CN108426267A - A kind of folding V-type bluff body eddy flameholder - Google Patents

Abstract

The invention discloses a folding V-shaped blunt body vortex flame stabilizer, which belongs to the field of thermal energy and power engineering. The stabilizer unit consists of two equal-section, equal-span length airfoils welded at an angle α, or directly made by high-temperature alloy additive manufacturing; the combination form is radial, circumferential, or radial and circumferential mix. When working, the incoming flow carries fuel through the two airfoils, and the fluid forms a pair of flow direction vortices downstream of the flat V-shaped blunt body, and the incoming flow flows from the edge openings of the two airfoils to the central plane of the two airfoils , forming a vortex distributed along the span direction; the flow vortex and the vortex distributed in the span direction form a pair of stagnant vortices downstream, and an ignition device is arranged at the center of the stagnant vortex. The flame remains stable, the blowout boundary is wide, and the total pressure recovery coefficient is high; it is easy to match with the existing models of aero-engines and improve the performance of existing aero-engines.

Description

A folded V-shaped blunt body vortex flame stabilizer

technical field

The invention belongs to the field of thermal energy and power engineering, in particular to a folding V-shaped blunt body vortex flame stabilizer.

Background technique

The afterburner is one of the important features that distinguish military aviation gas turbine engines from civil aviation engines. The gas temperature and gas velocity ejected from the nozzle greatly increase the engine thrust in a short period of time.

The afterburner can increase the thrust-to-weight ratio of the aircraft in a short period of time, comprehensively improve the maneuverability of the fighter and expand the flight envelope (the ceiling can be increased to 22-23km, the maximum flight Mach number can be increased to 2.5-3), and the short-distance take-off of the fighter can be improved. , air control, interception, defense penetration and escape and other key capabilities, its performance also directly affects the ultimate performance of fighter jets, missiles and other weapons and equipment, often within minutes or even seconds after the afterburner is turned on, it will determine whether the fighter jet and the pilot The life and death of the missile determines the success or failure of the missile penetration and the hit rate. However, because the afterburner always works near the extreme working conditions of the engine, its working environment is also one of the worst conditions in the hot end parts of the engine. The harsh working conditions bring the primary problem to the design of the afterburner of the aero-engine , is the problem of combustion instability. For example, reference [1]: "Combustion Instability Simulation Experiment Technology"; by Zhang Mengzheng, Northwestern Polytechnical University Press, the combustion instability of the afterburner is divided into Low, mid and high frequency combustion instabilities.

The combustion instability in the afterburner chamber may not only lead to flame oscillation quenching (extinct), but may also lead to (1) an increase in the local thermal load of the combustion chamber, resulting in deformation, ablation or even complete failure of structural materials; damage; ③ cause the engine performance to deviate from the design point, and the thrust fluctuates violently, such as combustion instability during the take-off stage, which will lead to serious accidents such as sudden thrust drop and aircraft crash; Tube) precise control brings difficulties. Therefore, a flame stabilizer that matches the design performance and working conditions of the engine must be reasonably designed and installed in the afterburner chamber to ensure better organization of ignition and stable combustion under severe conditions.

The structure and layout of the flame stabilizer determine the ignition performance, flame stability, combustion efficiency and flow resistance of the afterburner. Therefore, improving the comprehensive combustion performance of the flame stabilizer and reducing the resistance of the flame stabilizer can directly improve The performance of the afterburner, thereby improving the overall performance of the engine.

For example, the U.S. YF-120 used a new method of three-dimensional flow design in the development of the prototype to overcome the problem that a large number of radial stabilizers in the afterburner would easily lead to combustion oscillations, and proposed a radial flame stabilizer. The afterburner combustion stabilization scheme composed of a central annular V-shaped stabilizer and 12 radial stabilizers; Reference [2]: "Aero-engine Structural Design Analysis", written by Chen Guang.

