Suction-free air inlet channel design method capable of giving consideration to wide-range operation and performance

Abstract

The invention discloses a wide-range operation and performance considered non-suction air inlet channel design method, and belongs to the field of ramjet internal flow aerodynamics, and the method comprises the following steps: S1, designing an outer compression surface of an air inlet channel according to the incoming flow condition of a design point; s2, carrying out viscosity correction on the outer compression surface; s3, solving the minimum through-flow area corresponding to the lip shock wave post-wave parameters; s4, a reference molded surface of the air inlet channel is designed according to the minimum through-flow area; s5, aiming at the reference molded surface air inlet channel, the self-adaptive adjustment capability of the pneumatic throat channel is checked in the operation range; s6, the reference molded surface of the air inlet channel is rotated along the symmetry axis, and the inward rotation type air inlet channel with the pneumatic throat self-adaptive adjusting capacity is obtained; and S7, carrying out optimization iteration on the performance of the inward rotation type air inlet channel. By adopting the air inlet channel designed by the invention, wide-range operation can be realized without flow control such as suction and variable geometry adjustment, and the air inlet channel is suitable for high-speed air inlet channel design of a high-speed ramjet engine and a high-speed air suction type combined cycle engine.

Description

Technical Field

[0001] The present invention relates to the field of ramjet internal flow aerodynamics, and more specifically, to a method for designing a non-suction inlet duct that takes both wide-range operation and performance into consideration. Background Art

[0002] Fixed geometry inlets are very important for high-speed flight. For example, the United States' HRE inlet (M5-7), X-51A inlet (M4.5-6.5), HyFly (M3.5-6), etc. all use fixed geometry inlet solutions, but it is difficult to find information on the design method of fixed geometry inlets. The X-51A flight test used a binary fixed geometry high-speed inlet, hoping to achieve M4.5-6.5 operation, but the flight test only achieved about M5 (the flight Mach number increased by 0.2 in 200 seconds), and it was found that the inlet was very fragile and could easily fail to start under the action of combustion back pressure. In the second X-51 flight test in June 2011, the inlet failed to start, causing the flight test to be terminated prematurely. The M7 and M10 flight tests of the US X-43A flight test aircraft used binary inlets with design points of M7 and M10, respectively.

[0003] In order to achieve wide range operation, fixed geometry inlet faces many problems in design. If the efficiency of the cruise state is to be maintained, the performance of the non-design state (including low Mach number and non-design flight attitude) must be sacrificed. If the design is unreasonable, there may be problems such as the operating range or performance not meeting expectations, including entering the surge (no start) state, the hysteresis loop is too large, or the hysteresis jump is too large.

[0004] At present, the methods for achieving wide range operation of the inlet duct are mainly divided into two types: flow control method and variable geometry method. Flow control methods usually include suction or boundary layer blowing, while variable geometry methods are mostly implemented by dynamic adjustment mechanisms such as splitters.

[0005] The implementation of the flow control method is mainly based on boundary layer suction (hole / slot venting, leakage) and boundary layer blowing measures. In the existing document "Research on Adaptive Pressure Relief Control Technology of Wide-Range Constant Geometry Hypersonic Inlet", the adaptive pressure relief technology (essentially boundary layer suction) of a fixed geometry high-speed inlet suitable for a wide range of working conditions is studied. The leakage groove with a total leakage area accounting for 47% of the inlet capture area is used to discharge about 2% of the captured flow, thereby reducing the self-starting Mach number of the high-speed inlet and achieving a wide range of operation of the inlet. There are also other documents such as "Study on Variable Geometry Leakage Cavity of TBCC Inlet", which carried out numerical simulation and experimental verification of the application of slotted leakage in TBCC inlet, and verified the feasibility of gaining inlet performance by losing a small part of the flow through slotted leakage. In Russell LD's computational research on the air fluid compression method in supersonic inlets, the first shock wave angle of the inlet is controlled by an adjustable pressure jet, thereby adjusting the flow capacity of the inlet in an over-rated non-design state; the document "Concept and Preliminary Verification of a Constant Geometry Hypersonic Adjustable Inlet Based on Shock Wave Shape Control" further uses holes or slits with a certain distribution pattern at the front end of each external compression section, and uses jets to control the bending of each stage of compression shock waves, thereby controlling the position of the external compression shock wave incident on the lip, to improve the self-starting performance of the inlet and reduce the self-starting Mach number.

