A strut flame stabilizer combining a vortex generator and a cavity

Abstract

The present invention relates to a strut flame stabilizer with a combination of vortex generators and cavities. The strut flame stabilizer is composed of a leading edge, a straight section, and a V-shaped bottom surface. Structures combining vortex generators and cavities are arranged on both side surfaces of the straight section. The advantages and beneficial effects of the present invention are as follows: When the afterburner adopts the strut flame stabilizer with a combination of vortex generators and cavities, it has good flame stabilization performance, a high flame propagation speed, small flow resistance loss, and high combustion efficiency.

Description

Technical Field

[0001] The invention relates to a support plate flame stabilizer composed of a vortex generator and a concave cavity, which can be used for an integrated afterburner combustion chamber of an aero-engine with a high thrust-to-weight ratio and belongs to the field of aero-technology. Background Art

[0002] The new generation of afterburning turbofan engines pursues a high thrust-to-weight ratio. In terms of the afterburner, it requires simple parts, low cold flow resistance loss, a small proportion of the afterburner section length, and high afterburner combustion efficiency. The afterburner uses a flame stabilizer to stabilize the flame and organize combustion. The performance of the flame stabilizer is a decisive factor affecting the performance of the afterburner. Most of the new generation of afterburner turbofan engines use an integrated afterburner with an integrated design of a rectifier support plate and a flame stabilizer. However, conventional support plate flame stabilizers produce Karman vortex street-type recirculation vortices, which have poor stability and can lead to locally unstable combustion.

[0003] Due to the small proportion of the afterburner section length, the distance from the fuel injection to the trailing edge of the flame stabilizer becomes smaller accordingly. The fuel atomization, evaporation and mixing are not sufficient before ignition, which can easily lead to unstable combustion. When combined with the unstable combustion caused by the recirculation vortex, the combustion instability problem will be amplified, thereby affecting the combustion reaction process. The distance from the trailing edge of the flame stabilizer to the nozzle outlet becomes smaller accordingly, the combustion section becomes shorter, and the flame in the recirculation zone behind the flame stabilizer does not have time to spread horizontally throughout the entire combustion chamber. Part of the oil-gas mixture is not fully burned, and part of the oil-gas mixture does not participate in combustion and is directly discharged, which seriously affects the afterburner combustion efficiency. Summary of the invention

[0004] The object of the present invention is to provide a support plate flame stabilizer with a vortex generator and a concave cavity as the composite structure, and a vortex generator and a concave cavity as the composite structure are arranged on both sides of the support plate flame stabilizer to improve flame stability, accelerate flame propagation, reduce flow losses and increase combustion efficiency.

[0005] The present invention is achieved through the following technical solutions.

[0006] The invention discloses a support plate flame stabilizer with a composite vortex generator and a concave cavity. The composite structure of the vortex generator and the concave cavity is arranged on both sides of the support plate flame stabilizer.

[0007] Furthermore, the support plate flame stabilizer has a chord length of 90 to 150 mm, and the extension is determined by the specific engine. It consists of a leading edge, a straight section, and a V-shaped bottom surface. The leading edge is an elliptical surface, and the major axis of the ellipse is 1.5 to 2.2 times the minor axis. The leading edge is tangent to the straight section, the straight section is 24 to 36 mm wide, and the V-shaped bottom surface has an included angle of 100° to 150°.

[0008] Furthermore, the structure in which the vortex generator is combined with the cavity is composed of the front wall of the cavity, the bottom wall of the cavity, the rear wall of the cavity and the inclined surface of the vortex generator. The cross-section of the cavity is trapezoidal. The front wall of the cavity is perpendicular to the bottom wall of the cavity. The included angle between the rear wall of the cavity and the bottom wall of the cavity is 140°-160°. The bottom wall of the cavity is parallel to the straight section and is 5-7 mm away from the surface of the straight section. The inclined surface of the vortex generator starts to incline outward from the surface of the straight section at the tangent point between the circular arc of the wave crest and the serrated edge on the front wall of the cavity, and encloses a wedge-shaped vortex generator shape with the front wall of the cavity. The highest point of the inclined surface of the vortex generator protrudes 4-7 mm from the surface of the straight section; in the top view direction, the front wall of the cavity and the rear wall of the cavity are wavy, including 3-5 wavelengths, starting and ending at the wave crest position. The wavy shape is obtained by rounding the corners at the wave crest and wave trough of the serrated wave. The serrated edge of the serrated wave on the front wall of the cavity forms a chordal angle of 30°-50° with the chord of the strut flame stabilizer. The fillet radius of the wave crest on the front wall of the cavity is 13-18 mm, and the fillet radius of the wave trough on the front wall of the cavity is 3-7 mm. The tangent point between the circular arc of the wave crest and the serrated edge on the front wall of the cavity is 35-45 mm away from the trailing edge of the strut flame stabilizer. The amplitude of the serrated wave on the rear wall of the cavity is 9-15 mm. The chordal distance from the midline of the serrated wave at the leading edge of the rear wall of the cavity to the trailing edge of the strut flame stabilizer is 20-30 mm. The fillet radii of the wave crest and wave trough on the rear wall of the cavity are both 15-25 mm.

