Steady-state temperature distortion air inlet runner and design method

Abstract

The invention belongs to the technical field of aero-engine turbine tests, and particularly relates to a steady-state temperature distortion air inlet runner and a design method.The air inlet runner comprises an inner ring and an outer ring, and the inner ring and the outer ring form an annular air inlet runner; the air inlet flow channel is sequentially divided into a rectification section, a heating section, a contraction section, a straight section and a switching section in the air flow direction. Wherein the inner ring of the contraction section comprises a first contraction section inner ring (3) which is gradually contracted and a straight second contraction section inner ring (4), and an included angle between the first contraction section inner ring (3) and the second contraction section inner ring (4) is adjusted and designed, so that the flow capacity of a flow channel is improved, and the flow loss is reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of aero-engine turbine testing, and in particular relates to a steady-state temperature-distorted inlet flow duct and a design method thereof. Background Art

[0002] Temperature distortion is a destabilizing factor affecting aircraft engine aerodynamic stability, severely impacting smooth and safe engine operation. Based on the distortion characteristics, temperature distortion can be categorized as steady-state and transient. To comprehensively evaluate aircraft engine performance under temperature distortion conditions, both steady-state and transient temperature distortion tests are typically required. The electrically heated steady-state temperature distortion generator is a novel device specifically designed for steady-state temperature distortion testing, offering advantages such as high safety, low construction and testing costs, and high simulation accuracy.

[0003] However, in order to balance simulation accuracy and test economy in the steady-state temperature distortion test, higher precision requirements are placed on the inlet flow channel of the distortion test device. First, the steady-state temperature distortion test lasts for a long time, resulting in a large energy consumption for heating the airflow, and the airflow in the inlet flow channel will exchange heat with the external environment through the outer wall of the flow channel, thereby generating heat dissipation. Therefore, the flow channel design needs to minimize internal heat dissipation and improve the energy utilization efficiency of the heating unit to reduce the test cost. Secondly, in order to ensure accurate simulation of steady-state temperature distortion without introducing other destabilizing factors, it is necessary to ensure the uniformity of the total pressure field and achieve low total pressure loss during the airflow transport process. Finally, the uniformity of the temperature field inside the high-temperature zone in the heating sector should be ensured as much as possible to improve the simulation accuracy of the distortion temperature field.

[0004] Therefore, it is urgent to develop a steady-state temperature distortion inlet flow duct with low total pressure loss, low heat dissipation and high temperature field uniformity to meet the test requirements of higher precision and efficiency. Summary of the Invention

[0005] In order to solve the above problems, the present application provides a steady-state temperature distortion intake air duct, comprising: an inner ring and an outer ring, the inner ring and the outer ring forming an annular intake air duct; The inlet air duct is divided into a straightening section, a heating section, a contraction section, a straight section and a transition section in sequence along the airflow direction; The inner rings include a rectifying section inner ring located in the rectifying section, a heating section inner ring located in the heating section, a first contraction section inner ring and a second contraction section inner ring located in the contraction section, a straight section inner ring located in the straight section, and a transition section inner ring located in the transition section; the heating section inner ring is a straight cylinder, the front end of which is blocked by the hemispherical rectifying section inner ring, and the rear end of which is connected to the first contraction section inner ring, the radius of which gradually decreases along the airflow direction; the second contraction section inner ring, the straight section inner ring, and the transition section inner ring are all straight cylinders; The outer ring includes a rectifying section outer ring located in the rectifying section, a heating section outer ring located in the heating section, a contraction section outer ring located in the contraction section, a straight section outer ring located in the straight section, and a transition section outer ring located in the transition section; wherein, the rectifying section outer ring, the heating section outer ring, the straight section outer ring and the transition section outer ring are all straight cylindrical, the radius of the contraction section outer ring gradually decreases along the airflow direction, and a heating tube is arranged between the heating section inner ring and the heating section outer ring.

[0006] Preferably, a plurality of circumferentially distributed thermal insulation partitions are provided in the heating section, the contraction section and the straight section, and the thermal insulation partitions divide the inlet air flow passages of the heating section, the contraction section and the straight section into a plurality of sector-shaped areas, wherein each sector-shaped area of ​​the heating section is covered with heating tubes.

