A pre-chamber head structure of a strong radial diffusion combustion chamber based on a progressive eccentric intake

Abstract

The application relates to a precombustion head structure of a strong radial diffusion type combustion chamber based on a progressive eccentric air inlet, and relates to the technical field of combustion chambers. The precombustion head structure comprises a swirl cup and an eccentric air inlet type precombustion chamber; one end of the swirl cup is sleeved on a pressure swirl type fuel atomizing nozzle, and the other end extends to an inlet of the eccentric air inlet type precombustion chamber; the eccentric air inlet type precombustion chamber comprises a 45-degree expansion section and a precombustion chamber straight section; the precombustion chamber straight section is connected to one end of the 45-degree expansion section away from the swirl cup; and three-stage eccentric air inlet holes are arranged on the 45-degree expansion section. The precombustion head structure has the characteristics of strong radial diffusion, can fully exchange heat and mass with a discrete main combustion stage head arranged around the precombustion head structure, and thus easily ignites the main combustion stage and assists the main combustion stage to stably combust in a lean oil state.

Description

Technical Field

[0001] This invention relates to the field of combustion chamber technology, specifically to a pre-combustion stage head structure for a strong radial diffusion combustion chamber based on progressive eccentric air intake. Background Technology

[0002] Most existing aero-engine combustor head structure designs adopt a centrally staged head structure, characterized by:

[0003] 1. It is circular in shape overall;

[0004] 2. The pre-combustion stage is located in the center and occupies a large radial dimension, and usually adopts a swirl cup-Venturi type combustion organization mode;

[0005] 3. The main combustion stage surrounds the pre-combustion stage in a single / multi-stage axial / radial swirler structure. It occupies a small radial dimension and organizes combustion by setting multiple discrete transverse fuel injection holes in the swirler blade channels.

[0006] In this type of centrally staged combustion chamber head structure, because the pre-combustion stage occupies a large radial dimension, it does not require strong radial diffusion to easily ignite the main combustion stage.

[0007] In recent years, for heavy-duty gas turbines on land / ship, in order to reduce their NOx emissions... x To reduce emissions of pollutants such as soot, multi-nozzle lean combustion technology has been proposed and widely accepted. This multi-nozzle combustor head structure is characterized by: an overall shape that is not strictly limited and can be adjusted according to the number and arrangement of nozzles; and main combustion stages typically consisting of multiple independent heads, each organized for combustion and interconnected via a separate aerodynamic structure (such as a cyclone separator). Therefore, compared to a centrally staged combustor head structure, each main combustion stage in a multi-nozzle combustor head structure occupies a larger area, resulting in lower area utilization. Due to these characteristics of the main combustion stages, the pre-combustion stage head in a multi-nozzle combustor head structure occupies a much smaller area than in a centrally staged combustor head structure. Given the smaller area of ​​the pre-combustion stage itself, achieving good interconnection (heat and mass transfer) between the pre- and main combustion stages, enabling the pre-combustion stage to easily ignite the main combustion stage and assist in stabilizing the flame, requires higher standards for the pre-combustion stage's combustion organization structure layout and radial diffusion.

[0008] Therefore, how to provide a pre-combustion stage head structure for a strong radial diffusion combustor based on progressive eccentric air intake has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a pre-combustion stage head structure of a strong radial diffusion combustor based on progressive eccentric air intake. It has the characteristics of strong radial diffusion and can fully transfer heat and mass with the discrete main combustion stage head arranged around it, thereby easily igniting the main combustion stage and assisting the main combustion stage in stable combustion under lean fuel conditions.

[0010] To achieve the above objectives, the present invention provides a pre-combustion stage head structure of a strong radial diffusion combustor based on progressive eccentric air intake, comprising: a swirl cup and an eccentric air intake pre-combustion chamber;

[0011] One end of the swirl cup is fitted onto the pressure swirl fuel atomizing nozzle, and the other end extends to the inlet of the eccentric air intake pre-combustion chamber.

[0012] The eccentric air intake pre-combustion chamber includes a 45° expansion section and a straight section of the pre-combustion chamber; the straight section of the pre-combustion chamber is connected to the end of the 45° expansion section away from the swirl cup; and the 45° expansion section is provided with three-stage eccentric air intake holes.

