A combustion chamber wall structure for suppressing oblique detonation wave-induced boundary layer separation

Abstract

The application discloses a combustion chamber wall surface structure for inhibiting oblique detonation wave-induced boundary layer separation, comprising multiple columns of induction units, which are arranged on an oblique wall at a top corner of an engine combustion chamber, and the multiple columns of induction units are arranged on the slope of the oblique wall along the length direction of the oblique wall, each column of induction units comprises multiple scale reflection plates arranged side by side along the width direction of the oblique wall, the scale reflection plate is in the shape of a platform body, has a lower bottom surface, an upper bottom surface and an inclined side surface, and the included angle between the inclined side surface and the lower bottom surface is an obtuse angle, one side of each scale reflection plate is fixed with the oblique wall, the multiple columns of induction units are divided into odd-numbered column induction units and even-numbered column induction units, the scale reflection plates in the odd-numbered column induction units and the scale reflection plates in the even-numbered column induction units are arranged alternately, and the smooth wall surface of the combustion chamber is additionally provided with the multiple columns of induction units to form a scale type induction structure, and the expansion wave formed by the scale type induction structure continuously weakens and inhibits the boundary layer separation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engine, and particularly relates to a combustion chamber wall structure for inhibiting oblique detonation wave-induced boundary layer separation. BACKGROUND

[0002] The traditional oblique detonation engine structure is shown in FIG. 1, which mainly comprises a hollow integrated air inlet channel section W1, a combustion chamber section W2 and a tail nozzle section W3, the combustion chamber section W2 is provided with an initiation wedge N at the end, and the upper wall of the combustion chamber section W2 and the tail nozzle section W3 form an inflection point M. Figure 1 The working principle of the oblique detonation engine is as follows: supersonic airflow passes through the air inlet channel section W1 to compress, mixes with the fuel in the combustion chamber section W2, and then impacts the initiation wedge N to form an oblique detonation wave, which extends obliquely upwards from the initiation wedge N to the upper wall of the combustion chamber W2.

[0003] Since the traditional oblique detonation engine combustion chamber wall is usually designed as a smooth wall, the oblique detonation wave is prone to reflection instability on the upper wall. The traditional solution is to let the oblique detonation wave hit the inflection point M or the rear of the inflection point M during design, and use the expansion wave to weaken the reflection instability of the oblique detonation wave. There is a very strong expansion fan at the inflection point M. If the oblique detonation wave hits the inflection point M, the reflection instability can be effectively inhibited. However, due to the instability of the incoming flow, it is difficult to achieve the oblique detonation wave hitting the inflection point M. If the oblique detonation wave hits the inflection point M, a new boundary layer separation will be induced at the rear of the inflection point M, which will cause the detonation wave to be unstable and choked, and the engine performance will be reduced, and even stall. SUMMARY

[0004] The present application aims to provide a combustion chamber wall structure for inhibiting oblique detonation wave-induced boundary layer separation, so as to solve the problem of easy induction of new boundary layer separation in the process of weakening detonation wave reflection instability by using expansion wave in the prior art.

[0005] The technical scheme of the present application is as follows:

[0006] A combustion chamber wall structure for inhibiting oblique detonation wave-induced boundary layer separation, comprising a plurality of induction units, which are arranged on the oblique wall at the inflection point of the top of the engine combustion chamber, and the plurality of induction units are arranged on the inclined surface of the oblique wall along the length direction of the oblique wall, each induction unit comprises a plurality of scale reflection plates arranged side by side along the width direction of the oblique wall, the scale reflection plate is in the shape of a platform, has a lower bottom surface, an upper bottom surface and an inclined side surface, and the included angle between the inclined side surface and the lower bottom surface is obtuse, one side of each scale reflection plate is fixed to the oblique wall, the plurality of induction units are divided into odd-numbered induction units and even-numbered induction units, the scale reflection plates in the odd-numbered induction units and the scale reflection plates in the even-numbered induction units are arranged alternately, and the scale reflection plates in the adjacent two lower induction units shield the side region of the scale reflection plate in the upper induction unit close to the oblique wall.

[0007] Preferably, as a further improvement of the present application, the obtuse angle is 120°-150°.

[0008] Preferably, as a further improvement of the present application, the lower base and the upper base are both circular, the radius of the upper base is R, the upper base of the two adjacent rows of the lower fin reflector plates shields the lower base of the upper fin reflector plate, and the length L of the shielding area is equal to the radius R of the upper base.

[0009] Preferably, as a further improvement of the present application, the lower base and the upper base are both elliptical, the minor axis of the elliptical shape is arranged along the length direction of the inclined wall, the minor axis diameter of the upper base is B, the upper base of the two adjacent rows of the lower fin reflector plates shields the lower base of the upper fin reflector plate, and the length L of the shielding area is equal to the minor axis diameter B of the upper base.

[0010] Preferably, as a further improvement of the present application, the thickness of the fin reflector plate is 2mm-5mm.

[0011] Preferably, as a further improvement of the present application, the material of the fin reflector plate is high-temperature-resistant alloy or high-temperature-resistant ceramic matrix composite material.

[0012] Preferably, as a further improvement of the present application, the fin reflector plate is integrally processed with the inclined wall.

[0013] Compared with the prior art, the present application has the following beneficial effects:

[0014] 1. A plurality of induction units are additionally arranged on the smooth inclined wall of the original combustion chamber, each of the induction units includes a plurality of fin reflector plates arranged side by side along the width direction of the inclined wall, and the fin reflector plates in the odd-numbered induction units and the fin reflector plates in the even-numbered induction units are arranged alternately, thus forming a fish scale type induction structure, thereby forming a reflective wall surface with the fish scale type induction structure, the lower base and the inclined side of the fin reflector plate can induce the formation of expansion waves, one fin reflector plate induces one expansion fan, and the expansion waves at the edge of the fish scale type induction structure continuously weaken and suppress the boundary layer.

[0015] 2. The traditional oblique detonation engine requires that the oblique detonation wave hits the inflection point, which is difficult to achieve in the real flight environment. The combustion chamber wall structure designed in the present application only needs to hit the oblique detonation wave on the wall surface with the fin reflector plate, thereby reducing the use limitation condition. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 FIG. 1 is a structural schematic diagram of the prior art oblique detonation engine.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] Figure 6 This is a schematic diagram of the fluid computation domain for a combustion chamber wall structure that suppresses boundary layer separation induced by oblique detonation waves, according to the present invention.

[0022] 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.

[0023] Figure 8 This is a temperature contour map showing the numerical simulation results of a combustion chamber wall structure for suppressing boundary layer separation induced by oblique detonation waves, according to the present invention. Detailed Implementation

[0024] 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.

[0025] 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.

[0026] Example

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] The thickness of the scale reflector 2 is 2mm to 5mm, depending on the size of the engine combustion chamber.

[0033] 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.

[0034] Furthermore, to ensure strength, the scale reflector 2 is integrally machined with the inclined wall 1 and the entire combustion chamber wall.

[0035] 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 8 The upper right image shows the combustion chamber wall with scale-like reflectors 2, where the oblique detonation wave will be reflected. (Example:) ​ 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.

[0036] 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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