Parametric design method of double adjustable bump inlet and bypass duct for turbofan aircraft

Abstract

This invention proposes a parametric design method for the inlet / bypass of a turboprop aircraft with dual adjustable bumps. This method rearranges the heights of various cross-sections of the air intake / bypass according to the centerline equations by changing the control parameters of the centerline equations of the main and bypass air intakes, thereby achieving parametric control of the dual bumps in the inlet / bypass. This invention provides a design method and physical profile support for parametric optimization of inlet / bypass airflow rejection efficiency and aerodynamic performance.

Description

Technical Field

[0001] This invention relates to the field of aircraft design, and in particular to a parametric design method for the air intake of a turboprop aircraft with a dual-bulge adjustable bypass channel. Background Technology

[0002] Turboprop engines have significant advantages such as high propulsion efficiency, low fuel consumption, and good economic performance. They are widely used in short and medium-range transportation at small and medium-sized airports and even simple airfields, and occupy an important position in the fields of regional passenger aircraft and military transport aircraft.

[0003] Turboprop aircraft face various complex and challenging flight environments when performing certain special missions. They may encounter hail while traversing clouds, birds during takeoff and landing, and even ingest sand and gravel during dust storms or on runways such as concrete, grass, or snow. Additionally, ice buildup on the propeller and air intake lip may break off and be ingested into the main engine air intake. Foreign objects entering the air intake can have serious consequences for the engine and the entire aircraft: the mixing of inlet airflow with foreign objects leads to a decrease in flow field quality; larger objects can severely obstruct the inlet airflow, causing significant changes in the total pressure recovery coefficient and total pressure distortion of the air intake. More seriously, if these foreign objects are ingested into the main engine, they can cause severe structural damage, ranging from reduced engine propulsion efficiency and reduced service life to engine surge or shutdown, jeopardizing the flight safety of the turboprop aircraft. Therefore, designing a turboprop aircraft air intake with a bypass channel and high foreign object removal efficiency is crucial.

[0004] The intake duct with a bypass channel has a complex profile, and its profile generation method has been disclosed in Chinese patent application CN114741779A. However, the technical solution disclosed in that patent application does not include the bulges in the main intake channel and the bypass channel.

[0005] The present invention aims to provide a parametric design method for the air intake and bypass passage of a turboprop aircraft with dual adjustable bumps. By parametrically controlling the height of the bumps, the air intake and bypass passages can be controlled to improve the air rejection efficiency and aerodynamic performance, thereby enhancing the safety of the aircraft engine. Summary of the Invention

[0006] Purpose of the invention: This invention provides a parametric design method for the intake and bypass channels of a turboprop aircraft with dual adjustable bulges. By changing the control equations of the centerline of the main channel and the bypass channel, the height of each section of the profile is rearranged so that both the main channel and the bypass channel of the intake have inward bulges. At the same time, the height of the bulges is parametrically controlled to achieve controllable dual bulges in the intake and bypass channels.

[0007] Technical solution: This invention provides a parametric design method for the air intake and bypass passage of a turboprop aircraft with dual adjustable bulges, comprising the following steps:

[0008] 1) Extract the cross-sectional capture profiles of the inlet and outlet of the main intake channel, and express the cross-sectional capture profiles in the form of point sets; then calculate the geometric profiles of each cross-section along the main intake channel based on each cross-section of the inlet and outlet of the main intake channel;

[0009] 2) Arrange the geometric profiles of each section of the main intake channel according to the height variation law of each section along the main intake channel, and form the main intake channel profile; form a main channel bulge protruding into the main intake channel at a designated position of the main intake channel profile.

[0010] 3) Take a preset point in the generated main channel as the interface and extract the cross-sectional profile at the interface. Take the cross-sectional profile at the interface as the inlet cross-sectional profile of the bypass channel and extract the outlet cross-sectional profile of the bypass channel. Form a bypass bulge convex inward into the bypass channel at a specified position on the bypass channel profile of the intake duct. Then, based on the inlet cross-sectional profile and the outlet cross-sectional profile of the bypass channel, calculate the cross-sectional profiles of each bypass channel along the path.

