RU2190772C2 - Turbo-ejector engine - Google Patents

Abstract

FIELD: air-breathing gas-turbine engines primarily of ejector type; engine manufacture. SUBSTANCE: turbo- ejector engine has high-pressure channel of its gas ejector communicating on one end with compressor through main combustion chamber and on other end, with turbine through mixing chamber; low-pressure channel of gas ejector communicates on one end directly with atmosphere through inlet device and on other end, with turbine through mixing chamber. EFFECT: enhanced thrust and efficiency at supersonic flying speeds. 2 cl, 14 dwg

Description

 The invention relates to aircraft engine manufacturing.

 There are various types of jet engines (WFD), which are divided into two large groups: gas turbine (GTE) and ramjet (ramjet) (Theory and calculation of jet engines. Edited by S. M. Shlyakhtenko, M.: Engineering, 1987, p. 10, fig. 1).

 The most important characteristics of the WFD are: the overall engine efficiency (the ratio of the useful work of movement to the spent energy of the fuel) and the range of Mach numbers (Mn), at which the use of this engine is possible and advisable.

At subsonic and small supersonic flight speeds (Mn ≈ 0 ÷ 2) turbojet engines (turbojet engines) have the best characteristics. At moderate supersonic flight speeds (Mp ≈ 2 ÷ 3), forced turbojet engines (turbofan engines) are used. At high supersonic speeds (Mp more than three), the turbojet engines degenerate (Theory and Calculation of Air-Jet Engines. Edited by S. M. Shlyakhtenko, Moscow: Mashinostroenie, 1987, p. 435). The causes of the degeneration of turbojet engines are:
1. The decrease in performance (reduced air flow) of axial compressors due to kinetic heating of the working fluid.

 2. The decrease in the useful work of the Brighton cycle due to the restriction on the temperature of the gas at the outlet of the main combustion chamber.

 The indicated drawbacks are absent in ramjet and turbo-ramjet (turbofan) engines of jet engines (Theory and design of jet engines. Edited by S.M. Shlyakhtenko, Moscow: Mashinostroenie, 1987, pp. 436, 485).

 However: 1. The ramjet does not have a starting thrust and is ineffective at low flight speeds (Mp less than 2).

 2. A turbojet engine is a combined engine in which one circuit is running, and the other at this time creates additional resistance, which makes the overall engine efficiency worse than a turbojet engine at low speeds and worse than a ramjet engine at high speeds.

 Known turbojet engine ejection type (RI Kruziner. Jet engines of high supersonic flight speeds. M: Engineering, 1989, p. 161, Fig. 4.5).

 A known jet engine having an air pressure ejector located between the compressor and the turbine (Patent RU 2066777, IPC 7 F 02 K 3/08, 1996).

 Expanding the range of GTE applications while simultaneously increasing the overall engine efficiency is achieved by the fact that a gas ejector with a mixing chamber is installed between the main combustion chamber and the turbine of a known forced turbojet engine, in which the low pressure channel is connected to the atmosphere directly through the input device, bypassing the compressor.

The essence of the invention lies in the fact that the "cold" air, the amount of which is not limited by the capabilities of the compressor, enters from the atmosphere into the mixing chamber of the gas ejector and cools the "hot" gas coming from the main combustion chamber, which allows:
- increase the temperature of the gas at the outlet of the main combustion chamber (increase the cycle);
- increase the flow rate of the working fluid through the turbine and the engine as a whole.

 These factors make it possible to significantly (up to Mn ≈ 4 or more) push the boundary of degeneration of a gas turbine engine, which positively affects the overall efficiency of a turbojet engine (TRDE) (Theory and calculation of air-jet engines. Edited by S. M. Shlyakhtenko, M .: Mechanical Engineering , 1987, p. 53, Fig. 1.27).

The degree of pressure increase by a sonic gas ejector is π _ezh ~ 3 (G.N. Abramovich. Applied gas dynamics, Moscow: Nauka, 1976), which does not allow TRRE to have high efficiency at low flight speeds. In this regard, for aircraft with both subsonic and supersonic cruising flight modes, it is advisable to use turbojet engines with a variable ratio of nozzle areas of ejected and ejected gases and adjustable turbine nozzle devices (TRDeu is a turbojet engine with a controlled ejector).