At present, the most commonly used blunt body structure of the afterburner flame stabilizer for military aero-engines is a V-shaped blunt body, that is, the two-dimensional unit structure of the flame stabilizer is a V-shaped structure, and according to actual needs, two The three-dimensional V-shaped unit is stretched into a three-dimensional flame stabilizer unit, and finally these three-dimensional flame stabilizer units are combined into an annular flame stabilizer, a radial flame stabilizer or a combination of annular and radial through a certain combination form , in fact, the evaporative flame stabilizer used to form the duty flame can also be regarded as a V-shaped blunt body with its own oil and gas nozzle.

However, the disadvantages of the V-shaped blunt body are also very clear, that is, the total pressure loss in the non-augmented state is large, the flame stability is only controlled by the oil-gas ratio of the incoming flow, the ignition oil-gas ratio is high, the fuel-lean stable combustion range is narrow, and the high-altitude connection booster The reliability of the force is poor, the wall temperature of the flame stabilizer is uneven, and the structure is easily deformed. For this reason, a simple improvement in the early stage is to adopt the slit V-shaped (double V-shaped) blunt body structure, reference [3]: Zhang Hongbin, Wang Jigen. Development and application of double V-shaped flame stabilizer [J]. Propulsion Technology, 1994, 15(3):38-43.), the main design parameters of the double V-shaped flame holder are basically the same as those of the V-shaped flame holder, the difference is that a smaller front edge is added to the double V-shaped flame holder The V-shaped stabilizer forms two air intake slots of a certain width on the head through the nesting of large and small flame stabilizers.

Compared with the V-shaped flame stabilizer, the airflow structure of the double V-shaped flame stabilizer has changed: it is composed of two airflows, one is the mainstream bypassing the main stabilizer, and the other is bypassing the small stabilizer, Pre-combustion flow into the interior of the main stabilizer. These two flows respectively form two recirculation areas, large and small, and through the interaction of the two recirculation areas, a narrow and long large recirculation area is finally formed. The vortex center of this recirculation area is in the main stabilizer, and the ignition The flame stabilizer is set in the main stabilizer and near the rear edge of the small stabilizer. The principle of flame maintenance is the same as that of the V-shaped flame stabilizer - relying on the recirculation zone to draw the unfueled gas into the burned area to ensure the continuation of the combustion process.

Compared with the V-shaped flame stabilizer, the biggest improvement of the double-V flame stabilizer is that it reduces the plugging ratio and the total pressure loss. For the other shortcomings of the V-shaped flame stabilizer, the improvement is limited, and it is actually closer to a head-optimized evaporation type flame stabilizer. At the same time, the double-V flame stabilizer increases the structural complexity and thus leads to a decrease in reliability and an increase in structural weight, which is a retrogression for the overall development trend of the flame stabilizer. So far, the most bold, radical and successful attempt on the flame stabilizer with blunt body structure is the "dune vortex (BD) flame stabilizer" invented by Professor Gao Ge of Beihang University; reference [4]: Gao Ge, Ning Yu. Dune Theoretical and experimental research on the stability of the vortex flame [J]. Journal of Engineering Thermophysics, 1982, V3(1): 89-95. The working principle of the BD flame stabilizer is to increase the pressure gradient in the vortex tail by shortening or shrinking the vortex tail , reduce the curvature of the streamline at the turning point of the vortex counterflow and increase the shear velocity gradient at this point, and finally form a stagnant vortex structure between the two horns downstream of the blunt body, which significantly improves the stability of the vortex. Since the vortex itself is stable, ignition and combustion in this area Good combustion stability is also obtained.

From the point of view of performance, the BD flame stabilizer significantly widens the lean oil blowout boundary of the two-dimensional unit structure flame stabilizer represented by the V-shaped blunt body, and reduces the flow resistance by about 75% to 80%, which solves many problems at that time. A key model military turbojet engine afterburner flame stability problem; and from the perspective of design theory, the significance of the BD flame stabilizer is more prominent - on the one hand, the vortex stability theory based on the BD flame stabilizer, reference [5]: Gao Ge. Research on the local stability of the vortex [J]. Journal of Engineering Thermophysics, 1981, V2(4): 394-400. Really change the design of the flame stabilizer from the "subjective design" driven by engineering experience It has risen to the level of "positive rational design" driven by vortex dynamics theory, which is a leap forward in the design methodology of aero-engine core components; on the other hand, it is based on the interaction mechanism between three-dimensional vortices, using the The active construction of the "storage vortex" structure with strong stability by the three-dimensional geometric body in space is a major breakthrough in the design theory of the afterburner flame stabilizer based on the two-dimensional unit structure in the past. But it is undeniable that the BD flame stabilizer also has some shortcomings that limit its further development and application:

(1) The constricted sharp angles at both ends lead to certain difficulties in the circumferential cross-flaming, and the design of the curved surface at the maximum groove width is also not conducive to the radial cross-flaming. Therefore, it is necessary to add an additional cross-flaming structure between the units of the BD flame stabilizer. This has brought about an increase in structural complexity, a reduction in reliability (the cross-fire structure is not easy to cool, and is easy to ablate) and an increase in structural weight.

(2) The excessively stable trapped vortex structure leads to a relatively small diffusion angle of the downstream wake shear layer, which has an adverse effect on the propagation of the flame in the entire afterburner chamber, and is prone to the problem of uneven outlet temperature distribution. Additional circumferential annular flame holders are added.

(3) The BD flame stabilizer with complex curved surface and the theory of vortex stability it relies on directly bring about problems in terms of too many design parameters, increased design difficulty, and model adaptability, which also limits its use in subsequent turbofans. Further development and application in the engine development phase.

(4) Different from the V-shaped flame stabilizer structure, the BD flame stabilizer is composed of two complex curved surfaces with relatively poor processing technology, and in the afterburner chamber with high temperature, high speed and high load, it is prone to uneven surface temperature distribution. Uniformity and appearance deformation lead to problems such as decline in combustion stabilization effect or even failure, which is also unacceptable for a new generation of military gas turbine engines that have high requirements in terms of reliability and maintainability.

In the following years, due to many reasons, neither the BD flame stabilizer nor the vortex stability theory related to the mechanism of the vortex has been well continued and developed, and these defects of the BD flame stabilizer have not been truly resolved. , and the research work related to it has been carried out very little, which is very regrettable.

Contents of the invention

In order to solve the problems of high fuel ignition difficulty and difficulty in maintaining stable combustion of the flame under the condition of high speed and unsteady incoming flow, the present invention proposes a folding V-shaped blunt body vortex flame stabilizer, which can not only be applied to military high-performance jet Aeroengine main combustion chamber and afterburner, missile (high-speed UAV) engine supersonic combustion chamber and other power machinery fields that require stable combustion in high-speed airflow; it can also be used in the field of civilian combustion devices.

The folded V-shaped blunt body vortex flame stabilizer is composed of several groups of folded V-shaped blunt body vortex flame stabilizers with the same or similar structure. Each flame stabilizer monomer includes two equal-section, For airfoils of equal span length, the design features of two traditional straight-sided V-shaped blunt bodies are selected for the two airfoils, which include the two parameters of groove width D and apex angle ρ.

The groove width D is calculated according to the afterburner flame stability formula:

V _FH is the blow-out velocity; T _t is the afterburner flow temperature; P _sFH is the afterburner blow-out pressure; K _st is the stability parameter;

At the same time, the folded V-shaped blunt body vortex flame stabilizer forms a sweep angle α between the two airfoils, and the angle range of the sweep angle α is 60 degrees to 150 degrees; Depends on the size of the vortex area. The two airfoils are welded together according to the angle α, or directly made by high-temperature alloy additive manufacturing; the span length of the airfoil is 4 to 8 times the slot width of L;

Considering the convenience of processing and assembly, each flame stabilizer unit also includes two parameters, the span length A of the unit and the flow chord length d, which are:

The combination form of several flame stabilizer monomers is: radial, circumferential, or a combination of radial and circumferential directions, installed in the afterburner section of the aero-engine, and the combined outer ends of several flame stabilizer monomers are based on afterburner The barrel structure of the afterburner is connected with the barrel of the afterburner using a conventional structure, and the inner end is adjacent to the central cone of the afterburner.

