CN108612598B - Method for changing combustion mode of bi-mode ramjet engine and engine combustion chamber - Google Patents
Method for changing combustion mode of bi-mode ramjet engine and engine combustion chamber Download PDFInfo
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- CN108612598B CN108612598B CN201810371951.8A CN201810371951A CN108612598B CN 108612598 B CN108612598 B CN 108612598B CN 201810371951 A CN201810371951 A CN 201810371951A CN 108612598 B CN108612598 B CN 108612598B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02K—JET-PROPULSION PLANTS
- F02K7/00—Plants in which the working fluid is used in a jet only, i.e. the plants not having a turbine or other engine driving a compressor or a ducted fan; Control thereof
- F02K7/10—Plants in which the working fluid is used in a jet only, i.e. the plants not having a turbine or other engine driving a compressor or a ducted fan; Control thereof characterised by having ram-action compression, i.e. aero-thermo-dynamic-ducts or ram-jet engines
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
- F02C9/00—Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants
- F02C9/48—Control of fuel supply conjointly with another control of the plant
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
- F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
- F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
- F23R3/26—Controlling the air flow
Abstract
The invention provides a method for changing combustion modes of a dual-mode ramjet engine and an engine combustion chamber, wherein air, namely air jet flow, is sprayed into the engine, the flow rate of the sprayed air is 20-30% of the air flow at an inlet of the engine, the temperature of the jet air is 10-55 ℃, and the mode in the combustion chamber of the dual-mode ramjet engine is changed from a hyper-combustion state to a sub-combustion state; the method can simply and conveniently influence or change the combustion mode of the dual-mode ramjet, is different from the existing method for influencing and changing the combustion mode of the dual-mode ramjet, does not need to change the inlet airflow condition and the oil injection condition, has the characteristics of simple operation and strong realizability, and provides a new method for solving the problem of forming and converting the combustion mode of the dual-mode ramjet.
Description
Technical Field
The invention belongs to the technical field of hypersonic aircraft engines, and particularly relates to a method for changing a combustion mode of a bimodal ramjet engine and an engine combustion chamber used by the method.
Background
Due to the low specific impulse and high cost of rocket engines, ramjet engines have become the preferred propulsion means for hypersonic aircraft. Particularly for a hypersonic aircraft flying in a wide Mach number range, the bimodal ramjet engine shows good propulsion performance, and when the Mach number is in a range of 3-6, combustion is carried out in a combustion chamber of the engine at subsonic speed (Ma <1), namely a subsonic combustion mode; when the flight mach number is greater than 6, combustion is at supersonic speed (Ma >1) within the engine combustion chamber, referred to as the scram mode. For aircraft flying in a wide mach number range, the mode in the engine combustion chamber is changed from sub-combustion to super-combustion, and the dual-mode ramjet is called, so that the combustion mode forming and conversion of the dual-mode ramjet needs to be controlled and influenced.
Sullins et al successfully demonstrated that it is possible to switch a dual mode ramjet from a sub-combustion mode to a hyper-combustion mode by varying the total temperature of the incoming flow by varying the total temperature of the engine inlet flow. Mitani et al, by increasing the fuel flow rate, have hydrogen fueled dual mode ramjet engines going from a weak combustion mode to a strong combustion mode. Le et al achieve combustion mode conversion by adjusting the fuel equivalence ratio. Takahashi et al achieve a transition in combustion modes of a scramjet engine by varying the downstream size of the combustion chamber. Kanda et al obtained different combustion modes by varying the injection position of the fuel. Sadatake et al achieve modal conversion in a bimodal ramjet engine by employing boundary layer suction.
The above methods are implemented by changing the air flow condition at the inlet of the engine or changing the fuel injection condition of the engine or changing the configuration of the engine to influence and change the combustion mode of the engine, and some methods are complex and difficult to implement.
Disclosure of Invention
In view of the above-described drawbacks of the prior art, it is an object of the present invention to provide a method of changing the combustion mode of a dual-mode ramjet engine and an engine combustion chamber for use in such a method that does not require changes in inlet air flow conditions and fuel injection conditions.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a method for changing combustion modes of a dual-mode ramjet engine comprises the steps of injecting air, namely air jet into the engine, wherein the flow rate of the injected air is 20% -30% of the air flow rate of an inlet of the engine, the temperature of the jet air is 10-55 ℃, and the mode in a combustion chamber of the dual-mode ramjet engine is changed from a hyper-combustion state to a sub-combustion state.