[0007] Preferably, the outer ring is composed of an outer shell of a heat-insulating layer located on the outer layer, a heat-insulating material located on the middle layer, and an inner shell of a heat-insulating layer located on the inner layer.

[0008] A method for designing a steady-state temperature-distorted intake air duct is provided, and includes the following steps: Step 1: Determine the outer ring radius R1 and the inner ring radius R2 of the contraction section inlet based on the determined cross-sectional dimensions of the heating section outlet; determine the outer ring radius R3 and the inner ring radius R4 of the transition section outlet based on the dimensions of the compressor inlet connected to the rear end of the intake duct; Step 2: Based on the sum of the preset axial lengths L of the contraction section, straight section, and transition section; with the rectification requirements of the straight section and transition section as constraints, and the minimum length of the straight section and transition section as the optimization goal, optimize and determine the length of the straight section. l 1. Transfer section length l 2; Step 3: Based on the outer ring radius R1 of the contraction section inlet, the inner ring radius R2 of the contraction section inlet, the outer ring radius R3 of the transition section outlet, the inner ring radius R4 of the transition section outlet, and the length of the straight section l 1 and the length of the transfer section l 2. The turning angle of the inner wall of the contraction section is determined by the maximum axial change rate of the cross-sectional area of ​​the inlet flow channel being less than the set threshold. α 2. Chamfer r at the junction of the contraction section wall and the straight section wall; Step 4: Simulate and extract the aerodynamic parameters of the inlet duct outlet section, calculate the flow rate, radial temperature distortion intensity, and circumferential total pressure unevenness at the outlet of the inlet duct section, and output the geometric parameters of the inlet duct if the flow rate, radial temperature distortion intensity, and circumferential total pressure unevenness meet the test requirements. If they do not meet the requirements, return to step 3.

[0009] Preferably, the calculation method of radial temperature distortion intensity includes: The outlet cross section is divided into n circular rings of equal area along the radial direction. The radial distortion intensity of the i-th circular ring is for: ; Where, is the average temperature at the outlet of the cross section, and the calculation formula is:

[0010] Where, is the temperature obtained at the measuring point, Expressed as the average temperature of the ith ring in the radial direction, The definition is as follows:

[0011] represents the function obtained by linear fitting of the temperature distribution along the circumferential direction on the i-th ring, Indicates the circumferential angle of the measuring point.

[0012] Preferably, Circumferential total pressure unevenness The expression is:

[0013] Where, is the low-pressure average total pressure recovery coefficient, is the average total pressure recovery coefficient on the engine inlet aerodynamic interface, and its expression is:

[0014] Where, are the circumferential starting and ending positions of the low-pressure zone boundary, Indicates the relative radius of the inlet section hub, Represents polar coordinates The total pressure recovery coefficient at Indicates the circumferential angle of the measuring point, Indicates the radial height of the measuring point.

[0015] The intake air duct of the present application has the advantages of low pressure loss, low heat loss and high uniformity of temperature field. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a longitudinal cross-sectional view of a steady-state temperature distortion intake air duct according to a preferred embodiment of the present application.

[0017] Figure 2 This is a cross-sectional view of a steady-state temperature-distorted intake air duct according to a preferred embodiment of the present application.

[0018] Figure 3 This is a schematic diagram of the external environmental temperature layer structure of the steady-state temperature distortion inlet flow duct in a preferred embodiment of the present application.

[0019] Figure 4 This is a schematic diagram of the structural design parameters of the steady-state temperature distortion intake air duct according to a preferred embodiment of the present application.

[0020] Figure 5 This is a flow chart of the design of a steady-state temperature-distorted intake air duct according to a preferred embodiment of the present application.

[0021] Figure 6 This is a graph of the area and Mach number along the conventional flow channel design in a preferred embodiment of the present application.

[0022] Figure 7 This is a graph of cross-sectional area and Mach number along the steady-state temperature distortion flow channel design in a preferred embodiment of the present application.

