A cavity flame stabilizer with a raised fuel jet on the front slope of the cavity

Abstract

The present invention relates to a cavity flame stabilizer with a raised fuel jet on the front ramp of the cavity. The cavity flame stabilizer is composed of a rearward step and a forward step. The leading edge of the cavity flame stabilizer is chamfered, and a pair of ramps is arranged on the chamfered surface corresponding to each pair of fuel jet holes. The advantages and beneficial results obtained by the present invention are as follows: When the cavity flame stabilizer with a raised fuel jet on the front ramp of the cavity is adopted in a scramjet combustion chamber, it can increase the fuel penetration depth, promote fuel-air mixing, and improve the combustion efficiency.

Description

Technical Field

[0001] The present invention relates to a cavity flame stabilizer with a ramp on the front slope of the cavity to elevate the fuel jet, which can be used in the combustion chamber of a scramjet engine and belongs to the field of aviation technology. Background Art

[0002] A scramjet engine is an ideal power plant for hypersonic aircraft. In the combustion chamber of a scramjet engine, the air flow moves at supersonic speed, and the residence time of the fuel in the combustion chamber is only on the order of milliseconds. By using a flame stabilization device to establish a recirculation zone in the combustion chamber, the flow velocity in the recirculation zone is reduced, and the residence time of the fuel-air mixture in the combustion chamber is increased. In this way, the flame can stay in the recirculation zone and serve as a fire source to maintain the continuous existence and propagation of the flame throughout the combustion chamber.

[0003] As the most widely used flame stabilization device at present, the performance of the cavity flame stabilizer has been widely recognized. Structurally, it consists of a forward step and a backward step. In the combustion chamber, when the high-speed air flow passes through the cavity flame stabilizer, a recirculation zone is formed in the cavity flame stabilizer. Since the flow velocity in the cavity flame stabilizer is relatively low, a free shear layer is formed between the mainstream and the recirculation zone. The gas flow structure in the cavity flame stabilizer can also induce acoustic disturbances, which can enhance the fuel-air mixing together with the large-scale structures shed from the trailing edge of the cavity flame stabilizer. Although the cavity flame stabilizer has no physical intrusion structure, it is easy to cause the fuel to accumulate in the wall shear layer, resulting in a large wall heat flux. Summary of the Invention

[0004] The purpose of the present invention is to provide a cavity flame stabilizer with a ramp on the front slope of the cavity to elevate the fuel jet. The cavity is beveled at the front edge, and a ramp is arranged on the beveled surface to increase the fuel penetration depth, shorten the complete combustion distance of the combustion chamber, expand the combustion area downstream of the combustion chamber, significantly increase the combustion efficiency, and reduce the total pressure loss.

[0005] The present invention is realized by the following technical solutions.

[0006] A cavity flame stabilizer with a ramp on the front slope of the cavity to elevate the fuel jet, the front edge of the cavity flame stabilizer is beveled, and a pair of ramps are arranged on the beveled surface corresponding to each pair of fuel nozzles.

[0007] Further, the concave cavity flame stabilizer is connected to the lower wall surface of the ram combustion chamber at the leading edge and the trailing edge. Its width is determined by the specific engine. It mainly consists of a forward step and a backward step, and can be subdivided into a leading edge, a front wall, a bottom wall, a rear wall, a trailing edge, and a fuel nozzle. The front wall is perpendicular to the bottom wall. The height of the front wall is 35 - 65 mm, the length of the bottom wall is 140 - 180 mm, the height of the rear wall is 20 - 50 mm, and the included angle between the rear wall and the bottom wall is 30° - 70°. A fuel nozzle is arranged upstream of the leading edge. The diameter of the fuel nozzle is 2 - 5 mm, the distance between the fuel nozzle and the leading edge is 5 - 50 mm, and the spacing between adjacent fuel nozzles is 10 - 40 mm.

[0008] Further, the leading edge of the concave cavity flame stabilizer is beveled. The starting position of the bevel is 10 - 50 mm away from the leading edge, and the bevel angle is 10° - 30°.

[0009] Further, the ramp is in the shape of a trapezoidal wedge. The leading edge of the ramp coincides with the starting position of the bevel. The width of the leading edge of the ramp is 15 - 28 mm. The plane of the tail of the ramp coincides with the plane where the front wall is located. The width of the tail of the ramp is 4 - 15 mm. The height of the tail of the ramp is 10 - 25 mm. The included angle between the inner side surface of each pair of ramps and the leading edge of the ramp is 75° - 85°. The included angle between the outer side surface of each pair of ramps and the leading edge of the ramp is 65° - 80°. The spacing between the leading edges of each pair of ramps is 0 - 10 mm.

