A steady temperature distortion inlet and design method

Abstract

The application belongs to the technical field of turbine test of an aero-engine, and particularly relates to a steady-state temperature distortion inlet flow channel and a design method. The inlet flow channel comprises an inner ring and an outer ring, and the inner ring and the outer ring form an annular inlet flow channel. The inlet flow channel is sequentially divided into a straightening section, a heating section, a contraction section, a straight section and a transition section along an airflow direction. The inner ring of the contraction section comprises a first contraction section inner ring (3) which gradually contracts and a second contraction section inner ring (4) which is straight. By adjusting the included angle between the first contraction section inner ring (3) and the second contraction section inner ring (4), the flow capacity of the flow channel is improved, and the flow loss is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aero-engine turbomachinery test, and particularly relates to a steady-state temperature distortion inlet flow channel and a design method. BACKGROUND

[0002] Temperature distortion is one of the factors affecting the aero-engine aerodynamic stability, and seriously affects the smooth and safe operation of the engine. According to the distortion characteristics, temperature distortion can be divided into steady-state temperature distortion and transient temperature distortion. In order to comprehensively evaluate the working ability of the aero-engine under the condition of temperature distortion, it is usually necessary to carry out steady-state and transient temperature distortion tests respectively. Among them, the electric heating type steady-state temperature distortion generating device is a new type of device for steady-state temperature distortion test, which has the advantages of high safety, low construction and test cost, and high simulation accuracy.

[0003] However, in order to consider both simulation accuracy and test economy in steady-state temperature distortion test, higher precision requirements are put forward for the inlet flow channel of the distortion test device. First, the steady-state temperature distortion test lasts for a long time, resulting in large energy consumption of the heated airflow, and the airflow exchanges heat with the outside environment through the outer wall of the flow channel, thereby generating heat dissipation, so the flow channel design needs to minimize internal heat dissipation and improve the energy utilization efficiency of the heating unit to reduce test cost. Secondly, in order to ensure accurate simulation of steady-state temperature distortion without introducing other stability reduction factors, the uniformity of the total pressure field needs to be ensured, and low total pressure loss needs to be achieved during airflow transportation. Finally, the temperature field uniformity 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 channel with low total pressure loss, low heat dissipation and high temperature field uniformity to meet the test requirements of higher precision and efficiency. SUMMARY

[0005] In order to solve the above problems, the application provides a steady-state temperature distortion inlet flow channel, which comprises: an inner ring and an outer ring, the inner ring and the outer ring form an annular inlet flow channel;

[0006] The inlet flow channel is sequentially divided into a straightening section, a heating section, a contraction section, a straight section and an adapter section along the airflow direction;

[0007] The inner ring comprises a straightening section inner ring located in the straightening 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 an adapter section inner ring located in the adapter section; wherein the heating section inner ring is a straight cylinder, the front end of which is blocked by a hemispherical straightening section inner ring, and the rear end is connected to the first contraction section inner ring with a gradually decreasing radius along the airflow direction, the second contraction section inner ring, the straight section inner ring and the adapter section inner ring are all straight cylinders;

[0008] The outer ring comprises an outer ring of the rectifying section, an outer ring of the heating section, an outer ring of the converging section, an outer ring of the straight section, and an outer ring of the transition section; wherein the outer rings of the rectifying section, the heating section, the straight section, and the transition section are straight cylinders, the radius of the outer ring of the converging section gradually decreases along the airflow direction, and the heating pipes are arranged between the inner ring of the heating section and the outer ring of the heating section.

[0009] Preferably, a plurality of heat preservation partitions are arranged in the heating section, the converging section, and the straight section, and the heat preservation partitions divide the air inlet channel of the heating section, the converging section, and the straight section into a plurality of fan-shaped areas, wherein each fan-shaped area of the heating section is filled with heating pipes.

[0010] Preferably, the outer ring is composed of an outer shell of the heat preservation layer located in the outer layer, a heat preservation material located in the middle layer, and an inner shell of the heat preservation layer located in the inner layer.

