Integrated afterburner method based on high ejection velocity fan nozzle

Abstract

The application discloses an integrated afterburning scheme based on a high-ejection-speed fan-shaped nozzle and belongs to the field of aero-engine combustion.The high-ejection-speed fan-shaped nozzle is used to spray fuel into an afterburning chamber in a fan-shaped oil mist surface shape along a branch plate in a radial direction, so that the radial space uniformity of fuel behind the branch plate is improved.A large-area flame surface profile is formed behind the branch plate, a larger physical space is provided for chemical reaction, and the fuel particles are rapidly combusted, so that higher combustion efficiency is obtained.The high-ejection-speed fan-shaped nozzle is applied to the combustion scheme on both sides of an integrated branch plate flame stabilizer.Under the premise that the branch plate blockage ratio is not changed, new flow loss is not introduced, and the overall performance in a non-afterburning state is not reduced, the combustion efficiency of the integrated afterburning chamber is improved by improving a fuel supply strategy from the perspective of organizing combustion, so the application has great application prospect.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine combustion and relates to a combustion organization technology for integrated afterburners, which enhances the combustion chemical reaction in the afterburner. Background Technology

[0002] Afterburners, due to their excellent thrust output characteristics, are employed by most fighter jets to ensure high maneuverability during takeoff, climb, pursuit, and acceleration. Therefore, developing advanced afterburner technology is crucial. Traditional afterburners use direct-injection nozzles, which, due to their small atomization angle (generally less than 5 degrees), struggle to diffuse fuel in the typical flow field where axial and circumferential velocities are much greater than in the afterburner. This results in poor fuel uniformity in the fuel space behind the struts, leading to decreased combustion efficiency. To improve radial uniformity of fuel in the strut direction, the number of nozzles is typically increased radially. However, while maintaining the same nozzle diameter, doubling the number of direct-injection nozzles significantly reduces the fuel injection velocity because the fuel flow rate remains constant. This results in shallower fuel penetration, making it difficult for residual oxygen between the struts to fully participate in the combustion reaction. This effectively reduces the total amount of oxygen in the chemical reaction, ultimately leading to lower combustion efficiency.

[0003] Enhancing combustion efficiency in afterburners through the design of novel support plate structures is a key research focus in the field of afterburner combustion. The support plate-type flame stabilizer invented by Yan Yingwen's team [patent application number: CN202110284718.8] enhances combustion by strengthening turbulent mixing without increasing the blockage ratio. However, the technologies of other teams [patent application numbers: CN202310407703.5, CN202310407720.9, CN202111019554.2] almost all involve adding various turbulence structures to both sides of the support plate. While these can stabilize the flame, since afterburners do not operate under full conditions, these turbulence structures will further increase the flow channel blockage ratio, and the various vortex structures generated will significantly increase flow losses in non-afterburner states. This combustion enhancement scheme, which sacrifices the overall thrust performance in non-afterburner states, is undesirable. Furthermore, the presence of turbulence devices may lead to oscillating combustion problems in the afterburner. Therefore… The development direction of the next generation of afterburners is to organize efficient combustion without changing the flow channel blockage ratio or introducing unnecessary non-afterburning flow losses. Summary of the Invention

[0004] This invention addresses the generally low combustion efficiency of new-generation integrated afterburners by proposing a high-injection-velocity fan-shaped nozzle structure for integrated afterburners. The aim is to improve the combustion efficiency of integrated afterburners by enhancing the mixing degree of fuel and mainstream combustion gases in the radial direction of the flame stabilizer, without changing the support plate blockage ratio or introducing additional flow losses in the non-afterburning state.

[0005] This invention is implemented as follows:

[0006] An integrated afterburner design based on a high-injection-velocity fan-shaped nozzle is characterized by comprising a support plate flame stabilizer, an afterburner housing, and an afterburner center cone. For the integrated afterburner, considering the nozzle's thermal protection, the injector rod and nozzle need to be installed inside the support plate. The nozzle is mounted on the injector rod. Traditional afterburners use direct-injection nozzles, resulting in a small atomization cone angle for the injected fuel. This makes it difficult for the fuel to diffuse spatially in the high-speed flow field of the afterburner, leading to uneven distribution of fuel droplets behind the support plate, particularly noticeable in the radial direction of the support plate. Due to the concentrated fuel, the chemical reaction behind the support plate only occurs in the concentrated fuel area, resulting in a small chemical reaction flame area.

