CN104019465B - The super combustion chamber of turbine base combined cycle engine - Google Patents

Abstract

The invention discloses a super combustor of a turbo-based combined cycle engine. Key components include: a diverter ring, a rear variable-area bleed valve, a diverter tongue, a square wave lobe mixer, an oil injection rod in zone I, a central cone, Oil injection ring in zone II, evaporator tube flame stabilizer, heat shield, super combustion chamber cylinder, radial flame stabilizer with variable groove width extending outward and radial flame stabilizer extending inward. The distribution of the flow field in the super combustion chamber provided by the present invention is reasonable, there will be no reverse flow phenomenon from the stamping duct to the turbofan duct, and there will be no flow separation inside the square lobe mixer, and the evaporator tube flame stabilizer can realize super "Soft ignition" of the combustion chamber. The entire super combustor has high mixing efficiency, low cold flow resistance, high combustion efficiency, and reasonable temperature distribution, which can meet the requirements of various working conditions in the entire flight envelope of the super combustor and the propulsion performance requirements of the turbofan ramjet.

Description

Turbo-based combined cycle engine super combustor

technical field

The invention belongs to the technical field of air-breathing engines, in particular to a turbine-based combined cycle engine.

Background technique

Turbine-based combined cycle engine (TBCC for short), as an air-breathing engine, has the advantages of wide flight range, conventional take-off and landing, and reusability, and is considered to be the most promising hypersonic vehicle power plant at this stage. Since the world's earliest TBCC prototype J58 was successfully applied to the SR-71 Blackbird reconnaissance aircraft, countries around the world have begun to invest a lot of manpower and financial resources in the research and development of combined hypersonic power devices, especially the RTA program of NASA in the United States and Japan. The HYPR program has achieved remarkable results.

At present, domestic research and development of turbo-based combined cycle engines is still in its infancy, and there is a large technological gap with the United States and Japan. Some preliminary conceptual studies on its working mode, working principle, and mode conversion process have been made, but no in-depth analysis has been done on the design method of the turbo-based combined cycle engine, the working cooperation process between different working modes, and different design parameters. , The influence of the adjustment law on the performance of the engine and other specific issues. In particular, there is no published literature on the design and specific implementation of the supercombustor as both the afterburner in the TBCC turbofan mode and the ram combustor in the ram mode.

Compared with traditional afterburner and ram combustor, the design of super combustor mainly has the following technical difficulties:

(1) Mixing of two streams of inner and outer streams: Structurally, the previous lobe mixers are directly connected to the diverter ring. When there is a certain axial distance between the two, the one with a larger expansion angle Lobe mixers are prone to flow separation inside the lobes, which affects the formation of flow vortices; in terms of flow conditions, most of the previous studies are in the flow state of the afterburner, which is similar to that of the TBCC turbofan The modes are similar, and the channel ratio varies greatly in the entire working range of TBCC, so it is particularly important to suppress the reverse flow of the engine in the ram mode with a large bypass ratio. Therefore, taking into account the low-resistance and high-efficiency mixing in each working mode of the super combustor with a large bypass ratio has become the primary task of its combustion organization.

(2) Reliable ignition and flame stability: Compared with traditional aero-engine combustors, a notable feature of the super combustor is that the airflow parameters vary widely, and its low temperature, high speed, and low pressure ranges are wider, within the entire flight envelope. It is more difficult for the engine to achieve reliable ignition, flame transfer and flame stability under low resistance.

(3) Matching design between fuel injection structure, blender and flame stabilizer: In order to achieve efficient combustion in each working mode of the super combustor, innovative fuel nozzle layout, flame stabilizer and blender are required Matching, so that the gas mixture in the combustion zone behind the flame stabilizer has an oil-gas ratio suitable for combustion and flame transfer.

Therefore, the design of the super combustor has its own technical difficulties. On the basis of the existing aero-engine combustion chamber technology, it is very necessary to design a combustion organization scheme of a super combustion chamber that can well solve the above three technical difficulties.