[0006] The variable geometry method is widely used in supersonic inlets, but there are also studies on its application in high-speed inlets. The maximum flight Mach number of the SR-71 is only 3.2. It uses an axisymmetric variable geometry inlet. The variable geometry structure includes a movable fairing, a center cone, adjustable front and rear bypass valves, a center body boundary layer porous suction system (controls the center body boundary layer) and a throat wall suction system (controls the internal shock wave position and boundary layer flow). The axial position of the center cone is adjusted with the flight state. When taking off from the ground to an altitude of 9km (the flight Mach number is about 0.8), the center cone position is fixed. When the altitude is higher than 9km, the center cone is unlocked, but it remains in the forward position until the Mach number reaches 1.6; after exceeding Mach 1.6, the center cone retracts 4.13cm for every 0.1 increase in the flight Mach number. When the flight Mach number reaches 3.2, the cone is compressed and the shock wave seals, and the center cone reaches the innermost position. In order to improve the aerodynamic performance of the SR-71 inlet and expand its operating Mach number range, Colvill et al. from the Department of Aerospace Engineering at the University of Maryland used the SR-71 inlet as a basis and used numerical simulation methods to study the effects of adjusting parameters such as the center cone angle, lip mask angle, and center cone shoulder range on the inlet. The results showed that when the lip mask angle and the center cone angle are adjusted at the same time, the maximum operating Mach number of the inlet can reach more than 6.0. The Lewis Research Center of NASA in the United States combines the adjustment of the compression surface, inlet throat, and expansion section of the dual inlet to achieve a wide range of operating capabilities. Two adjustment schemes were studied, one is compression surface rotation-throat translation-expansion section rotation, and the other is compression surface deformation-throat translation-expansion section inclined plate rotation.

[0007] However, these flow control and variable geometry schemes face the problem of high-temperature airflow damaging the structure under high-speed conditions. The thermal protection of the pore (gap) structure of the flow control method itself is difficult; in addition, the blowing scheme needs to carry an air source, valves, and control auxiliary systems, which increases the weight of the structure; and the high-temperature airflow discharged in the leakage scheme is difficult to discharge, requiring a specially designed exhaust pipe and its thermal protection system. In the variable geometry scheme, a complex mechanical system is required, which has to pay a price in terms of volume and weight, and the structure is difficult to implement. The more positions of variable geometry, the greater the difficulty of control. In addition, the active structure must also solve the problem of gap heat protection and high-temperature dynamic sealing. Long-term operation faces severe thermal protection difficulties, especially for the irregular surfaces in the three-dimensional inward-rotating air intake. There is no mature solution for how to achieve reliable operation of the variable geometry mechanism.

[0008] It should be noted that there are also wide-range inlet design methods in the prior art, such as a wide-range adaptive aerodynamic trapped vortex inlet design method with patent application number 202311774369.3, which is a subsonic inlet design method and does not involve the inlet wave distribution problem. It is not suitable for supersonic inlet design that requires wave distribution. Summary of the invention

[0009] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0010] In order to achieve these objectives and other advantages of the present invention, a method for designing a non-suction inlet duct that takes into account both wide-range operation and performance is provided. During the design of the high-speed inlet duct, the inlet section of the high-speed inlet duct is designed based on the aerodynamic throat function of the shoulder separation zone in the high-speed inlet duct, so that under different incoming flow conditions, the aerodynamic throat area can be adjusted by changing the morphology of the shoulder separation zone in the aerodynamic throat, so as to achieve wide-range operation of the inlet duct without suction and variable geometry adjustment while taking into account the performance of the design and non-design states.