[0007] The high-injection-speed fan-shaped nozzle invented in this paper modifies the nozzle's orifice structure. After passing through the fan-shaped nozzle, the fuel forms a radially distributed oil mist field with a large fan angle. This high-injection-speed fan-shaped nozzle's fuel droplet spatial trajectory increases the uniformity of fuel droplet space in the radial direction of the support plate. Because the fuel vapor is widely distributed along the radial direction of the support plate, the area of ​​the chemical reaction flame surface (the flame surface outline of the assembled high-injection-speed fan-shaped nozzle) formed radially behind the support plate is large. This is equivalent to increasing the flame surface area, which further promotes fuel atomization and evaporation, enabling rapid fuel evaporation and combustion. Therefore, using a fan-shaped nozzle can achieve higher combustion efficiency.

[0008] Unlike existing designs that open nozzles on the side of a cylinder (patent application numbers: CN201810219294.5; CN201810219559.1), in order to achieve the fuel atomization effect of a high-injection-speed fan-shaped nozzle, the nozzle of this invention adopts a diamond-shaped nozzle design, with the flow area gradually increasing along the nozzle injection direction, that is, the two diagonals of the diamond gradually increase along the injection direction.

[0009] The maximum major axis of the rhombus at the nozzle outlet is defined as L, the maximum minor axis as W, the minimum major axis as l, and the minimum minor axis as w. The maximum and minimum major axes determine the atomization sector angle α. The major axis direction must align with the radial direction of the support plate, while the minor axis aligns perpendicularly to the support plate. Considering atomization performance parameters such as penetration depth, injection velocity, and atomization sector angle, the following relationships must be satisfied for each dimension:

[0010] 5 mm > L > 2 W

[0011] 3 mm > W > 0.6 mm

[0012] 1.5 mm > l > 2w

[0013] 1 mm > w > 0.2 mm

[0014]

[0015] Furthermore, unlike ordinary fan-shaped nozzle structures, the oil mist fan-shaped zone formed by the fan-shaped nozzle with a diamond-shaped nozzle of this invention has a larger oil mist mass flow rate and momentum in the middle region (region 2). This part of the fuel has a deeper penetration depth and can be sprayed into the middle region between the two support plates, where it is fully mixed with oxygen for combustion, increasing the total amount of oxygen participating in combustion and thus improving combustion efficiency. The regions on both sides of the oil mist fan-shaped zone (regions 1 and 3) expand along the radial direction of the support plates, increasing the uniformity of the spatial distribution of fuel droplets in the radial direction of the support plates, thereby increasing the flame surface area behind the support plates, and thus achieving higher combustion efficiency.

[0016] The advantages of this invention over the prior art are as follows:

[0017] 1) The integrated afterburning method based on a high-injection-velocity fan-shaped nozzle invented in this invention improves the combustion efficiency of the integrated afterburning chamber by improving the fuel supply strategy, without changing the blockage ratio of the support plate or introducing new flow losses.

[0018] 2) The high-injection-speed fan-shaped nozzle with a diamond-shaped nozzle of the present invention has a high momentum zone and a low momentum zone for the atomized fuel, which are responsible for supplying fuel to the area between the two support plates and the radial rear of the support plates, respectively. While ensuring good penetration depth, it can improve the uniformity of fuel space in the radial direction of the support plates and greatly improve the uniformity of fuel space behind the afterburner.

[0019] 3) The nozzle of the integrated afterburner is installed inside the support plate, and fuel is injected from the bottom of the nozzle. Traditional fan-shaped nozzles have a connected nozzle structure on the side and bottom. Due to the adhesive effect of the solid wall on the fuel, fuel accumulates and drips from the nozzle outlet during actual operation. If used directly in an afterburner, this can cause fuel to drip inside the flame stabilizer of the support plate, easily leading to detonation and other phenomena. The high-injection-velocity fan-shaped nozzle of this invention has a diamond-shaped nozzle located at the bottom of the nozzle. Under the action of liquid pressure energy and the airflow around the nozzle, the fuel is directly injected into the afterburner at high speed, avoiding fuel dripping inside the support plate. Attached Figure Description

[0020] Figure 1 This is a simplified structural diagram of an integrated afterburner.