[0011] 4) Based on the center curve of the bypass, rearrange the heights of each section of the bypass to form the bypass profile;

[0012] 5) Chamfer the bypass channel profile and the main channel profile in the modeling software to form an intake duct and bypass channel profile with dual bulges.

[0013] Furthermore, in step 2), the arrangement of each section height follows the centerline control equation, forming the main channel profile. The control equation is:

[0014]

[0015]

[0016] Different parameter b can be selected to create different main channel bulge heights.

[0017] Furthermore, in step 3), the point at 1 / 9 of the main channel length is the extreme point of the centerline control equation in step 2).

[0018] Furthermore, in step 4), the arrangement of each section height follows the centerline control equation, forming a bypass channel profile. The control equation is:

[0019]

[0020]

[0021] Changing parameter 'a' changes the height of the bypass bulge.

[0022] Furthermore, the apex of the inwardly convex main channel bulge is located on the plane of the interface.

[0023] Furthermore, in step (3), the interface is taken at 1 / 9 of the length of the generated main channel, and the cross-sectional profile at this point is extracted as the cross-sectional profile of the side channel entrance.

[0024] Furthermore, the apex of the inwardly protruding bulge of the side channel is located in the middle of the side channel.

[0025] Furthermore, the bypass duct bulge extends downwards from its apex to both sides to form transitional arc-shaped surfaces, wherein the transitional arc-shaped surface near the bypass duct inlet is used to introduce airflow into the main intake duct.

[0026] Beneficial Effects: Compared with existing technologies, the significant feature of this invention is the adjustable height of the dual bulges in the main and bypass channels. By parametrically controlling the height of the bulges, the air intake and bypass channel clearance efficiency and aerodynamic performance can be parametrically controlled and optimized. The main channel bulge prevents large foreign objects such as birds from entering the main channel during the descent of a turboprop aircraft at an angle of attack. The bypass channel bulge reduces the performance degradation of the main channel caused by the main channel bulge. Through the parametric dual-bulge design, the air intake and bypass channel clearance efficiency and aerodynamic performance can be controlled, thereby improving the safety of the aircraft engine.

[0027] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-described design method.

[0028] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-described design method. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the discrete point set of the profile captured by the inlet and outlet cross-section of the present invention;

[0030] Figure 2 This is a schematic diagram of the transition law control of the present invention;

[0031] Figure 3 This is a schematic diagram of the flow direction cross-section of the present invention;

[0032] Figure 4 This is a schematic diagram of the control equation for the centerline of the main channel of the present invention;

[0033] Figure 5 This is a schematic diagram of the main channel profile of the present invention;

[0034] Figure 6 This is a schematic diagram of the control equation for the bypass centerline of the present invention;

[0035] Figure 7 This is a schematic diagram of the overall profile of the dual-drum air intake and bypass channel of the present invention. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0037] This invention provides a parametric design method for the air intake and bypass passage of a turboprop aircraft with dual adjustable bulges, comprising the following steps:

[0038] 1) Extract the cross-sectional capture profiles of the inlet and outlet of the main intake channel. The cross-sectional capture profiles are expressed in the form of point sets.

[0039] Please see Figure 1 As shown, the capture profiles of any given inlet and outlet cross-sections of the inlet are discretized. Let the discretization of the capture profiles of the inlet and outlet cross-sections be ( , , The sequence points of ) where =1, ..., I, and the rotation angle between each point can be calculated using the following formula based on the coordinates above:

[0040]

[0041] The angle between the i-th point of the inlet section and the horizontal line is... The angle between the i-th point of the exit section and the horizontal line is . , , Let x and y be the x and y coordinates of the i-th discrete point at the inlet cross-section, respectively. If the cross-section profile is symmetrical, half of the cross-section profile can be used for calculation. This paper designs based on half of the profile. Similarly, the length of the line segment between adjacent points at the inlet and outlet cross-sections can be calculated.

[0042] .

[0043] Based on the calculated rotation angle between discrete points of the inlet and outlet cross-section capture profile and the line segment length between adjacent discrete points, the rotation angle between discrete points of each cross-section along the path and the line segment length between adjacent discrete points are calculated again.