[0009] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0010] First, the flame stability performance is good. The conventional strut flame stabilizer generates a von Kármán vortex street type recirculation vortex, and the stability of its recirculation vortex is poor, and combustion instability problems are likely to occur. After arranging the structure in which the vortex generator is combined with the cavity on both sides of the conventional strut flame stabilizer, a K-H type recirculation vortex is generated, and the stability of the recirculation vortex is enhanced. The vortices in the cavity and the streamwise vortices dragged out from the vortex generator are beneficial to the evaporation and mixing of fuel, and are conducive to stable and efficient combustion. The vortices in the cavity make the mainstream near the wall surface flow towards the rear wall of the cavity. The wavy rear wall of the cavity makes the fuel more concentrated downstream of the wave trough of the wavy rear wall relative to downstream of the wave crest. Therefore, the fuel content along the span of the flame stabilizer is also distributed in a wavy shape, which is beneficial to broadening the flame stability range. And the fuel distribution matches the size of the transverse recirculation zone and the position of the streamwise vortex, which further facilitates obtaining stable and efficient combustion.

[0011] Second, the flame propagation speed is fast. Compared with the conventional strut flame stabilizer, the recirculation zone downstream of the wave trough of the wavy rear wall of the strut flame stabilizer combined with the vortex generator and the cavity becomes wider, and the recirculation zone downstream of the wave crest becomes narrower. The streamwise vortices dragged out from the vortex generator are located on both sides of the recirculation zone downstream of the wave trough, further expanding the range of the recirculation zone downstream of the wave trough, strengthening the heat and mass convective transport between the recirculation and the mainstream on both sides, and the fuel is relatively concentrated downstream of the wave trough. Therefore, the combustion reaction is more intense downstream of the wave trough. All these are beneficial to obtaining a faster flame propagation speed.

[0012] Third, the flow resistance loss is small. To achieve the same flame stability performance and flame propagation speed, compared with increasing the blockage width of a conventional strut flame stabilizer, arranging a structure that combines a vortex generator and a cavity on both sides of the conventional strut flame stabilizer causes less flow resistance loss. Moreover, replacing the continuously shedding and breaking Karman vortex street type recirculation vortex with a stable K-H type recirculation vortex is beneficial to reducing the flow resistance loss.

[0013] Fourth, the combustion efficiency is high. The vortices in the cavity of the strut flame stabilizer combined with the vortex generator and the streamwise vortices dragged out from the vortex generator not only facilitate the evaporation and mixing of fuel, but also make the fuel relatively enriched downstream of the trough of the wavy rear wall of the cavity, and expand the recirculation zone downstream of the trough. As a result, the fuel distribution matches the size of the transverse recirculation zone and the position of the streamwise vortices. The streamwise vortices can strengthen the heat and mass convective transport between the recirculation and the mainstream on both sides. Therefore, under these combined effects, high combustion efficiency can be obtained within a short distance. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Isometric view of the strut flame stabilizer combined with the vortex generator and the cavity in the present invention.

[0015] Figure 2 Side view of the strut flame stabilizer combined with the vortex generator and the cavity in the present invention.

[0016] Figure 3 Top view of the strut flame stabilizer combined with the vortex generator and the cavity in the present invention.

[0017] Figure 4 Front view of the strut flame stabilizer combined with the vortex generator and the cavity in the present invention.

[0018] Figure 5 Rear view of the strut flame stabilizer combined with the vortex generator and the cavity in the present invention.