[0011] A design method of a steady-state temperature distortion air inlet channel, for designing the steady-state temperature distortion air inlet channel, comprising the following steps:

[0012] Step 1: determining the outer ring radius R1 of the converging section inlet and the inner ring radius R2 of the converging section inlet according to the determined cross-sectional size of the heating section outlet; determining the outer ring radius R3 of the transition section outlet and the inner ring radius R4 of the transition section outlet according to the size of the compressor inlet connected at the rear end of the air inlet channel;

[0013] Step 2: determining the length of the straight section based on the sum L of the axial lengths of the converging section, the straight section, and the transition section; taking the rectification requirements of the straight section and the transition section as constraints, and taking the minimum length of the straight section and the transition section as the optimization target; l 1, the length of the transition section l 2;

[0014] Step 3: based on the outer ring radius R1 of the converging section inlet, the inner ring radius R2 of the converging section inlet, the outer ring radius R3 of the transition section outlet, the inner ring radius R4 of the transition section outlet, the length l 1 of the straight section, and the length l 2 of the transition section, determining the turning angle α 2 of the inner wall surface of the converging section and the chamfer r of the connection between the wall surface of the converging section and the wall surface of the straight section, so that the maximum value of the cross-sectional area change rate of the air inlet channel along the axial direction is less than a set threshold value;

[0015] Step 4: simulating and extracting the aerodynamic parameters of the outlet cross section of the air inlet channel, calculating the flow rate, the radial temperature distortion intensity, and the circumferential total pressure non-uniformity of the outlet cross section of the air inlet channel, and outputting the geometric parameters of the air inlet channel when the flow rate, the radial temperature distortion intensity, and the circumferential total pressure non-uniformity all meet the test requirements; otherwise, returning to Step 3.

[0016] Preferably, the method for calculating the radial temperature distortion intensity comprises:

[0017] The outlet section is divided into n equal-area annuli in the radial direction, and the radial distortion intensity of the i-th annulus is :

[0018] ;

[0019] wherein, is the average temperature at the outlet of the section, and the calculation formula is:

[0020]

[0021] wherein, is the temperature obtained at the measuring point, represents the average temperature of the i-th annulus in the radial direction, is defined as follows:

[0022]

[0023] represents a function obtained by linear fitting the circumferential distribution of the temperature in the i-th annulus, represents the circumferential angle of the measuring point.

[0024] Preferably,

[0025] The circumferential total pressure non-uniformity is expressed as:

[0026]

[0027] wherein, is the average total pressure recovery coefficient in the low-pressure area, is the average total pressure recovery coefficient on the aerodynamic interface of the engine inlet, and the expression is:

[0028]

[0029] wherein, are the circumferential start and end positions of the low-pressure area boundary, represents the relative radius of the hub of the inlet section, represents the total pressure recovery coefficient at the polar coordinate , represents the circumferential angle of the measuring point, represents the radial height of the measuring point.

[0030] The inlet flow channel of the present application has the advantages of low pressure loss, low heat loss, and high uniformity of the temperature field. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1is a preferred embodiment of the application steady-state temperature distortion inlet flow passage longitudinal section view.

[0032] Figure 2 is a preferred embodiment of the application steady-state temperature distortion inlet flow passage cross section view.

[0033] Figure 3 is a preferred embodiment of the application steady-state temperature distortion inlet flow passage outer ring insulation layer structure schematic diagram.

[0034] Figure 4 is a preferred embodiment of the application steady-state temperature distortion inlet flow passage structure design parameter schematic diagram.

[0035] Figure 5 is a preferred embodiment of the application steady-state temperature distortion inlet flow passage design flow chart.

[0036] Figure 6 is a preferred embodiment of the application conventional flow passage design along the way area and Mach number curve diagram.

[0037] Figure 7 is a preferred embodiment of the application steady-state temperature distortion flow passage design along the way cross-sectional area and Mach number curve diagram.

[0038] Figure 8 is a preferred embodiment of the application steady-state temperature distortion flow passage design flow passage outlet cross section radial temperature distortion strength diagram. DETAILED DESCRIPTION

[0039] In order to make the technical scheme of the application and its advantages clearer, the technical scheme of the application will be further clearly, completely and specifically described below with reference to the drawings. It should be understood that the specific examples described herein are only part of the embodiments of the application, and are used to explain the application, but not to limit the application. It should be noted that, for the convenience of description, only parts related to the application are shown in the drawings, and other related parts can be referred to the general design. In the case of no conflict, the embodiments in the application and the technical features in the embodiments can be combined to obtain new embodiments.

