A nested nacelle for scale flight testing and design method

Abstract

The application belongs to the technical field of wing-engine matching design, and particularly relates to a nested nacelle for scale flight test and a design method. The nested nacelle comprises: the outer nacelle is directly obtained by scaling the actual nacelle of an aircraft scheme; the inner nacelle is nested in the outer nacelle, a gas flow channel is formed between the inner nacelle and the outer nacelle, the inner nacelle has an inner nacelle air inlet inside, the inner nacelle comprises an inner nacelle front section and an inner nacelle rear section, an opening is arranged between the inner nacelle front section and the inner nacelle rear section, the opening is connected with the gas flow channel and a nozzle cooling channel; the engine is arranged inside the inner nacelle and connected with the inner nacelle air inlet, and the engine tail is provided with a nozzle. The application is used for scale flight test of a wing-mounted large aircraft and can solve the wing-engine matching problem in scale flight test.

Description

Technical Field

[0001] This application belongs to the field of flight-engine matching design technology, and specifically relates to a nested nacelle and its design method for scaled-down flight testing. Background Technology

[0002] Large aircraft generally employ high-bypass turbofan engines, but scaled-down flight tests of large aircraft typically require smaller turbojet engines. A directly scaled-down nacelle of a large aircraft's actual nacelle is difficult to match with the turbojet engine used in scaled-down flight tests, necessitating a complete nacelle redesign. Mounting the newly designed nacelle on the scaled-down test aircraft significantly alters the nacelle's lift-drag characteristics and the interference between the nacelle and the aircraft fuselage, thus affecting the scaled-down flight test's verification objectives. Technically, using a directly scaled-down nacelle of a large aircraft's actual nacelle is preferable, as this best simulates the nacelle's drag characteristics and the interference between the nacelle and the aircraft fuselage. Therefore, developing a nested nacelle for scaled-down flight tests has significant engineering practical value in addressing this flight-engine matching problem.

[0003] Therefore, there is an urgent need for a technical solution to overcome or mitigate at least one of the aforementioned defects in the existing technology. Summary of the Invention

[0004] The purpose of this application is to provide a nested nacelle and its design method for scaled-down flight testing, in order to solve at least one problem existing in the prior art.

[0005] The technical solution of this application is:

[0006] The first aspect of this application provides a nested nacelle for scaled-down flight testing, comprising:

[0007] The outer nacelle is obtained by directly scaling down the actual nacelle of the aircraft design.

[0008] An embedded nacelle is nested inside an outer nacelle, forming an airflow channel between the embedded nacelle and the outer nacelle. The embedded nacelle has an air intake duct inside. The embedded nacelle includes a front section and a rear section, and an opening connecting the airflow channel and the nozzle cooling channel is provided between the front section and the rear section.

[0009] An engine is installed inside the embedded nacelle and connected to the air intake of the embedded nacelle. A nozzle is provided at the rear of the engine.

[0010] In at least one embodiment of this application, the engine is a scaled-down flight test engine.

[0011] In at least one embodiment of this application, the embedded nacelle is designed in detail according to the geometry of the outer nacelle and the scaled-down flight test engine, so that the embedded nacelle provides the required airflow for the scaled-down flight test engine.

[0012] In at least one embodiment of this application, the opening position corresponds to the nozzle inlet position.

[0013] A second aspect of this application provides a nested nacelle design method for scaled-down flight testing, comprising:

[0014] Step S1: Select the nested nacelle design point based on the typical flight altitude and Mach number of the scaled-down flight test;

[0015] Step S2: Design the throat area of ​​the embedded nacelle;

[0016] Step S3: Design the inlet area of ​​the embedded nacelle;

[0017] Step S4: Design the length of the embedded nacelle air intake;

[0018] Step S5: Determine the shape of the embedded nacelle inlet;

[0019] Step S6: Design the lip profile of the embedded short pod;

[0020] Step S7: Design the hull profile of the embedded nacelle diffuser section;

[0021] Step S8: Design the profile of the embedded nacelle cover;

[0022] Step S9: Design the airflow channel between the embedded nacelle and the outer nacelle.

[0023] In at least one embodiment of this application, in step S2, the area of ​​the embedded nacelle throat satisfies:

[0024] ;

[0025] Where m is the flow rate at the throat section, γ is the specific heat ratio, R is the gas constant, T0 is the total temperature at the throat section, P0 is the total pressure at the throat section, M is the throat Mach number, and A TH This represents the area of ​​the larynx.