Contents of the invention

The problem to be solved by the present invention is to provide a super combustor of a turbine-based combined cycle engine, which has the characteristics of low cold flow resistance, high combustion efficiency, and reasonable temperature distribution, and can meet the requirements of various operating modes in the entire flight envelope. Stable work and propulsion performance requirements of TBCC.

A supercombustor of a turbo-based combined cycle engine according to the present invention comprises a diverter ring, a rear variable area air release valve, a guide tongue, a square lobe mixer, a central cone, and an oil supply valve installed on the central cone The device, the flame stabilizer, the heat shield, and the super combustor cylinder cover are on the outermost layer; the square lobe mixer is separated from the diverter ring, and there is an axial distance; the guide tongue is fixed in the flow channel, and tightly After the rear variable-area purge valve, it is directly above the trough of the square-lobe mixer in a discrete manner.

As a further improvement of the above technical solution, the flame stabilizer is mainly composed of an evaporating tube flame stabilizer, an outwardly extending variable groove width radial flame stabilizer installed on the outer edge of the evaporating tube flame stabilizer and a radial flame stabilizer installed on the evaporating tube flame stabilizer. The inside of the stabilizer is composed of an inwardly extending radial flame stabilizer with a plugging ratio of 43.6%; the evaporating tube flame stabilizer includes an on-duty fuel injection rod, an oil splash plate, an air induction pipe, a pre-gas inlet, and a fuel-rich mixture outlet. Air holes, evaporation tubes and V-shaped grooves; several radial flame stabilizers with variable groove width and a sweep angle of 45°~60° with the axis of the super combustor are evenly fixed on the V-shaped groove and are close to the super combustor cylinder The groove width at the body is larger, and the groove width near the V-shaped groove is smaller; the radial stabilizer extending inward is fixedly connected to the tail end of the central cone.

As a further improvement of the above-mentioned technical solution, the oil supply device includes an oil injection rod in area I, an oil injection ring in area II, and the on-duty oil injection rod; the oil injection rod in area I is located at the outlet of the square lobe mixer, and The lobe mixer diaphragm is facing.

As a further improvement of the above technical solution, the square lobe mixer adopts lobes with unequal expansion angles up and down.

As a further improvement of the above technical solution, the number of the guide tongues is the same as the number of lobes of the square lobe mixer, and the deflection angle of the air flow is equal to the expansion angle at the trough of the lobe mixer.

As a further improvement of the above technical solution, the surface of the central cone is ellipsoidal, and together with the guide tongue and the square lobe mixer, the mixing task of the super combustion chamber is completed.

As a further improvement of the above technical solution, the fuel injection rod in zone I adopts circumferential side spray, the fuel spray ring in zone II adopts radial side spray, and the fuel spray rod on duty adopts radial spray mode.

The turbo-based combined cycle engine super combustor provided by the invention has the following advantages:

1. The super combustor of the turbo-based combined cycle engine provided by the present invention can well solve the key technical difficulties of the super combustor compared with the traditional afterburner. The design of each component is reasonable, the flow field distribution is reasonable in each working mode of the super combustor, and the combustion temperature distribution is reasonable, which can meet the propulsion requirements of the turbine-based combined cycle engine.

2. The super combustor of the turbine-based combined cycle engine provided by the invention is designed with a mixing chamber capable of taking into account the low-resistance and high-efficiency mixing in the super combustor when the bypass ratio changes greatly. On the one hand, there will be no flow separation inside the square-lobe mixer; on the other hand, in the stamping state with relatively large ducts, there will be no backflow from the stamping ducts to the turbofan ducts, which will not cause excessive Large flow resistance loss. The designed evaporating tube type duty flame stabilizer has superior lean ignition and lean flameout performance, which can ensure the "soft ignition" performance of the super combustor. The extended radial flame stabilizer with variable slot width has good combustion stability and flame transfer characteristics, can accelerate the intersection of flame fronts between two radial flame stabilizers with variable slot width extended outward, and improve the combustion efficiency in the super combustion chamber.

