Improved structure of a heat shield of a tail nozzle of a wall-attached gas film hole type

Abstract

The application provides a structure of a tail nozzle heat shield of an improved wall-attached gas film hole type, which comprises a heat shield, a plurality of gas film cooling holes and an adjusting sheet wall surface, a cooling gas flow channel is formed between the heat shield and the adjusting sheet wall surface, the gas film cooling holes are discretely distributed on the heat shield wall surface, the heat shield comprises a convergent section heat shield and a divergent section heat shield; two sides of the gas film cooling hole are respectively a cooling gas flow inlet and a cooling gas flow outlet, the cooling gas flow inlet is communicated with the cooling gas flow channel, and the cooling gas flow outlet is expanded to the heat shield wall surface in the span direction. The improved plurality of wall-attached gas film holes generates a Coanda effect to realize the flow of the cooling gas adhering to the heat shield wall surface. The application improves the gas film cooling efficiency of the heat shield gas film cooling single hole, increases the original hole arrangement interval, reduces the cooling gas flow and saves the cooling gas consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engine thermal management, in particular, especially relates to a tail nozzle heat shield structure with improved wall-attached film hole type. BACKGROUND

[0002] In recent years, due to the improvement of thrust performance demand of supersonic aero-engine, the increase of engine inlet temperature makes the heat dissipation of components such as combustion chamber and tail nozzle which are directly contacted with high-temperature gas face greater thermal management problems. The tail nozzle is a device for expanding and accelerating high-temperature and high-pressure gas and discharging the machine body, converting the available heat energy of the gas into kinetic energy, providing vector thrust for the whole machine, and always facing complex working conditions such as high temperature, high pressure and large load variation range. At present, the tail nozzle device mainly applies film cooling technology of heat shield. The low-temperature and high-pressure cold gas generated by the compressor is covered on the heat shield through discrete film cooling holes arranged in a certain rule, so as to isolate the main flow from the nozzle wall and reduce the wall temperature.

[0003] The cylindrical hole is the most widely used hole type in the current aero-engine film cooling application, which has the advantages of easy processing and little influence on the overall structural strength. However, the cylindrical hole makes the cooling fluid quickly separate from the wall and interact with the main flow to form a kidney-shaped vortex, which will roll the high-temperature gas to the wall, and there is no spanwise expansion, so the film coverage and uniformity need to be improved. With the development of research in recent years and the continuous maturity of additive manufacturing, the design of various new hole types can improve the above-mentioned shortcomings of cylindrical holes to improve the film cooling efficiency, coverage and uniformity, reduce the cooling flow consumption and exhaust consumption, and improve the thrust. SUMMARY

[0004] According to the technical problems of heat shield cylindrical hole film cooling flow and heat transfer proposed above, a tail nozzle heat shield structure with improved wall-attached film hole type is provided.

[0005] The technical means adopted by the present application are as follows:

[0006] A tail nozzle heat shield structure with improved wall-attached film hole type, comprising: a heat shield, a plurality of film cooling holes and an adjusting sheet wall, the heat shield and the adjusting sheet wall form a cooling gas flow channel in the middle, the film cooling holes are discretely distributed on the heat shield wall, and the heat shield comprises a convergent section heat shield and a divergent section heat shield.

[0007] The two sides of the film cooling hole are cooling gas inlet and cooling gas outlet respectively, the cooling gas inlet is connected with the cooling gas flow channel, and the cooling gas outlet is spanwise expanded to the heat shield wall, and the film cooling hole (improved wall-attached film hole type) generates Coanda effect to realize the flow of cooling gas adhering to the heat shield wall.

[0008] Further, the gas film cooling hole comprises a circular arc segment and a cylindrical segment connected in sequence, the cylindrical segment is a cylindrical hole, the circular arc segment is extended in the spanwise direction based on one end of the cylindrical segment, the side of the circular arc segment is the cooling gas flow outlet, and the side of the cylindrical segment is the cooling gas flow inlet; the curved surface between the edge of the connection between the circular arc segment and the cylindrical segment and the lower circular arc edge of the expansion outlet is the arc back.

