A method for testing and simulating wide-range flow coefficient of a back-mounted embedded air inlet

Abstract

The application belongs to the intake wind tunnel test method, and discloses a kind of wide-range flow coefficient test simulation method of back-carrying embedded intake, comprising: when the lower boundary control of intake flow is carried out, by setting the intake orifice plate of different flow rates that can be replaced in the intake, the effective control of lower boundary of intake flow is realized;When the upper boundary control of intake flow is carried out, by setting the internal flow passage suction device on the intake, the effective control of upper boundary of intake flow is realized;By setting the intake lip static pressure and dynamic pressure measurement module that can be replaced, and the wall static pressure measurement module distributed along the intake, the intake lip bulge pressure measurement is completed;And by setting total static pressure pressure gage at the end of intake, the calculation of flow coefficient and internal resistance is completed, to realize the quantitative analysis to the performance of intake.

Description

Technical Field

[0001] This application pertains to wind tunnel testing methods for air intakes, and particularly relates to a method for simulating the wide-area flow coefficient test of a backpack-mounted embedded air intake. Background Technology

[0002] With the continuous development of aircraft design technology, the requirements for air intake performance are also constantly increasing. Especially under complex flight conditions, such as transonic and high angle-of-attack flight, the flow characteristics of the air intake are affected by a variety of factors, such as flow separation, shock wave interference, and the interaction between internal and external flows. In order to accurately simulate the air intake performance under these complex conditions, a test method that can cover a wide range of flow coefficients is needed.

[0003] Current air intake design methods for flying wing aircraft generally employ dorsal embedded air intakes. Compared to ventral air intakes, this layout effectively reduces infrared scattering sources. However, it commonly suffers from internal and external flow coupling issues. Specifically, under the suction effect of the air intake, external flow structures such as leading-edge vortices are easily drawn into the intake, affecting intake uniformity and consequently impacting engine performance. Furthermore, air intake overflow and suction effects also influence external flow structures, thus affecting aerodynamic characteristics.

[0004] Current research on the intake and exhaust effects of air intakes generally only simulates the flow coefficient of a single air intake, rarely considering the influence of external airflow on the fuselage. Therefore, to understand the internal and external flow coupling characteristics of this type of aircraft, this invention discloses an experimental simulation method for the wide-area flow coefficient of the air intake of a full-wing flying wing configuration aircraft. Summary of the Invention

[0005] The purpose of this application is to overcome the problems of the prior art by disclosing a method for simulating the wide-area flow coefficient of a backpack-mounted inlet, thereby achieving precise control and comprehensive measurement of the flow field inside the inlet.

[0006] The objective of this application is achieved through the following technical solution:

[0007] A method for simulating the wide-area flow coefficient of a backpack-mounted embedded air intake, the method comprising:

[0008] When controlling the lower boundary of the intake flow rate, the lower boundary of the intake flow rate is effectively controlled by setting up an intake orifice plate with different flow rates that can be replaced inside the intake. When controlling the upper boundary of the intake flow rate, the upper boundary of the intake flow rate is effectively controlled by setting up an internal flow channel suction device on the intake.

[0009] The intake lip bulge pressure is measured by setting up replaceable intake duct lip static pressure and dynamic pressure measurement modules, as well as wall static pressure measurement modules distributed along the intake duct; and the flow coefficient and internal resistance are calculated by setting a total static pressure measuring rake at the end of the intake duct, so as to achieve quantitative analysis of intake duct performance.

[0010] According to a preferred embodiment, the internal flow channel suction device includes an ejector and an air supply line. The ejector is disposed inside the air intake channel and connected to the external air supply line. The ejector is provided with several detachable nozzles, thereby increasing the upper boundary of the air intake channel flow rate to achieve control of different flow coefficients.

[0011] According to a preferred embodiment, the nozzles on the ejector have different opening degrees to achieve precise control of the flow coefficient.

[0012] According to a preferred embodiment, the total static pressure measuring rake adopts a cross-shaped layout, with the intersection point of the cross as the origin, and several total pressure and static pressure measuring points are arranged in the direction of the cross extension to obtain the pressure distribution at the intake outlet.

[0013] According to a preferred embodiment, the flow coefficient is defined as the ratio of the actual flow rate entering the intake manifold to the reference flow rate of the intake manifold, as follows:

[0014]

[0015] In the formula, For flow coefficient, This represents the actual airflow rate entering the intake manifold, expressed in kg / s. This is the reference flow rate for the air intake.