[0010] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0011] First, it increases the fuel penetration depth. First, the ramp raises the fuel nozzle; second, beveling the leading edge of the concave cavity reduces the scale of the recirculation vortex in the concave cavity, weakens the entrainment and induction effect of the recirculation vortex on the fuel jet, thereby increasing the penetration depth of the fuel jet itself; the superposition of the two increases the fuel penetration depth.

[0012] Second, it promotes fuel-air mixing. The increase in fuel penetration depth positions the fuel jet in the middle of the combustion chamber away from the wall surface, preventing the fuel from being drawn into the concave cavity and forming an accumulation. The fuel jet can mix with sufficient air from all around, and the streamwise vortices generated behind the ramp are also conducive to strengthening fuel-air mixing. Therefore, beveling the leading edge of the concave cavity and arranging a ramp to raise the fuel nozzle can effectively promote fuel-air mixing.

[0013] Third, it improves the combustion efficiency. Beveling the leading edge of the concave cavity and arranging a ramp to raise the fuel nozzle increases the fuel penetration depth and promotes fuel-air mixing, thereby significantly improving the combustion efficiency of the scramjet combustion chamber. Description of the Drawings

[0014] Figure 1 It is an isometric view of a conventional concave cavity flame stabilizer.

[0015] Figure 2Isometric view of the cavity flame stabilizer with the front ramp of the cavity raising the fuel jet in the present invention.

[0016] Figure 3 Side view of the cavity flame stabilizer with the front ramp of the cavity raising the fuel jet in the present invention.

[0017] Figure 4 Top view of the cavity flame stabilizer with the front ramp of the cavity raising the fuel jet in the present invention.

[0018] Figure 5 Front view of the cavity flame stabilizer with the front ramp of the cavity raising the fuel jet in the present invention.

[0019] Figure 6 Rear view of the cavity flame stabilizer with the front ramp of the cavity raising the fuel jet in the present invention.

[0020] Figure 7 C2H4 component distribution of the cross-section of the combustion chamber of the cavity flame stabilizer with the front ramp of the cavity raising the fuel jet in the present invention.

[0021] Figure 8 Temperature distribution of the combustion chamber of the cavity flame stabilizer with the front ramp of the cavity raising the fuel jet in the present invention.

[0022] Figure 9 C2H4 component distribution of the cross-section of the combustion chamber of the cavity flame stabilizer with a conventional cavity in the present invention.

[0023] Figure 10 Temperature distribution of the cross-section of the combustion chamber of the cavity flame stabilizer with a conventional cavity in the present invention.

[0024] Figure 11 Local streamline diagram of the combustion chamber of the cavity flame stabilizer with the front ramp of the cavity raising the fuel jet in the present invention.

[0025] In the drawings, 1 is the leading edge; 2 is the front wall; 3 is the bottom wall; 4 is the rear wall; 5 is the trailing edge; 6 is the ramp, 7 is the fuel nozzle, and 8 is the lower wall surface of the ramjet combustion chamber.

[0026] Among them, L1 is the length of the bottom wall; L2 is the width of the cavity flame stabilizer; L3 is the distance from the fuel nozzle to the leading edge; L4 is the spacing between adjacent fuel nozzles; H1 is the height of the front wall; H2 is the height of the rear wall; H3 is the height of the ramp tail; α1 is the angle between the rear wall and the bottom wall; α2 is the bevel angle; α3 is the angle between the inner side of the ramp and the leading edge of the ramp; α4 is the angle between the outer side of the ramp and the leading edge of the ramp; D is the diameter of the fuel nozzle; S1 is the distance from the bevel starting position to the leading edge; S2 is the width of the ramp leading edge; S3 is the width of the ramp tail; S4 is the distance between the ramp leading edges. Detailed implementation mode

[0027] The present invention will be further described in detail below in conjunction with the Figures 1 to 6 drawings and embodiments.

[0028] A cavity flame stabilizer with a raised fuel jet on the front ramp of the cavity has its leading edge 1 of the cavity flame stabilizer chamfered, and a pair of ramps 6 are arranged on the chamfered surface corresponding to each pair of fuel nozzles 7.