[0013] Furthermore, the three-stage eccentric air intake is arranged in three rows along the axial direction. The radius of the inlet of each row of eccentric air intakes expands gradually and the expansion range is consistent. The distance between each row is consistent, and the diameter and length of each eccentric air intake are consistent.

[0014] Furthermore, the diameter of the eccentric air intake is d=2mm, and the eccentricity is e=12mm~23mm.

[0015] Furthermore, the straight section of the pre-combustion chamber has multiple cooling holes evenly distributed around its circumference.

[0016] Furthermore, the swirl cup includes an inner swirl blade, an inner venturi tube, an outer swirl blade, and an outer venturi tube; the inner swirl blade surrounds the circumference of the pressure swirl fuel atomizing nozzle, the inner venturi tube is sleeved on the inner swirl blade, and a gap is provided between the inner swirl blade and the inner swirl blade; the outer swirl blade is connected to the end of the inner venturi tube away from the inner swirl blade, one end of the outer venturi tube is sleeved on the inner venturi tube, and the other end extends to the inlet of the eccentric intake pre-combustion chamber.

[0017] Furthermore, the rotation direction of the outer swirl blade is consistent with the rotation direction of the three-stage eccentric air inlet, and opposite to the rotation direction of the inner swirl blade.

[0018] Furthermore, it also includes a swirl cup fixing cover plate, which is fixedly installed at the end of the eccentric intake pre-combustion chamber by screws.

[0019] Furthermore, an oil circuit adapter is installed at the end of the pressure swirl fuel atomizing nozzle away from the swirl cup.

[0020] The beneficial effects of this invention are as follows:

[0021] This invention features a swirl cup and an eccentric intake pre-combustion chamber, which has strong radial diffusion characteristics. By setting three-stage eccentric intake holes on the 45° expansion section, it can fully transfer heat and mass with the discrete main combustion stage head arranged around it, thereby easily igniting the main combustion stage and assisting the main combustion stage in stable combustion under lean conditions. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 for Figure 1 BB section view;

[0024] Figure 3 This is a schematic diagram of the eccentric air inlet of the present invention;

[0025] Figure 4 This is a schematic diagram of the flow field simulation results of the present invention.

[0026] 1. Eccentric intake pre-combustion chamber; 1-1. 45° expansion section; 1-2. Straight section of pre-combustion chamber; 1-3. Three-stage progressive eccentric intake port; 1-4. Cooling holes on the pre-combustion chamber wall; 2. Swirl cup; 2-1. Inner swirling blade; 2-2. Inner venturi tube; 2-3. Outer swirling blade; 2-4. Outer venturi tube; 3. Pressure swirling fuel atomizing nozzle; 4. Fuel circuit adapter; 5. Swirl cup fixing cover; 6. Screws. Detailed Implementation

[0027] To achieve the above objectives and effects, the technical means and structure adopted by the present invention will be described in detail with reference to the accompanying drawings, focusing on the features and functions of the preferred embodiments of the present invention.

[0028] like Figures 1-3 As shown, the present invention provides a pre-combustion stage head structure of a strong radial diffusion combustor based on progressive eccentric air intake, comprising: a swirl cup 2 and an eccentric air intake pre-combustion chamber 1;

[0029] One end of the swirl cup 2 is fitted onto the pressure swirl fuel atomizing nozzle 3, and the other end extends to the inlet of the eccentric air intake pre-combustion chamber 1.

[0030] The main function of the eccentric inlet pre-combustion chamber 1 is to further organize the flow field following the swirl cup 2. Combined with the three-stage progressive eccentric inlet holes 1-3, this allows for strong radial diffusion of the airflow at the pre-combustion chamber outlet, thereby enabling better heat and mass exchange with the main combustion stage and assisting in the ignition and stable combustion of the main combustion stage. The eccentric inlet pre-combustion chamber 1 includes a 45° expansion section 1-1 and a straight pre-combustion chamber section 1-2. The straight pre-combustion chamber section 1-2 is connected to the end of the 45° expansion section 1-1 furthest from the swirl cup 2. The 45° expansion section 1-1 expands radially from the outlet of the swirl cup 2 along a 45° angle generatrix, and then maintains its inner diameter while connecting to the straight pre-combustion chamber section 1-2. The 45° expansion section 1-1 is provided with three-stage eccentric inlet holes. Multiple pre-combustion chamber wall cooling holes 1-4 are evenly distributed circumferentially on the straight pre-combustion chamber section 1-2. The function of the pressure swirl fuel atomizing nozzle 3 is to achieve initial fuel atomization by using the fuel supply differential pressure, and to form a hollow cone-shaped oil mist distribution at the outlet. At the end of the hollow oil mist cone, the fuel is fully atomized under the action of oil pressure and enters the shearing zone of the inner and outer two-stage counter-swirling air, where it is further atomized by the shearing action.