α = F₁/F₂ - отношение площадей сопел эжектирующего (F₁) и эжектируемого (F₂) газов;
q(λ_см) - плотность тока газа на выходе из камеры смешения;
Fca_o - площадь минимального проходного сечения соплового аппарата турбины высокого давления при закрытой заслонке.This goal is achieved by the fact that at the entrance to the mixing chamber a separation damper is installed - a sound nozzle, which blocks the air supply channel into the mixing chamber at subsonic and moderate supersonic flight speeds. At higher flight speeds (Mp more than 2.5), the damper is installed in an intermediate position, providing air access to the mixing chamber, being at the same time a sound nozzle for gas coming from the combustion chamber, and nozzle devices are deployed, allowing gas to pass through the turbine. For a cylindrical mixing chamber, the optimal law for changing the area of the nozzle apparatus (Fca) of a high-pressure turbine is a dependence expressed by the formula:

α = F ₁ / F ₂ - the ratio of the areas of the nozzles of the ejecting (F ₁ ) and ejected (F ₂ ) gases;
q (λ _cm ) is the gas current density at the outlet of the mixing chamber;
Fca _o - the minimum flow area of the nozzle apparatus of the high-pressure turbine with the shutter closed.

Figure 1 shows a diagram of TRDE;
figure 2 shows the cycle of the inner circuit;
figure 3 shows the cycle of the outer contour;
figure 4 shows the forced cycle of the inner circuit;
figure 3 shows the forced cycle of the outer contour;
figure 6 shows a diagram of TRREu.

 TRDE with unregulated flow sections of the gas-air path (Fig. 1) consists of an input device 1, a compressor 2, a main combustion chamber 3, a gas ejector 4, a mixing chamber 5, a turbine 6, an afterburner 7, an output device 8. Moreover, the channel is high the pressure of the gas ejector 4 is connected to the compressor 2 through the main combustion chamber 3, and the low pressure channel of the same ejector is connected to the atmosphere directly through the inlet 1, bypassing the compressor 2. The high and low pressure channels are divided between d on the basis of a daisy mixer. The mixing chamber 5 on the one hand is connected to the ejector 4, and on the other hand to the turbine 6.

 The operation of the engine is as follows. Air from the atmosphere through the inlet 1 enters the compressor 2 for compression. Compressed to a predetermined pressure, air is continuously directed into the main combustion chamber 3, where finely atomized fuel is injected simultaneously through the nozzles. The gas generated as a result of combustion enters the high pressure channel of the ejector 4 and then through the nozzle (the narrow part of the channel) to the mixing chamber 5. The flow rate increases when the air flows out of the nozzle and the static pressure drops, which creates conditions for air ejection from the input device 1 ( through the low pressure channel) into the mixing chamber. In the mixing chamber, air and gas are mixed, decelerated, as a result of which, at the outlet of the mixing chamber, an increased (relative to the air pressure in the input device) full gas pressure is established. From the mixing chamber 5, the gas enters the turbine and rotates it. The turbine drives the compressor. The gas exiting the turbine enters the afterburner of the combustion chamber, after which it expands in the outlet device and flows out at high speed into the atmosphere, creating thrust.

 In contrast to the known turbojet engines, the turbojet engine has two thermodynamic cycles (the Written cycle), which are realized in the internal (ejection gas) and external (ejected gas) engine circuits. Figure 2 shows in p-v coordinates the ideal cycle of the internal circuit, figure 3 shows the ideal cycle of the external circuit of the TRDE. Isoentropic process n-in corresponds to compression in the input device, in-to - in the compressor. The heat supply process is characterized by isobar cc in the cycle (Fig. 2) and polytropic cc in the cycle (Fig. 3). In this case, the heat supplied to the site c-g (figure 3) corresponds to the heat removed to the site cc-g (figure 2). The isoentropic expansion process in the turbine is indicated by the g-t segment and expansion in the jet nozzle by the t-s segment. The process of heat dissipation into the atmosphere corresponds to the segment SN.

где Lц₁ - работа цикла внутреннего контура,
Lц₂ - работа цикла наружного контура,
m - коэффициент эжекции.The total work of cycles per 1 kg of the working fluid is defined as

where L ₁ - the work cycle of the inner circuit,
Lc ₂ - work cycle of the outer circuit,
m is the ejection coefficient.

The work of the Written Le cycle (taking into account mixing losses), as shown by theoretical studies performed by the author, at speeds of Mn more than 2, is almost always greater than the work of the Brighton cycle. So, for example, under the well-known condition T ^* _k = T ^* _g, the Brighton cycle degenerates, while the Written cycle has a positive job. The latter is due to the fact that the gas temperature limit at the outlet of the main combustion chamber T ^* _ks for a turbojet engine is always higher than for a turbojet engine, where T ^* _ks = T ^* _g .

