Nested S-shaped air inlet channel for boundary layer suction type propulsion system

Abstract

The invention relates to the technical field of aero-engines, in particular to a nested S-shaped air inlet channel for a boundary layer suction type propulsion system, which comprises a first air inlet pipeline, a second air inlet pipeline and a third air inlet pipeline, the second air inlet pipeline is arranged on the first air inlet pipeline in a sleeving manner and is matched with the outer wall of the first air inlet pipeline to form an outer ring auxiliary flow channel; the outer ring auxiliary flow channel is used for sucking boundary laminar flow; an inlet of the first air inlet pipeline and an inlet of the second air inlet pipeline are rectangular, and a first gap is formed between the outer top face of the inlet of the first air inlet pipeline and the inner top face of the inlet of the second air inlet pipeline. A second gap is formed between the outer bottom surface of the inlet of the first air inlet pipeline and the inner bottom surface of the inlet of the second air inlet pipeline; the second gap is larger than the first gap. According to the invention, the efficiency and stable reservation of the fan can be ensured, and the earnings of the BLI propulsion system are further increased.

Description

Technical Field

[0001] The present disclosure relates to the technical field of aeroengines, and particularly to a nested S-shaped air intake for a boundary layer ingestion propulsion system. Background Art

[0002] In modern aeroengine design, with the increasing requirements for carbon emissions and fuel consumption rate, the boundary layer ingestion propulsion system layout has become a research hotspot. This type of propulsion system is semi-buried in the upper or tail part of the fuselage, and the low-energy boundary layer fluid on the fuselage is sucked to accelerate it to achieve the function of obtaining the target thrust with less work. The S-shaped air intake is widely used in the BLI (Boundary Layer Ingestion) layout due to its excellent stealth performance and compact layout. However, due to the fact that the BLI propulsion system relies on sucking the low-energy fluid on the fuselage boundary layer to do work, the inlet airflow of the S-shaped air intake in the traditional BLI propulsion system is not uniform. Therefore, the airflow is prone to flow separation during the flow process, which further exacerbates the complexity of the internal flow of the intake pipe and leads to a large distortion of the outlet airflow, thus affecting the performance of the subsequent fan components and further affecting the propulsion efficiency of the engine, resulting in the problem that the benefits of the new BLI propulsion system are not obvious. Summary of the Invention

[0003] In view of the above problems, the present disclosure is proposed. The present disclosure provides a nested S-shaped air intake for a boundary layer ingestion propulsion system.

[0004] According to one aspect of the present disclosure, there is provided a nested S-shaped air intake for a boundary layer ingestion propulsion system, including:

[0005] A first intake pipe for sucking in a uniform oncoming flow;

[0006] A second intake pipe sleeved on the first intake pipe and cooperating with the outer wall of the first intake pipe to form an outer ring auxiliary flow channel; the outer ring auxiliary flow channel is used for sucking in boundary layer flow;

[0007] The inlets of the first intake pipe and the second intake pipe are both rectangular, and there is a first gap between the outer top surface at the inlet of the first intake pipe and the inner top surface at the inlet of the second intake pipe, and there is a second gap between the outer bottom surface at the inlet of the first intake pipe and the inner bottom surface at the inlet of the second intake pipe; the second gap is greater than the first gap.

[0008] For the nested S-shaped air intake for a boundary layer ingestion propulsion system according to one aspect of the present disclosure, the outlet of the outer ring auxiliary flow channel is annular.

[0009] The nested S-shaped air intake for a boundary layer ingestion propulsion system according to one aspect of the present disclosure further includes a first support member. One end of the first support member is fixedly connected to the outer wall of the first air intake pipe, and the other end is fixed to the inner wall of the second air intake pipe.

[0010] The number of the first support members is plural, and the plural first support members are arranged at the outlet of the outer ring auxiliary flow passage; the plural first support members are evenly distributed along the circumferential direction of the first air intake pipe.

[0011] For the nested S-shaped air intake for a boundary layer ingestion propulsion system according to one aspect of the present disclosure, the center line of the inlet of the first air intake pipe is parallel to the center line of the outlet of the first air intake pipe; the first air intake pipe is S-shaped along the direction from the inlet to the outlet.