[0011] Preferably, the method comprises the following steps:

[0012] S1. Under the given design point inflow conditions, the external compression surface and the lip are designed according to the inlet outlet parameter requirements to obtain an inlet profile scheme in which the external compression shock wave and the lip shock wave meet the shock wave contact requirements;

[0013] S2, make a viscosity correction to the external compression surface configuration in the inlet profile solution obtained in S1, so that the external compression shock wave of the design point in the flow field under viscosity conditions is close to the inlet;

[0014] S3. Under the given starting point flow conditions, solve the minimum flow area A corresponding to the lip shock wave parameters min ;

[0015] S4. The minimum flow area A according to S3 min Designing the profile of the inlet section of the air intake duct to obtain the reference profile of the air intake duct, wherein the starting point flow condition given by S3 must provide sufficient flow capacity for the reference profile of the air intake duct;

[0016] S5. Carry out CFD calculation within the operating range for the reference profile of the air intake duct described in S4, and check the adaptive adjustment capability of the pneumatic throat in the air intake duct according to the flow field characteristics. If the requirements are met, proceed to S6, otherwise return to S3;

[0017] S6. Based on the inlet reference profile that has passed the inspection, construct an inward-turning inlet profile with an aerodynamic throat;

[0018] S7, performing CFD calculation on the inner rotating air intake obtained in S6, and obtaining performance parameters of the air intake with the aerodynamic throat adaptive adjustment capability under various operating conditions according to the calculation results, and comparing the performance parameters with the design index to evaluate whether the current design meets the index requirements, and if not, returning to S3 to adjust the design of the flow channel wall surface in the inlet section of the air intake;

[0019] Among them, in S3, the minimum flow area A corresponding to the lip shock wave parameters is solved min When considering the unevenness of the airflow in the flow section, the minimum flow area A min Add a 25% margin to the solution.

[0020] Preferably, in S3, the minimum flow area A corresponding to the lip shock wave parameters is solved. min The methods include:

[0021] S31, given the flow conditions at the starting point, calculate the external compression shock wave and lip shock wave in the inlet profile scheme modified by S2;

[0022] S32, obtain the total pressure recovery coefficient σ of the lip shock wave after the starting point flow condition 21 、Mach number Ma 21 and capture flow q2;

[0023] S33, total pressure recovery coefficient σ after the lip shock wave obtained according to S32 21 、Mach number Ma 21 And capture the flow rate q2, use the flow relationship to solve the lip shock wave parameters corresponding to the minimum flow area A min .

[0024] Preferably, in S4, the upper wall surface of the inner flow channel in the inlet section profile is a horizontal wall surface, and the lower wall surface is a plane that forms an angle with the outer compression surface or a curved surface with a parameter law.

[0025] Preferably, in the air inlet with the aerodynamic throat adaptive adjustment capability, a shoulder separation zone is formed at the lip shock wave incident position of the air inlet, and the flow area A of the external mainstream zone at the apex of the separation zone is min Minimum, the minimum flow cross section is the pneumatic throat, and the upstream and downstream of the pneumatic throat form contraction and expansion sections respectively;

[0026] The adaptive adjustment capability of the pneumatic throat means that as the incoming flow conditions change, the shape of the shoulder separation zone will change accordingly, thereby causing the pneumatic throat area to change accordingly, achieving adaptive adjustment.

[0027] Preferably, in S5, the method of testing the adaptive adjustment capability of the aerodynamic throat in the air inlet is to determine that the design fails when the separation shock wave is located upstream of the lip and causes a large amount of overflow, or the shoulder separation area produces large-amplitude oscillations.

[0028] Preferably, in S6, the method of constructing the inner-rotating air inlet profile with the aerodynamic throat is:

[0029] S60, based on the air intake duct reference profile in S6, rotating along the symmetry axis to form an axisymmetric inner cone air intake duct;

[0030] S61, obtaining the capture area of ​​the air inlet according to the capture flow rate q2, and designing the shape of the air inlet according to the capture area;

[0031] S62. In the flow field of the inner cone inlet, streamlines are traced from the inlet entrance to form a series of streamlines;

[0032] S63. Combine the streamlines downstream of the leading edge shock wave to form an inward-turning inlet profile with an aerodynamic throat.

[0033] Preferably, in S7, the design scheme for adjusting the flow channel wall surface in the inlet section of the air inlet mainly includes:

[0034] When the outlet Mach number is too high, the flow area needs to be reduced to increase the compression capacity;

[0035] When the total pressure recovers too low, it is necessary to expand the flow area to reduce the total pressure loss.