 The advantage of the forced Written cycle (Figs. 4, 5) over the forced Brighton cycle (with the same gas temperature restrictions in front of the turbine) appears when the speeds Mn are more than 2.5, which is associated with the process of degeneration of gas-turbine engines of classical schemes (in turbojet engines due to the lack of direct connection between the temperatures at the exit from the main combustion chamber and at the entrance to the turbine do not degenerate at flight speeds of Mach number less than four).

 An obvious disadvantage of TRDE is the lack of economical modes at subsonic flight speeds, which is associated with low degrees of pressure increase in gas ejectors.

 The specified disadvantage is absent in TRREu (Fig.6).

 In TRREU new elements are the damper - the sound nozzle 9 (hereinafter the damper), adjustable nozzle devices of the turbines 10.

 The operation of the engine is as follows. At subsonic and small supersonic flight speeds (Mn less than 2.5), the damper is in the upper position, blocking the access of air from the input device 1 to the mixing chamber 5 (Fig.6, top view). The engine runs in turbojet mode. At increased flight speeds (Mp more than 2.5), the damper is installed in an intermediate position (Fig.6, bottom view), thereby providing air access from the inlet device 1 to the mixing chamber 5, and the nozzle devices 10 of the turbines are deployed, providing gas passage. The engine runs in TRDE mode.

As one of the variants of the engine, an engine is proposed (Fig.6), having:
1. Sound gas ejector.

 2. The cylindrical mixing chamber.

 3. Two-stage low pressure compressor.

 4. Two-position (“closed”, “open”) shutter 9, the opening of which is carried out at supersonic flight speeds from the condition of ensuring a subcritical mode of operation of the gas ejector (P less than Po) (GN Abramovich. Applied gas dynamics, M .: Nauka , 1976, p. 516, Fig. 9.14).

где Fca - площадь минимального проходного сечения соплового аппарата турбины высокого давления при открытой заслонке;
Fca_o - площадь минимального проходного сечения соплового аппарата турбины высокого давления при закрытой заслонке;
α = F₁/F₂ - отношение площадей сопел эжектирующего (F₁) и эжектируемого (F₂) газов при открытой заслонке;
q(λ_см) - плотность тока газа на выходе из камеры смешения при открытой заслонке.5. Adjustable nozzle turbine units. In this case, the nozzle apparatus of the high-pressure turbine is regulated in accordance with the law

where Fca is the minimum passage area of the nozzle apparatus of the high pressure turbine with the valve open;
Fca _o is the minimum passage area of the nozzle apparatus of the high-pressure turbine with the shutter closed;
α = F ₁ / F ₂ - the ratio of the areas of the nozzles of the ejecting (F ₁ ) and ejected (F ₂ ) gases with the valve open;
q (λ _cm ) is the gas current density at the outlet of the mixing chamber with the shutter open.

 The specific schemes and characteristics of turbofan engines are considered in the monograph (V.L. Pismenny. Fundamentals of the theory of calculation of turbojet engines. GLITS named after Chkalov, dep. At TsVNI MO RF V-4195, 2000, 43 pp.).

 Theoretical studies show that turbojet engines at cruising flight speeds (Mn = 3.5 ÷ 3.8) in their gasdynamic characteristics approach the ramjet engine (the total efficiency of a turbojet engine at cruising flight speeds of more than 40%). In this case, unlike ramjet engines, the engines have a starting thrust necessary for the takeoff of the aircraft.

Claims (2)

 1. A turbojet engine comprising an input device, a compressor, a main combustion chamber, a gas ejector, a mixing chamber, a turbine, an afterburner, an output device, characterized in that the high pressure channel of the gas ejector is connected to the compressor through the main combustion chamber on one side, and on the other hand, with the turbine through the mixing chamber, while the low-pressure channel of the gas ejector is on the one hand connected to the atmosphere directly through the input device, bypassing the compressor, and on the other hand ones - to the turbine through the mixing chamber. 2. The turbojet engine according to claim 1, characterized in that the gas ejector is made sound, the mixing chamber is cylindrical, and the ratio of the nozzle area of the ejected and ejected gases is controlled by a dividing flap with simultaneous regulation of the passage areas of the turbine nozzle devices in accordance with the formula
Fca = [(1 + α) / α] q (λcm) Fca _o ,
where Fсa is the area of the minimum passage section of the nozzle apparatus of the high-pressure turbine;
Fca ₀ is the area of the minimum passage section of the nozzle apparatus of the high-pressure turbine with the shutter closed;
α = F ₁ / F ₂ - the ratio of the areas of the nozzles of the ejecting (F ₁ ) and ejected (F ₂ ) gases;
q (λcm) is the gas current density at the outlet of the mixing chamber.

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