[0012] The center line of the inlet of the second air intake pipe is parallel to the center line of the outlet of the second air intake pipe; the second air intake pipe is S-shaped along the direction from the inlet to the outlet.

[0013] For the nested S-shaped air intake for a boundary layer ingestion propulsion system according to one aspect of the present disclosure, the radius calculation formula of the outlet of the second air intake pipe is:

[0014]

[0015] Wherein, R is the radius of the outlet of the second air intake pipe, is the aerodynamic function value at the inlet , A in is the inlet area, q(Ma out ) is the aerodynamic function value at the inlet , and σ is the total pressure recovery coefficient of the air intake pipe.

[0016] For the nested S-shaped air intake for a boundary layer ingestion propulsion system according to one aspect of the present disclosure, the radius calculation formula of the outlet of the first air intake pipe is:

[0017]

[0018] Wherein, r is the radius of the outlet of the first air intake pipe, q(Ma 主 ) is the aerodynamic function value of the first air intake pipe at Ma 主 , A in_in is the inlet area of the first air intake pipe, q(Ma out ) is the aerodynamic function value at the inlet .

[0019] The nested S-shaped air inlet for a boundary layer ingestion propulsion system according to an aspect of the present disclosure, wherein the cross-sectional shapes of the first air inlet pipe and the second air inlet pipe are constructed by a super-ellipse equation;

[0020] The super-ellipse equation is:

[0021]

[0022] where a is the major axis, b is the minor axis, and n is the exponent.

[0023] The method for constructing the cross-sectional shapes of the first air inlet pipe and the second air inlet pipe by a super-ellipse equation for the nested S-shaped air inlet for a boundary layer ingestion propulsion system according to an aspect of the present disclosure includes:

[0024] Taking a point on a pre-determined center line as the origin, constructing a profile perpendicular to the tangent of the point on the center line, and the profile is determined by the major axis, minor axis and exponent in the super-ellipse equation;

[0025] Constructing the major axis, minor axis and exponent into a quartic polynomial function;

[0026] Solving the coefficients of each quartic polynomial function and substituting them into each quartic polynomial function to obtain the polynomial functions corresponding to the major axis, minor axis and exponent;

[0027] Determining the corresponding profiles at each point on the center line according to the polynomial functions.

[0028] The nested S-shaped air inlet for a boundary layer ingestion propulsion system according to an aspect of the present disclosure further includes a second support member;

[0029] The second support member is located in the outer ring auxiliary flow channel, one end of which is connected to the outer wall of the first air inlet pipe, and the other end is fixedly connected to the inner wall of the second air inlet pipe;

[0030] The second support member is located in the middle of the first air inlet pipe in the axial direction.

[0031] As will be described in detail below, for the nested S-shaped air inlet for a boundary layer ingestion propulsion system according to an embodiment of the present disclosure, by reconfiguring the air inlet pipe into a nested S-shaped air inlet, the separation of the airflow in the air inlet pipe is avoided, and the low non-uniformity of the airflow at the outlet of the air inlet pipe is ensured, thereby ensuring the efficiency and stability of the fan, and further increasing the benefits of the BLI propulsion system.

[0032] It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the claimed technology. Brief Description of the Drawings

[0033] The embodiments of the present disclosure will become more apparent from the following detailed description in conjunction with the accompanying drawings. The above and other objects, features, and advantages of the present disclosure will become more obvious. The accompanying drawings are used to provide a further understanding of the embodiments of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the present disclosure and do not constitute a limitation to the present disclosure. In the drawings, the same reference numerals generally represent the same components or steps.