[0023] Figure 8 This is a diagram of the radial temperature distortion intensity of the flow channel outlet cross section in a steady-state temperature distortion flow channel design according to a preferred embodiment of the present application. DETAILED DESCRIPTION

[0024] To make the technical solution and its advantages of the present application clearer, the technical solution of the present application will be described in further detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of the present application and are only used to explain the present application, not to limit the present application. It should be noted that, for ease of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0025] like Figure 1-Figure 4 As shown, the present application provides a steady-state temperature distortion intake air duct, the cross section of which is a semicircle or a full circle, including: an inner ring and an outer ring, the inner ring and the outer ring forming an annular intake air duct; The inlet air duct is divided into a straightening section, a heating section, a contraction section, a straight section and a transition section in sequence along the airflow direction; The inner rings include a rectifying section inner ring 1 located in the rectifying section, a heating section inner ring 2 located in the heating section, a first contraction section inner ring 3 and a second contraction section inner ring 4 located in the contraction section, a straight section inner ring 5 located in the straight section, and a transition section inner ring 6 located in the transition section. The heating section inner ring 2 is a straight cylinder, with its front end blocked by the hemispherical rectifying section inner ring 1 and its rear end connected to the first contraction section inner ring 3, whose radius gradually decreases along the airflow direction. The second contraction section inner ring 4, the straight section inner ring 5, and the transition section inner ring 6 are all straight cylinders. The outer ring includes a straight section outer ring 7 located in the straight section, a heating section outer ring 8 located in the heating section, a contraction section outer ring 9 located in the contraction section, a straight section outer ring 10 located in the straight section, and a transition section outer ring 11 located in the transition section; wherein, the straight section outer ring 7, the heating section outer ring 8, the straight section outer ring 10 and the transition section outer ring 11 are all straight cylindrical, the radius of the contraction section outer ring 9 gradually decreases along the airflow direction, and a heating tube 12 is arranged between the heating section inner ring 2 and the heating section outer ring 8.

[0026] In some optional embodiments, a plurality of circumferentially distributed thermal insulation partitions 13 are provided in the heating section, the contraction section and the straight section, and the thermal insulation partitions 13 divide the inlet air flow passages of the heating section, the contraction section and the straight section into a plurality of sector-shaped areas, wherein each sector-shaped area of ​​the heating section is covered with heating tubes 12.

[0027] In some optional embodiments, the outer ring is composed of an outer shell 16 of a thermal insulation layer located on the outer layer, a thermal insulation material 15 located on the middle layer, and an inner shell 14 of a thermal insulation layer located on the inner layer.

[0028] A design method for a steady-state temperature-distorted intake duct, such as Figure 5 As shown, the method for designing the steady-state temperature distortion intake air duct includes the following steps: Step 1: Determine the outer and inner radii R1 and R2 of the contraction section inlet based on the determined cross-sectional dimensions of the heating section outlet, specifically based on engine size. Determine the outer and inner radii R3 and R4 of the transition section outlet based on the dimensions of the compressor inlet connected to the rear end of the intake duct, specifically based on the spacing between the front and rear devices.

[0029] Step 2: Based on the sum of the preset axial lengths L of the contraction section, straight section, and transition section; with the rectification requirements of the straight section and transition section as constraints, and the minimum length of the straight section and transition section as the optimization goal, optimize and determine the length of the straight section. l 1. Transfer section length l 2; Step 3: Based on the outer ring radius R1 of the contraction section inlet, the inner ring radius R2 of the contraction section inlet, the outer ring radius R3 of the transition section outlet, the inner ring radius R4 of the transition section outlet, and the length of the straight section l 1 and the length of the transfer section l 2. The turning angle of the inner wall of the contraction section is determined by the maximum axial change rate of the cross-sectional area of ​​the inlet flow channel being less than the set threshold. α 2. The chamfer r at the junction of the contraction section wall and the straight section wall is used to control the change of the cross-sectional area of ​​the inlet flow channel along the airflow direction within a certain range. α The existence of 2 causes the cross-sectional integral of the intake flow passage to change twice, making the cross-sectional area change more gradual.