Among them, the radial combination form is divided into equal-length combination or long-short combination according to the working characteristics of afterburner of different aero-engines. The equal-length combination means that 12 to 20 equal-length folded V-shaped flame stabilizer units are distributed at equal intervals in a circle, and each equal-length folded V-shaped flame stabilizer unit is fixed on the afterburner through the airfoil end face on the round wall of

The combination of length and length includes long and short flame stabilizer monomer combinations at equal intervals. The length of the short flame stabilizer monomer combination is selected from 1 to 2 flame stabilizer monomers welded together end-to-end. The length of the combination of flame stabilizer monomers is selected from 2 to 3 flame stabilizer monomers welded together end-to-end.

The number of long flame stabilizer monomer combinations and short flame stabilizer monomer combinations in the combination of long and short flame stabilizers is determined according to the diameter of the afterburner, and the value of the number of flame stabilizer monomers selected in the long flame stabilizer monomer combination is Less than or equal to 2 times the number of flame stabilizer monomers in the combination of short flame stabilizer monomers.

The airfoil end face of each long flame stabilizer unit combination or short flame stabilizer unit unit is fixed on the round wall of the afterburner;

The circumferential combination form consists of 8 to 20 flame stabilizer units of equal length, the end faces are welded together in the form of first connection, and fixed on the round wall of the afterburner; the circumferential combination of flame stabilizer units The number and size of the flame stabilizer unit are determined by the design requirements of the afterburner. The circumferential combination form and the afterburner cylinder and sudden expansion can be connected with heat-resistant metal trusses.

The mixed combination of radial and circumferential directions includes not only the circumferential flame stabilizer single connection form, but also the radial flame stabilizer single connection form; and the circumferential connection form is set to 1 turn~ 3 circles, and installed on the inner side of the entire combined structure, and connected with the inner side of the radial flame stabilizer by welding to achieve functions such as on-duty flame maintenance.

The combination method and assembly principle of the above-mentioned flame stabilizer monomers directly follow the original V-shaped blunt body arrangement, or make changes according to actual needs.

Working principle and process:

The folded V-shaped blunt body vortex flame stabilizer of the present invention, when working, the incoming flow entrains fuel to flow through the two airfoils. Since the section of the flame stabilizer has a curvature of ρ, the plane V-shaped blunt with a height of D body, the fluid must be separated from the plane V-shaped blunt body, and form a pair of flow direction vortices downstream of the plane V-shaped blunt body, because the folded V-shaped blunt body has two symmetrical sections with a certain sweep angle α and a length L. The two extended airfoils form an overall V-shape in three-dimensional space on the orthogonal plane of the plane V-shaped blunt body, so the incoming flow will also flow from the edge openings of the two airfoils to the two airfoils. Flow in the direction of the center plane of the , and form a vortex distributed along the span;

The flow direction vortex falling off from the plane V-shaped blunt body cross-section is perpendicular to the direction of the spanwise distributed vortex, interacting, and finally forms a pair of stable spatial positions downstream of the folded V-shaped blunt body flame stabilizer, which is not easy to change with the change of incoming flow conditions of the vortex. Arranging the ignition device at the center of the vortex can ensure the stable combustion of the flame, and exert a stable combustion effect exceeding that of the traditional flat V-shaped blunt body.

The advantages of the present invention are:

(1) A folded V-shaped blunt body vortex flame stabilizer, which has good adaptability to the incoming flow. By adjusting the design parameters of the blunt body α, ρ, L, D, the incoming flow Ma=0.1～1, Re=60000 Within the working condition range of ~200000, a stable dwelling vortex is formed whose spatial position does not change with the incoming flow;

(2) A folded V-shaped blunt body vortex flame stabilizer, which inherits the characteristics of the BD flame stabilizer, which has good fuel-lean ignition characteristics and good combustion stability, and can complete ignition in the lean-fuel state. Compared with the sudden change, the flame can still remain stable, and the blowout boundary is wider;