[0016] According to a preferred embodiment, the intake reference flow rate It is obtained by calculation using the following formula.

[0017]

[0018] in, Indicates the total incoming pressure. T 0 indicates the total incoming temperature. Indicates the incoming flow velocity coefficient. A i This indicates the intake capture area of ​​the air intake. m Represents a constant. Let be the flow rate function of the far-field incoming flow.

[0019] According to a preferred embodiment, the actual flow rate entering the intake manifold... The total pressure at the intake outlet was calculated using the measured value of the intake manifold.

[0020] According to a preferred embodiment, the actual flow rate entering the intake manifold... During the calculation, treating the intake duct as a whole, the actual flow rate through the intake duct cross-section can be expressed as:

[0021]

[0022] in, This represents the average total pressure outlet at the inlet duct outlet section. To measure the cross-sectional area of ​​the air intake duct, Let be the average flow rate function of the inlet outlet section. T 0 represents the total incoming temperature, and m represents a constant.

[0023] According to a preferred embodiment, the average total pressure outlet of the inlet duct outlet section... The total pressure data on the pressure gauge at the intake outlet was obtained by using the flow averaging method.

[0024] The aforementioned main solution and its various further alternative solutions can be freely combined to form multiple solutions, all of which are solutions that can be adopted and are claimed in this application. Those skilled in the art, after understanding the solution of this application, will realize that there are many combinations based on the prior art and common general knowledge, all of which are technical solutions to be protected in this application, and will not be exhaustively listed here.

[0025] The beneficial effects of this application are:

[0026] The method described in this application enables precise control and comprehensive measurement of the internal flow field of the air intake of an all-aircraft flying wing configuration aircraft. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the intake duct orifice plate design structure of this application;

[0028] Figure 2 This is a schematic diagram of the intake ejector structure of this application;

[0029] Figure 3 This is a schematic diagram of the intake manifold pressure measurement device of this application;

[0030] Figure 4 It is the result of pressure measurement along the intake manifold;

[0031] Figure 5 This is a schematic diagram of the cross-shaped total / static pressure measuring rake structure of this application;

[0032] Figure 6 This is the result of flow coefficient measurement;

[0033] Among them, 1 is the installation position of the air intake orifice plate, 2 is the air intake orifice plate, 3 is the air intake, 4 is the ejector, 5 is the air supply pipeline, 6 is the static pressure measurement module, 7 is the dynamic pressure measurement module, 8 is the wall static pressure measurement module, 9 is the total static pressure measuring rake, and 10 is the cross-shaped distribution design of the total / static pressure probes. Detailed Implementation

[0034] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0036] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0038] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0039] Furthermore, it should be noted that unless otherwise specified in this application, the specific structures, connections, positions, power sources, etc. involved are all things that a person skilled in the art can know without creative effort based on the prior art.

[0040] refer to Figures 1 to 6 This application discloses a method for simulating the wide-area flow coefficient of a backpack-mounted embedded air intake, which includes the following four parts.

[0041] 1. Lower boundary control of intake flow rate

[0042] When controlling the lower boundary of the flow rate of the intake duct 3, the lower boundary of the flow rate of the intake duct 3 can be effectively controlled by setting an intake duct orifice plate 2 with different flow rates that can be replaced inside the intake duct 3.

[0043] Preferably, each air inlet orifice plate 2 can be quickly replaced according to test requirements, thereby changing the minimum flow rate of the internal flow channel to simulate the performance of a real aircraft under actual operating conditions such as overflow. This allows for flexible adaptation to different test requirements, ensuring the authenticity and reliability of the test results. At the same time, the replaceable design greatly improves test efficiency and reduces maintenance costs.

[0044] In a specific embodiment, the intake orifice plate 2 is made of 18Ni (200D) low-temperature steel, and its shape and size are consistent with those of the intake duct 3. Each set of intake orifice plates 2 has a different number and size of flow holes to achieve different flow rates. For example, small-diameter, low-density orifice plates are suitable for low-flow conditions, while large-diameter, high-density orifice plates are suitable for high-flow conditions.

[0045] The intake duct perforated plate 2 is connected to the inside of the intake duct 3 through a limiting groove and threads. When disassembling and replacing, it can be directly removed from the belly of the fuselage without disassembling other parts.

[0046] 2. Intake duct flow upper boundary control

[0047] When controlling the upper boundary of the flow rate of the intake duct 3, a higher flow coefficient can be simulated by setting an internal flow channel suction device on the intake duct 3, so as to achieve effective control of the upper boundary of the flow rate of the intake duct 3.