[0036] The present invention includes at least the following beneficial effects: in view of the design dilemma of existing high-speed air inlets operating in a wide range, a high-speed air inlet suitable for a high-speed ramjet engine air inlet and a high-speed air-breathing combined cycle engine designed based on the design method of the present invention can achieve wide-range operation without flow control such as suction and variable geometry adjustment. The fixed-geometry air inlet designed by the design method can utilize the adaptive adjustment function of the separation zone to maintain the efficiency in the cruise state and have good non-design state performance. The design method can realize the matching design of the external compression of the high-speed air inlet and the flow channel profile in the inlet section.

[0037] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a design flow chart of the high-speed air intake of the present invention;

[0039] Figure 2 It is a schematic diagram of the configuration of the inlet outer compression surface and the outer compression wave system;

[0040] Figure 3 This is a schematic diagram of the design point shock wave flow field under viscous conditions;

[0041] Figure 4 A schematic diagram of the inlet section of the plane that forms an angle with the outer compression surface;

[0042] Figure 5The schematic diagram of the aerodynamic throat adaptively adjusting the inlet duct at the curved inlet section;

[0043] Figure 6 It is a design schematic diagram after forming an axisymmetric inner cone air intake on the air intake reference surface;

[0044] Figure 7 This is a schematic diagram of the inward-turning air intake design;

[0045] Figure 8 The design diagram of the basic inner and outer compression surfaces of the air intake duct in Example 1;

[0046] Fig. 9 This is the design drawing before the viscosity correction is performed on the outer compression surface of the inlet profile in Example 1;

[0047] Fig.10 This is the design drawing after the viscosity correction is performed on the outer compression surface of the inlet profile in Example 1;

[0048] Fig.11 It is a schematic diagram of the inlet channel and parameters in the plane of the inlet section in Example 1;

[0049] Fig.12 The schematic diagram of the CFD flow field of the inlet duct in the inlet section plane in Example 1 when the Mach number is 3;

[0050] Fig.13 The schematic diagram of the CFD flow field of the inlet duct in the inlet section plane in Example 1 when the Mach number is 4;

[0051] Fig.14 The schematic diagram of the CFD flow field of the inlet duct in the inlet section plane in Example 1 when the Mach number is 5;

[0052] Fig.15 The schematic diagram of the CFD flow field of the inlet duct in the inlet section plane in Example 1 when the Mach number is 6;

[0053] Fig.16 The schematic diagram of the CFD flow field of the inlet duct in the inlet section plane in Example 1 when the Mach number is 7;

[0054] Fig.17 Schematic diagram of the inward-rotating air intake designed for Example 1. DETAILED DESCRIPTION

[0055] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0056] The present invention is used for the design and optimization of the inlet section profile of an air-breathing ramjet engine. When the fixed-geometry high-speed inlet designed based on this method is in operation, the morphology of the separation zone of its inlet section achieves adaptive adjustment of a wide range of non-design conditions by responding to changes in the incoming flow conditions, thereby achieving wide-range operation and performance assurance of the fixed-geometry inlet. Specifically, under high-speed flight conditions, the design method of the present invention mainly utilizes the "aerodynamic throat" function of the high-speed inlet shoulder separation zone to rationally design the parameters of the high-speed inlet inlet section to achieve adaptive adjustment of the inlet under a wide range of operation. This design method is mainly used for the matching design of the external compression of the high-speed inlet and the internal flow channel profile of the inlet section. The designed fixed-geometry inlet can utilize the adaptive adjustment function of the separation zone to maintain the efficiency of the cruise state and have good non-design state performance.

[0057] Further, such as Figure 1 As shown, the present invention proposes a design method for realizing wide-range operation of a high-speed inward-rotating inlet based on adaptive adjustment of aerodynamic throat, and its specific technical solution includes:

[0058] Step 1: Under the flow conditions of a given design point (generally exceeding Mach number 5), according to the requirements of the inlet outlet parameters (total pressure recovery coefficient, Mach number), the outer compression surface 1 and the lip 2 are designed by two-dimensional shock wave theory to generate the following: Figure 2 The inlet profile shown enables the external compression shock wave 3 and the lip shock wave 4 to meet the shock wave contact requirements.