[0034] Figure 1 is a sectional view of the intake duct proposed by the present invention;

[0035] Figure 2 is a schematic end face view at the inlet of the intake duct proposed by the present invention;

[0036] Figure 3 is a schematic end face view at the outlet of the intake duct proposed by the present invention;

[0037] Figure 4 is a schematic view of the intake duct proposed by the present invention;

[0038] Figure 5 is a three-dimensional schematic view of the intake duct proposed by the present invention;

[0039] Figure 6a is a schematic streamline view of a conventional S-shaped intake duct;

[0040] Figure 6b is a schematic streamline view of the nested S-shaped intake duct proposed by the present invention;

[0041] Figure 7a is the total pressure contour map at the outlet of the conventional S-shaped intake duct;

[0042] Figure 7b is the total pressure contour map at the outlet of the nested S-shaped intake duct proposed by the present invention;

[0043] Figure 8a is the DPCP at the outlet of the conventional S-shaped intake duct avg value variation diagram with the distribution of the target ring;

[0044] Figure 8b is the DPCP at the outlet of the nested S-shaped intake duct proposed by the present invention avg value variation diagram with the distribution of the target ring.

[0045] Explanation of reference numerals:

[0046] 1 - First intake duct, 2 - Second intake duct, 3 - Outer ring auxiliary flow channel, 4 - First gap, 5 - Second gap, 6 - First support member, 7 - Second support member. Detailed implementation manners

[0047] To make the objectives, technical solutions, and advantages of the present disclosure more apparent, exemplary embodiments in accordance with the present disclosure will be described in detail below with reference to the accompanying drawings. Apparently, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments of the present disclosure. It should be understood that the present disclosure is not limited by the exemplary embodiments described herein.

[0048] In the case of a traditional S-shaped inlet, separation is likely to occur in the face of the inherent flow distortion of the BLI propulsion system. Since the boundary layer fluid with a relatively low velocity cannot obtain the centripetal force required for turning due to the pressure gradient at the first turn at the bottom of the air duct, it moves away from the wall surface and forms a low-pressure area at the first turn. At the second turn at the bottom of the air duct, it interacts with the wall surface, and the wall surface provides the centripetal force required for the second turn, thus forming a high-pressure area at the second turn. Therefore, there is an adverse pressure gradient at the bottom of the traditional S-shaped inlet. Since the boundary layer flow with a relatively low velocity is inhaled at the bottom, the ability to resist the adverse pressure gradient is very weak, and it is very easy for the velocity to become 0 or even reverse accelerate under the action of the pressure gradient, thus generating a separated boundary layer area. The separation of the airflow in the intake duct will cause a decrease in the total pressure of the airflow and increase the non-uniformity of the airflow at the outlet section of the intake duct, thereby reducing the efficiency and stability margin of the subsequent fan and causing a decline in the overall performance of the propulsion system.

[0049] To address the above problems, the present disclosure proposes a nested S-shaped inlet for a boundary layer ingestion propulsion system. Please refer to Figures 1 to 5 , which includes a first intake duct 1 and a second intake duct 2.

[0050] The first intake duct 1 is used to inhale a uniform oncoming flow. The second intake duct 2 is sleeved on the first intake duct 1 and cooperates with the outer wall of the first intake duct 1 to form an outer ring auxiliary flow channel 3. The outer ring auxiliary flow channel 3 is used to inhale the boundary layer flow. In practical applications, the first intake duct 1 is connected to the core duct of the engine, and the outer ring auxiliary flow channel 3 is communicated with the bypass duct of the engine.

[0051] Since the first intake duct 1 and the outer ring auxiliary flow channel 3 intake air independently, the first intake duct 1 is used to guide the uniform main flow, and the outer ring auxiliary flow channel 3 is used to guide the boundary layer fluid and a small part of the main flow, and further adjusts the airflow method in the outer ring auxiliary flow channel 3 to reduce flow separation.

[0052] The inlets of the first intake duct 1 and the second intake duct 2 are both rectangular, and there is a first gap 4 between the outer top surface at the inlet of the first intake duct 1 and the inner top surface at the inlet of the second intake duct 2, and there is a second gap 5 between the outer bottom surface at the inlet of the first intake duct 1 and the inner bottom surface at the inlet of the second intake duct 2; the second gap 5 is larger than the first gap 4. Through this setting method, the lower side of the outer ring auxiliary flow channel 3 has a larger inlet area, the intake air volume at this place increases, and when the air entering at this place enters the first turning point, it is affected by the action of the bottom of the first intake duct 1 and the change in the cross-sectional shape of the outer ring auxiliary flow channel 3 located below the first intake duct 1, so as to adjust the air flow in the outer ring auxiliary flow channel 3 to reduce flow separation.