[0030] Step 4: Simulate and extract the aerodynamic parameters of the intake duct outlet section. This includes: Using commercial software, calculate the flow field within the intake duct under typical operating conditions. Set the intake duct inlet and outlet boundary conditions to "inlet total pressure minus outlet static pressure." By adjusting the static pressure, approach the intake duct's design operating conditions or ultimate flow capacity. Output the flow field calculation results, and extract the aerodynamic parameters of the intake duct outlet section from the calculation results. Calculate the flow rate, radial temperature distortion intensity, and circumferential total pressure non-uniformity at the outlet of the intake duct section. If the flow rate, radial temperature distortion intensity, and circumferential total pressure non-uniformity meet the test requirements, output the geometric parameters of the intake duct. If not, return to step 3.

[0031] Preferably, the calculation method of radial temperature distortion intensity includes: The outlet cross section is divided into n circular rings of equal area along the radial direction. The radial distortion intensity of the i-th circular ring is for: ; Where, is the average temperature at the outlet of the cross section, and the calculation formula is:

[0032] Where, is the temperature obtained at the measuring point, Expressed as the average temperature of the ith ring in the radial direction, The definition is as follows:

[0033] represents the function obtained by linear fitting of the temperature distribution along the circumferential direction on the i-th ring, Indicates the circumferential angle of the measuring point.

[0034] Preferably, the circumferential total pressure unevenness The expression is:

[0035] Where, is the low-pressure average total pressure recovery coefficient, is the average total pressure recovery coefficient on the engine inlet aerodynamic interface, and its expression is:

[0036] Where, are the circumferential starting and ending positions of the low-pressure zone boundary, Indicates the relative radius of the inlet section hub, Represents polar coordinates The total pressure recovery coefficient at Indicates the circumferential angle of the measuring point, Indicates the radial height of the measuring point.

[0037] The intake flow channel of the present application has the advantages of low pressure loss, low heat loss, and highly uniform temperature field, as shown in Table 1, which shows the outlet cross-sectional flow rate and pressure loss of the two flow channel designs. At the extreme flow rate, the steady-state temperature-distorted intake flow channel flow rate of the present application increased from 3.76 kg / s to 4.24 kg / s, and the total pressure loss decreased from 5.08% to 4.89%. The steady-state temperature-distorted intake flow channel of the present application has better flow capacity and lower total pressure loss.

[0038] Figure 6 、 Figure 7 It is the conventional flow channel design method of along-line area and Mach number and the along-line area and Mach number of this application. Figure 6 The airflow in the conventional flow channel decreases rapidly along the area in the region of X / L=0.4~0.62, and the Mach number increases rapidly, reaching the maximum Mach number of 0.73 when X / L=0.62 along the flow channel. Figure 7 The steady-state temperature-distorted inlet flow duct shown optimizes the turning angle of the inner wall of the contraction section, so the changes in area and Mach number along the way are smoother.

[0039] Table 1 Outlet cross-sectional flow rate and pressure loss

[0040] In the steady-state temperature distortion inlet flow duct of this application, under the extreme state, the blockage of the total pressure field on the upper wall is eliminated, the uniformity of the pressure field is significantly improved, and the cross-sectional flow capacity is significantly enhanced.

[0041] This application uses radial temperature distortion intensity to evaluate the uniformity of the outlet flow field of the designed intake duct. Figure 8 As shown, the radial temperature distortion intensity in the single-channel model reaches its maximum at the third ring, which is only 2.0%, meeting the working requirements. Therefore, the steady-state temperature distortion flow channel of the present invention has lower temperature dissipation and high uniformity of the temperature field.

[0042] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A steady-state temperature distortion intake air duct, characterized in that: include: The inner ring and the outer ring form an annular intake air flow passage; The inlet air duct is divided into a straightening section, a heating section, a contraction section, a straight section and a transition section in sequence along the airflow direction; The inner ring comprises a rectifying section inner ring (1) located in the rectifying section, a heating section inner ring (2) located in the heating section, a first contraction section inner ring (3) and a second contraction section inner ring (4) located in the contraction section, a straight section inner ring (5) located in the straight section, and a transition section inner ring (6) located in the transition section; wherein the heating section inner ring (2) is straight-cylindrical, its front end is blocked by the hemispherical rectifying section inner ring (1), and its rear end is connected to the first contraction section inner ring (3) whose radius gradually decreases along the airflow direction; the second contraction section inner ring (4), the straight section inner ring (5), and the transition section inner ring (6) are all straight-cylindrical; The outer ring comprises a rectifying section outer ring (7) located in the rectifying section, a heating section outer ring (8) located in the heating section, a contraction section outer ring (9) located in the contraction section, a straight section outer ring (10) located in the straight section, and a transition section outer ring (11) located in the transition section; wherein the rectifying section outer ring (7), the heating section outer ring (8), the straight section outer ring (10), and the transition section outer ring (11) are all straight-cylinder-shaped, the radius of the contraction section outer ring (9) gradually decreases along the airflow direction, and a heating tube (12) is arranged between the heating section inner ring (2) and the heating section outer ring (8).