[0031] The air intake at the head of the pre-combustion stage is divided into two parts. One part passes through the dual-stage counter-rotating axial swirl cup 2, and the other part enters the combustion zone of the pre-combustion stage through the three-stage progressive eccentric air intake holes 1-3 to participate in combustion. The air volume distribution ratio between the swirl cup 2 and the three-stage eccentric air intake holes is approximately 2:3 in this embodiment. This ratio can be adjusted appropriately according to different engineering requirements.

[0032] In this embodiment, the three-stage eccentric air inlet is arranged in three rows along the axial direction. The radius (about the axis) at the inlet of each row of eccentric air inlets expands progressively, and the expansion range is consistent. The distance between each row is consistent, and the diameter and length (wall thickness of the drilled portion) of each eccentric air inlet are consistent. The diameter of the eccentric air inlet is d=2mm, and the eccentricity is between e=12mm and 23mm.

[0033] The 45° expansion section 1-1 is the main body of the flow channel profile organization at the outlet of the swirl cup 2. Its functions are twofold: first, to provide suitable engineering space for the setting of the three-stage eccentric air inlets, allowing the inlet radius of the three-stage eccentric air inlets to continuously increase, thus achieving the goal of continuously increasing the tangential velocity of the flow with the radius; second, to deprive the expansion structure of the angular vortex backflow space at the outlet of the swirl cup 2, which is beneficial for suppressing flame oscillation. The function of the straight section 1-2 of the pre-combustion chamber is to isolate the combustion zone at the flame root of the pre-combustion stage from the cold air entering before the main combustion stage is activated, providing a relatively independent space for the combustion at the flame root of the pre-combustion stage, so that it is not affected by the unburned air of the main combustion stage during ignition, preventing the pre-combustion stage flame from being blown out by the cold air of the main combustion stage. The function of the cooling holes 1-4 on the wall of the pre-combustion chamber is to distribute a small amount of air to uniformly cover and cool the wall of the straight section 1-2 of the pre-combustion chamber, while ensuring that the opening direction is roughly the same as the local airflow direction, so as not to interfere with the main flow field structure.