[0048] The internal flow channel suction device includes an ejector 4 and an air supply line 5. The ejector 4 is located inside the air intake duct 3 and is externally connected to the air supply line 5. The ejector 4 is equipped with several detachable nozzles to increase the upper boundary of the flow rate in the air intake duct 3, thereby achieving control of different flow coefficients. The opening degree of each nozzle on the ejector 4 is different to achieve precise control of the flow coefficient.

[0049] The basic principle of the internal flow channel suction device is that when external gas flows through the air inlet 3 and through the ejector 4, the ejector assembly is connected to the external air source, and the nozzle will spray out a high-speed airflow. This high-speed airflow is used to accelerate the mainstream speed of the air inlet 3, which is equivalent to a suction effect, thereby achieving the adjustment of different flow rates.

[0050] 3. Pressure measurement of the bulge at the 3rd lip of the air intake.

[0051] The pressure measurement of the lip bulge of the intake 3 is completed by setting up a replaceable static pressure measurement module 6 and dynamic pressure measurement module 7 at the intake duct 3 lip, as well as a wall static pressure measurement module 8 distributed along the intake duct 3. Figure 4 This is a schematic diagram of the obtained pressure distribution curve. In the figure, the horizontal axis L represents the distance of the pressure measuring hole from the origin, and the vertical axis Cp represents the pressure coefficient, which is a dimensionless value and has no unit.

[0052] The static pressure measurement module 6 acquires flow characteristics such as flow separation and shock wave interference by arranging multiple static pressure measurement points in the lip region of the inlet 3. The dynamic pressure measurement module 7 is used to measure the dynamic pressure distribution within the inlet 3, providing data for analyzing flow separation characteristics at high angles of attack and flow characteristics at transonic speeds.

[0053] High-precision, multi-point measurements can comprehensively reflect the dynamic changes in the internal flow field of the air intake 3. Meanwhile, the modular design makes the measurement system more flexible and easier to maintain.

[0054] 4. Measurement of flow coefficient and resistance in internal flow channels

[0055] The flow coefficient and internal resistance are calculated by setting a total static pressure measuring rake 9 at the end of the intake duct 3, so as to realize the quantitative analysis of the performance of the intake duct 3.

[0056] Preferably, the total static pressure measuring rake 9 adopts a cross-shaped layout, with the intersection point of the cross as the origin, and several total pressure and static pressure measuring points are arranged in the direction of the cross extension to obtain the pressure distribution at the outlet of the air intake duct 3.

[0057] The flow coefficient is defined as the ratio of the actual flow rate entering the intake duct 3 to the reference flow rate of the intake duct 3. The reference flow rate is the flow rate passing through the free tube at the far front of the intake duct 3, whose cross-sectional area is equal to the inlet capture area of ​​the intake duct 3. It should be noted that the capture area of ​​the intake duct 3 is the projected area of ​​the area enclosed by the circumference of the leading edge of the intake duct 3 in a plane perpendicular to the incoming flow. Therefore, when processing data for different angles of attack, the capture area of ​​the intake duct 3 also needs to be calculated. Figure 6 This refers to the flow coefficients at different Mach numbers obtained by combining total / static pressure gauges with advanced calculation methods. In the figure, the horizontal axis M represents the Mach number, which is a dimensionless value and has no unit. The vertical axis... The value represents the flow coefficient, and α is the angle between the line connecting the leading and trailing edges of the test model and the incoming flow, which represents the angle of attack.

[0058] Specifically, flow coefficient for:

[0059]

[0060] In the formula, This represents the actual airflow rate entering the intake manifold, expressed in kg / s. This is the reference flow rate for the air intake.

[0061] Furthermore, the intake reference flow rate It is obtained by calculation using the following formula.

[0062]

[0063] in, Indicates the total incoming pressure. T 0 indicates the total incoming temperature. Indicates the incoming flow velocity coefficient. A i This indicates the intake capture area of ​​the air intake. m Represents a constant. Let be the flow rate function of the far-field incoming flow.

[0064] Preferably, the actual flow rate entering the intake manifold The total pressure at the intake outlet was calculated using the measured value of the intake manifold.

[0065] Furthermore, the actual flow rate entering the intake manifold During the calculation, treating the intake duct as a whole, the actual flow rate through the intake duct cross-section can be expressed as:

[0066]

[0067] in, This represents the average total pressure outlet at the inlet duct outlet section. To measure the cross-sectional area of ​​the air intake duct, Let be the average flow rate function of the inlet outlet section. T 0 represents the total incoming temperature, and m represents a constant.