[0026] In at least one embodiment of this application, the throat Mach number M is 0.45 to 0.60.

[0027] In at least one embodiment of this application, in step S3, the inlet area of ​​the embedded nacelle satisfies the following condition: the inlet shrinkage ratio is 1.50 to 2.20.

[0028] In at least one embodiment of this application, in step S4, the length of the embedded nacelle air intake is 0.65D to 1.15D, where D is the engine inlet diameter.

[0029] In at least one embodiment of this application, in step S5, the shape of the embedded nacelle inlet is a circular or two-segment elliptical design.

[0030] In at least one embodiment of this application, in step S6, the embedded nacelle lip profile includes an inner lip profile and an outer lip profile, both of which are designed using 1 / 4 hyperellipse parameters. The hyperellipse equation is:

[0031] ;

[0032] Where a is the major semi-axis of the hyperellipse, b is the minor semi-axis of the hyperellipse, and n is the control parameter.

[0033] In at least one embodiment of this application, in step S7, the ratio of the X-direction length of the inflection point of the embedded nacelle diffuser section from the starting point of the diffuser section to the X-direction length of the entire diffuser section is used as a design control parameter.

[0034] In at least one embodiment of this application, in step S8, the embedded nacelle outer cover profile includes a front section and a rear section of the outer cover.

[0035] In at least one embodiment of this application, the aspect ratio of the rear section of the outer cover, the shrinkage ratio of the rear section of the outer cover, and the rear edge angle of the outer cover are used as design control parameters for the rear section of the outer cover.

[0036] In at least one embodiment of this application, in step S9, the minimum cross-sectional area A of the airflow channel between the inner nacelle and the outer nacelle is... min Conditions met:

[0037] ;

[0038] in, These are flow control parameters.

[0039] The invention has at least the following beneficial technical effects:

[0040] The nested nacelle of this application for scaled-down flight testing, used for scaled-down flight testing of large wing-mounted aircraft, can solve the flight-engine matching problem faced in scaled-down flight testing. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of a nested nacelle for scaled-down flight testing according to one embodiment of this application;

[0042] Figure 2This is a schematic diagram of the airflow of a nested nacelle for scaled-down flight testing according to one embodiment of this application.

[0043] Figure 3 This is a schematic diagram of the embedded nacelle profile definition of one embodiment of this application;

[0044] Figure 4 This is a schematic diagram of the airflow channel control area between the embedded nacelle and the outer nacelle according to one embodiment of this application.

[0045] in:

[0046] 1-Outer nacelle; 2-Inner nacelle; 3-Engine; 4-Nozzle. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0048] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. 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. Therefore, they should not be construed as limiting the scope of protection of this application.

[0049] The following is in conjunction with the appendix Figures 1 to 4 This application will be described in further detail.

[0050] The first aspect of this application provides a nested nacelle for scaled-down flight testing, comprising: an outer nacelle 1, an inner nacelle 2, an engine 3, and a nozzle 4.

[0051] like Figure 1As shown, the outer nacelle 1 is directly scaled down from the actual nacelle of the aircraft design; the inner nacelle 2 is nested inside the outer nacelle 1, and an airflow channel is formed between the inner nacelle 2 and the outer nacelle 1. The inner nacelle 2 has an inner nacelle air intake. The inner nacelle 2 includes a front section and a rear section. An opening connecting the airflow channel and the nozzle cooling channel is provided between the front section and the rear section of the inner nacelle; the engine 3 is installed inside the inner nacelle 2 and connected to the inner nacelle air intake. A nozzle 4 is provided at the tail of the engine 3.

[0052] The nested nacelle used in this application for scaled-down flight testing has an engine 3 that is a scaled-down flight test engine. Based on the geometry of the outer nacelle 1 and the scaled-down flight test engine, the inner nacelle 2 is designed in detail to provide the required airflow for the scaled-down flight test engine. The opening position corresponds to the inlet position of the nozzle 4.

[0053] The nested nacelle used in this application for scaled-down flight testing comprises an outer nacelle 1 directly scaled down from the actual nacelle of the aircraft design to maximize the simulation of nacelle drag characteristics and interference between the nacelle and the aircraft fuselage, ensuring the reliability of the scaled-down flight test verification results. The inner nacelle 2 is designed in detail based on the geometry of the outer nacelle 1 and the engine used in the scaled-down flight test, providing the required airflow for the engine. An airflow channel is formed between the outer nacelle 1 and the inner nacelle 2. An opening connecting the airflow channel and the inner nacelle's air intake is provided between the front and rear sections of the inner nacelle. Figure 2 As shown, during aircraft flight, the airflow entering the intake of the outer nacelle 1 is divided into two parts: a central airflow enters the inner nacelle 2, and a peripheral airflow enters the airflow channel formed between the outer nacelle 1 and the inner nacelle 2. The airflow flowing into the airflow channel between the inner nacelle 2 and the outer nacelle 1 is split again at the inlet of the nozzle 4 of the downstream engine 3; part of it is discharged directly, and the other part flows through the engine nozzle wall to cool the engine nozzle.