[0034] The function of the swirl cup 2 is to create a small core recirculation zone inside the pre-combustion chamber, which is used to organize the pre-combustion stage ignition and stabilize the flame at the outlet of the swirl cup 2 and inside the pre-combustion chamber, providing a strong flame root for the secondary expansion flame structure of the pre-combustion stage. The swirl cup 2 includes an inner swirl blade 2-1, an inner venturi tube 2-2, an outer swirl blade 2-3, and an outer venturi tube 2-4; the inner swirl blade 2-1 surrounds the circumference of the pressure swirl fuel atomizing nozzle 3, the inner venturi tube 2-2 is sleeved on the inner swirl blade 2-1, and a gap is provided between the inner swirl blade 2-1 and the inner swirl blade 2-2; the outer swirl blade 2-3 is connected to the end of the inner venturi tube 2-2 away from the inner swirl blade 2-1, and one end of the outer venturi tube 2-4 is sleeved on the inner venturi tube 2-2, and the other end extends to the inlet of the eccentric intake pre-combustion chamber 1. In this invention, the swirl direction of the inner swirling blade 2-1 is opposite to that of the mainstream swirling direction in the flow structure, thereby creating a swirling airflow in this part of the intake. This swirling airflow forms a reverse shearing action with the swirling airflow at the outlet of the outer swirling blade 2-3 in the tangential direction, causing the oil mist particles in the shearing zone to be rapidly broken up by tangential deformation and further atomized. The inner venturi tube 2-2, in conjunction with the inner swirling blade 2-1, applies a flow channel contraction effect to the swirling airflow at the outlet of the inner swirling channel. According to the principles of conservation of momentum and angular momentum, the axial velocity and tangential velocity of this part of the airflow will increase significantly. Then, at the outlet of the inner venturi tube 2-2, it encounters a sudden expansion of the flow channel. The strongly swirling airflow, no longer restricted by the wall, will expand outward because the centripetal force is less than the centrifugal force, resulting in violent shearing and mixing with the outer swirling airflow. The rotation direction of the outer swirl blades 2-3 is consistent with that of the third-stage eccentric air inlet, and opposite to that of the inner swirl blades 2-1. The air intake volume of the outer swirl channel is greater than that of the inner swirl channel. This portion of the air volume is the main part used to create the core recirculation zone at the root of the flame inside the pre-combustion chamber. It also has the function of creating a shear zone by rotating in the opposite direction to the inner swirl air to promote fuel atomization. The outer Venturi tube 2-4 is the main body of the flow channel profile of the entire vortex cup 2. Together with the outer vortex blade 2-3, it organizes the generation of the recirculation zone flow field in a vortex-contraction-expansion structure according to the principles of momentum conservation and angular momentum conservation. Due to the centripetal force required for the swirling flow, a pressure gradient is formed pointing towards the center of rotation, making the center of rotation also a negative pressure center. In the expansion section, the airflow expands due to the centrifugal force of the vortex. When it expands to a certain radial position, the centripetal attraction provided by the negative pressure center exceeds the centrifugal force at this time. Therefore, while flowing axially downstream, it turns back radially upward towards the center of rotation, thus presenting a recirculation as a whole. The recirculation zone used to stabilize the flame is thus generated.

[0035] The fuel atomization section is designed with a standardized pressure swirl fuel atomizing nozzle 3 and a two-stage counter-rotating axial swirler, located at the center of the swirl cup 2. The atomization principle is that the hollow cone-shaped initial fuel mist generated by the pressure centrifugal nozzle, in this embodiment, is positioned so that it precisely enters the confluence of two opposing airflows at the outlet of the inner and outer swirl channels. The two airflows undergo intense shearing and mixing in the tangential direction, further breaking down the entrained fuel mist and achieving complete atomization.

[0036] The present invention also includes a swirl cup fixing cover plate 5, which is fixedly installed at the end of the eccentric air intake pre-combustion chamber 1 by screws 6. The swirl cup fixing cover plate binds and positions the swirl cup 2 to the eccentric air intake pre-combustion chamber 1 by screws 6, while providing a certain amount of floating in the radial direction for the installation of the swirl cup 2.

[0037] In this embodiment, an oil circuit adapter 4 is installed at the end of the pressure swirl fuel atomizing nozzle 3 away from the swirl cup 2. The function of the oil circuit adapter 4 is to connect and seal the oil circuit with the pressure swirl fuel atomizing nozzle 3, and at the same time help position the nozzle with other parts of the experimental piece.

[0038] The design concept and working principle of this invention are as follows:

[0039] ① First, a small-sized, low-volume swirl cup is used to create a small-sized recirculation zone in the pre-combustion chamber, so that the pre-combustion stage flame can be ignited and burn stably in the pre-combustion chamber without being disturbed by the main combustion stage airflow.

[0040] ② Because the reflux zone created by the swirl cup closes too early (i.e., the bottom dead center of the reflux zone is too close to the upstream), the radial diffusion of the pre-combustion stage flow field at the pre-combustion chamber outlet is poor, and it cannot effectively exchange heat and mass with the main combustion stage combustion zone to assist the main combustion stage in ignition and flame stabilization.

[0041] ③ Therefore, a three-stage eccentric air inlet structure with a large air volume is set in the 45° expansion section after the swirl cup. The air inlet direction of the eccentric air inlet is as parallel as possible to the airflow direction at the outlet of the swirl cup. This achieves the effect of not disturbing the flow structure of the small recirculation zone inside the pre-combustion chamber, while wrapping the outside of the small recirculation zone flow with three layers of stronger (and progressively stronger) swirling flow (see the angular momentum formula for the principle).