[0009] Further, the gas film cooling hole comprises a circular arc segment and a cylindrical segment connected in sequence, the cylindrical segment is a cylindrical hole, the circular arc segment is extended in the spanwise direction based on one end of the cylindrical segment, the side of the circular arc segment is the cooling gas flow outlet, and the side of the cylindrical segment is the cooling gas flow inlet; the curved surface between the edge of the connection between the circular arc segment and the cylindrical segment and the lower circular arc edge of the expansion outlet is the arc back.

[0010] Further, the gas film cooling hole comprises a circular arc segment and a cylindrical segment connected in sequence, the cylindrical segment is a cylindrical hole, the circular arc segment is extended in the spanwise direction based on one end of the cylindrical segment, the side of the circular arc segment is the cooling gas flow outlet, and the side of the cylindrical segment is the cooling gas flow inlet; the curved surface between the edge of the connection between the circular arc segment and the cylindrical segment and the lower circular arc edge of the expansion outlet is the arc back.

[0011] Further, the arc back is tangent to the heat shield wall surface and the cylindrical hole wall surface at the connection, or the arc back of one circular arc segment is tangent to the heat shield wall surface and the other circular arc segment at the connection.

[0012] Further, the cross section of the expansion outlet is in the shape of a trapezoid with the upper and lower edges being circular arcs, the lower edge circular arc is formed by the expansion of the cylindrical hole in the downstream and lateral directions, the upper edge circular arc is part of the cylindrical hole, and the two waists are tangent to the upper edge circular arc at the intersection.

[0013] Further, the total length lh of the gas film cooling hole is 0.2-3 mm, and the length l2 of the circular arc segment is 0.5-1 times the total length lh.

[0014] Further, the diameter dh of the cylindrical segment is 0.5-2 mm, the inclination angle a is 30-90 degrees, the expansion length l1 of the circular arc segment in the downstream direction is 0.5-1.5 times the diameter dh, and the expansion angle β is 30-60 degrees.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] 1. The improved tail nozzle heat shield structure with the improved wall-attached gas film hole type provided by the present application, the improved gas film cooling hole type structure makes the cooling gas more easily attached to the wall surface due to the Coanda effect, can effectively inhibit the formation of kidney-shaped vortexes, and improves the single-hole gas film cooling efficiency.

[0017] 2. The improved tail nozzle heat shield structure with the improved wall-attached gas film hole type provided by the present application, the spanwise expansion of the gas film cooling hole outlet improves the single-hole gas film cooling coverage, reduces the number of gas film hole arrangements, reduces the cooling flow consumption, saves the tail gas consumption, and improves the thrust of the tail nozzle.

[0018] 3. The improved structure of the heat shield of the wall-attached gas film hole type of the tail nozzle of the present application, compared with other outlet expansion hole type structures, retains more heat shield structures and removes less material, and has higher structural strength.

[0019] 4. The improved structure of the heat shield of the wall-attached gas film hole type of the tail nozzle of the present application can be processed on the basis of the original cylindrical hole designed heat shield to improve the heat shield gas film cooling structure of the existing cylindrical hole.

[0020] In summary, the technical solution of the present application can improve the cooling gas film and wall separation, kidney vortex formation, and gas film coverage and uniformity of the existing technology of the cylindrical gas film cooling hole of the heat shield gas film cooling.

[0021] Based on the above reasons, the present application can be widely popularized in the field of aero-engine thermal management technology. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0023] Figure 1 The structure of the present application is shown in the figure.

[0024] Figure 2 The improved wall-attached gas film hole type structure of the present application is shown in the figure.

[0025] Figure 3 The front view of the improved wall-attached gas film hole type structure of the present application is shown in the figure.

[0026] Figure 4 The top view of the improved wall-attached gas film hole type structure of the present application is shown in the figure.