3. The super combustor of the turbine-based combined cycle engine provided by the invention has a scientific and reasonable layout among the mixing chamber, the flame stabilizer and the nozzle structure. The flow direction vortex generated by the mixing chamber strengthens the momentum and energy mixing of the airflow between the turbofan duct and the ram duct, and promotes the mixing of most of the fuel and air under the action of the flow direction vortex, forming a more uniform mixture into the flame The rear of the stabilizer is involved in the combustion. This layout is not only beneficial to the evaporation of fuel, the mixing of fuel and air, and the formation of an oil-gas ratio suitable for combustion behind the flame stabilizer, but also is conducive to the ignition performance and extended groove width of the evaporator tube type flame stabilizer on duty. Improved flame stability for radial stabilizers.

Description of drawings

Fig. 1 is the structural representation of the turbo-based combined cycle engine super combustor of the present invention;

Fig. 2a is a perspective view of the structure of the evaporating tube type flame stabilizer, and Fig. 2b is a front view of the structure of the evaporating tube type flame stabilizer;

Fig. 3a and Fig. 3b are the matching schematic diagrams of square lobe mixer 4, flame stabilizer and nozzle structure; Fig. 3a is a front view, Fig. 3b is a perspective view;

Fig. 4 is a numerical simulation streamline diagram of the super combustor of a turbo-based combined cycle engine under various working states, where Fig. 4a is the turbofan mode, Fig. 4b is before the mode transition, Fig. 4c is after the mode transition, and Fig. 4d is Stamping mode;

Fig. 5 is the change curve of the flow resistance coefficient along the process of each working mode of the super combustor of the turbo-based combined cycle engine;

Fig. 6 is a cloud map of the temperature distribution along the super combustor of the turbo-based combined cycle engine at a typical state point;

Fig. 7 is a schematic diagram of the distribution of radii in the super combustor outlet section of the turbo-based combined cycle engine;

Fig. 8 is the temperature distribution curve of each radius of the outlet section of the super combustor of the turbo-based combined cycle engine in Fig. 7 .

detailed description

The super combustor of the turbo-based combined cycle engine proposed by the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, a supercombustor of a turbo-based combined cycle engine disclosed by the present invention includes a splitter ring 1, a rear variable area purge valve 2, a guide tongue 3, a square lobe mixer 4, and a central cone 6 1. An oil supply device, a flame stabilizer, a heat shield 9 installed on the central cone 6, and a super combustor barrel 10 covering the outermost layer. The square-lobe mixer 4 adopts lobes with unequal expansion angles up and down, and is separated from the diverter ring 1, and there is a certain axial distance; the guide tongue 3 is fixed in the flow channel, and is placed next to the variable area After the air valve 2, it is directly above the trough of the square lobe mixer 4 in a discrete shape, and its airflow deflection angle is equal to the expansion angle at the trough of the lobe mixer 4. The lobes of the square-lobe mixer 4 and the number of guide tongues 3 are 10. The surface of the central cone 6 is ellipsoidal, and together with the guide tongue 3 and the square lobe mixer 4, it completes the mixing task between the two airflows of the super combustion chamber. Under the action of the special profile of the square-lobe mixer 4, the two airflows generate mutually penetrating radial component velocities, and form a flow direction vortex downstream of the square-lobe mixer 4. And the exchange of energy, strengthen blending. However, because the design of the super combustor requires a certain axial distance between the square-lobe mixer 4 and the splitter ring 1, and the expansion angle at the trough of the square-lobe mixer is relatively large, flow separation is prone to occur inside the square-lobe mixer 4 The phenomenon affects the generation of flow direction vortex, the total pressure loss increases, and the mixing efficiency decreases. Therefore, at the position corresponding to the trough of the square-lobe mixer 4, the guide tongue 3 with the same airflow deflection angle as the trough expansion angle is arranged to suppress flow separation. The number of lobes and the number of guide tongues of the lobe mixer in the present invention are evenly 10, in order to match the number of slots of the flame stabilizer, and the number of lobes and guide tongues can be selected according to actual needs.