[0042] ④ Within a very short axial distance within the pre-combustion chamber, the aforementioned small recirculation zone and the three external rotating wakes cannot achieve complete mixing. Therefore, the boundaries between the airflow layers at the pre-combustion chamber outlet remain relatively distinct, manifested in a step-like abrupt change in tangential velocity along the radial direction. The effect of this phenomenon is that at the pre-combustion chamber outlet, the outer layer of strong swirling wakes suddenly loses the reaction pressure constraint from the inner wall of the pre-combustion chamber. The centripetal force provided by the relatively weak swirling negative pressure center of the inner layer is less than the centrifugal force generated by the high-speed rotation of the outer layer, causing the outer airflow to be violently thrown towards the outer main combustion stage combustion zone at the pre-combustion chamber outlet.

[0043] ⑤ Furthermore, because the airflow layers at the pre-combustion chamber outlet are not uniformly mixed, the phenomenon described in ④ occurs in a layered manner at the pre-combustion chamber outlet. The centrifugal force experienced by the airflow in different layers is different, and their axial velocities are also different. Therefore, the flow trajectories after flowing out of the pre-combustion chamber and into the flame tube are also different. The outermost layer of airflow with the highest swirling intensity experiences the greatest centrifugal force and diffuses the fastest radially. The inner layer of swirling accompanying flow experiences less centrifugal force and diffuses more slowly radially. When it diffuses to the radial position where the centrifugal force and centripetal force are balanced, backflow begins, thus creating a larger-scale backflow zone with a weaker backflow intensity within the flame tube.

[0044] ⑥ The phenomena described in conclusion ⑤ above are all beneficial to combustion organization. Among them, the strong diffusion of the outer airflow helps the pre-combustion stage assist the main combustion stage in ignition and stable combustion. Creating a large-scale recirculation zone within the flame tube is beneficial to the macroscopic combustion organization of the combustion chamber and to the overall flame stability of the combustion chamber.

[0045] The geometric parameters of the eccentric air intake are shown in Table 1:

[0046]

[0047] Table 1

[0048] The geometric parameters of the swirl cup are shown in Table 2:

[0049]

[0050] Table 2

[0051] The geometric parameters of the eccentric intake pre-combustion chamber are shown in Table 3:

[0052]

[0053] Table 3

[0054] One-dimensional simplified analysis of the intake flow process:

[0055] 1) Basic assumptions:

[0056] ①Since the diameter of the eccentric air inlet is only d=2mm and the eccentricity is between 12mm and 23mm, it can be simplified to assume that the eccentricity at each point of the flow section of the eccentric air inlet is the same as the eccentricity at the axis of the hole.

[0057] ②The product of the momentum flux along the hole axis on the flow cross section of the eccentric air inlet and the eccentricity becomes part of the total flow angular momentum flux after air intake.

[0058] ③ In a flow section with a recirculation zone, the direction of the angular momentum flux of the flow is parallel to the axial direction. Its tangential velocity component shows a linear increase with the radius in a small radius range, while it is uniformly distributed in other radial positions.

[0059] ④ In the flow field created by the head structure of this pre-combustion stage and its downstream region, only the swirl cup and the eccentric air inlet are throttling sections, and the air pressure drop is 3% when flowing through the above two throttling sections.

[0060] 2) Conservation of angular momentum during the flow process:

[0061] The air intake of the pre-combustion stage head structure is mainly divided into two parts: the first is the air intake from the inner and outer axial cyclones at the cyclone cup inlet; the second is the air intake at the eccentric inlet holes with gradually increasing eccentricity in the three stages. The angular momentum flux brought by the air intake from the cyclone cup section is:

[0062]

[0063] The subscript 'inner' indicates an inner swirling flow channel, and the subscript 'outer' indicates an outer swirling flow channel. , , Let represent the air density, axial velocity component, and tangential velocity component at the radial position r on the upper part of the integral section, respectively. Here, it is assumed that the axial and tangential velocity vectors are equal on any ring surface of equal radius of the integral section under study. The subscript x represents the vortex cup part, and L is the symbol for angular momentum.

[0064] In the cross-section of the hydrocyclone blade passage, we can simplify by assuming that the tangential velocity at any position is the component of the through-hole velocity vector in the tangential direction. Then, the above equation can be quantitatively expressed as:

[0065]

[0066] Where Rii represents the inner radius of the inner swirling channel, Rio represents the outer radius of the inner swirling channel, Roi represents the inner radius of the outer swirling channel, and Roo represents the outer radius of the outer swirling channel. This indicates the angle between the internal swirling blades and the axis. This indicates the angle between the outer swirling blade and the axial direction.