[0027] Figure 5 A specific improved wall-attached gas film hole type structure of the present application is shown in the figure.

[0028] In the figure: 1, heat shield; 11, convergent section heat shield; 12, divergent section heat shield; 2, gas film cooling hole; 3, adjusting piece wall surface; 4, circular arc section; 41, arc back; 42, divergent outlet; 5, cylindrical section. DETAILED DESCRIPTION

[0029] It should be noted that the embodiments and features of the present application can be combined with each other, if there is no conflict. The present application will be described in detail below with reference to the drawings and embodiments.

[0030] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. The description of the at least one exemplary embodiment below is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0031] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0032] Unless specifically stated otherwise, the relative arrangement of components and steps, numerical expressions, and numerical values set forth in the various embodiments described herein are not limiting. It should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportions. The techniques, methods and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered as part of the authorized description. In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary, and not as a limitation. Therefore, other examples of exemplary embodiments can have different values. It should be noted that similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0033] In the description of the present application, it should be understood that the orientation words such as "front, back, upper, lower, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship are generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, without making the opposite statement, these orientation words do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the scope of protection of the present application: the orientation words "inner, outer" refer to the inner and outer relative to the contour of each component itself.

[0034] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper" and the like can be used herein to describe the spatial position relationship of one device or feature with other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawing is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0035] In addition, it should be noted that the use of "first", "second" and the like to define parts is only for the convenience of distinguishing the corresponding parts, and the above words have no special meaning unless otherwise stated, therefore it cannot be understood as a limitation on the scope of protection of the present application.

[0036] In view of the defects of the existing air engine nozzle thermal management film cooling technology, the present application provides an improved wall-attached film hole type nozzle heat shield structure and a new film wall-attached hole type applied to the heat shield, which is mainly used for making the cooling film adhere to the wall surface of the heat shield to flow, improving the cooling efficiency of single hole, thereby increasing the hole arrangement interval and reducing the cooling gas flow.

[0037] The application discloses a tail nozzle heat shield structure with improved gas film wall-attached hole type, which is applied to an aero-engine and comprises a tail nozzle heat shield 1, discrete gas film cooling holes 2 (circular arc gas film hole type structure) and a tail nozzle adjusting piece wall 3, wherein the heat shield 1 comprises a converging section heat shield 11 and a diverging section heat shield 12. The cooling gas flow channel is formed between the heat shield 1 wall and the adjusting piece wall 3. The gas film cooling holes 2 are regularly and discretely distributed on the heat shield 1 wall. The main body of the discrete gas film cooling hole 2 is divided into two parts, namely a circular arc section 4 and a cylindrical section 5. One side of the cylindrical section 5 is a cooling gas inlet, and one side of the circular arc section 4 is a cooling gas outlet. The circular arc section 4 comprises an arc back 41 and a diverging outlet 42. The arc back 41 is an arc-shaped curved surface connecting the inlet of the circular arc section 4 and the diverging outlet 42, and can generate a Coanda effect to realize the flow of the cooling gas film adhering to the heat shield 1 wall.

[0038] Preferably, the arc back 41 is tangent to the intersection of the heat shield 1 wall and the cylindrical section 5 hole wall, so that the gas flow adheres to the wall. The diverging outlet 42 of the circular arc section 4 hole is a trapezoid with upper and lower circular arcs, which expands to the downstream and both sides, and the two waists of the expanded trapezoid are tangent to the original cylindrical hole outlet. The upper edge (upper edge circular arc) of the trapezoid of the diverging outlet 42 is part of the original cylindrical hole outlet, and the lower edge is a circular arc formed after the circular hole extends backward by an extension length l1 (i.e. the lower edge circular arc is formed by the extension of the cylindrical hole to the downstream and transversely), and the two waists of the outlet trapezoid are tangent to the upper edge circular arc at the connection.