[0059] Step 2: For the surface design of step 1, the CFD numerical simulation method is used to perform viscosity correction on the external compression surface configuration, so that the external compression shock wave of the design point in the flow field under viscosity conditions is close to the mouth, such as Figure 3 shown.

[0060] Step 3: Under the condition of the incoming flow at a given starting point (generally lower than Mach number 4), calculate the external compression shock wave 5 and the lip shock wave 6 of the inlet profile scheme, and obtain the total pressure recovery coefficient σ of the lip shock wave under the starting point condition. 21 、Mach number Ma 21 And the captured flow rate q2, according to the captured flow rate and the above parameters, use the flow relationship to solve the minimum flow area A corresponding to the lip shock wave parameters min .

[0061] The flow relationship is as follows:

[0062]

[0063] In the above formula, q is the flow rate, which means the flow rate flowing through the channel being solved, unit: kg / s;

[0064] γ is the specific heat ratio, which represents the ratio of the specific heat at constant pressure to the specific heat at constant volume. In the present invention, the specific heat ratio of the air used is: 1.4;

[0065] R is the gas constant of air, and R = 287.058 Jm 3 / (kg.k);

[0066] T0 is the total temperature of the incoming flow, which indicates the stagnation temperature of the incoming flow, that is, the temperature when the incoming flow isentropically stagnates to zero flow velocity, unit: K;

[0067] p0 is the total pressure of the incoming flow, which indicates the stagnation point pressure of the incoming flow, that is, the pressure when the incoming flow is entropically stagnates to zero flow velocity, unit: Pa

[0068] σ is the total pressure recovery coefficient, which represents the ratio of the total pressure at a certain point in the flow field (in the inlet duct) to the total pressure of the incoming flow;

[0069] M is the Mach number, which represents the ratio of the gas velocity at a point in the flow field to the local sound speed;

[0070] A is the flow area, which means the area of ​​the flow channel, unit: m 2 ;

[0071] Step 4: According to the minimum flow area requirement A min , design the profile of the inlet section. In this section design, the upper wall of the inner flow channel is usually a horizontal wall, and the lower wall can be selected according to needs, which can be a plane that forms an angle with the outer compression surface (such as Figure 4 ), or a surface with a specific parameter rule (such as Figure 5 The design principle is to provide sufficient flow capacity for the incoming flow conditions at the starting point and form the reference profile of the air inlet.

[0072] Step 5: For the reference profile of the inlet formed in step 4, CFD calculation is carried out within the operating range, and the adaptive adjustment ability of the aerodynamic throat is tested according to the flow field characteristics. In the inlet with the adaptive adjustment ability of the aerodynamic throat, the shoulder separation zone is formed at the incident position of the lip shock wave. The flow area of ​​the external mainstream area at the vertex of the separation zone is the smallest. The minimum flow cross section is the aerodynamic throat, and the contraction and expansion sections are formed upstream and downstream of the aerodynamic throat. With the change of the incoming flow conditions, the shoulder separation zone here adaptively adjusts its shape, and the aerodynamic throat area also changes accordingly. The position of the separation zone is always maintained near the incident point of the lip shock wave. Although the intensity of the separation shock wave is also adaptively adjusted with the change of the incoming flow, its position is always maintained in the inner flow channel instead of separating from the lip to cause overflow. If the flow field obtained by unsteady calculation is observed, the small-amplitude high-frequency oscillation of the shoulder separation zone and its wave system may be captured, but there will never be large-amplitude low-frequency oscillations that cause inlet surge. If within the design operating range, the separation shock wave is located upstream of the lip, causing a large amount of overflow, or large-amplitude oscillations occur in the shoulder separation area, it means that the design has failed and it is necessary to return to step three and appropriately expand the flow capacity of the low Mach number section of the inlet or redesign the inlet entrance section.

[0073] Step 6: Rotate the reference profile of the air inlet designed in step 5 along the axis of symmetry to form an axisymmetric inner cone air inlet 21, as shown in FIG. Figure 6-Figure 7 As shown, the capture area of ​​the inlet entrance is obtained according to the captured flow rate q2. The inlet entrance shape 22 can be rectangular, elliptical, circular or other shapes. In the inner cone inlet flow field, streamlines are traced from the inlet entrance 22 to form a series of streamlines. The streamlines 24 downstream of the leading edge shock wave 23 are combined to form an inward-turning inlet profile 25 with an aerodynamic throat.