(3) A folded V-shaped blunt body vortex flame stabilizer, compared with the BD flame stabilizer, the cross-flame performance is better, and each monomer can be connected in parallel without gaps to form a complete and closed ring, ensuring uniform flame distribution in the circumferential direction;

(4) A folded V-shaped blunt body vortex flame stabilizer, the downstream of the blunt body has good gas mixing performance, and when the radial structure is adopted, it can also realize the effective mixing of inner and outer airflows in the state of no force;

(5) A folded V-shaped blunt body vortex flame stabilizer with small flow resistance and high total pressure recovery coefficient;

(6) A folded V-shaped blunt body vortex flame stabilizer, the structure is much simpler than the BD flame stabilizer, only two control parameters are added to the traditional V-shaped blunt body flame stabilizer, and it is easy to fully grasp its different The flow and combustion characteristics under working conditions are easier to match with existing models of aero-engines and improve the performance of existing aero-engines.

Description of drawings

Fig. 1 is the structural representation of a kind of folded V-shaped blunt body vortex flame stabilizer of the present invention;

Fig. 2 is a partial view of a folded V-shaped blunt body vortex flame stabilizer of the present invention;

Fig. 3 is a schematic diagram of the installation position of a folded V-shaped blunt body vortex flame stabilizer of the present invention;

Fig. 4 is the radial combination schematic diagram of a kind of folded V-type blunt body vortex flame stabilizer of the present invention;

Fig. 5 is a schematic diagram of the circumferential combination of a folded V-shaped blunt body vortex flame stabilizer of the present invention;

Fig. 6 is a radial and circumferential combination diagram of a folded V-shaped blunt body vortex flame stabilizer according to the present invention.

Fig. 7 is a schematic diagram of a vortex structure with different sweep angles α of a folded V-shaped blunt body vortex flame stabilizer of the present invention;

Figure 8a is a schematic diagram of a traditional V-shaped blunt body flame holder with only shedding vortex A and separation vortex B at both ends;

Fig. 8b is a schematic diagram of a folded V-shaped blunt body vortex flame stabilizer of the present invention forming a pair of reverse rotating vortex C at the head;

Fig. 9a is a schematic diagram of the trapped vortex structure obtained when the sweep angle α=90 degrees and Re=100000 according to the present invention;

Fig. 9b is a schematic view of the streamline diagram obtained when the sweep angle α=90 degrees and Re=100000 according to the present invention;

Fig. 10 is a schematic diagram of the position of the trapped vortex obtained when the sweep angle α and Re take different values in the present invention.

Detailed ways

The specific implementation method of the present invention will be described in detail below in conjunction with the accompanying drawings.

Based on the in-depth study of the mechanism of stationary vortex combustion, the present invention combines the respective advantages of the dune vortex flame stabilizer and the traditional V-shaped flame stabilizer, and proposes a three-dimensional flow folded V-shaped blunt body vortex flame stabilizer. device.

The folded V-shaped blunt body vortex flame stabilizer, as shown in Figure 1, is composed of several groups of folded V-shaped blunt body vortex flame stabilizers with the same or similar structure, and each flame stabilizer monomer Including two airfoils with equal cross-section and equal span length, as shown in Figure 2, the V-shaped blunt body section follows the design features of the traditional V-shaped blunt body, including the two parameters of groove width D and apex angle ρ.

The groove width D is calculated according to the afterburner flame stability formula:

V _FH is the blow-out velocity, generally Mach number M = 0.1 ~ 0.35; T _t is the afterburner flow temperature, according to the internal and external gas temperature, generally T _t = 300K ~ 900K, P _sFH is the afterburner The blow-off pressure is taken as P _sFH =69kpa, and K _st is the stability parameter. According to the typical design conditions of domestic aero-engines, K _st is generally taken as 5-9.

According to experience, the vertex angle ρ is generally taken at 30-45 degrees. If the value is too large, the blocking ratio and flow resistance will increase sharply, and if the value is too small, it will not be conducive to the formation of the recirculation zone.