[0053] In specific implementation, the outlet of the outer ring auxiliary flow channel 3 is circular. That is, the outlets of the first intake duct 1 and the second intake duct 2 are both circular, and the outlet of the first intake duct 1 and the outlet of the second intake duct 2 are coaxially arranged.

[0054] In some implementation manners, in order to ensure the relative position between the first intake duct 1 and the second intake duct 2, a first support member 6 is further included. The first support member 6 is a rod member. One end of the first support member 6 is fixedly connected to the outer wall of the first intake duct 1, and the other end is fixed to the inner wall of the second intake duct 2. The function of the first support member 6 is not only to support the first intake duct 1 and the second intake duct 2, but also to play a role in guiding the flow. In some implementation manners, the dimension of the first support member 6 in the circumferential direction of the first intake duct 1 first becomes larger and then smaller along the intake direction, that is, the cross-section of the first support member 6 is shuttle-shaped to reduce the resistance generated to the air flow.

[0055] The number of the first support members 6 is multiple, and the multiple first support members 6 are arranged at the outlet of the outer ring auxiliary flow channel 3; the multiple first support members 6 are evenly distributed along the circumferential direction of the first intake duct 1. In some implementation manners, the number of the first support members 6 can be 10 to 30.

[0056] In some implementation manners, the center line of the inlet of the first intake duct 1 is parallel to the center line of the outlet of the first intake duct 1; the first intake duct 1 is in an S shape along the direction from the inlet to the outlet; the center line of the inlet of the second intake duct 2 is parallel to the center line of the outlet of the second intake duct 2; the second intake duct 2 is in an S shape along the direction from the inlet to the outlet. In specific implementation, the center line of the second intake duct 2 is also in an S shape, and the center lines of the first intake duct 1 and the second intake duct 2 do not completely coincide. In practical applications, the center lines of the first intake duct 1 and the second intake duct 2 should be smooth curves.

[0057] In some implementations, it further includes a second support member 7; the second support member 7 is located in the outer ring auxiliary flow channel 3, one end of which is connected to the outer wall of the first intake pipe 1, and the other end is fixedly connected to the inner wall of the second intake pipe 2; the second support member 7 is located in the middle of the first intake pipe 1 in the axial direction. In specific implementation, the second support member 7 mainly has two functions. One is to stabilize the structure and make the entire intake pipe more stable. The other is to suppress the upward movement of the low-energy fluid at the bottom due to the pressure difference, resulting in a wide range of low-pressure areas at the outlet.

[0058] The following further illustrates with an intake pipe of certain parameters.

[0059] Table 1 Design Requirements of Nested S-Type Intake Duct

[0060] Inlet width (mm) Inlet height (mm) Outlet (Ma) First intake duct 1530 740 0.55 Second intake duct 1800 1200 0.55

[0061] The design requirements of a certain nested S-type intake duct are shown in Table 1, and the length of the entire nested S-type intake duct is 3.8 meters, and the offset is 1.82 meters.

[0062] The verification case of this nested S-type intake duct is a certain model of aircraft. The cruise altitude of this aircraft is 11000 m, and the cruise Mach number is 0.85. From its aerodynamic shape, the aerodynamic parameters of the inlet air flow of the S-type intake duct can be known. The boundary layer flow rate is 54 kg / s, the height distribution is 400 mm, the average Ma is 0.6 Ma, the mainstream flow rate is 126 kg / s, and the mainstream design Ma is 0.7 Ma.

[0063] Under the above conditions, the average Ma at the inlet of the nested S-type intake duct can be expressed as:

[0064]

[0065] where is the design flow rate of the mainstream, is the design flow rate of the boundary layer, Ma 主 is the inlet Ma of the mainstream, is the average inlet Ma of the boundary layer. Therefore, given the inlet dimensions, oncoming flow conditions, and the outlet design Ma, the design parameter of the radius of the outer circle at the outlet can be obtained through the flow rate formula.