Preferably, the method comprises the steps of: (1) air flows into the engine; (2) jetting air into the engine at 20% of the total working time of the engine; (3) at 32.5% of the total time of engine operation, fuel is injected into the engine; (4) the igniter is turned on at the moment 32.5% of the total working time of the engine; (5) the igniter is closed at the moment of 65 percent of the total working time of the engine; (6) at 75% of the total time of the engine operation, the air jet stops; (7) when the total working time of the engine is over, the fuel is stopped to be sprayed, and the air does not flow into the engine any more; the total time of the engine operation refers to the time from the start of air flow into the engine to the stop of air flow into the engine.
As an optimal mode, the upper portion of the engine combustion chamber comprises a first oil injection block, an igniter on the right side of the first oil injection block, a second oil injection block on the right side of the igniter, an air jet block on the right side of the second oil injection block, an engine groove is formed in the upper wall surface of an outlet of an engine isolation section, the first oil injection block and the igniter are located in the engine groove, a third oil injection block is located on the lower wall surface of the opposite side of the engine groove, a third oil injection block is arranged on the lower portion of the combustion chamber, a fourth oil injection block on the right side of the third oil injection block, jet holes perpendicular to the inner wall surface are formed in the air jet block, and jet air is sprayed into the engine through the inner wall surface of the perpendicular air jet.
Preferably, the jet hole is 150mm from the trailing edge of the engine recess.
As the preferred mode, the jet hole is 20 round holes with the diameter of 3mm which are uniformly distributed in the width direction of the engine.
In order to achieve the purpose, the invention further provides an engine combustion chamber, the upper portion of the combustion chamber comprises a first oil injection block, an igniter on the right side of the first oil injection block, a second oil injection block on the right side of the igniter and an air jet block on the right side of the second oil injection block, an engine groove is located on the upper wall surface of an outlet of an engine isolation section, the first oil injection block and the igniter are located in the engine groove, a third oil injection block is located on the lower wall surface on the opposite side of the engine groove, a third oil injection block and a fourth oil injection block on the right side of the third oil injection block are arranged on the lower portion of the combustion chamber, jet holes perpendicular to the inner wall surface are formed in the air jet block, and jet air is injected into the engine through the inner wall surface of the vertical air jet.
The invention has the beneficial effects that: the method can simply and conveniently influence or change the combustion mode of the dual-mode ramjet, is different from the existing method for influencing and changing the combustion mode of the dual-mode ramjet, does not need to change the inlet airflow condition and the oil injection condition, has the characteristics of simple operation and strong realizability, and provides a new method for solving the problem of forming and converting the combustion mode of the dual-mode ramjet.
Drawings
FIG. 1(a) is a block diagram of a combustion chamber of a dual-modality ramjet engine of the present invention;
FIG. 1(b) is a block diagram of the air jet block and jet hole of FIG. 1 (a);
FIG. 2 is a bimodal ramjet flame development without air jets;
FIG. 3 is a bimodal ramjet flame development with air jets of the present invention;
FIG. 4 is a graph of flow field mass weighted Mach number with and without air jets.
FIG. 5 is a bimodal ramjet flame development for different flow ratio air jets of the present invention.
FIG. 6 is a graph of flow field mass weighted Mach number for different flow ratio air jets and no air jets at 20 ms.
Wherein, 1 is the engine combustion chamber, 2 is first notes oil piece, 3 is some firearm, 4 are second notes oil piece, 5 are air jet piece, 6 are third notes oil piece, 7 are the engine recess, 8 are fourth notes oil piece, 9 are the jet hole.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
As shown in fig. 1(a) and fig. 1(b), the engine combustion chamber of this embodiment, the upper portion of the combustion chamber includes a first oil injection block 2, an igniter 3 on the right side of the first oil injection block 2, a second oil injection block 4 on the right side of the igniter 3, and an air jet block 5 on the right side of the second oil injection block 4, an engine recess 7 is located on an upper wall surface of an outlet of an engine isolation section, the first oil injection block 2 and the igniter 3 are located in the engine recess 7, a third oil injection block 6 is located on a lower wall surface opposite to the engine recess 7, a third oil injection block 6 and a fourth oil injection block 8 on the right side of the third oil injection block 6 are arranged on the lower portion of the combustion chamber, a jet hole 9 perpendicular to an inner wall surface is arranged on the air jet block 5, and jet air is injected into the engine through the inner wall surface of the vertical air jet block 5 at the rear portion.