However, different from the traditional straight-edge V-shaped blunt body, a folded V-shaped blunt body vortex flame stabilizer forms a sweep angle α between the two airfoils, and the angle range of the sweep angle α is 60 degrees to 150 degrees. The desired position of the trapped vortex is related to the size of the trapped vortex area. The two airfoils are made of two traditional straight-edge V-shaped blunt bodies welded at an angle α, or directly made by high-temperature alloy additive manufacturing; the wingspan length L of the airfoil is 4 to 8 times the groove width;

Reference 6: Gao Ge. Research on the local stability of the vortex [J]. Journal of Engineering Thermophysics, 1981, V2(4): 394-400; , has nothing to do with the incoming flow velocity, but is only related to the four design parameters of the folded V-shaped blunt body vortex flame stabilizer. Therefore, when the three parameters L, D, and ρ are all determined, the general law for the parameter α is as shown in Figure 7 As shown, when Re=40500, when α>90°, the larger α is, the longer the flow length of the vortex is, and the narrower the span width is; when 60°<α<90°, the flow direction of the vortex and the span The length shrinks first, then basically remains unchanged, and the stability is further enhanced; when α<60°, there is no meaningful flow structure anymore.

Considering the convenience of processing and assembly, each flame stabilizer unit also includes two parameters: the span length A of the unit and the chord length d in the flow direction. Obviously, there are:

Compared with the traditional V-shaped blunt body flame stabilizer controlled by only two parameters, slot width D and apex angle ρ, the folded V-shaped blunt body vortex flame stabilizer actually only increases the two parameters of wingspan L and sweep angle α.

Combination forms of several flame stabilizer monomers are: radial, circumferential, or mixed radial and circumferential, etc., installed in the afterburner section of the aero-engine, as shown in Figure 3, the number of flame stabilizer monomers The combined outer end (radially outer side) is connected with the afterburner barrel using conventional structures such as bolts, mortise and tenon joints, and key sheaths according to the cylinder structure of the afterburner, and the inner end (radially inner side) is adjacent to the afterburner The central cone (burst) of the chamber.

The radial combination forms are divided into equal-length combinations or long-short combinations according to the working characteristics of afterburners of different aero-engines. The equal-length combination means that 12 to 20 folded V-shaped flame stabilizer units of equal length are distributed at equal intervals in a circle. The equal length refers to the length of a single flame stabilizer unit, or 2 to 3 flame stabilizers The length of the monomer welded end-to-end; each equal-length folded V-shaped flame stabilizer monomer is fixed on the round wall of the afterburner through the airfoil end face;

As shown in Figure 4, the long-short combination includes equally spaced long flame stabilizer monomer combinations and short flame stabilizer monomer combinations. The length of the stabilizer unit and the length of the long flame stabilizer unit combination is selected from 2 to 3 flame stabilizer units welded together end-to-end.

The number of long flame stabilizer monomer combinations and short flame stabilizer monomer combinations in the combination of long and short flame stabilizers is determined according to the diameter of the afterburner, and the value of the number of flame stabilizer monomers selected in the long flame stabilizer monomer combination is Less than or equal to 2 times the number of flame stabilizer monomers in the combination of short flame stabilizer monomers.

The airfoil end face of each long flame stabilizer unit combination or short flame stabilizer unit unit is fixed on the round wall of the afterburner;

As shown in Figure 5, the circumferential combination form consists of 8 to 20 equal-length flame stabilizer monomers that weld the end faces together in the form of first connection and fix them on the round wall of the afterburner; the circumferential combination The number of flame stabilizer units and the size of the flame stabilizer units are determined by the design requirements of the afterburner. The circumferential combination form and the afterburner cylinder and sudden expansion can be connected with heat-resistant metal trusses.

As shown in Figure 6, the mixed combination of radial and circumferential is equivalent to a combination of radial and circumferential combinations, including both the circumferential flame stabilizer single connection form and the radial flame stabilizer Single connection form; and the circumferential connection form is set to 1 to 3 turns according to needs, and is installed on the inner side of the entire composite structure, and is connected to the inner side of the radial flame stabilizer by welding to realize duty Flame maintenance and other functions.