[0054] The second aspect of this application provides a nested nacelle design method for scaled-down flight testing, used to design the aforementioned nested nacelle for scaled-down flight testing, the design method comprising:

[0055] Step S1: Select the nested nacelle design point based on the typical flight altitude and Mach number of the scaled-down flight test;

[0056] Step S2: Design the throat area of ​​the embedded nacelle;

[0057] Step S3: Design the inlet area of ​​the embedded nacelle;

[0058] Step S4: Design the length of the embedded nacelle air intake;

[0059] Step S5: Determine the shape of the embedded nacelle inlet;

[0060] Step S6: Design the lip profile of the embedded short pod;

[0061] Step S7: Design the hull profile of the embedded nacelle diffuser section;

[0062] Step S8: Design the profile of the embedded nacelle cover;

[0063] Step S9: Design the airflow channel between the embedded nacelle and the outer nacelle.

[0064] First, in step S1, the nested nacelle design point is selected based on the typical flight altitude and flight Mach number of the scaled-down flight test. The typical flight altitude, flight Mach number, and engine operating status are selected as the nested nacelle design point.

[0065] In step S2, when determining the throat area, it is essential to ensure that no airflow blockage occurs at the throat cross-section under various flight conditions. To reduce the total pressure loss of the inlet, the throat Mach number is further required to be no greater than 0.7. Under design conditions, the recommended range for the throat Mach number of the embedded nacelle inlet is 0.45 to 0.60. The throat area of ​​the embedded nacelle inlet is calculated based on the one-dimensional isentropic relationship between flow rate and area:

[0066] (1);

[0067] Where m is the flow rate at the throat section, γ is the specific heat ratio, R is the gas constant, T0 is the total temperature at the throat section, P0 is the total pressure at the throat section, M is the throat Mach number, and A TH This represents the area of ​​the larynx.

[0068] In step S3, for the scaled-down flight test engine, which is typically a small turbojet engine with a relatively large maximum circumferential profile, the embedded nacelle needs to enclose the engine structure. Therefore, the nacelle section thickness is relatively large, requiring a relatively large inlet area, which corresponds to a larger inlet shrinkage ratio. The recommended range for the inlet shrinkage ratio is 1.50–2.20.

[0069] In step S4, the shorter the nacelle air intake duct length, the greater the weight gain of the nacelle structure. Under the premise of ensuring air intake performance, the smaller the air intake duct length should be selected as much as possible. The selection of the length of the embedded nacelle air intake duct also needs to take into account the circumferential profile dimensions of the engine to ensure a smooth transition of the nacelle surface. The nacelle air intake duct length can be selected in the range of 0.65D to 1.15D, where D is the engine inlet diameter.

[0070] In step S5, the wing-mounted nacelle inlet is located under the wing. Due to the wing's upwash, the airflow in front of the inlet is deflected upwards. To align the inlet with the incoming flow, the inlet is tilted forward. However, for an embedded nacelle, its inlet is located within the flow field of the outer nacelle. The wing's upwash effect or the angle of attack has negligible impact on the inlet airflow. Therefore, the embedded nacelle inlet can have no forward tilt angle or a very small forward tilt angle.

[0071] The cross-sectional shape of the inlet throat of the embedded nacelle can adopt a circular or two-elliptical design scheme, with the centers of the ellipses coinciding. Designing outward from the inlet throat, the inlet shape adopts a circular or two-elliptical design scheme.

[0072] In step S6, the lip and mouth shape design is done separately for the inner and outer lips. For example... Figure 3 As shown, the embedded nacelle lip profile includes an inner lip profile and an outer lip profile. Both the inner and outer lip profiles are designed using 1 / 4 hyperellipse parameters, and the hyperellipse equation is:

[0073] (2);

[0074] Where a is the major semi-axis of the hyperellipse, b is the minor semi-axis of the hyperellipse, and n is the control parameter.