In the method for changing the combustion mode of the dual-mode ramjet engine, air, namely air jet flow, is sprayed into the engine, the flow rate of the sprayed air is 20% -30% of the air flow rate of an inlet of the engine, the temperature of the jet air is 10-55 ℃, and the mode in a combustion chamber of the dual-mode ramjet engine is changed from a hyper-combustion state to a sub-combustion state.
The method comprises the following steps: (1) air flows into the engine; (2) jetting air into the engine at 20% of the total working time of the engine; (3) at 32.5% of the total time of engine operation, fuel is injected into the engine; (4) the igniter is turned on at the moment 32.5% of the total working time of the engine; (5) the igniter is closed at the moment of 65 percent of the total working time of the engine; (6) stopping the air jet at 75% of the total working time of the engine; (7) when the total working time of the engine is over, the fuel is stopped to be sprayed, and the air does not flow into the engine any more; the total time of the engine operation refers to the time from the start of air flow into the engine to the stop of air flow into the engine.
Specifically, the jet hole 9 is 150mm away from the rear edge of the engine recess 7.
Specifically, the jet hole is 20 round holes with the diameter of 3mm and evenly distributed in the width direction of the engine.
The effectiveness of this method, air jet, was verified using numerical simulations, which took 20ms total time due to the long time spent on unsteady chemical reaction flow. FIG. 1 is a block diagram of a dual-mode ramjet engine of the present invention in which high velocity air flows from left to right through the engine combustion chambers. Fig. 2 to 6 show the extraordinary results of simulation using the AHL3D numerical simulation software with proprietary intellectual property whose reliability has been widely verified at present. Figure 2 shows the distribution of the kerosene combustion flame for a dual mode ramjet engine without the use of air jets, where the location of the combustion zone is marked with the carbon dioxide as a product of kerosene combustion. As can be seen from the simulation results of fig. 3 and 4: in a bimodal scramjet engine flow field without an air jet method, the lower wall flame is finally extinguished and does not burn stably. This can be seen from fig. 3, where t is 6ms, the lower wall surface is already without a flame; in a flow field for implementing the air jet method, the lower wall surface flame is stably combusted, and the lower wall surface flame is stably existed at the moment t being 6 ms.
As can be seen from FIG. 5, the weighted Mach numbers of the full flow field of the dual-mode ramjet engine without air jet are all larger than 1, so the combustion mode is hyper-combustion; the weighted Mach numbers of the main combustion areas of the combustion flow field for implementing the air jet flow are all less than 1, so that the combustion mode is sub-combustion. FIG. 6 is a graph showing that after the air jet is implemented for the super-combustion mode of FIG. 3, the air jet can change the combustion mode, and the air jets with the flow ratios of 10%, 20% and 30% are respectively implemented (flow ratio: ratio of air jet flow to engine inlet air flow), and it can be seen that the air jet with the flow ratio of 10% has no effect, and the kerosene on the lower wall surface is still not combusted; in the engine combustion flow field for implementing air jet with 20% flow ratio and 30% flow ratio, the kerosene on the lower wall surface can be stably combusted. As can be seen from fig. 6, the weighted mach number of the engine with the 10% flow ratio air jet applied is substantially the same as the weighted mach number without the air jet applied, and is not effective. And the weighted Mach numbers of the main combustion zone of the dual-mode ramjet engine implementing the air jet with the flow ratio of 20% and the flow ratio of 30% are both smaller than 1, the combustion mode is successfully converted from super-combustion to sub-combustion, and the larger the flow ratio of the jet is, the larger the sub-combustion zone is. It can thus be seen that air jets are an effective way to influence and alter the combustion mode of a dual mode ramjet engine.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (5)
1. A method of modifying a combustion mode of a dual mode ramjet engine, comprising: injecting air, namely air jet flow, into the engine, wherein the flow rate of the injected air is 20-30% of the air flow at the inlet of the engine, the temperature of the jet air is 10-55 ℃, and the mode in a combustion chamber of the dual-mode ramjet engine is changed from a hyper-combustion state to a sub-combustion state;
the method specifically comprises the following steps: (1) air flows into the engine; (2) jetting air into the engine at 20% of the total working time of the engine; (3) at 32.5% of the total time of engine operation, fuel is injected into the engine; (4) the igniter is turned on at the moment 32.5% of the total working time of the engine; (5) the igniter is closed at the moment of 65 percent of the total working time of the engine; (6) at 75% of the total time of the engine operation, the air jet stops; (7) when the total working time of the engine is over, the fuel is stopped to be sprayed, and the air does not flow into the engine any more; the total time of the engine operation refers to the time from the start of air flow into the engine to the stop of air flow into the engine.
