a turbine, a heat exchanger located behind the turbine, the refrigerant of which is fuel (liquid hydrogen), an output device, characterized in that the heat exchanger is located inside the freezer, which is located inside the outlet device and at the outlet from which a centrifugal separator is installed, heated by exhaust gases, the separator collector is connected to a container that is connected to the internal cavity of the drum Vågå compressor. 2. The steam turbine engine according to claim 1, characterized in that inside the freezer there is a heat exchanger having a common working fluid with a heat exchanger placed in the atmosphere. 3. The steam turbine engine according to claim 1, characterized in that the separator manifold is connected to a mixing chamber located in front of the turbine. 4. The steam turbine engine according to claim 1, characterized in that the compression ratio of the compressor is more than 30. 5. The steam turbine engine according to claim 1, characterized in that the internal cavity of the compressor drum through perforated holes is connected to the flow part of the compressor.

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