The combination and assembly principle of the above-mentioned flame stabilizer is no different from the traditional V-shaped blunt body or BD-shaped blunt body. The original V-shaped blunt body arrangement can be directly used, or it can be changed according to actual needs.

Working principle and process:

The folded V-type blunt body vortex flame stabilizer of the present invention, when working, the incoming flow entrains fuel and flows through the two airfoils from the direction shown in Figure 1. Since the section of the flame stabilizer has a curvature of ρ, the height is a plane V-shaped bluff body of D, the fluid must be separated from the plane V-shaped bluff body, and form a pair of flow direction vortices downstream of the plane V-shaped bluff body, as shown in Figure 8a, the traditional V-shaped bluff body flame A and the separation vortex B at both ends realize ignition and combustion in the low-pressure area of the vortex center that flows to the vortex.

And because the folded V-shaped blunt body has two symmetrical airfoils stretched at a certain cross-section with a certain sweep angle α and a length L, a three-dimensional space is formed on the orthogonal plane of the flat V-shaped blunt body Therefore, the incoming flow will also flow from the edge openings of the two airfoils to the center plane of the two airfoils, and form vortices distributed along the span;

Numerical calculations and experimental studies show that, as shown in Figure 8b, the flow vortices shed from the cross-section of the planar V-shaped bluff body are perpendicular to the direction of the spanwise distributed vortices, interacting, and finally form a pair of A stationary vortex whose spatial position is stable and not easy to change with the change of incoming flow conditions.

The vortex center of the stagnant vortex can stably exist at a specific position downstream of the bluff body, and does not change with the incoming flow conditions, and is only related to the above-mentioned geometric design parameters of the bluff body. According to this characteristic, the arrangement of the ignition device at the center of the pair of trapped vortices can ensure that the ignition is completed under extremely complex and unsteady flow conditions, and the flame can be kept burning stably. Stable combustion effect.

Example:

Numerical experiments were carried out on a folded V-shaped blunt body vortex flame stabilizer with α=90 degrees. When Re=100000, the vortex structure diagram was obtained as shown in Figure 9a, and the streamline diagram was shown in Figure 9b. Studies have shown that the flame can burn stably in the blunt body stationary vortex and the downstream area of the stationary vortex under the condition of high Reynolds number, and the total pressure loss is small, and the combustion efficiency is high.

As shown in Figure 10, when the Re values are 30000, 40500, 50600, 60750, 70900 and 81000, the position of the trapped vortex does not change with the incoming flow velocity.

At the same time, when the sweep angle α is 180 degrees, the vortex shedding can be seen alternately on the wingspan section of the traditional V-shaped blunt body flame stabilizer; when the sweep angle α is 150 degrees, the frequency of vortex shedding decreases. When the sweep angle α is 120 degrees, the dwelling vortex is gradually formed; when the sweep angle α is 90 degrees, a complete dwelling vortex is formed. When the sweep angle α is 60 degrees, the dwelling vortex is reduced and the stability is enhanced.

Claims (6)

1. a kind of folding V-type bluff body eddy flameholder, which is characterized in that by the same or similar folding V of several groups structure Type bluff body eddy flameholder combination of monomers at, each flameholder monomer include two cross-sections, etc. spanwise lengths Aerofoil, two aerofoils select the design feature of the traditional straight flange V-type bluff body of two panels, including groove width D and apex angle ρ two parameters；

Groove width D is calculated according to after-burner flame holding formula：

V_FHFor blow-off velocity；T_tFor after-burner temperature of incoming flow；P_sFHPressure is put out for after-burner；K_stJoin for stability Number；Apex angle ρ rule of thumb values；

Meanwhile it folding V-type bluff body eddy flameholder and foring an angle of sweep α between two aerofoils；Two aerofoils are pressed Angle [alpha] welding is put together, or is directly prepared by high temperature alloy increasing material manufacturing；