[0040] As shown in Figures 1-4 , the application provides a steady-state temperature distortion inlet flow passage, which has a semi-circular or circular cross section, comprising: an inner ring and an outer ring, the inner ring and the outer ring forming an annular inlet flow passage;

[0041] The inlet flow passage is sequentially divided into: a straightening section, a heating section, a contraction section, a straight section and a transition section along the airflow direction;

[0042] The inner ring includes a rectification section inner ring 1 located at the rectification section, a heating section inner ring 2 located at the heating section, a first contraction section inner ring 3 and a second contraction section inner ring 4 located at the contraction section, a straight section inner ring 5 located at the straight section, and a transition section inner ring 6 located at the transition section; wherein the heating section inner ring 2 is a straight cylinder, the front end of which is blocked by the semispherical rectification section inner ring 1, and the rear end is connected to the first contraction section inner ring 3, the second contraction section inner ring 4, the straight section inner ring 5, and the transition section inner ring 6, all of which are straight cylinders, and the radius of the first contraction section inner ring 3 gradually decreases along the airflow direction.

[0043] The outer ring includes a rectification section outer ring 7 located at the rectification section, a heating section outer ring 8 located at the heating section, a contraction section outer ring 9 located at the contraction section, a straight section outer ring 10 located at the straight section, and a transition section outer ring 11 located at the transition section; wherein the rectification 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 cylinders, the radius of the contraction section outer ring 9 gradually decreases along the airflow direction, and the heating section inner ring 2 and the heating section outer ring 8 are arranged with a heating pipe 12 therebetween.

[0044] In some optional embodiments, a plurality of circumferentially distributed heat preservation partitions 13 are arranged in the heating section, the contraction section, and the straight section, and the heat preservation partitions 13 divide the gas inlet flow channel of the heating section, the contraction section, and the straight section into a plurality of fan-shaped areas, wherein each fan-shaped area of the heating section is filled with the heating pipe 12.

[0045] In some optional embodiments, the outer ring is composed of a heat preservation layer outer shell 16 located at the outer layer, a heat preservation material 15 located at the middle layer, and a heat preservation layer inner shell 14 located at the inner layer.

[0046] A design method of a steady-state temperature distortion inlet flow channel, as shown in Figure 5 for designing the steady-state temperature distortion inlet flow channel, comprising the following steps:

[0047] Step 1: determining the contraction section inlet outer ring radius R1 and the contraction section inlet inner ring radius R2 according to the determined cross-sectional size of the heating section outlet, and specifically according to the engine size; determining the transition section outlet outer ring radius R3 and the transition section outlet inner ring radius R4 according to the size of the compressor inlet connected at the rear end of the inlet flow channel, and specifically according to the distance between the front and rear devices.

[0048] Step 2: optimizing the length of the straight section L1 and the length of the transition section L2 according to the sum of the lengths of the contraction section, the straight section, and the transition section, taking the rectification requirements of the straight section and the transition section as constraints, and taking the minimum length of the straight section and the transition section as the optimization target. l 1, the length of the transition section l 2;

[0049] Step 3: determining the length of the heating section L3 based on the contraction section inlet outer ring radius R1, the contraction section inlet inner ring radius R2, the transition section outlet outer ring radius R3, the transition section outlet inner ring radius R4, the length of the straight section L1, and the length of the transition section L2. l1 and the length of the transition section l 2, the maximum value of the axial variation rate of the cross-sectional area of the inlet flow passage is less than a set threshold to determine the turning angle of the inner wall surface of the contraction section α 2, the chamfer r at the connection between the wall surface of the contraction section and the wall surface of the straight section, that is, the variation of the cross-sectional area of the inlet flow passage in the direction of the airflow is controlled within a certain range, α 2, the presence of which causes the cross-sectional area of the inlet flow passage to change twice, making the change in cross-sectional area more gradual.