[0067] Because the diameter of the eccentric air inlet is very small (2mm), it can be simplified by assuming that the eccentricity relative to the head axis of the pre-combustion stage is the same at all points within the flow section of each tangential inlet. During the process of external air flowing into the front end of the pre-combustion chamber through the eccentric air inlet, its flow momentum can be decomposed in both tangential and radial directions. The tangential portion is converted into angular momentum, and the radial portion is converted into a portion of the axial momentum of the mainstream air after merging with it. In this structure, the eccentric air inlet is divided into three stages, supplying air to the mainstream in stages, with a different eccentricity at each stage. The angular momentum flux brought by the partial intake of air through the eccentric air inlet is:

[0068]

[0069] Where k represents the stage number of the eccentric air intake, there are three stages in total; This represents the eccentricity of the k-th stage eccentric intake relative to the axis. For eccentric intakes of the same stage, their... All are the same; n represents the number of circumferentially equidistantly distributed eccentric air intakes in each stage; This represents the flow cross-sectional area of ​​a single eccentric air intake. The subscript T indicates the eccentric air intake portion.

[0070] Figure 4 The simulation results of the flow field under the pre-combustion stage head structure are shown, where the color scale represents the axial velocity distribution and the white solid line is the boundary of the recirculation zone.

[0071] This invention features a swirl cup and an eccentric intake pre-combustion chamber, which has strong radial diffusion characteristics. By setting three-stage eccentric intake holes on the 45° expansion section, it can fully transfer heat and mass with the discrete main combustion stage head arranged around it, thereby easily igniting the main combustion stage and assisting the main combustion stage in stable combustion under lean conditions.

[0072] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A pre-chamber head structure for a progressive eccentric intake based strong radial diffusion combustion chamber, characterized by, The utility model relates to a pressure swirl fuel atomizing nozzle with eccentric intake precombustion chamber and swirl cup, which comprises: a swirl cup and an eccentric intake precombustion chamber; one end of the swirl cup is sleeved on the pressure swirl fuel atomizing nozzle, and the other end extends to the inlet of the eccentric intake precombustion chamber; the eccentric intake precombustion chamber comprises a 45° expansion section and a precombustion chamber flat section; the precombustion chamber flat section is connected to one end of the 45° expansion section away from the swirl cup; the 45° expansion section is provided with three-stage eccentric intake holes; the three-stage eccentric intake holes are eccentric intake holes arranged in three rows along the axial direction; the radius at the inlet of each row of eccentric intake holes presents a step-by-step expansion, and the expansion amplitude is consistent; the distance between each row is consistent; the hole diameter of each eccentric intake hole is consistent, and the hole length is consistent; the hole diameter d of the eccentric intake hole is 2mm, and the eccentric distance e is 12mm-23mm; the swirl cup comprises inner swirl vanes, an inner venturi, outer swirl vanes, and an outer venturi; the inner swirl vanes are circumferentially arranged around the pressure swirl fuel atomizing nozzle; the inner venturi is sleeved on the inner swirl vanes, and a gap is arranged between the inner swirl vanes and the inner venturi; the outer swirl vanes are connected to one end of the inner venturi away from the inner swirl vanes; one end of the outer venturi is sleeved on the inner venturi, and the other end extends to the inlet of the eccentric intake precombustion chamber; the rotation direction of the outer swirl vanes is consistent with that of the three-stage eccentric intake holes and opposite to that of the inner swirl vanes; a swirl cup fixing cover plate is further included, which is fixedly installed on the end of the eccentric intake precombustion chamber by screws.

2. A pre-chamber head structure for a progressive eccentric intake based strong radial diffusion combustion chamber as claimed in claim 1, wherein, a plurality of precombustion chamber wall surface cooling holes are circumferentially arranged on the precombustion chamber flat section.

3. A pre-chamber head structure for a progressive eccentric intake based strong radial diffusion combustion chamber as claimed in claim 1, wherein an oil line adapter is installed on one end of the pressure swirl fuel atomizing nozzle away from the swirl cup.

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