[0066]

[0067] In the formula, K is the gas constant, A in is the inlet area, and this value is known. is the aerodynamic function value at the inlet under the condition, q(Ma out ) is the aerodynamic function value at the outlet flow velocity of Ma outThe pneumatic function value under and are the total temperatures at the inlet and outlet of the intake duct respectively. During the process of the airflow passing through the intake duct, we usually consider it adiabatic, so the values of these two are the same. Considering the influence of the total pressure loss of the intake duct, the relationship between the total pressures at the inlet and outlet of the intake duct can be expressed as:

[0068]

[0069] where σ is the total pressure recovery coefficient of the intake duct. From this, the outlet area of the nested intake duct can be obtained as:

[0070]

[0071] Therefore, the formula for calculating the radius of the outlet of the second intake duct 2 is:

[0072]

[0073] where R is the radius of the outlet of the second intake duct 2, is the pneumatic function value at the inlet under, A in is the inlet area, q(Ma out ) is the pneumatic function value at the inlet under, and σ is the total pressure recovery coefficient of the intake duct.

[0074] The formula for calculating the radius of the outlet of the first intake duct 1 is:

[0075]

[0076] where r is the radius of the outlet of the first intake duct 1, q(Ma 主 ) is the pneumatic function value of the first intake duct 1 at Ma 主 under, A in_in is the inlet area of the first intake duct (1), q(Ma out ) is the pneumatic function value at the inlet under.

[0077] Since the first intake duct 1 sucks in a uniform mainstream fluid, its inlet velocity is Ma 主 . At the same time, due to the uniformity of its mainstream, there is little flow separation in the internal channel and the total pressure loss is small. Therefore, the influence of the total pressure loss recovery coefficient σ of the intake duct components is ignored in the calculation of r.

[0078] Through the above process, the design of the outlet is completed.

[0079] After determining the design dimensions of the inlet and outlet, the overall trend of change of the intake duct is determined by constructing the centerline of the intake duct. Points are taken on the centerline as the centers of the cross-sections, and the cross-sectional shapes are constructed by the super-ellipse equation. That is, the cross-sectional shapes of the first intake duct 1 and the second intake duct 2 are constructed by the super-ellipse equation; specifically, the method for constructing the cross-sectional shapes of the first intake duct 1 and the second intake duct 2 by the super-ellipse equation includes: taking the point on the pre-determined centerline as the origin, constructing a surface perpendicular to the tangent of the point on the centerline, and the surface is determined by the major axis, minor axis and exponent in the super-ellipse equation; constructing the major axis, minor axis and exponent into a quartic polynomial function; solving the coefficients of each quartic polynomial function and substituting them into each quartic polynomial function to obtain the polynomial functions corresponding to the major axis, minor axis and exponent; determining the corresponding surfaces at each point on the centerline according to the polynomial functions.

[0080] The super-ellipse equation is:

[0081]

[0082] where a is the major axis, b is the minor axis, and n is the exponent.

[0083] Taking a certain point on the centerline as the origin to construct a surface perpendicular to the tangent of the point on the centerline, when determining the major axis a, minor axis b and exponent n of the surface, the cross-sectional coordinates can be determined by the above formula. The major axis a and minor axis b determine the span in the spreading direction and longitudinal direction of the surface, while n determines the shape change of the surface. In fact, since the inlet of the intake duct is similar to a rectangle and the outlet is a circle, along the axial direction of the centerline, the cross-sectional shape should be gradually changing. Taking the second intake duct of the nested intake duct as an example, a, b, and n are all constructed as quartic functions of the axial coordinate.

[0084]

[0085] The variation laws of the major axis, minor axis and the surface exponent n along the x-axis are all determined by quartic polynomials. Each formula has five unknowns, so the change of each parameter requires five corresponding equations to determine the change law of the surface. For the parameters a and b, the x-axis positions at the inlet and outlet and the values of the surface a and b are all determined by the above design parameters. The surface parameters at the intermediate positions and the derivative functions at the inlet and outlet positions are supplemented as follows.