The combining form of several flameholder monomers is：Radial, circumferentially, or radial direction is mixed with circumferential, is installed on aeroplane engine The after-burner section of machine, several flameholder monomers combine tube structure of the outer end according to after-burner, using normal The cylinder for advising structure and after-burner connects, conical inner body of the inner end close to after-burner；

Wherein radial combining form, according to the working characteristics of different aeroengine thrust augmentation combustion chambers, be divided into isometric combination or Combination of long drives and drop shots is combined；

End face is welded on by the flameholder monomer of 8~20 equal lengths by end to end form by circumferential combining form Together, it is fixed on the circle wall of after-burner；The ruler of the flameholder monomer number, flameholder monomer that circumferentially combine The very little design requirement by after-burner determines；Circumferential combining form can use heating resisting metal with after-burner cylinder, sudden expansion Truss is attached；

The radial hybrid combining with circumferential direction had both contained circumferential flameholder monomer type of attachment, had also contained radial Flameholder monomer type of attachment；And circumferential type of attachment is arranged as required to enclose for 1 circle~3, and it is mounted on entire group It closes structure in the inner part, is connect with the inside of radial flameholder monomer using welding manner.

2. a kind of folding V-type bluff body eddy flameholder as described in claim 1, which is characterized in that the angle of sweep α Angular range be 60 degree to 150 degree.

3. a kind of folding V-type bluff body eddy flameholder as described in claim 1, which is characterized in that the aerofoil The groove width that the value of spanwise length L is 4~8 times.

4. a kind of folding V-type bluff body eddy flameholder as claimed in claim 3, which is characterized in that each fire Flame stabilizer monomer further includes monomer span-wise length A and flows to two parameters of chord length d, and formula is as follows：

5. a kind of folding V-type bluff body eddy flameholder as described in claim 1, which is characterized in that described isometric group The folding V-flame stabilizer monomer of i.e. 12~20 equal lengths of equidistantly distributed in a circumference is closed, each equal length V-flame stabilizer monomer is folded to be fixed on the circle wall of after-burner by aerofoil end face；

Combination of long drives and drop shots includes equally spaced long flameholder combination of monomers and short flameholder combination of monomers, short flame stabilization The length of device combination of monomers selects end-to-end 1~2 welded together flameholder monomer, long flame stabilizer combination of monomers Length select end-to-end 2~3 welded together flameholder monomer；Each long flameholder combination of monomers or The aerofoil end face of short flameholder combination of monomers is fixed on the circle wall of after-burner；

The number of long flameholder combination of monomers and short flameholder combination of monomers is fired according to reinforcing in combination of long drives and drop shots combination The diameter for burning room determines, wherein the flameholder monomer numerical value selected in long flameholder combination of monomers, is less than or equal to 2 times of a numerical value of short flameholder combination of monomers Flame stabilizer monomer.

6. a kind of folding V-type bluff body eddy flameholder as described in claim 1, which is characterized in that operation principle and mistake Journey：

The folding V-type bluff body eddy flameholder, when work, incoming volume takes fuel and flows through two aerofoils, due to flame The section of stabilizer is that curvature is ρ, is highly the plane V-type bluff body of D, and fluid is inevitable to be detached from plane V-type bluff body, and in plane V-type bluff body downstream forms a pair and flows to vortex, due to fold V-type bluff body gather around there are two it is symmetrical, with certain angle of sweep α, length L Two aerofoils that cross-section stretches, on the orthogonal plane of plane V-type bluff body, and constitute the whole V on a three dimensions Type, therefore incoming will also flow from the rim openings of two aerofoils to the central plane direction of two aerofoils, and formed and extended To the vortex of distribution；

Fall off from plane V-type bluff body section flow to vortex with open up it is vertical to the vortex direction of distribution, interaction, finally rolling over Folded V-type bluff body flameholder downstream forms that a pair of of spatial position is stable, is not easy with inlet flow conditions variation and what is changed stay Whirlpool；Igniter is arranged in standing vortex center, it can be ensured that flame stabilization burns, and plays more than conventional planar V-type bluff body Steady fuel efficiency fruit.