As shown in Fig. 2a, 2b, Fig. 3a and Fig. 3b, the flame stabilizer is composed of an evaporating tube type flame stabilizer 8, a radial flame stabilizer 11 extending outwardly with variable groove width and a radial flame stabilizer 12 extending inwardly, Its blockage ratio is 43.6%. The evaporator tube flame stabilizer 8 realizes the "soft ignition" performance requirements in the super combustion chamber, including the on-duty fuel injection rod 8-1, oil splash plate 8-2, bleed air pipe 8-3, pre-gas Air inlet 8-4, fuel-rich mixed air outlet 8-5, evaporation tube 8-6 and V-shaped groove 8-7. The evaporating tube flame stabilizer 8 is a full ring in the super combustion chamber, located in the internal airflow, and is mainly used to provide a stable ignition source. 10 radial flame stabilizers 11 with external extension and variable groove width are evenly fixed on the V-shaped groove 8-7, and the groove width near the super combustion chamber cylinder 10 is larger, and the groove width near the V-shaped groove 8-7 Smaller, such layout is conducive to the flame transmission between the grooves, so that the flame fronts between the 11 extended and variable groove width flame stabilizers meet as soon as possible, improve combustion efficiency, shorten the length of the super combustion chamber, and make the outlet temperature distribution of the super combustion chamber reasonable. There is a sweep angle of 45° to 60° between the radial flame stabilizer 11 and the axis of the super combustor. The exothermic pulsation caused by concentration suppresses the generation of low-frequency oscillating combustion, and the effect is best when the sweep angle is 60°. Each extended radial stabilizer 11 with variable slot width is facing the trough of the square-lobe mixer 4, so that the stabilizer slot is located in the high-temperature gas flow coverage area. Two inwardly extending radial stabilizers 12 are fixedly connected to the V-shaped groove 8-7 at the tail end of the central cone 6. The radial stabilizer 11 with variable slot width extending outward and the radial stabilizer 12 extending inward are used for flame stabilization of the super combustor under various working conditions.

The working principle of the evaporating tube flame stabilizer is as follows: the fuel is supplied by the fuel injection rod 8-1 on duty, sprayed onto the oil splash plate 8-2, and is atomized for the first time under the action of aerodynamic force. One drop of oil. The oil droplets move downstream with the airflow in the bleed air pipe 8-3 and are heated and evaporated in the evaporation pipe 8-6 to form an oil-rich mixed gas that is ejected through the fuel-rich mixed gas outlet hole 8-5. The oil film is formed on the wall of the outlet hole of the fuel-mixed gas, and is atomized again under the aerodynamic force of the pre-gas. Since the angle between the mixed gas jetted out of the rich-fuel mixed gas outlet and the flow direction of the pre-gas is 45°~90° (60° is indicated in Fig. 2B), the mixed gas jet jetted out of the rich-fuel mixed gas outlet and the The gas is well mixed and mixed into a premixed gas suitable for ignition and combustion. It enters the low-speed recirculation zone behind the V-shaped groove and ignites and burns in the recirculation zone. Because the atomization effect of the evaporating tube 8-6 on fuel oil is better, the evaporating tube type flame stabilizer 8 has better lean ignition and flameout performance. The fuel supply quantity (ignition oil-air ratio) of the fuel injection rod 8-1 on duty can be independently controlled, so it can meet the requirement of lean fuel ignition when the regulating flow condition in the super combustion chamber changes greatly.

The super combustor of the turbo-based combined cycle engine adopts partition oil supply. The fuel supply device includes the oil injection rod 5 in zone I, the fuel injection ring 7 in zone II and the on-duty fuel injection rod 8-1, and the fuel supply accounts for 75%, 15% and 10% of the total fuel supply respectively, all using 0.5 mm direct injection nozzle oil supply. The fuel injection rod 5 in zone I is located at the outlet of the square-lobe mixer 4 and faces the square-lobe mixer 4 partition. There are 54 nozzles in the fuel injection rod 5 in zone I, which are sprayed circumferentially to the sides of the variable groove width radial flame stabilizer (11) respectively. 10 nozzles are evenly arranged in the fuel injection ring 7 in zone II, and radial side spray is adopted. The oil spray rod 8-1 on duty has 10 nozzles, which adopt the radial spray mode and atomize in the oil splash plate and the evaporation tube.