[0086]

[0087] where the value of a in is half of the width L2 of the inlet of the second intake duct, a oit is the outlet R, a mid selects an empirical value of 0.5L2 + 0.7(R - 0.5L2), x in is 0, x outThe axial length of the intake duct is 3.8 m, and x mid is 1.9 m. Thus, the variation law of the variable a of the second intake duct along the axial direction can be determined. Similarly, b(x) and n(x) are solved.

[0088]

[0089] In the above formula, b in is half of the height H2 at the inlet of the second intake duct, and b out is the outlet R. For b mid an empirical value of 0.6H2 + 0.7(R - 0.5H2) is selected. For n in the inlet super-elliptical index is 9, and for n out the outlet super-elliptical index is 2, and for n mid the middle position profile super-elliptical index is 7. Thus, all the parameters and variables of the second intake duct of the intake duct are known. For example, the three-dimensional coordinates of different points on each cross-section of the second intake duct of the intake duct can be exported through MATLAB and imported into ICEMCFD for modeling. Using the same method to construct the profile parameter design function of the first intake duct of the intake duct, which will not be elaborated here too much. When constructing, n(x) is the same as that of the second intake duct, and the functions of a(x) and b(x) need to change the inlet and outlet values. When constructing the first intake duct, the value of a in is half of the inlet width L1 of the first intake duct, and a out is the outlet r. For a mid an empirical value of 0.5L1 + 0.7(r - 0.5L1) is selected. For b in is half of the height H1 at the inlet of the first intake duct, and b out is the outlet R. For b mid an empirical value of 0.6H1 + 0.7(R - 0.5H1) is selected.

[0090] To verify the advantage of the nested S-shaped intake duct over the traditional S-shaped intake duct in terms of anti-distortion ability, under the same total pressure radial distortion intake conditions, the traditional S-shaped intake duct and the nested S-shaped intake duct with a design flow rate of 180 kg / s each are simulated and verified. There is obvious flow separation at the bottom of the traditional S-shaped intake duct, and the recirculation area of the streamlines is large, while for the nested S-shaped intake duct, some streamlines have a tendency to rise without obvious recirculation, and only a pair of vortex structures are formed at the outlet.

[0091] Please refer to Figure 6a and Figure 6b, there is a reverse velocity distribution of intake air at the bottom of the traditional S-shaped inlet, while the meridional flow velocity of the nested S-shaped inlet is along the intake direction. This proves that the traditional S-shaped inlet will generate flow separation under the condition of inherent intake distortion, while the nested S-shaped inlet still has good anti-separation ability even in the face of inherent intake distortion, thus ensuring the high efficiency of the propulsion system. The separation of air flow in the intake duct will cause an increase in the total pressure loss of the gas, an increase in the distortion degree and range of the outlet section. These changes in the flow field will lead to a decrease in the efficiency and stability margin of the subsequent fan, thus causing a decline in the overall propulsion performance of the aircraft propulsion system; while in the nested layout, it can be seen that there is no obvious reverse flow separation area in both the first intake duct and the second intake duct, indicating that the nested S-shaped inlet has the ability to resist flow separation, thus ensuring that the air flow inside the flow channel is more uniform compared to the traditional S-shaped inlet.

[0092] Please refer to Figure 7a and Figure 7b , the proportion of the low-pressure area at the outlet of the traditional S-shaped inlet with flow separation in the flow channel is large; while the total pressure at the outlet of the first intake duct of the nested S-shaped inlet is high and uniform, and there is only a small low-pressure area in the outer ring auxiliary flow channel. Compared with the traditional S-shaped inlet, the outlet of the nested intake duct is more uniform than that of the traditional S-shaped inlet.

[0093] To quantify the weakening distortion ability of the nested S-shaped inlet compared with the traditional S-shaped inlet when facing the total pressure distortion of the incoming flow at the inlet, the DPCP distortion index is introduced to evaluate the circumferential distortion of the air flow at the outlet of the intake duct.

[0094]

[0095] The outlet section of the intake duct is divided into i = 1…n rings, where i is the number of rings on the outlet interface rake, and Pt avg,i is the average total pressure on ring i, and Pt low,avg,i is the average total pressure of the area where the total pressure is lower than Pt avg,i .