[0050] Step 4: Simulate the extraction of the aerodynamic parameters of the outlet cross-section of the inlet flow passage, which specifically includes: based on commercial software, calculate the flow field in the inlet flow passage under typical operating conditions. Set the inlet and outlet boundary conditions of the inlet flow passage as "inlet total pressure-outlet static pressure", and approach the design operating conditions or the limit flow capacity of the inlet flow passage by adjusting the static pressure, output the flow field calculation results, and extract the aerodynamic parameters of the outlet cross-section of the inlet flow passage from the calculation results;

[0051] Calculate the flow rate, radial temperature distortion intensity, and circumferential total pressure non-uniformity at the outlet of the inlet flow passage cross-section. When the flow rate, radial temperature distortion intensity, and circumferential total pressure non-uniformity meet the test requirements, output the geometric parameters of the inlet flow passage; if not, return to step 3.

[0052] Preferably, the calculation method of the radial temperature distortion intensity includes:

[0053] Divide the outlet cross-section into n equal-area annuli along the radial direction, and the radial distortion intensity of the i-th annulus is :

[0054] ;

[0055] In the formula, is the average temperature at the outlet cross-section, and the calculation formula is:

[0056]

[0057] In the formula, is the temperature obtained at the measuring point, represents the average temperature of the i-th annulus in the radial direction, is defined as follows:

[0058]

[0059] represents the function obtained by linear fitting the circumferential distribution of the temperature in the i-th annulus, represents the circumferential angle of the measuring point.

[0060] Preferably, the circumferential total pressure non-uniformity is expressed as:

[0061]

[0062] wherein, is the low pressure average total pressure recovery coefficient, is the average total pressure recovery coefficient on the engine inlet aerodynamic interface, which is expressed as:

[0063]

[0064] wherein, is the circumferential starting position and ending position of the low pressure zone boundary, represents the relative radius of the inlet cross-section hub, represents the total pressure recovery coefficient at the polar coordinate represents the circumferential angle of the measuring point, represents the radial height of the measuring point.

[0065] The inlet flow channel of the present application has the advantages of low pressure loss, low heat loss and high uniformity of temperature field. As shown in Table 1, Table 1 is the outlet cross-section flow and pressure loss of two flow channel designs. Under the limit flow, the steady-state temperature distortion inlet flow channel of the present application increases the flow from 3.76 kg / s to 4.24 kg / s and the total pressure loss decreases from 5.08% to 4.89%, and the steady-state temperature distortion inlet flow channel of the present application has better flow capacity and lower total pressure loss.

[0066] Figure 6 、 Figure 7 is the conventional flow channel design along the area and Mach number design method and the along the area and Mach number of the present application. Figure 6 The gas flow in the conventional flow channel in the present application rapidly decreases along the area and rapidly increases the Mach number in the region of X / L=0.4~0.62, and reaches the maximum Mach number 0.73 at the along the X / L=0.62. Figure 7 The steady-state temperature distortion inlet flow channel shown in the present application optimizes the turning angle of the inner wall of the contraction section, so that the along the area and the Mach number change more gently.

[0067] Table 1 Outlet cross-section flow and pressure loss

[0068]

[0069] The steady-state temperature distortion inlet flow channel of the present application eliminates the plugging phenomenon of the upper wall total pressure field under the limit state, significantly improves the uniformity of the pressure field, and significantly enhances the cross-section flow capacity.

[0070] The present application uses the radial temperature distortion strength to evaluate the design of the outlet flow field uniformity of the inlet flow channel. As Figure 8 ​As shown, the radial temperature distortion strength in the single-channel model reaches the maximum at the third circular ring, and is only 2.0%, which meets the working requirements, so that the steady-state temperature distortion runner has lower temperature dissipation and high uniformity of temperature field.