The square lobe mixer 4, the flame stabilizer and the nozzle structure are arranged in a matching manner. The evaporator tube flame stabilizer 8 is arranged in the high-temperature airflow of the turbofan duct. In addition, the duty fuel injection rod 8-1 is located in the peak high-temperature airflow of the square lobe mixer 4, which is beneficial to the duty fuel injection rod 8-1. The evaporation of the fuel oil in 1 is beneficial to the flame stability and ignition of the evaporation tube type flame stabilizer 8. Each radial stabilizer 11 with variable groove width is facing the peak high-temperature airflow of the square lobe mixer, and the high temperature of the airflow is conducive to the improvement of the flame stability of the radial stabilizer 11 with variable groove width. The fuel injection rod 5 in zone I is located in the peak area of the outlet of the square-lobe mixer 4, close to the partition, and sprays to the area between the two outer radial stabilizers 12 with variable groove width by using circumferential side spray. Since the fuel supply of fuel injection rod 5 in zone I accounts for the vast majority (75%) of the total fuel supply, the distribution of this part of fuel in the super combustion chamber directly affects the combustion performance of the super combustion chamber, so this part of fuel is distributed in the super combustion chamber The outlet of the square-lobe mixer 4 is supplied, and the mixing between oil and gas is strengthened under the driving action of the flow direction vortex. The nozzle holes are arranged near the partition plate in the wave peak area, and the hot air flow at the wave peak can be used to heat the fuel oil. It is conducive to the evaporation of fuel oil and creates favorable conditions for the combustion zone behind the flame stabilizer.

The performance of the turbo-based combined cycle engine super combustor of the present invention is verified:

The numerical simulation method is used to study the internal flow field of the super combustor of the turbo-based combined cycle engine provided by the present invention. The pressure-based SIMPLE algorithm is adopted, and the second-order upwind method is used to discretize the governing equations. The Realizablek-ε model is selected as the turbulence model, and the wall is processed by the non-equilibrium wall function. The boundary conditions used in the numerical simulation include: the inlet of the turbofan duct and the inlet of the ram duct are mass flow inlets, the outlet of the calculation domain is the pressure outlet, and the periodic boundary conditions are used on both sides of the fan section. The parameters of the inlet and outlet boundary conditions depend on the different working conditions of the supercombustor, and the high-temperature gas at the inlet of the turbofan is given by the mass fractions of oxygen, carbon dioxide and water vapor. Figures 4a-4d are the streamline diagrams of the super combustor under various working modes under the numerical simulation. It can be seen from the streamline diagram that there is no flow separation inside the lobe mixer under each working condition. There is no reverse flow at the positions corresponding to the peaks and troughs at the trailing edge of the lobe mixer, and the velocity distribution when entering the stabilizer is basically uniform. It shows that the design of the mixing chamber in the present invention is reasonable, and can take into account the high-efficiency mixing under various working conditions. When the working mode is not completely converted to stamping, the lobe mixer can play the role of high-efficiency mixing, which is conducive to improving combustion efficiency; In the ram state, it can effectively restrain the reverse flow from the ram duct to the turbofan duct, and improve the propulsion performance of the engine. It can be seen from the streamline diagram that there is an obvious low-velocity recirculation zone behind the flame stabilizer. The internal flow velocity of the on-duty stabilizer is small, which is conducive to the ignition of the super combustion chamber; there are large-scale low-velocity recirculation zones behind the inwardly extending radial stabilizer and the outwardly extending radial stabilizer, which provide the super combustion chamber with flame transfer and Flame stabilization provides favorable conditions.

The flow resistance characteristics of the present invention are studied by numerical simulation method. In Fig. 5, the first straight line perpendicular to the horizontal axis is the outlet section of the square lobe mixer, and the second straight line perpendicular to the horizontal axis is the trailing edge section of the flame stabilizer. It can be seen from Figure 5 that the flow resistance coefficients at the right boundary are all less than 2.2, and the loss in the mixing zone inside the square-lobe mixer and from the square-lobe mixer to the trailing edge of the flame stabilizer is relatively large.