[0074] Step seven, perform CFD calculations on the internal rotating inlet formed in step six, and based on the calculation results, design an inlet with the ability to adaptively adjust the aerodynamic throat. Measure the performance parameters of the inlet under various operating conditions (such as the outlet total pressure recovery coefficient and the outlet Mach number) and compare them with the design indicators. If it does not meet the indicator requirements, return to step three and adjust the design of the flow channel wall at the inlet entrance section: if the outlet Mach number is too high, the flow area needs to be appropriately reduced to increase the compression capacity; if the total pressure recovery is too low, the flow area needs to be appropriately expanded to reduce the total pressure loss; if it meets the design indicator requirements, the design of the aerodynamic throat adaptive adjustment inlet is completed.

[0075] Example 1

[0076] 1. Operating conditions:

[0077] The static pressure of the incoming flow is 2549Pa, the static temperature of the incoming flow is 221.5K, the Mach number at the design point is 6, and the Mach number at the starting point is 4.

[0078] 2. Design goals:

[0079] Under the design point conditions, the total pressure recovery coefficient at the inlet outlet is greater than 0.4, and the Mach number is less than 2.7; when operating at the starting point, the flow capture is higher than 0.20kg / s, the total pressure recovery is higher than 0.65, and the outlet Mach number is less than 2.4.

[0080] 3. Design process:

[0081] Step 1: Under the inlet design point inflow condition (Mach number 6), according to the inflow condition and inlet exit parameter requirements, the two-dimensional oblique shock wave theory is used to design the inlet profile (such as Figure 8 As shown in the figure, the outer compression surface 1 and the lip 2 of the inlet are designed so that the outer compression shock wave 3 and the lip shock wave 4 meet the shock wave contact requirements. The geometric dimensions of the inlet are shown in Table 1:

[0082] Table 1

[0083]

[0084]

[0085] Step 2: Perform CFD calculation on the inlet profile in step 1. Due to the viscosity effect, the external compression shock wave 5 calculated by CFD deviates from the lip 2, and a viscosity correction is performed on the external compression surface (e.g. Figure 9-10 As shown in the figure, CFD calculation is performed on the modified inlet profile to obtain the outer compression surface shock wave 3 and the lip shock wave 4, and the wave system structure is basically close to the inlet.

[0086] Step 3: Under the inlet starting point flow condition (Mach number 4), CFD calculation is carried out on the viscosity-corrected configuration in step 2, and the total pressure recovery after the lip shock wave is 0.75, the local average Mach number is 1.63, and the captured flow rate is 0.22 kg / s. Substituting into the flow relationship, the required flow area is solved to be 722 mm 2 , that is, the flow height of the inner flow channel at this location needs to be at least 7.22mm. Considering the unevenness of the air flow in the cross section, a 25% margin is reserved. The flow height of the inner flow channel of the currently designed 100mm wide binary inlet channel should be greater than 9.02mm.

[0087] Step 4: According to the design requirement in step 3 that the height of the inner flow channel should be greater than 9.02 mm, design the inner flow channel wall surface of the inlet section. The upper wall surface is kept as a horizontal wall surface, and the lower wall surface of the inner flow channel is constructed with a curved wall surface with a 2° expansion angle. The distance between the upper and lower walls is selected to be 12.5 mm. The resulting inlet section flow channel profile is as follows: Fig.11 shown.