2. The method of changing the combustion mode of a dual mode ramjet according to claim 1, wherein: the upper portion of engine combustion chamber (1) includes first notes oil piece (2), some firearm (3) on first notes oil piece (2) right side, second notes oil piece (4) on some firearm (3) right side, air jet stream piece (5) on second notes oil piece (4) right side, engine recess (7) are located the last wall of engine isolated section export, first notes oil piece (2) and some firearm (3) are located engine recess (7), third notes oil piece (6) are located the lower wall of engine recess (7) offside, the lower part of combustion chamber is equipped with third notes oil piece (6), fourth notes oil piece (8) on third notes oil piece (6) right side, be equipped with on air jet stream fast (5) perpendicular to internal wall hole (9), the jet air is spouted into in the engine at the interior wall of the perpendicular air jet stream piece (5) of engine recess rear portion.
3. The method of changing the combustion mode of a dual mode ramjet according to claim 1, wherein: the distance between the jet hole (9) and the rear edge of the engine groove (7) is 150 mm.
4. The method of changing the combustion mode of a dual mode ramjet according to claim 1, wherein: the jet holes are 20 round holes with the diameter of 3mm and evenly distributed in the width direction of the engine.
5. An engine combustion chamber, characterized by: combustion chamber upper portion includes first notes oil piece (2), some firearm (3) on first notes oil piece (2) right side, second notes oil piece (4) on some firearm (3) right side, air jet block (5) on second notes oil piece (4) right side, engine recess (7) are located the last wall of engine isolated section export, first notes oil piece (2) and some firearm (3) are located engine recess (7), third notes oil piece (6) are located the lower wall of engine recess (7) offside, the lower part of combustion chamber is equipped with third notes oil piece (6), fourth notes oil piece (8) on third notes oil piece (6) right side, be equipped with jet hole (9) perpendicular to internal face on air jet block (5) fast (5), the jet air is spouted in the engine at the interior wall of engine recess rear portion perpendicular air jet block (5).
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| CN110541773B (en) * | 2019-09-25 | 2021-09-28 | 上海交通大学 | Wide-speed-range ramjet engine combustion chamber and working method thereof |
| CN111664023A (en) * | 2020-07-03 | 2020-09-15 | 中国空气动力研究与发展中心 | Fuel mixing device of scramjet engine |
| CN111998387A (en) * | 2020-08-18 | 2020-11-27 | 中国空气动力研究与发展中心 | Method and device for promoting scramjet engine to realize starting ignition |
| CN116335852B (en) * | 2023-02-07 | 2023-09-01 | 中国空气动力研究与发展中心空天技术研究所 | Stamping engine tail nozzle of integrated enhanced rocket and design and working methods thereof |
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| US4272957A (en) * | 1977-11-05 | 1981-06-16 | Lucas Industries Limited | Fuel control system for a ram jet engine |
| US8265851B2 (en) * | 2009-05-18 | 2012-09-11 | Closed-Loop Engine Technology, Llc | Method of controlling engine performance |
| CN107420221A (en) * | 2016-05-23 | 2017-12-01 | 杨庆春 | A kind of engine combustion modal identification method |
| CN106837550B (en) * | 2017-02-06 | 2018-10-09 | 厦门大学 | The design method of hypersonic triple channel air intake duct |
| CN107013327B (en) * | 2017-02-17 | 2018-07-20 | 北京动力机械研究所 | A kind of double combustion chamber's scramjet engine and its control method |
| CN107701312B (en) * | 2017-11-10 | 2020-11-03 | 中国空气动力研究与发展中心计算空气动力研究所 | Hypersonic engine |
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