2. The steady-state temperature distortion intake air duct according to claim 1, characterized in that: A plurality of circumferentially distributed heat-insulating partitions (13) are provided in the heating section, the contraction section, and the straight section. The heat-insulating partitions (13) divide the air inlet passages of the heating section, the contraction section, and the straight section into a plurality of sector-shaped areas, wherein each sector-shaped area of ​​the heating section is covered with heating tubes (12).

3. The steady-state temperature distortion intake air duct according to claim 1, characterized in that: The outer ring is composed of an outer shell (16) of a heat-insulating layer located on the outer layer, a heat-insulating material (15) located on the middle layer, and an inner shell (14) of a heat-insulating layer located on the inner layer.

4. A method for designing a steady-state temperature-distorted intake air duct, for designing a steady-state temperature-distorted intake air duct according to any one of claims 1 to 3, characterized in that: The steps include: Step 1: Determine the outer ring radius R1 and the inner ring radius R2 of the contraction section inlet based on the determined cross-sectional dimensions of the heating section outlet; determine the outer ring radius R3 and the inner ring radius R4 of the transition section outlet based on the dimensions of the compressor inlet connected to the rear end of the intake duct; Step 2: Based on the sum of the preset axial lengths L of the contraction section, straight section, and transition section; with the rectification requirements of the straight section and transition section as constraints, and the minimum length of the straight section and transition section as the optimization goal, optimize and determine the length of the straight section. l 1. Transfer section length l 2; Step 3: Based on the outer ring radius R1 of the contraction section inlet, the inner ring radius R2 of the contraction section inlet, the outer ring radius R3 of the transition section outlet, the inner ring radius R4 of the transition section outlet, and the length of the straight section l 1 and the length of the transfer section l 2. The turning angle of the inner wall of the contraction section is determined by the maximum axial change rate of the cross-sectional area of ​​the inlet flow channel being less than the set threshold. α 2. Chamfer r at the junction of the contraction section wall and the straight section wall; Step 4: Simulate and extract the aerodynamic parameters of the inlet duct outlet section, calculate the flow rate, radial temperature distortion intensity, and circumferential total pressure unevenness at the outlet of the inlet duct section, and output the geometric parameters of the inlet duct if the flow rate, radial temperature distortion intensity, and circumferential total pressure unevenness meet the test requirements. If they do not meet the requirements, return to step 3.

5. The method for designing a steady-state temperature distortion intake air duct according to claim 4, wherein: The calculation method of radial temperature distortion intensity includes: The outlet cross section is divided into n circular rings of equal area along the radial direction. The radial distortion intensity of the i-th circular ring is for: ； Where, is the average temperature at the outlet of the cross section, and the calculation formula is: ； Where, is the temperature obtained at the measuring point, Expressed as the average temperature of the ith ring in the radial direction, The definition is as follows: ， represents the function obtained by linear fitting of the temperature on the ith ring along the circumferential direction, Indicates the circumferential angle of the measuring point.

6. The method for designing a steady-state temperature distortion intake air duct according to claim 4, wherein: The circumferential total pressure unevenness The expression is: ； Where, is the low-pressure average total pressure recovery coefficient, is the average total pressure recovery coefficient on the engine inlet aerodynamic interface, and its expression is: ； ； ； Where, are the circumferential starting and ending positions of the low-pressure zone boundary, Indicates the relative radius of the inlet section hub, Represents polar coordinates The total pressure recovery coefficient at Indicates the circumferential angle of the measuring point, Indicates the radial height of the measuring point.

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