[0021] Figure 2 It is a spatial trajectory diagram of fuel droplets from a direct-fire nozzle;

[0022] Figure 3 This is a spatial trajectory diagram of fuel droplets from a high-injection-velocity fan-shaped nozzle;

[0023] Figure 4 It is a cloud map of the spatial distribution of fuel vapor and the outline of the flame surface when the direct-injection nozzle is installed.

[0024] Figure 5 It is a cloud map of the spatial distribution of fuel vapor and the outline of the flame surface when equipped with a high-injection-speed fan-shaped nozzle.

[0025] Figure 6 It includes the diamond-shaped nozzle size parameters of the high-speed fan nozzle and the actual spatial distribution of droplets in the oil mist field;

[0026] Figure 7 This is an enlarged view of the spatial position of the assembly of the high-speed fan-shaped nozzle and the support plate;

[0027] Among them, 1-Afterburner inlet, 2-Integrated support plate flame stabilizer, 3-Afterburner casing, 4-Center cone, 5-Injection rod, 601-Direct injection nozzle, 602-High injection speed fan nozzle, 701-Fuel droplet spatial trajectory of direct injection nozzle, 702-Fuel droplet spatial trajectory of high injection speed fan nozzle, 801-Flame surface profile of direct injection nozzle, 802-Flame surface profile of high injection speed fan nozzle, L-Maximum major axis of rhombic nozzle, W-Maximum minor axis of rhombic nozzle, l-Minimum major axis of rhombic nozzle, w-Minimum minor axis of rhombic nozzle, α-Fuel mist fan angle. Detailed Implementation

[0028] To make the objectives and effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It should be noted that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0029] Figure 1 This is a simplified schematic diagram of the integrated afterburner structure of a turbofan aircraft engine, showing only the fan-shaped structure at a 120° circumferential angle. The main exhaust gas flows downstream along the incoming flow direction 001, passing sequentially through the afterburner inlet 1 and the integrated support plate flame stabilizer 2. The outer boundary of the airflow is the afterburner casing 3, and the inner boundary is the afterburner center cone 4.

[0030] Figure 2 The integrated flame stabilizer 2 and direct-injection nozzle 601, as shown, form a fuel space trajectory – the fuel droplet space trajectory 701 of the direct-injection nozzle. Because the direct-injection nozzle has a small atomization angle and the axial velocity of the afterburner chamber is much greater than the radial and circumferential velocities, the fuel has difficulty spreading radially along the stabilizer. Figure 4 As can be seen from the spatial distribution of fuel vapor in the direct-injection nozzle and the flame profile 801 of the direct-injection nozzle, the uniformity of the fuel vapor space in the radial direction behind the integrated support plate flame stabilizer 2 is poor. Therefore, the flame profile formed behind the support plate - the flame profile 801 of the direct-injection nozzle is relatively dispersed and the flame area is small.

[0031] like Figure 3 As shown, the afterburner of this invention integrates the integrated support plate flame stabilizer 2 and the nozzle into a single design. The nozzle is a high-speed fan-shaped nozzle 602, which is installed inside the integrated support plate flame stabilizer 2. The high-speed fan-shaped nozzle 602 adopts a diamond-shaped nozzle design, and the flow area gradually increases along the nozzle spray direction, that is, the two diagonals of the diamond gradually increase along the spray direction.

[0032] Figure 3 As can be seen from the spatial trajectory of fuel droplets ejected by the medium-high injection speed fan nozzle, i.e. the spatial trajectory of fuel droplets of the high injection speed fan nozzle 702, since the fan nozzle injects fuel radially into the mainstream in the shape of a fan-shaped oil mist surface, the atomization characteristics of the fan nozzle improve the radial spatial uniformity of the fuel droplets.

[0033] from Figure 5The fuel vapor space distribution cloud map and flame surface profile of the high injection speed fan nozzle show that the fuel space uniformity in the radial direction behind the integrated support plate flame stabilizer 2 is good. Therefore, the flame surface profile 802 of the assembled high injection speed fan nozzle formed in the radial direction behind the support plate is larger, providing a larger physical space for chemical reaction. At the same time, the larger flame surface further promotes fuel atomization and evaporation, accelerates the rapid combustion of fuel particles, and thus obtains higher combustion efficiency.