[0071] The above merely illustrates the specific implementation of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A steady temperature distortion inlet flow passage characterized by, Comprise: Inner ring and outer ring, the inner ring and the outer ring form a ring-shaped intake passage; The intake passage is divided into: rectification section, heating section, contraction section, straight section and adapter section in turn along the airflow direction; The inner ring includes rectification section inner ring (1) located in the rectification section, heating section inner ring (2) located in the heating section, first contraction section inner ring (3) and second contraction section inner ring (4) located in the contraction section, straight section inner ring (5) located in the straight section and adapter section inner ring (6) located in the adapter section; wherein the heating section inner ring (2) is a straight cylinder, the front end is blocked by the hemispherical rectification section inner ring (1), and the rear end is connected with the first contraction section inner ring (3) with gradually decreasing radius along the airflow direction; the second contraction section inner ring (4), the straight section inner ring (5) and the adapter section inner ring (6) are all straight cylinders; The outer ring includes rectification section outer ring (7) located in the rectification section, heating section outer ring (8) located in the heating section, contraction section outer ring (9) located in the contraction section, straight section outer ring (10) located in the straight section and adapter section outer ring (11) located in the adapter section; wherein the rectification section outer ring (7), the heating section outer ring (8), the straight section outer ring (10) and the adapter section outer ring (11) are all straight cylinders, the radius of the contraction section outer ring (9) gradually decreases along the airflow direction, and the heating pipe (12) is arranged between the heating section inner ring (2) and the heating section outer ring (8).

2. The steady temperature distortion inlet flow path of claim 1 wherein, A plurality of circumferentially distributed heat preservation partitions (13) are arranged in the heating section, the contraction section and the straight section, and the heat preservation partitions (13) divide the intake passage of the heating section, the contraction section and the straight section into a plurality of fan-shaped areas, wherein each fan-shaped area of the heating section is filled with the heating pipe (12).

3. The steady temperature distortion inlet flow path of claim 1 wherein, The outer ring is composed of a heat preservation layer outer shell (16) located in the outer layer, a heat preservation material (15) located in the middle layer and a heat preservation layer inner shell (14) located in the inner layer.

4. A method of designing a steady temperature distortion inlet flow passage for designing a steady temperature distortion inlet flow passage according to any one of claims 1 to 3, characterized in that, Comprise the following steps: Step 1: determine the contraction section inlet outer ring radius R1 and the contraction section inlet inner ring radius R2 according to the determined cross-sectional size of the heating section outlet; determine the adapter section outlet outer ring radius R3 and the adapter section outlet inner ring radius R4 according to the size of the compressor inlet connected at the rear end of the intake passage; Step 2: according to the sum L of the axial lengths of the preset contraction section, straight section and adapter section; taking the straight section and adapter section fairing requirements as constraints, and taking the minimum length of the straight section and adapter section as the optimization target, the length of the straight section is determined l 1, adapter 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 adapter section outlet, the inner ring radius R4 of the adapter section outlet, the length of the straight section l 1 and the length of the adapter section l 2, the maximum axial variation rate of the cross-sectional area of the intake flow passage is less than a set threshold to determine the turning angle of the inner wall surface of the contraction section α 2 and the chamfer r at the connection between the wall surface of the contraction section and the wall surface of the straight section Step 4: simulate and extract the aerodynamic parameters of the intake passage outlet cross section, calculate the flow rate, radial temperature distortion intensity and circumferential total pressure non-uniformity of the intake passage cross section outlet, and output the geometric parameters of the intake passage when the flow rate, radial temperature distortion intensity and circumferential total pressure non-uniformity all meet the test requirements; if not, return to step 3.

5. The method of designing a steady temperature distortion inlet according to claim 4, wherein The calculation method of radial temperature distortion intensity comprises: Divide the outlet section into n equal-area annuli in the radial direction, and the radial distortion intensity of the i-th annulus is wherein: ； In the formula, is the cross-sectional outlet average temperature, and the calculation formula is: ； wherein the temperature acquired for the measuring point, the average temperature expressed as the i-th circular ring in the radial direction, is defined as follows: ， represents a function of the temperature along the circumferential direction linearly fitted on the i-th annulus, represents the circumferential angle of the measuring point.

6. The method of designing a steady temperature distortion inlet according to claim 4, wherein the circumferential total pressure non-uniformity The expression is: ； wherein is the low pressure average total pressure recovery coefficient, is the average total pressure recovery coefficient at the engine inlet aerodynamic interface, expressed as: ； ； ； wherein the circumferential start and end positions of the low pressure zone boundary, denotes the relative radius of the inlet section hub, denotes the polar coordinate the total pressure recovery coefficient at the point, denotes the circumferential angle of the measuring point, denotes the radial height of the measuring point.

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