Combustion chamber wall surface structure for inhibiting oblique detonation wave induced boundary layer separation

Abstract

The invention discloses a combustion chamber wall surface structure for inhibiting oblique detonation wave induced boundary layer separation, which comprises a plurality of columns of induction units arranged on an oblique wall at a top inflection point of an engine combustion chamber, and the plurality of columns of induction units are arranged on an oblique surface of the oblique wall along the length direction of the oblique wall; each row of induction units comprises a plurality of scale reflecting plates which are arranged side by side in the width direction of the inclined wall, each scale reflecting plate is in a table shape and is provided with a lower bottom surface, an upper bottom surface and an inclined side surface, the included angle between each inclined side surface and the lower bottom surface is an obtuse angle, and the inclined side surface on one side of each scale reflecting plate is fixed to the inclined wall; the multiple columns of induction units are divided into odd columns of induction units and even columns of induction units, and the scale reflecting plates in the odd columns of induction units and the scale reflecting plates in the even columns of induction units are arranged in a staggered mode; a plurality of rows of induction units are additionally arranged on the smooth wall face of the combustion chamber to form a fish scale type induction structure, and expansion waves formed by the fish scale type induction structure are used for continuously weakening and restraining boundary layer separation.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, specifically to a combustion chamber wall structure that suppresses boundary layer separation induced by oblique detonation waves. Background Technology

[0002] The structure of a traditional oblique detonation engine is as follows: Figure 1 As shown, it mainly consists of a hollow, integrated intake section W1, a combustion chamber section W2, and a tailpipe section W3. The end of the combustion chamber section W2 is equipped with a detonation wedge N, and an inflection point M is formed at the connection between the upper wall of the combustion chamber section W2 and the tailpipe section W3. The working principle of the oblique detonation engine is as follows: the supersonic airflow is compressed through the intake section W1 and mixes with the fuel inside the combustion chamber section W2. This mixture impacts the detonation wedge N, forming an oblique detonation wave. The oblique detonation wave extends obliquely upwards from the detonation wedge N to the upper wall of the combustion chamber W2.

[0003] Because the combustion chamber walls of traditional oblique detonation engines are typically designed with smooth surfaces, oblique detonation waves are highly susceptible to reflection and instability on the upper wall. A traditional solution is to design the detonation wave to strike at or behind the inflection point M, utilizing expansion waves to weaken the reflection instability. There is a strong expansion fan at the inflection point M; if the detonation wave strikes precisely at this point, it effectively suppresses reflection instability. However, due to the instability of the incoming flow, it is difficult to achieve a precise strike at the inflection point M. If the detonation wave strikes after the inflection point M, it can induce new boundary layer separation after M, leading to detonation wave instability, congestion, decreased engine performance, and even stall. Summary of the Invention

[0004] The purpose of this invention is to provide a combustion chamber wall structure that suppresses boundary layer separation induced by oblique detonation waves, so as to solve the problem that existing technologies using expansion waves to weaken the instability of detonation wave reflection can easily induce the formation of new boundary layer separation.

[0005] The technical solution of this invention is: A combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves includes multiple rows of induction units for installation on the oblique wall at the top inflection point of the engine combustion chamber. The multiple rows of induction units are arranged along the length of the oblique wall. Each row of induction units includes multiple scale reflectors arranged side by side along the width of the oblique wall. The scale reflectors are platform-shaped and have a lower bottom surface, an upper bottom surface, and an inclined side surface. The angle between the inclined side surface and the lower bottom surface is an obtuse angle. One inclined side surface of each scale reflector is fixed to the oblique wall. The multiple rows of induction units are divided into odd-numbered rows of induction units and even-numbered rows of induction units. The scale reflectors in the odd-numbered rows of induction units and the scale reflectors in the even-numbered rows of induction units are staggered. The scale reflectors in the lower rows of two adjacent rows of scale reflectors shield the area of ​​the scale reflectors in the upper rows that is close to the oblique wall.

[0006] Preferably, as a further improvement of the present invention, the obtuse angle is 120°~150°.

[0007] Preferably, as a further improvement of the present invention, both the lower and upper bottom surfaces are circular, and the radius of the upper bottom surface is R. The upper bottom surfaces of the two adjacent rows of scale reflectors located below will block the lower bottom surfaces of the scale reflectors located above, and the length L of the blocking area is equal to the radius R of the upper bottom surface.

[0008] Preferably, as a further improvement of the present invention, both the lower bottom surface and the upper bottom surface are elliptical, and the minor axis of the ellipse is arranged along the length direction of the inclined wall. The minor axis diameter of the upper bottom surface is B. The upper bottom surface of the two adjacent columns of scale reflectors located below will block the lower bottom surface of the scale reflectors located above, and the length L of the blocking area is equal to the minor axis diameter B of the upper bottom surface.

[0009] Preferably, as a further improvement of the present invention, the thickness of the scale reflector is 2mm to 5mm.