[0044] Please see Figure 2 As shown, based on the calculated rotation angle between discrete points of the inlet and outlet cross-sections and the line segment length between adjacent discrete points, the rotation angle between discrete points of each cross-section along the path and the line segment length between adjacent discrete points are calculated again.

[0045] Based on step 1), the rotation angles between discrete points of the inlet and outlet cross-section capture profile and the line segment lengths between adjacent points are extracted. Each discrete point corresponds one-to-one with the others, and the difference in their rotation angles is:

[0046]

[0047] Similarly, the lengths of the line segments between adjacent discrete points can be obtained:

[0048]

[0049] in Let be the length of the line segment formed by the i-th point and the (i+1)-th point at the exit section. Let be the length of the line segment formed by the i-th point and the (i+1)-th point at the entrance section;

[0050] Following the above method, the difference in rotation angle between each corresponding discrete point and the line segment length between adjacent discrete points can be obtained. Based on the required transition speed of the cross-section capturing profile, appropriate rotation angle and length transition rules are selected for control. A continuous curve with monotonically changing values ​​from 0 to 1 is taken, with the horizontal axis representing the number of cross-sections J along the path and the vertical axis representing the j-th cross-section. m The rate of change of angular rotation at each cross section, c jm The calculation rule for the change in angle rotation at the corresponding point on this cross section is as follows:

[0051]

[0052] Along the jth m The length of the line segment between adjacent discrete points at each cross section is calculated as follows:

[0053]

[0054] in, For the jth m The rotation angle at the i-th discrete point on each cross section. For the j-th m The length of the line segment between the i-th discrete point and the (i+1)-th adjacent point at each cross section.

[0055] The selection of transition rules can be specifically provided by using a 5th-degree polynomial to construct transition rules:

[0056]

[0057] Constraints are imposed on the conditions:

[0058]

[0059] get:

[0060]

[0061] It can be seen With four unknowns (x, b, c, d) and only three equations, it is possible to adjust the equations, where the x-coordinate is... m For j m / J,y m Let c be the rate of change. jm .

[0062] Based on the rotation angle between discrete points of each cross section along the path and the line segment length between adjacent discrete points, the geometric lines of each cross section along the path are calculated in reverse. The calculated geometric lines of each cross section along the path are expressed in the form of point sets.

[0063] Please see Figure 3 As shown, based on the above steps, the j-th... m The rotation angles of discrete points on each cross section and the line segment lengths between adjacent points were calculated. Knowing only the coordinates of a point on each cross section allows for the inverse calculation of the geometric profile of each cross section along the path. This geometric profile is expressed as a point set. For any j... m Coordinates of the first point of the cross section Rotation angles of discrete points on each cross section along the path Then j m The coordinates of the i-th discrete point on the cross section are:

[0064] .

[0065] The z-coordinate of the flow direction is distributed equidistantly from the inlet and outlet. At this point, the arbitrary coordinates of the entire surface have been solved.

[0066] 2) Arrange the profiles of each section of the main channel according to the height variation law of the geometric profiles of each section along the route, and form the profile of the main channel;

[0067] Please see Figure 4 As shown, the arrangement of the heights of each section follows a formula to form the main channel profile, as follows:

[0068]

[0069]

[0070] Different parameter b can be selected to create different main channel bulge heights.

[0071] 3) At 1 / 9 of the length of the generated main channel (i.e., the position with the largest bulge height, and...) Figure 2 The horizontal axis (corresponding to the position) serves as the interface, and the cross-sectional profile at this point is extracted. This cross-sectional profile is then used as the bypass entrance profile, and the bypass exit cross-sectional profile is also extracted. Based on the bypass entrance and exit cross-sectional profiles, the cross-sectional profiles along the entire route are then calculated.

[0072] Please see Figure 5 As shown, the section at 1 / 9 of the main channel is used as the inlet profile of the bypass channel, and the outlet profile of the bypass channel is extracted. Then, based on the inlet and outlet profiles of the bypass channel, the profiles of each section along the route are calculated.

[0073] 4) Based on the center curve of the bypass, rearrange the heights of each section of the bypass and form the bypass profile.