[0068] Therefore, the flow coefficient is:

[0069]

[0070] Preferably, the average total pressure outlet of the intake duct outlet section The total pressure data from the intake manifold outlet pressure gauge is calculated using the flow averaging method, specifically as follows:

[0071]

[0072] Where j represents the j-th area element, and N represents the number of area elements. This represents the average total pressure of the j-th area element calculated using the arithmetic mean method. This represents the flow rate through the j-th area element. This represents the area of ​​the j-th area element. Let represent the flow function of the j-th area element.

[0073] Furthermore, the average flow function of the intake duct outlet section for:

[0074]

[0075] in, Let the flow function of the j-th area element be represented. This represents the average total pressure of the j-th area element calculated using the arithmetic mean method. A 2 indicates the air intake outlet area.

[0076] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for simulating the wide-area flow coefficient of a backpack-mounted embedded air intake, characterized in that, The experimental simulation method for the wide-area flow coefficient of the embedded air intake includes: When controlling the lower boundary of the intake flow rate, the lower boundary of the intake flow rate is effectively controlled by setting up an intake orifice plate with different flow rates that can be replaced inside the intake. When controlling the upper boundary of the intake flow rate, the upper boundary of the intake flow rate is effectively controlled by setting up an internal flow channel suction device on the intake. The intake lip bulge pressure is measured by setting up replaceable intake duct lip static pressure and dynamic pressure measurement modules, as well as wall static pressure measurement modules distributed along the intake duct; and the flow coefficient and internal resistance are calculated by setting a total static pressure measuring rake at the end of the intake duct, so as to achieve quantitative analysis of intake duct performance.

2. The experimental simulation method for wide-area flow coefficient of a backpack-mounted embedded air intake as described in claim 1, characterized in that, The internal flow channel suction device includes an ejector (4) and an air supply line (5). The ejector (4) is located inside the air intake channel (3) and connected to the air supply line (5). The ejector (4) is equipped with several detachable nozzles to increase the upper boundary of the air intake channel flow rate, so as to achieve control of different flow coefficients.

3. The experimental simulation method for wide-area flow coefficient of a backpack-mounted embedded air intake as described in claim 2, characterized in that, The nozzles on the ejector (4) have different openings to achieve precise control of the flow coefficient.

4. The experimental simulation method for wide-area flow coefficient of a backpack-mounted embedded air intake as described in claim 1, characterized in that, The total static pressure measuring rake (9) adopts a cross-shaped layout. With the cross intersection as the origin, several total pressure and static pressure measuring points are arranged in the extension direction of the cross to obtain the pressure distribution at the intake outlet.

5. The experimental simulation method for wide-area flow coefficient of a backpack-mounted embedded air intake as described in claim 4, characterized in that, The flow coefficient is defined as the ratio of the actual flow rate entering the intake manifold to the reference flow rate of the intake manifold, and is: In the formula, For flow coefficient, This represents the actual airflow rate entering the intake manifold, expressed in kg / s. This is the reference flow rate for the air intake.

6. The experimental simulation method for wide-area flow coefficient of a backpack-mounted embedded air intake as described in claim 5, characterized in that, Intake reference flow It is obtained by calculation using the following formula. in, Indicates the total incoming pressure. T 0 indicates the total incoming temperature. Indicates the incoming flow velocity coefficient. A i This indicates the intake capture area of ​​the air intake. m Represents a constant. Let be the flow rate function of the far-field incoming flow.

7. The experimental simulation method for wide-area flow coefficient of a backpack-mounted embedded air intake as described in claim 5, characterized in that, Actual airflow entering the intake manifold The total pressure at the intake outlet was calculated using the measured value of the intake manifold.

8. The experimental simulation method for wide-area flow coefficient of a backpack-mounted embedded air intake as described in claim 7, characterized in that, Actual airflow entering the intake manifold During the calculation, treating the intake duct as a whole, the actual flow rate through the intake duct cross-section can be expressed as: in, This represents the average total pressure outlet at the inlet duct outlet section. To measure the cross-sectional area of ​​the air intake duct, Let be the average flow rate function of the inlet outlet section. T 0 represents the total incoming temperature, and m represents a constant.

9. The experimental simulation method for wide-area flow coefficient of a backpack-mounted embedded air intake as described in claim 8, characterized in that, Average total pressure outlet of the inlet duct outlet section The total pressure data on the pressure gauge at the intake outlet was obtained by using the flow averaging method.

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