[0019] Figure 6 Longitudinal section V X distribution of the strut flame stabilizer combined with the vortex generator and the cavity in the present invention.

[0020] Figure 7 Transverse section V X distribution of the strut flame stabilizer combined with the vortex generator and the cavity in the present invention.

[0021] Figure 8 Streamlines of the strut flame stabilizer combined with the vortex generator and the cavity in the present invention Figure 1 .

[0022] Figure 9Streamlines of the strut flame holder with the combination of vortex generators and cavities in the present invention Figure 2 。

[0023] Figure 10 Streamlines of the strut flame holder with the combination of vortex generators and cavities in the present invention Figure 3 。

[0024] In the attached drawings, 1 is the leading edge; 2 is the straight section; 3 is the V-shaped bottom surface; 4 is the front wall of the cavity; 5 is the bottom wall of the cavity; 6 is the rear wall of the cavity; 7 is the inclined surface of the vortex generator; L1 is the span of the strut flame holder; L2 is the chord length of the strut flame holder; L3 is the chordwise distance from the midline of the serrated wave at the leading edge of the rear wall of the cavity to the trailing edge of the strut flame holder; L4 is the distance from the tangent point of the peak arc and the serrated edge of the front wall of the cavity to the trailing edge of the strut flame holder; L5 is the amplitude of the serrated wave on the rear wall of the cavity; W1 is the width of the straight section; H1 is the distance from the bottom wall of the cavity to the surface of the straight section; H2 is the height by which the highest point of the inclined surface of the vortex generator protrudes from the surface of the straight section; α1 is the included angle of the V-shaped bottom surface profile; α2 is the included angle between the rear wall and the bottom wall of the cavity; α3 is the included angle between the serrated edge of the serrated wave on the front wall of the cavity and the chord of the strut flame holder; R1 is the fillet radius of the peak and trough of the rear wall of the cavity; R2 is the fillet radius of the peak of the front wall of the cavity; R3 is the fillet radius of the trough of the front wall of the cavity. Detailed implementation manners

[0025] The following will further elaborate on the present invention in conjunction with the attached Figures 1 to 5 drawings and embodiments.

[0026] A strut flame holder with the combination of vortex generators and cavities has a structure in which vortex generators and cavities are combined and arranged on both side surfaces of the strut flame holder.

[0027] As a further improvement of the embodiment of the present invention, for the strut flame holder, the chord length L2 is 90 - 150 mm, specifically 120 mm in this embodiment, the span L1 is determined by the specific engine, specifically 180 mm in this embodiment, and it is composed of the leading edge 1, the straight section 2, and the V-shaped bottom surface 3. The leading edge 1 is an elliptical surface, and the major axis dimension of the ellipse is 1.5 - 2.2 times that of the minor axis, specifically 1.77 times in this embodiment. The leading edge 1 is tangent and continuous with the straight section 2. The width W1 of the straight section 2 is 24 - 36 mm, specifically 26 mm in this embodiment. The included angle α1 of the V-shaped bottom surface 3 profile is 100° - 150°, specifically 120° in this embodiment.