[0010] Preferably, as a further improvement of the present invention, the material of the scale reflector is a high-temperature resistant alloy or a high-temperature resistant ceramic matrix composite material.

[0011] Preferably, as a further improvement of the present invention, the scale reflector is integrally processed with the inclined wall.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. Multiple rows of induction units are added to the smooth inclined wall of the original combustion chamber. Each row of induction units includes multiple scale reflectors arranged side by side along the width of the inclined wall. The scale reflectors in the odd-numbered rows of induction units are staggered with those in the even-numbered rows of induction units, thus forming a fish-scale induction structure. This creates a reflective wall surface with a fish-scale induction structure. The bottom surface and inclined side surface of the scale reflectors can induce the formation of expansion waves. One scale reflector induces one expansion fan. The expansion waves at the edge of the fish-scale induction structure continuously weaken and suppress the boundary layer.

[0013] 2. Traditional oblique detonation engines require the oblique detonation wave to hit the inflection point exactly, which is difficult to achieve in a real flight environment. The combustion chamber wall structure designed in this invention only requires the oblique detonation wave to hit the wall surface with the scale reflector plate area, which reduces the usage restrictions. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of an existing oblique detonation engine.

[0015] Figure 2This is a bottom view schematic diagram of a combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves according to the present invention.

[0016] Figure 3 This is a schematic cross-sectional view of a combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves according to the present invention.

[0017] Figure 4 This is a schematic diagram of the shape of a scale reflector in a combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves, according to the present invention.

[0018] Figure 5 This is a schematic diagram of the shape of another scale reflector in a combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves according to the present invention.

[0019] Figure 6 This is a schematic diagram of the fluid computation domain of a combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves, according to the present invention.

[0020] Figure 7 This is a cross-sectional view of the numerical simulation physical model of a combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves according to the present invention.

[0021] Figure 8 The temperature contour map is a numerical simulation result of the combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation wave according to the present invention. Detailed Implementation

[0022] The following is combined with Figures 2-8 The specific embodiments of the present invention will be described in detail below. In the description of the invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0023] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of the invention, unless otherwise stated, "a plurality of" means two or more.

[0024] Example like Figures 2-5As shown, this embodiment of the invention provides a combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves. It includes multiple rows of induction units, which are installed on an oblique wall 1 at the top inflection point of the engine combustion chamber. These induction units are arranged along the length of the oblique wall 1 on its inclined surface. Each row of induction units includes multiple scale reflectors 2 arranged side-by-side along the width of the oblique wall 1. Each scale reflector 2 is platform-shaped, having a lower bottom surface 201, an upper bottom surface 202, and an inclined side surface 203. The angle between the inclined side surface 203 and the lower bottom surface 201 is obtuse. One inclined side surface 203 of each scale reflector 2 is fixed to the oblique wall 1. The multiple rows of induction units are divided into odd-numbered rows of induction units 21 and even-numbered rows of induction units 22. The scale reflectors 2 in the odd-numbered rows of induction units 21 and the scale reflectors 2 in the even-numbered rows of induction units 22 are staggered. The scale reflectors 2 in the lower rows of adjacent rows shield the area of ​​the scale reflectors 2 in the upper rows that is close to the oblique wall 1.

[0025] In this embodiment, Figure 1 Multiple rows of induction units are added to the inclined wall 1 at the inflection point of the area enclosed by the rectangular frame. Each row of induction units includes multiple scale reflectors 2 arranged side by side along the width direction of the inclined wall 1. The scale reflectors 2 in the odd-numbered rows of induction units 21 and the scale reflectors 2 in the even-numbered rows of induction units 22 are staggered to form a fish-scale induction structure. Since the bottom surface 201 and the inclined side surface 203 of the scale reflectors 2 in the fish-scale induction structure are set at obtuse angles, they can induce the formation of expansion waves. Each scale reflector 2 induces an expansion fan. The expansion waves at the edge of the fish-scale induction structure continuously weaken and suppress the boundary layer.

[0026] The obtuse angle is 120°~150°. If the angle is too small (close to 90 degrees), the expansion wave will be too strong and a backflow zone will be formed on the rear side of the inclined side 203 of the scale reflector 2. If the angle is too large (close to 180 degrees), the expansion wave will be too weak and will not have a suppression effect. Therefore, an expansion wave of moderate intensity can be formed within this range.

[0027] Furthermore, such as Figure 4 As shown, both the lower bottom surface 201 and the upper bottom surface 202 are circular, and the radius of the upper bottom surface 202 is R. The upper bottom surface 202 of the two adjacent rows of scale reflectors 2 located below will block the lower bottom surface 201 of the scale reflector 2 located above, and the length L of the blocked area is equal to the radius R of the upper bottom surface 202.