[0039] Preferably, the circular arc section 4 can continuously extend to the cooling gas inlet end of the cylindrical section 5, at this time, there is no cylindrical section 5, and the whole hole is the circular arc section 4, and the cooling gas inlet can adhere to the wall.

[0040] Preferably, the circular arc section 4 can also be applied to the cooling gas inlet end, so that the wall-attached cooling gas is more easily introduced into the gas film cooling hole. That is, the gas film cooling hole 2 comprises two connected circular arc sections 4, the two circular arc sections 4 are centrally symmetric, the first circular arc section 4 side is the diverging cooling gas outlet, and the second circular arc section 4 side is the diverging cooling gas inlet; the curved surface between the edge of the connection of the two circular arc sections 4 to the lower circular arc edge of the diverging outlet 42 (diverging inlet) is the arc back 41.

[0041] Preferably, the arc back 41 is tangent to the intersection of the edge of the connection of the cylindrical section 5 / circular arc section 4 and the lower edge circular arc of the diverging outlet 42.

[0042] Preferably, the total length of the gas film cooling hole 2 is lh, lh is 0.2-3 mm, and the length l2 of the circular arc section 4 is 0.5-1 times of lh.

[0043] Preferably, the diameter dh of the cylindrical section 5 is 0.5-2 mm, and the inclination angle a is 30°-90°. The extension length l1 of the circular arc section 4 to the downstream is 0.5-1.5 times of dh, and the extension angle b is 30°-60°.

[0044] The gas film cooling hole of the application makes the cooling gas film adhere to the heat shield wall flow, improves the heat shield gas film cooling single hole gas film cooling efficiency, thereby increases the original hole arrangement interval, reduces the cold gas flow, and saves the cold gas consumption. In addition, compared with other outlet expansion type hole structures, the improved gas film hole type structure retains more heat shield structure and removes less material, has higher structural strength, can be processed on the basis of the original cylindrical hole designed heat shield, and improves the cylindrical hole heat shield gas film cooling.

[0045] Embodiment 1

[0046] As shown in Figures 1-5 An improved gas film hole type nozzle heat shield structure for an aero-engine nozzle heat shield. The gas film cooling wall-attached hole type structure (gas film cooling hole 2) of the application for the aero-engine nozzle heat shield is regularly and discretely distributed on the wall surface of the heat shield 1. The gas film hole type structure (gas film cooling hole 2) includes a circular arc segment 4 and a cylindrical segment 5. The cylindrical segment 5 is a cylindrical hole, and the circular arc segment 4 is expanded in the span direction based on one end of the cylindrical segment 5. The circular arc segment 4 includes an arc back 41 and an expansion outlet 42. The curved surface between the edge of the connection between the circular arc segment 4 and the cylindrical segment 5 and the lower arc edge of the expansion outlet 42 is the arc back 41. The arc back 41 generates a conda effect to attach the cooling gas to the wall surface of the heat shield 1 and expand in the span direction, thereby expanding the cooling gas film coverage area. The cross-sectional shape of the expansion outlet 42 is a trapezoid with upper and lower edges being circular arcs.

[0047] In this embodiment, the diameter dh of the circular hole of the cylindrical segment 5 hole is 0.5-2mm, and the hole inclination angle α is 30°-90°, and in the illustration, it is 30°.

[0048] In this embodiment, the total length lh of the hole segment of the gas film cooling hole type structure is 0.5-3mm. The length l2 of the circular arc segment 4 is 0.5-1 times the total length lh. When l2=lh, the whole hole is a circular arc segment 4. The expansion length l1 is 0.5-1.5 times the length of the circular hole diameter dh.

[0049] In this embodiment, the expansion outlet 42 of the cooling hole is a trapezoid with upper and lower edges being circular arcs. The upper edge is part of the original cylindrical hole circular outlet. The lower edge is a circular arc formed by the circular hole extending backward by an expansion length l1, and the expansion angle β is 30°-60°.