[0028] As a further improvement of the embodiment of the present invention, the structure in which the vortex generator is combined with the cavity is composed of the front wall 4 of the cavity, the bottom wall 5 of the cavity, the rear wall 6 of the cavity, and the inclined surface 7 of the vortex generator. The cross-section of the cavity is trapezoidal. The front wall 4 of the cavity is perpendicular to the bottom wall 5 of the cavity. The included angle α2 between the rear wall 6 of the cavity and the bottom wall 5 of the cavity is 140° to 160°, specifically 155° in this embodiment. The bottom wall 5 of the cavity is parallel to the surface of the straight section 2, and the distance H1 from the surface of the straight section 2 is 5 to 7 mm, specifically 6 mm in this embodiment. The inclined surface 7 of the vortex generator starts to incline outward from the surface of the straight section 2 at the tangent point of the peak arc and the serrated edge of the front wall 4 of the cavity, and encloses a wedge-shaped vortex generator shape with the front wall 4 of the cavity. The height H2 of the highest point of the inclined surface 7 of the vortex generator protruding from the surface of the straight section 2 is 4 to 7 mm, specifically 5 mm in this embodiment; in the top view direction, the front wall 4 of the cavity and the rear wall 6 of the cavity are wavy, with 3 to 5 wavelengths, specifically 3 in this embodiment, starting and ending at the peak positions. The wavy shape is obtained by rounding the corners of the peaks and valleys of the sawtooth wave. The included angle α3 between the serrated edge of the sawtooth wave of the front wall 4 of the cavity and the chord of the strut flame stabilizer is 30° to 50°, specifically 40° in this embodiment. The fillet radius R2 of the peak of the front wall 4 of the cavity is 13 to 18 mm, specifically 15 mm in this embodiment. The fillet radius of the valley of the front wall 4 of the cavity is 3 to 7 mm, specifically 5 mm in this embodiment. The distance L4 from the tangent point of the peak arc and the serrated edge of the front wall 4 of the cavity to the trailing edge of the strut flame stabilizer is 35 to 45 mm, specifically 37.2 mm in this embodiment. The amplitude L5 of the sawtooth wave of the rear wall 6 of the cavity is 9 to 15 mm, specifically 12 mm in this embodiment. The chordal distance L3 from the midline of the leading-edge sawtooth wave of the rear wall 6 of the cavity to the trailing edge of the strut flame stabilizer is 20 to 30 mm, specifically 22 mm in this embodiment. The fillet radii R1 of the peaks and valleys of the rear wall 6 of the cavity are 15 to 25 mm, specifically 18 mm in this embodiment.

[0029] The above-described embodiments are only the preferred embodiments of the present invention, rather than an exhaustive list of all feasible embodiments of the present invention. For those of ordinary skill in the art, any obvious changes made without departing from the principles and spirit of the present invention should be considered to be included within the protection scope of the claims of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the said claims.

Claims

1. A strut flame stabilizer with a combination of a vortex generator and a cavity, characterized in that The described strut flame stabilizer has a chord length of 90 - 150 mm, and the span length is determined by the specific engine; the strut flame stabilizer consists of a leading edge (1), a straight section (2), and a V-shaped bottom surface (3). The leading edge (1) is an elliptical surface, and the major axis dimension of the ellipse is 1.5 - 2.2 times the minor axis. The leading edge (1) is tangent and continuous with the straight section (2). The width of the straight section (2) is 24 - 36 mm, and the included angle of the V-shaped bottom surface (3) is 100° - 150°. On both side surfaces of the strut flame stabilizer, a structure in which a vortex generator composed of a cavity front wall (4), a cavity bottom wall (5), a cavity rear wall (6), and a vortex generator inclined surface (7) is combined with the cavity is arranged. The cross-section of the cavity is trapezoidal. The cavity front wall (4) is perpendicular to the cavity bottom wall (5), and the included angle between the cavity rear wall (6) and the cavity bottom wall (5) is 140° - 160°. The cavity bottom wall (5) is parallel to the surface of the straight section (2) and is 5 - 7 mm away from the surface of the straight section (2). The vortex generator inclined surface (7) starts to incline outward from the surface of the straight section (2) at the tangent point of the wave crest arc and the serrated edge of the cavity front wall (4), enclosing a wedge-shaped vortex generator shape with the cavity front wall (4). The highest point of the vortex generator inclined surface (7) protrudes 4 - 7 mm from the surface of the straight section (2). In the top view direction, the cavity front wall (4) and the cavity rear wall (6) are wavy, with 3 - 5 wavelengths, starting and ending at the wave crest positions. The wavy shape is obtained by rounding the corners at the wave crests and troughs of the serrated wave. The included angle between the serrated edge of the serrated wave of the cavity front wall (4) and the chord direction of the strut flame stabilizer is 30° - 50°. The fillet radius of the wave crest of the cavity front wall (4) is 13 - 18 mm, the fillet radius of the wave trough of the cavity front wall (4) is 3 - 7 mm, the distance from the tangent point of the wave crest arc and the serrated edge of the cavity front wall (4) to the trailing edge of the strut flame stabilizer is 35 - 45 mm, the amplitude of the serrated wave of the cavity rear wall (6) is 9 - 15 mm, the chordwise distance from the midline of the leading-edge serrated wave of the cavity rear wall (6) to the trailing edge of the strut flame stabilizer is 20 - 30 mm, and the fillet radii of the wave crest and wave trough of the cavity rear wall (6) are both 15 - 25 mm.

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