[0096] The outlet of the traditional S-shaped inlet is evenly divided into five concentric target rings to calculate the DPCP avg of the outlet section under this configuration. Since the nested S-shaped inlet has two internal channels, the inner and outer channels are evenly divided and four target rings are placed in each. It can be seen that the target ring arrangement density of the second intake duct is greater than that of the inner channel. The reason is that the total pressure distribution at the outlet of the outer channel is more uneven than that of the inner channel. Such a target ring arrangement helps to focus on monitoring the unevenness of the outer channel. The measurement and calculation results of each target ring under the two configurations are as Figure 8a and Figure 8b shown.

[0097] Figure 8a The variation of DPCP values on each target ring with uniform distribution at the outlet section of the traditional S-shaped inlet duct Figure 8b is the variation of DPCP values on each target ring with uniform distribution in the inner and outer bypass ducts at the outlet section of the nested S-shaped inlet duct. Although the DPCP values of both configurations increase to varying degrees when approaching the outer ring due to the influence of the outlet on the vortex or separation situation, the DPCP values of the inner and outer bypass ducts of the nested S-shaped inlet duct are much smaller than those of the traditional S-shaped inlet duct. The DPCP of both configurations avg is statistically shown in Table 2.

[0098] Table 2 Comparison of DPCP at the outlet of inlet ducts with different configurations avg Value comparison table

[0099] Traditional S-shaped intake duct Nested S-shaped intake duct <![CDATA[DPCP avg > 0.1022 0.0162

[0100] The DPCP of the nested S-shaped inlet duct avg decreases by 0.086 compared with the traditional S-shaped inlet duct. Therefore, the nested S-shaped inlet duct proposed by the present invention can excellently solve the problem of large distortion of the flow field at the outlet of the intake pipe caused by the distortion of the inlet airflow. This intake pipe provides better intake conditions for the downstream component fan to achieve the excellent effect of improving the overall performance of the propulsion system.

[0101] It should be noted that in this application, the first intake pipe refers to the space inside the first intake pipe 1; the second intake pipe refers to the space inside the second intake pipe 2 and outside the first intake pipe 1.

[0102] The basic principles of the present disclosure have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, advantages, effects, etc. mentioned in the present disclosure are only examples and not limitations, and it cannot be considered that these advantages, advantages, effects, etc. are essential for each embodiment of the present disclosure. In addition, the above-mentioned specific details are only for the purpose of illustration and facilitation of understanding, and not for limitation. The above details do not limit the present disclosure to necessarily adopt the above specific details to implement.

[0103] The block diagrams of the devices, apparatuses, equipment, and systems involved in the present disclosure are only illustrative examples and do not intend to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any way. Words such as "including", "comprising", "having", etc. are open-ended words, meaning "including but not limited to", and can be used interchangeably with each other. The words "or" and "and" used herein refer to the word "and / or", and can be used interchangeably with each other, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to", and can be used interchangeably with each other.

[0104] In addition, as used herein, "or" as used in a listing of items beginning with "at least one" indicates a disjunctive listing such that, for example, a listing of "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Further, the phrase "exemplary" does not mean that the examples described are preferred or better than other examples.

[0105] It should also be noted that in the systems and methods of the present disclosure, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent solutions of the present disclosure.

[0106] Various changes, substitutions, and alterations to the technologies described herein can be made without departing from the teachings defined by the appended claims. In addition, the scope of the claims of the present disclosure is not limited to the specific aspects of the processes, machines, manufactures, compositions of events, means, methods, and acts described above. Processes, machines, manufactures, compositions of events, means, methods, or acts that are currently available or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding aspects described herein can be utilized. Accordingly, the appended claims include such processes, machines, manufactures, compositions of events, means, methods, or acts within their scope.

[0107] The foregoing description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0108] The foregoing description has been presented for purposes of illustration and description. In addition, this description is not intended to limit the embodiments of the present disclosure to the forms disclosed herein. Although numerous example aspects and embodiments have been discussed above, those skilled in the art will recognize some of their variations, modifications, alterations, additions, and subcombinations.