[0088] Step 5: Perform quasi-steady CFD calculations on the configuration in step 4 covering its operating range (flight Mach number M3 to M7) to obtain the flow field as follows: Figure 12-16 As shown ( Figure 12-16 The coordinate origin is Figure 8 The starting point of the middle and outer compression surfaces, the horizontal right direction from the origin of the coordinate is the positive direction of the horizontal axis, and the vertical upward direction from the origin of the coordinate is the positive direction of the vertical axis. The units of the vertical and horizontal coordinates are: m, U represents the speed of the airflow along the horizontal axis). The shoulder separation zone is formed at the lip shock wave incident position. The flow area of ​​the external mainstream area at the apex of the separation zone is the smallest. The minimum flow cross section is the aerodynamic throat (the section marked II in the figure, and the mark I is the inlet section of the inner flow channel). The contraction and expansion sections are formed upstream and downstream of the aerodynamic throat. As the incoming flow conditions change, the shoulder separation zone in the inlet duct adaptively adjusts its shape, and the area of ​​the aerodynamic throat (section II) also changes accordingly. The position of the separation zone is always maintained at the lip shock wave incident point. Although the separation shock wave intensity is also adaptively adjusted with the change of the incoming flow, its position is always maintained in the inner flow channel instead of separating from the lip to cause overflow.

[0089] Step 6: The inlet duct reference surface designed in step 5 is traced with an elliptical inlet shape to form a streamline. Fig.17 The inward-turning air intake is shown.

[0090] Step seven, CFD calculation is performed on the inner-rotating inlet formed in step six. In the case of the inlet outlet cross-section (x=361 mm), the outlet parameters of the inlet section curved inner flow channel and the inlet isolation section are shown in Table 2, which meet the design requirements.

[0091] Table 2

[0092] Total pressure recovery coefficient Target total pressure recovery coefficient Exit Mach number Target exit Mach number M4 0.62 Greater than 0.65 2.25 Less than 2.4 M6 0.41 Greater than 0.40 2.66 Less than 2.7

[0093] It should be noted that the inlet non-viscous wave system scheme in step 1 of this example can be adaptively replaced not only with a plane compression binary inlet scheme, but also with a curved surface compression inlet scheme based on curved shock wave theory.

[0094] The viscosity correction method in step two can not only be corrected by CFD method, but also replaced by theoretical calculation method and experimental method. The key point is to improve the inlet flow capture coefficient.

[0095] In the scheme for generating the flow channel wall surface in the inlet duct in step 4, the lower wall surface is not limited to being generated by parameterized curves, but can also be generated and replaced by methods such as streamline tracing to achieve a similar effect.

[0096] Example 1 proposes a method for achieving wide-range adaptive adjustment of the inlet duct by using reasonable surface design to obtain the separation zone under appropriate conditions, which is an innovation in the design method of fixed-geometry wide-range inlet duct. The effects achieved are: 1. After the geometric dimensions of the inlet duct are determined, there is no need to add additional flow control methods or change the geometric structure and dimensions during wide-range operation. The high-speed inlet duct can be directly used to achieve adaptive wide-range operation by using the aerodynamic throat; 2. The risk of thermal structure design is reduced, and it has higher feasibility.

[0097] The above solution is only an illustration of a preferred embodiment, but is not limited thereto. When implementing the present invention, appropriate replacement and / or modification can be performed according to user needs.

[0098] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0099] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized. Therefore, without departing from the general concept defined by the claims and equivalent scope, the present invention is not limited to the specific details and the illustrations shown and described here.

Claims

1. A method for designing a non-suction intake duct that takes into account both wide-range operation and performance, characterized in that: During the design process of the high-speed inlet, the inlet section of the high-speed inlet is designed based on the aerodynamic throat function of the shoulder separation zone in the high-speed inlet, so that under different incoming flow conditions, the aerodynamic throat area can be adjusted by changing the morphology of the shoulder separation zone in the aerodynamic throat, so as to achieve wide-range operation of the inlet without suction and variable geometry adjustment while taking into account the design and non-design state performance.