At a certain typical state point, the numerical simulation is carried out to the combustion characteristics of the super combustor provided by the present invention. The DPM model is used to calculate the oil mist field and the EDC model and chemical reaction are used to calculate the combustion. The nozzle structure in the super combustor adopts the direct injection nozzle model, the diameter of each nozzle hole is 0.5mm, and the initial oil droplet SMD is 50μm. Since the fuel evaporation process of the evaporator tube flame stabilizer cannot be truly simulated in FLUENT, the oil supply of the on-duty stabilizer is simplified, and the pneumatic atomizing nozzle is used to supply oil and the SMD of the initial oil droplet is set to 20 μm, so that the entering The fuel of the on-duty stabilizer can be better atomized, which is beneficial to start the chemical reaction. Numerical simulation results show that under the condition of residual gas coefficient of 1.53 at the typical state point, the average outlet temperature of the super combustor is 2026K, and the combustion efficiency is 96.4%. It can be seen from Figure 6 that the flame development process in the super combustion chamber firstly forms a high temperature zone in the low velocity zone behind the flame stabilizer and produces an initial flame. As shown in Fig. 7 and Fig. 8, the flames are connected to the outlet of the super combustion chamber, and the radial flame stabilizers with variable groove width are connected, and the temperature distribution is relatively reasonable.

Claims (7)

1. the super combustion chamber of turbine base combined cycle engine, it is characterized in that: comprise flow splitter (1), rear variable area vent valve (2), water conservancy diversion tongue piece (3), square lobed mixer (4), center cone (6), be arranged on fueller on center cone (6) and flameholder, heat screen (9), super combustion chamber cylindrical shell (10) covers on outermost layer; Be separated from each other between described square lobed mixer (4) and flow splitter (1), exist wheelbase from; Water conservancy diversion tongue piece (3) is fixed in runner, and after being next to rear variable area vent valve (2), is right against above square lobed mixer (4) trough with discrete shape.

2. the super combustion chamber of turbine base combined cycle engine according to claim 1, it is characterized in that: described flameholder primarily of evaporation tubular type flameholder (8), be arranged on evaporation tubular type flameholder (8) outer rim the radial flameholder (11) of overhanging change groove width and be arranged on and stretch radial flameholder (12) in evaporation tubular type flameholder (8) inner side and form, flameholder blockage ratio is 43.6%; Evaporation tubular type flameholder (8) comprises Fuel Injector Bar on duty (8-1), oil splasher (8-2), air entraining pipe (8-3), pre-gas inlet (8-4), fuel-rich mixed gas venthole (8-5), evaporation tube (8-6) and V-type groove (8-7); There is the angle of sweep of 45 ° ~ 60 ° in the radial flameholder (11) of some overhanging change groove widths and super combustion chamber axis, evenly be fixed on V-type groove (8-7), and the groove width at close cylindrical shell (10) place, super combustion chamber is comparatively large, the groove width near V-type groove (8-7) place is less; Inside stretch radial stabilizer (12) and be fixedly connected on center cone (6) tail end.

3. the super combustion chamber of turbine base combined cycle engine according to claim 2, is characterized in that: described fueller comprises I district's Fuel Injector Bar (5), II district's injection loop (7) and described Fuel Injector Bar on duty (8-1); I district's Fuel Injector Bar (5) is positioned at square lobed mixer (4) outlet, and just right with square lobed mixer (4) dividing plate.

4. the super combustion chamber of turbine base combined cycle engine according to claim 3, is characterized in that: described square lobed mixer (4) adopts up and down the lobe of the angle of flare such as not.

5. the super combustion chamber of turbine base combined cycle engine according to claim 4, it is characterized in that: the number of described water conservancy diversion tongue piece (3) is identical with the lobe number of square lobed mixer (4), its flow-deviation angle is equal with lobed mixer (4) the trough place angle of flare.

6. the super combustion chamber of turbine base combined cycle engine according to claim 5, it is characterized in that: described center cone (6) surface is spheroid shape, and jointly completes the blending task of super combustion chamber with water conservancy diversion tongue piece (3) and square lobed mixer (4).

7. the super combustion chamber of turbine base combined cycle engine according to claim 6, it is characterized in that: I described district's Fuel Injector Bar (5) adopts circumferential side spray, II district's injection loop (7) adopts radial side spray, and Fuel Injector Bar on duty (8-1) adopts radial spray mode.