Claims

1. A nested S-shaped inlet for a boundary layer ingestion propulsion system, characterized in that, Comprising: A first intake duct (1) for sucking in a uniform oncoming flow; A second intake duct (2) sleeved on the first intake duct (1) and cooperating with the outer wall of the first intake duct (1) to form an outer ring auxiliary flow channel (3); the outer ring auxiliary flow channel (3) is used for sucking in boundary layer flow; The inlets of both the first intake duct (1) and the second intake duct (2) are rectangular, and there is a first gap (4) between the outer top surface at the inlet of the first intake duct (1) and the inner top surface at the inlet of the second intake duct (2), and there is a second gap (5) between the outer bottom surface at the inlet of the first intake duct (1) and the inner bottom surface at the inlet of the second intake duct (2); the second gap (5) is greater than the first gap (4).

2. The nested S-shaped inlet for a boundary layer ingestion propulsion system according to claim 1, wherein The outlet of the outer ring auxiliary flow channel (3) is annular.

3. The nested S-shaped air inlet for a boundary layer ingestion propulsion system according to claim 2, wherein, It further includes a first support member (6), one end of the first support member (6) is fixedly connected to the outer wall of the first intake duct (1), and the other end is fixedly connected to the inner wall of the second intake duct (2); The number of the first support members (6) is multiple, and the multiple first support members (6) are arranged at the outlet of the outer ring auxiliary flow channel (3); the multiple first support members (6) are evenly distributed along the circumferential direction of the first intake duct (1).

4. The nested S-shaped inlet for a boundary layer ingestion propulsion system according to claim 3, characterized in that, The center line of the inlet of the first intake duct (1) is parallel to the center line of the outlet of the first intake duct (1); the first intake duct (1) is in an S shape along the direction from the inlet to the outlet; The center line of the inlet of the second intake duct (2) is parallel to the center line of the outlet of the second intake duct (2); the second intake duct (2) is in an S shape along the direction from the inlet to the outlet.

5. The nested S-shaped air inlet for a boundary layer ingestion propulsion system according to claim 4, wherein, The radius calculation formula for the outlet of the second intake duct (2) is: wherein, R is the radius of the outlet of the second intake pipe (2), is the aerodynamic function value at the inlet , A in is the inlet area, q(Ma out ) is the aerodynamic function value at the inlet , and σ is the total pressure recovery coefficient of the intake pipe.

6. The nested S-shaped inlet for a boundary layer ingestion propulsion system according to claim 4, wherein, The radius calculation formula for the outlet of the first intake duct (1) is: where r is the radius of the outlet of the first intake pipe (1), q(Ma 主 ) is the aerodynamic function value of the first intake pipe (1) at Ma 主 , A in_in is the inlet area of the first intake pipe (1), and q(Ma out ) is the aerodynamic function value at the inlet .

7. The nested S-shaped air inlet for a boundary layer ingestion propulsion system according to claim 4, wherein, The cross-sectional shapes of the first intake duct (1) and the second intake duct (2) are constructed by a super-ellipse equation; The super-ellipse equation is: Where a is the major axis, b is the minor axis, and n is the exponent.

8. The nested S-shaped air inlet for a boundary layer ingestion propulsion system according to claim 7, wherein The method for constructing the cross-sectional shapes of the first intake duct (1) and the second intake duct (2) by the super-ellipse equation includes: Taking the point on the pre-determined center line as the origin, constructing a profile perpendicular to the tangent of this point on the center line, and this profile is determined by the major axis, minor axis and exponent in the super-ellipse equation; Constructing the major axis, minor axis and exponent into a quartic polynomial function; Solving the coefficients of each quartic polynomial function and substituting them into each quartic polynomial function to obtain the polynomial functions corresponding to the major axis, minor axis and exponent; Determining the corresponding profiles at each point on the center line according to the polynomial functions.

9. The nested S-shaped air intake for a boundary layer ingestion propulsion system according to any one of claims 1-8, characterized in that, It further includes a second support member (7); The second support member (7) is located in the outer ring auxiliary flow channel (3), one end of it is connected to the outer wall of the first intake duct (1), and the other end is fixedly connected to the inner wall of the second intake duct (2); The second support member (7) is located in the middle of the first intake duct (1) in the axial direction.

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