2. A method for designing a non-suction intake duct that takes into account both wide-range operation and performance according to claim 1, characterized in that: The steps include: S1. Under the given design point inflow conditions, the external compression surface and the lip are designed according to the inlet outlet parameter requirements to obtain an inlet profile scheme in which the external compression shock wave and the lip shock wave meet the shock wave contact requirements; S2, make a viscosity correction to the external compression surface configuration in the inlet profile solution obtained in S1, so that the external compression shock wave of the design point in the flow field under viscosity conditions is close to the inlet; S3. Under the given starting point flow conditions, solve the minimum flow area A corresponding to the lip shock wave parameters min ; S4. The minimum flow area A according to S3 min Designing the profile of the inlet section of the air intake duct to obtain the reference profile of the air intake duct, wherein the starting point flow condition given by S3 must provide sufficient flow capacity for the reference profile of the air intake duct; S5. Carry out CFD calculation within the operating range for the reference profile of the air intake duct described in S4, and check the adaptive adjustment capability of the pneumatic throat in the air intake duct according to the flow field characteristics. If the requirements are met, proceed to S6, otherwise return to S3; S6. Based on the inlet reference profile that has passed the inspection, construct an inward-turning inlet profile with an aerodynamic throat; S7, performing CFD calculation on the inner rotating air intake obtained in S6, and obtaining performance parameters of the air intake with the aerodynamic throat adaptive adjustment capability under various operating conditions according to the calculation results, and comparing the performance parameters with the design index to evaluate whether the current design meets the index requirements, and if not, returning to S3 to adjust the design of the flow channel wall surface in the inlet section of the air intake; Among them, in S3, the minimum flow area A corresponding to the lip shock wave parameters is solved min When considering the unevenness of the airflow in the flow section, the minimum flow area A min Add a 25% margin to the solution.

3. A method for designing a non-suction intake duct that takes into account both wide-range operation and performance according to claim 2, characterized in that: In S3, solve the minimum flow area A corresponding to the lip shock wave parameters min The methods include: S31, given the flow conditions at the starting point, calculate the external compression shock wave and lip shock wave in the inlet profile scheme modified by S2; S32, obtain the total pressure recovery coefficient σ of the lip shock wave under the condition of the starting point flow 21 、Mach number Ma 21 and capture flow q2; S33, total pressure recovery coefficient σ after the lip shock wave obtained according to S32 21 、Mach number Ma 21 And capture the flow rate q2, use the flow relationship to solve the lip shock wave parameters corresponding to the minimum flow area A min .

4. A method for designing a non-suction intake duct that takes into account both wide-range operation and performance according to claim 2, characterized in that: In S4, the upper wall surface of the inner flow channel in the inlet section profile is a horizontal wall surface, and the lower wall surface is a plane that forms an angle with the outer compression surface or a curved surface with a parameter rule.

5. The method for designing a non-suction intake duct that takes into account both wide-range operation and performance according to claim 1, characterized in that: In the inlet with the ability of adaptive adjustment of the aerodynamic throat, a shoulder separation zone is formed at the lip shock wave incident position of the inlet, and the flow area A of the external mainstream zone at the apex of the separation zone is min Minimum, the minimum flow cross section is the pneumatic throat, and the upstream and downstream of the pneumatic throat form contraction and expansion sections respectively; The adaptive adjustment capability of the pneumatic throat means that as the incoming flow conditions change, the shape of the shoulder separation zone will change accordingly, thereby causing the pneumatic throat area to change accordingly, achieving adaptive adjustment.

6. A method for designing a non-suction intake duct that takes into account both wide-range operation and performance according to claim 2, characterized in that: In S5, the method of testing the adaptive adjustment capability of the aerodynamic throat in the inlet duct is that when the separation shock wave is located upstream of the lip and causes a large amount of overflow, or when a large amplitude oscillation occurs in the shoulder separation area, the design is judged to have failed.

7. The method for designing a non-suction intake duct that takes into account both wide-range operation and performance according to claim 2, characterized in that: In S6, the method of constructing the inner rotating inlet profile with aerodynamic throat is as follows: S60, based on the air intake duct reference profile in S6, rotating along the symmetry axis to form an axisymmetric inner cone air intake duct; S61, obtaining the capture area of ​​the air inlet according to the capture flow rate q2, and designing the shape of the air inlet according to the capture area; S62. In the flow field of the inner cone inlet, streamlines are traced from the inlet entrance to form a series of streamlines; S63. Combine the streamlines downstream of the leading edge shock wave to form an inward-turning inlet profile with an aerodynamic throat.

8. The method for designing a non-suction intake duct that takes into account both wide-range operation and performance according to claim 2, characterized in that: In S7, the design scheme for adjusting the flow channel wall surface in the inlet section mainly includes: When the outlet Mach number is too high, the flow area needs to be reduced to increase the compression capacity; When the total pressure recovers too low, it is necessary to expand the flow area to reduce the total pressure loss.

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