[0034] from Figure 6 Based on the dimensions of the rhomboid nozzle orifice and the actual spatial distribution of the oil mist field of the high-injection-speed fan-shaped nozzle, it is known that to achieve the fuel atomization effect of the high-injection-speed fan-shaped nozzle, the nozzle adopts a rhomboid nozzle design, with the flow area gradually increasing along the nozzle injection direction; that is, the two diagonals of the rhombus gradually increase along the injection direction. Let L be the maximum major axis of the rhombus at the nozzle outlet, W be the maximum minor axis, l be the minimum major axis, and w be the minimum minor axis. The maximum and minimum major axes determine the size of the atomization fan angle α. Simultaneously, the major axis direction must be arranged radially along the support plate, while the minor axis is arranged perpendicularly to the support plate. Considering atomization performance parameters such as penetration depth, injection speed, and atomization fan angle, the following relationships must be satisfied for each dimension:

[0035] 5 mm > L > 2 W

[0036] 3 mm > W > 0.6 mm

[0037] 1.5 mm > l > 2w

[0038] 1 mm > w > 0.2 mm

[0039]

[0040] Unlike ordinary fan-shaped nozzle structures, the fan-shaped nozzle with a diamond-shaped nozzle invented in this paper creates an oil mist fan-shaped zone. The central region (Region 2) has a larger oil mist mass flow rate and momentum, resulting in deeper fuel penetration. This allows fuel particles to be delivered to the area between the two support plates, where they are fully mixed with the mainstream oxygen for combustion, increasing the total amount of oxygen involved in combustion and thus improving combustion efficiency. The regions on both sides of the oil mist fan-shaped zone (Regions 1 and 3) expand radially along the support plates, increasing the uniformity of fuel spatial distribution in the radial direction and thus increasing the flame surface area behind the support plates, resulting in higher combustion efficiency.

[0041] from Figure 7 As can be seen from the enlarged view of the spatial position of the fan-shaped nozzle and the support plate, the diamond-shaped nozzle of the high-injection-speed fan-shaped nozzle of the present invention is located at the bottom of the nozzle. Under the action of liquid pressure energy and the airflow around the nozzle, the fuel will be directly injected into the afterburner at high speed, avoiding the situation where the fuel drips into the inside of the support plate.

[0042] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. An integrated afterburning method based on a high-velocity fan-shaped nozzle, characterized in that, The afterburner integrates the integrated support plate flame stabilizer (2) and the nozzle into one design. The nozzle is a high-speed fan nozzle (602), which is installed inside the integrated support plate flame stabilizer (2). The high-speed fan-shaped nozzle (602) adopts a diamond-shaped nozzle design, and the flow area gradually increases along the nozzle spray direction, that is, the two diagonals of the diamond gradually increase along the spray direction. Define the maximum major axis of the rhombus at the nozzle outlet as L, the maximum minor axis as W, the minimum major axis as l, and the minimum minor axis as w. The maximum and minimum major axes determine the atomization fan angle α. The major axis is arranged radially along the support plate, while the minor axis is arranged perpendicularly to the support plate. All dimensions must satisfy the following relationships: 5 mm > L > 2W 3 mm > W > 0.6 mm 1.5 mm > l > 2w 1 mm > w > 0.2 mm; The high-injection-speed fan-shaped nozzle (602) injects fuel into the main airflow channel of the afterburner in the shape of a fan-shaped fuel mist, and improves the radial uniformity of the fuel behind the support plate by utilizing the atomization characteristics of the nozzle. The high injection speed fan nozzle (602) modifies the nozzle orifice structure so that after the fuel passes through the fan nozzle, it forms a fuel droplet spatial trajectory (702) with a large fan angle in the radial direction of the high injection speed fan nozzle, thereby increasing the uniformity of fuel droplet space in the radial direction of the support plate. The high-speed fan nozzle (602) adopts a diamond-shaped nozzle design to form the middle area of ​​the oil mist fan area, and the areas on both sides of the oil mist fan area expand along the radial direction of the support plate.

2. The integrated afterburning method based on a high-velocity fan-shaped nozzle according to claim 1, characterized in that, High-speed fan-shaped nozzles (602) are placed on both sides of the integrated support plate flame stabilizer (2).

3. The integrated afterburning method based on a high-velocity fan-shaped nozzle according to claim 1, characterized in that, The diamond-shaped nozzle is located at the bottom of the high-velocity fan-shaped nozzle (602).

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