[0050] In this embodiment, when the length l2 of the circular arc segment 41 is equal to the total length lh of the hole segment, and the circular arc segment is used at the inlet and outlet of the cooling gas, the inlet and outlet gas flow can adhere to the wall to improve the single hole gas film cooling efficiency.

[0051] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An improved tailpipe heat shield structure with an attached film gas orifice, characterized in that, include: The heat insulation screen (1), several air film cooling holes (2) and adjusting plate wall surface (3) form a cooling gas flow channel between the heat insulation screen (1) and the adjusting plate wall surface (3). The air film cooling holes (2) are discretely distributed on the wall surface of the heat insulation screen (1). The heat insulation screen (1) includes a shrinking section heat insulation screen (11) and an expanding section heat insulation screen (12). The two sides of the air film cooling hole (2) are the cooling air inlet and the cooling air outlet, respectively. The cooling air inlet is connected to the cooling gas flow channel, and the cooling air outlet extends longitudinally to the wall of the heat insulation screen (1). The air film cooling hole (2) generates the Coanda effect to realize the cooling gas adhering to the wall of the heat insulation screen (1) and flowing. The air film cooling hole (2) includes at least an arc segment (4) of the cooling airflow outlet. The arc segment (4) includes an arc back (41) and an expansion outlet (42). The arc back (41) is an arc-shaped curved surface connecting the inlet of the arc segment (4) and the expansion outlet (42), generating the Coanda effect to realize the cooling air film adhering to the wall of the heat insulation screen (1), suppressing the formation of kidney vortex, improving the single-hole air film cooling efficiency, increasing the hole arrangement interval, and reducing the cold air flow rate. The arc back (41) is tangent to the wall of the heat insulation screen (1) at the connection point; The cross-sectional shape of the expansion outlet (42) is a trapezoid with rounded upper and lower sides. The lower rounded side is formed by the cylindrical hole extending downstream and laterally, and the upper rounded side is part of the cylindrical hole. The two sides are tangent to the upper rounded side at the intersection.

2. The improved tail nozzle heat shield structure with attached film gas orifice type according to claim 1, characterized in that, The air film cooling hole (2) includes a connected arc segment (4) and a cylindrical segment (5). The cylindrical segment (5) is a cylindrical hole. The arc segment (4) extends longitudinally based on one end of the cylindrical segment (5). The side of the arc segment (4) is the cooling air outlet, and the side of the cylindrical segment (5) is the cooling air inlet. The curved surface between the edge of the arc segment (4) and the cylindrical segment (5) and the lower arc edge of the expansion outlet (42) is an arc back (41).

3. The improved tail nozzle heat shield structure with attached film gas orifice type according to claim 1, characterized in that, The air film cooling hole (2) includes two connected, centrally symmetrical arc segments (4). The first arc segment (4) has an expansion cooling airflow outlet on one side and an expansion cooling airflow inlet on the other side. The curved surface between the edge of the connection between the two arc segments (4) and the lower arc edge of the expansion outlet (42) is an arc back (41).

4. The improved tail nozzle heat shield structure with attached film gas orifice type according to claim 2, characterized in that, The arc back (41) is tangent to the wall surface of the cylindrical section (5) at the connection point.

5. The improved tail nozzle heat shield structure with attached film gas orifice type according to claim 3, characterized in that, The arc back (41) of one arc segment (4) is tangent to the wall surface of the heat insulation screen (1) and another arc segment (4) at the connection point.

6. The improved attached film gas orifice heat shield structure for the tail nozzle according to any one of claims 2-5, characterized in that, The total length lh of the air film cooling hole (2) is 0.2 to 3 mm, and the length l2 of the arc segment (4) is 0.5 to 1 times the total length lh.

7. The improved tail nozzle heat shield structure according to claim 2 or 4, characterized in that, The diameter dh of the cylindrical segment (5) is 0.5 to 2 mm, and the inclination angle α is 30° to 90°; the downstream extension length l1 of the arc segment (4) is 0.5 to 1.5 times dh, and the extension angle β is 30° to 60°.

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