[0074] Please see Figure 6 As shown, the arrangement of the heights of each section follows a formula to form a bypass channel profile, as shown in the following formula:

[0075]

[0076]

[0077] 5) Chamfer the surfaces of the bypass and main intake channels in the modeling software to create an intake and bypass channel surface with dual bulges, such as... Figure 7 As shown.

[0078] Table 1 compares the total pressure recovery coefficient of the main channel and the sand removal efficiency under different parameters designed using the present invention.

[0079] Design parameters Flight Mach Number Main channel Mach number Main channel total pressure recovery coefficient C sand removal efficiency a=0.3, b=0.02 0.4 0.5 0.98583 0.93243 a=0.5, b=0.02 0.4 0.5 0.98559 0.94097 a=0.3, b=0.06 0.4 0.5 0.98055 0.93719 a=0.5, b=0.06 0.4 0.5 0.98071 0.94913 .

Claims

1. A parametric design method for the air intake and bypass passage of a turboprop aircraft with dual adjustable bulges, characterized in that, Includes the following steps: 1) Extract the cross-sectional capture profiles of the inlet and outlet of the main intake channel, and express the cross-sectional capture profiles in the form of point sets; then calculate the geometric profiles of each cross-section along the main intake channel based on each cross-section of the inlet and outlet of the main intake channel; 2) Arrange the profiles of each section of the main intake channel according to the height variation law of the geometric profiles along the main intake channel, and form the main intake channel profile; form a main channel bulge convex inward at a designated position on the main intake channel profile; the arrangement law of the height of each section is arranged according to the centerline control equation, and form the main channel profile, the control equation being: ， ， Different main channel bulge heights can be formed by selecting different parameters b; where the x-axis is the flow direction distance control factor and the y-axis is the cross-sectional height control factor; 3) Take a preset point in the generated main channel as the interface and extract the cross-sectional profile at the interface. Take the cross-sectional profile at the interface as the inlet cross-sectional profile of the bypass channel and extract the outlet cross-sectional profile of the bypass channel. Form a bypass bulge convex inward into the bypass channel at a specified position on the bypass channel profile of the intake duct. Then, based on the inlet cross-sectional profile and the outlet cross-sectional profile of the bypass channel, calculate the cross-sectional profiles of each bypass channel along the path. 4) Based on the center curve of the bypass, rearrange the heights of each section of the bypass to form the bypass profile; the arrangement of each section height follows the centerline control equation to form the bypass profile, and the control equation is: ， ， Changing parameter 'a' changes the height of the bypass bulge; where the x-axis is the flow distance control factor and the y-axis is the cross-sectional height control factor. 5) Chamfer the bypass channel profile and the main channel profile in the modeling software to form an intake duct and bypass channel profile with dual bulges.

2. The parametric design method for the inlet and bypass passage of a turboprop aircraft with dual adjustable bulges according to claim 1, characterized in that, In step 3), the point at 1 / 9 of the main channel length is the extreme point of the centerline control equation in step 2).

3. The parametric design method for the air intake and bypass passage of a turboprop aircraft with dual adjustable bulges according to claim 1, characterized in that, The apex of the inward bulge of the main channel is located on the plane of the interface.

4. The parametric design method for the air intake and bypass passage of a turboprop aircraft with dual adjustable bulges according to claim 3, characterized in that, In step (3), the interface is taken at 1 / 9 of the length of the generated main channel, and the cross-sectional profile at this point is extracted as the cross-sectional profile of the side channel entrance.

5. The parametric design method for the air intake and bypass passage of a turboprop aircraft with dual adjustable bulges according to claim 1, characterized in that, The apex of the inwardly protruding bulge in the side channel is located in the middle of the side channel.

6. The parametric design method for the air intake and bypass passage of a turboprop aircraft with dual adjustable bulges according to claim 5, characterized in that, The bulge of the bypass channel extends downward from the apex to both sides to form a transitional arc surface, wherein the transitional arc surface near the side of the bypass channel inlet is used to introduce airflow into the main intake channel.

7. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method described in any one of claims 1 to 6.

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