[0029] As a further improvement of the embodiment of the present invention, the cavity flame stabilizer is connected to the lower wall surface 8 of the ram combustion chamber at the leading edge 1 and the trailing edge 5. The width L2 is determined by the specific engine. In this embodiment, it is specifically 75 mm. It mainly consists of a forward step and a backward step, and can be subdivided into a leading edge 1, a front wall 2, a bottom wall 3, a rear wall 4, a trailing edge 5, and a fuel nozzle 7. The front wall 2 is perpendicular to the bottom wall 3. The height H1 of the front wall 2 is 35 - 65 mm, specifically 50.5 mm in this embodiment. The length L1 of the bottom wall 3 is 140 - 180 mm, specifically 163.2 mm in this embodiment. The height H2 of the rear wall 4 is 20 - 50 mm, specifically 34 mm in this embodiment. The included angle α1 between the rear wall 4 and the bottom wall 3 is 30° - 70°, specifically 45° in this embodiment. Fuel nozzles 7 are arranged upstream of the leading edge 1. The diameter D of the fuel nozzle 7 is 2 - 5 mm, specifically 3.4 mm in this embodiment. The distance L3 between the fuel nozzle 7 and the leading edge 1 is 5 - 50 mm, specifically 10 mm in this embodiment. The spacing L4 between adjacent fuel nozzles 7 is 10 - 40 mm, specifically 25 mm in this embodiment, so that a pair of fuel nozzles 7 are arranged in this embodiment.

[0030] As a further improvement of the embodiment of the present invention, the chamfering at the leading edge of the cavity flame stabilizer starts at a position with a distance S1 from the leading edge 1 of 10 - 50 mm, specifically 30 mm in this embodiment, and the chamfering angle α2 is 10° - 30°, specifically 15° in this embodiment.

[0031] As a further improvement of the embodiment of the present invention, the ramp 6 is in the shape of a trapezoidal wedge. The leading edge of the ramp 6 coincides with the starting position of the chamfering. The width S2 of the leading edge of the ramp 6 is 15 - 28 mm, specifically 17.5 mm in this embodiment. The plane of the tail of the ramp 6 coincides with the plane of the front wall 2. The width S3 of the tail of the ramp 6 is 4 - 15 mm, specifically 11.3 mm in this embodiment. The height H3 of the tail of the ramp 6 is 10 - 25 mm, specifically 18 mm in this embodiment. In this embodiment, a pair of ramps 6 are arranged corresponding to a pair of fuel nozzles 7. The included angle α3 between the inner side surface of each pair of ramps 6 and the leading edge of the ramp 6 is 75° - 85°, specifically 80° in this embodiment. The included angle α4 between the outer side surface of each pair of ramps 6 and the leading edge of the ramp 6 is 65° - 80°, specifically 70° in this embodiment. The spacing S4 between the leading edges of each pair of ramps 6 is 0 - 10 mm, and in this case it is 4 mm.

[0032] The above-described embodiments are only the preferred embodiments of the present invention, rather than an exhaustive list of all possible implementations of the present invention. For those of ordinary skill in the art, any obvious modifications made without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the said claims.

Claims

1. A cavity flame stabilizer that raises the fuel jet by padding the front slope of the cavity, characterized in that, Bevel the leading edge (1) of the cavity flame holder, and arrange a pair of ramps (6) on the beveled surface corresponding to each pair of fuel nozzles (7); The width of the described cavity flame holder is determined by the specific engine, and it includes a leading edge (1), a front wall (2), a bottom wall (3), a rear wall (4), a trailing edge (5) and fuel nozzles (7). The leading edge (1), the front wall (2) and the bottom wall (3) form a forward step, and the bottom wall (3), the rear wall (4) and the trailing edge (5) form a backward step. The leading edge (1) and the trailing edge (5) are connected to the lower wall surface (8) of the ram combustion chamber. The front wall (2) is perpendicular to the bottom wall (3). The height of the front wall (2) is 35 - 65 mm, the length of the bottom wall (3) is 140 - 180 mm, the height of the rear wall (4) is 20 - 50 mm, the included angle between the rear wall (4) and the bottom wall (3) is 30° - 70°. Fuel nozzles (7) are arranged upstream of the leading edge (1). The diameter of the fuel nozzles (7) is 2 - 5 mm, the distance between the fuel nozzles (7) and the leading edge (1) is 5 - 50 mm, and the spacing between adjacent fuel nozzles (7) is 10 - 40 mm; For the described beveling at the leading edge of the cavity flame holder, the starting position of the beveling is 10 - 50 mm away from the leading edge (1), and the beveling angle is 10° - 30°; The described ramp (6) is a trapezoidal wedge. The leading edge of the ramp (6) coincides with the starting position of the beveling. The width of the leading edge of the ramp (6) is 15 - 28 mm. The plane of the tail of the ramp (6) coincides with the plane where the front wall (2) is located. The width of the tail of the ramp (6) is 4 - 15 mm, and the height of the tail of the ramp (6) is 10 - 25 mm. The included angle between the inner side surface of each pair of ramps (6) and the leading edge of the ramp (6) is 75° - 85°, the included angle between the outer side surface of each pair of ramps (6) and the leading edge of the ramp (6) is 65° - 80°, and the spacing between the leading edges of each pair of ramps (6) is 0 - 10 mm.

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