[0028] Furthermore, such as Figure 5As shown, both the lower bottom surface 201 and the upper bottom surface 202 are elliptical, and the minor axis of the ellipse is arranged along the length of the inclined wall 1. The minor axis diameter of the upper bottom surface 202 is B. The upper bottom surface 202 of the two adjacent rows of scale reflectors 2 located below will block the lower bottom surface 201 of the scale reflector 2 located above, and the length L of the blocked area is equal to the minor axis diameter B of the upper bottom surface 202.

[0029] The thickness of the scale reflector 2 is 2mm to 5mm, depending on the size of the engine combustion chamber.

[0030] Furthermore, in order to adapt to high-temperature environments, the material of the scale reflector 2 is a high-temperature resistant alloy or a high-temperature resistant ceramic matrix composite material.

[0031] Furthermore, to ensure strength, the scale reflector 2 is integrally machined with the inclined wall 1 and the entire combustion chamber wall.

[0032] In another embodiment of the present invention, to verify the effect of the expansion wave induced by the fish-scale induced structure on the suppression of boundary layer separation, a simplified model is used for verification. Taking a scale reflector 2 with both the lower bottom surface 201 and the upper bottom surface 202 being circular as an example, the radius R of the lower bottom surface 201 of the scale reflector 2 is set to 10 mm, the thickness of the scale reflector 2 is 3 mm, and the obtuse angle is 148°. The following is selected... Figure 6 The area within the black wireframe is designated as the fluid computation domain. Figure 7 This is a cross-sectional view of the physical model for numerical simulation. The calculation model is for the detonation section and does not include structures such as fuel injection. Figure 7 The left side is the inlet, and the incoming flow is a supersonic hydrogen-air mixture. Figure 7 The right side is the combustion chamber outlet. Figure 7 The bottom right is the detonation wedge surface. Figure 7 The upper right image shows the combustion chamber wall with scale-like reflector plate 2, where the oblique detonation wave will be reflected. For example... Figure 8 The figure shows the flow field temperature cloud map obtained under the numerical simulation. It can be seen from the figure that the oblique detonation wave propagates and extends to the upper wall of the combustion chamber after being triggered by the detonation wedge. It is then reflected at the combustion chamber wall with scale reflector 2 and interacts with the boundary layer. However, the oblique detonation wave does not induce boundary layer separation with the boundary layer of the combustion chamber wall with scale reflector 2. This phenomenon is the result of the expansion wave induced by the obtuse angle of scale reflector 2.

[0033] The above-disclosed embodiments are merely preferred embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves, characterized in that, include: Multiple rows of induction units are used to be installed on the inclined wall (1) at the top inflection point of the engine combustion chamber. The multiple rows of induction units are arranged along the length of the inclined wall (1) on the inclined surface of the inclined wall (1). Each row of induction units includes multiple scale reflectors (2) arranged side by side along the width of the inclined wall (1). The scale reflectors (2) are platform-shaped and have a lower bottom surface (201), an upper bottom surface (202) and an inclined side surface (203). The included angle between the inclined side surface (203) and the lower bottom surface (201) is... The angle is obtuse. One side (203) of each scale reflector (2) is fixed to the inclined wall (1). The multi-column induction unit is divided into odd-column induction unit (21) and even-column induction unit (22). The scale reflectors (2) in the odd-column induction unit (21) and the scale reflectors (2) in the even-column induction unit (22) are arranged alternately. The scale reflectors (2) in the lower two adjacent columns will block the area of ​​the scale reflector (2) in the upper column that is close to the inclined wall (1).

2. The combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves according to claim 1, characterized in that, The obtuse angle is 120°~150°.

3. The combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves according to claim 1, characterized in that, Both the lower bottom surface (201) and the upper bottom surface (202) are circular, and the radius of the upper bottom surface (202) is R. The upper bottom surface (202) of the two adjacent columns of scale reflectors (2) located below will cover the lower bottom surface (201) of the scale reflectors (2) located above, and the length L of the covered area is equal to the radius R of the upper bottom surface (202).

4. The combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves according to claim 1, characterized in that, Both the lower bottom surface (201) and the upper bottom surface (202) are elliptical, and the minor axis of the ellipse is arranged along the length of the inclined wall (1). The minor axis diameter of the upper bottom surface (202) is B. The upper bottom surface (202) of the two adjacent columns of scale reflectors (2) located below will cover the lower bottom surface (201) of the scale reflectors (2) located above, and the length L of the covered area is equal to the minor axis diameter B of the upper bottom surface (202).

5. The combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves according to claim 1, characterized in that, The thickness of the scale reflector (2) is 2mm to 5mm.

6. The combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves according to claim 1, characterized in that, The material of the scale reflector (2) is a high-temperature resistant alloy or a high-temperature resistant ceramic matrix composite material.

7. The combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves according to any one of claims 1 to 6, characterized in that, The scale reflector (2) is integrally processed with the inclined wall (1).

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