[0075] In step S7, such as Figure 3 As shown, when designing the diffuser section profile, the inflection point position of the diffuser section profile is used as its design control parameter, and the ratio of the X-direction length of the inflection point position of the embedded nacelle diffuser section profile from the starting point of the diffuser section to the X-direction length of the entire diffuser section is used as the design control parameter.

[0076] In step S8, such as Figure 3 As shown, the outer casing profile is divided into two parts: the front section and the rear section. The slenderness ratio, contraction ratio, and trailing edge angle of the rear section are used as design control parameters. The front section profile connects smoothly with the lip profile and the rear section profile using spline lines. The inner nacelle outer casing profile must encompass the engine structure and leave space for the nacelle structure design.

[0077] In step S9, an airflow channel is formed between the outer nacelle and the inner nacelle. Part of the airflow entering the outer nacelle's intake will flow through this channel. After the inner nacelle design is completed, the flowability of this channel must be checked to avoid airflow blockage. The minimum cross-sectional area A of the airflow channel formed between the outer nacelle and the inner nacelle is... min The following conditions must be met:

[0078] (3);

[0079] in, These are flow control parameters.

[0080] The reference range for flow control parameters is 0.2 to 0.6, and the remaining parameters are the same as in equation (1). If the minimum cross-sectional area of ​​the flow channel between the outer nacelle and the inner nacelle does not meet the condition of equation (3), then it is necessary to adjust the outer profile of the inner nacelle or the inner profile of the outer nacelle. Figure 4 The profile within the area shown extends to A. min It satisfies formula (3).

[0081] The nested nacelle and design method of this application for scaled-down flight testing are applicable to scaled-down flight testing of large wing-mounted aircraft and can solve the flight-engine matching problem faced in scaled-down flight testing.

[0082] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A nested nacelle for scaled-down flight testing, characterized in that, include: The outer nacelle (1) is obtained by directly scaling down the actual nacelle of the aircraft design; An embedded nacelle (2) is nested inside the outer nacelle (1), and an airflow channel is formed between the embedded nacelle (2) and the outer nacelle (1). The embedded nacelle (2) has an air intake duct inside. The embedded nacelle (2) includes a front section and a rear section. An opening is provided between the front section and the rear section of the embedded nacelle to connect the airflow channel and the nozzle cooling channel. Engine (3), the engine (3) is installed inside the embedded nacelle (2) and connected to the air intake of the embedded nacelle, and the engine (3) is provided with a nozzle (4) at the tail.

2. The nested nacelle for scaled-down flight testing according to claim 1, characterized in that, The engine (3) is a scaled-down flight test engine.

3. The nested nacelle for scaled-down flight testing according to claim 2, characterized in that, Based on the geometry of the outer nacelle (1) and the scaled-down flight test engine, the inner nacelle (2) is designed in detail to provide the scaled-down flight test engine with the required airflow.

4. The nested nacelle for scaled-down flight testing according to claim 3, characterized in that, The opening position corresponds to the inlet position of the nozzle (4).

5. A nested nacelle design method for scaled-down flight testing, used to design a nested nacelle for scaled-down flight testing as described in any one of claims 1 to 4, characterized in that, include: Step S1: Select the nested nacelle design point based on the typical flight altitude and Mach number of the scaled-down flight test; Step S2: Design the throat area of ​​the embedded nacelle; Step S3: Design the inlet area of ​​the embedded nacelle; Step S4: Design the length of the embedded nacelle air intake; Step S5: Determine the shape of the embedded nacelle inlet; Step S6: Design the lip profile of the embedded short pod; Step S7: Design the hull profile of the embedded nacelle diffuser section; Step S8: Design the profile of the embedded nacelle cover; Step S9: Design the airflow channel between the embedded nacelle and the outer nacelle.

6. The nested nacelle design method for scaled-down flight testing according to claim 5, characterized in that, In step S2, the area of ​​the embedded nacelle throat satisfies: ； Where m is the flow rate at the throat section, γ is the specific heat ratio, R is the gas constant, T0 is the total temperature at the throat section, P0 is the total pressure at the throat section, M is the throat Mach number, and A TH This represents the area of ​​the larynx.

7. The nested nacelle design method for scaled-down flight testing according to claim 6, characterized in that, The Mach number M in the throat is 0.45 to 0.

60.

8. The nested nacelle design method for scaled-down flight testing according to claim 7, characterized in that, In step S3, the inlet area of ​​the embedded nacelle meets the following requirement: the inlet shrinkage ratio is 1.50 to 2.

20.

9. The nested nacelle design method for scaled-down flight testing according to claim 8, characterized in that, In step S4, the length of the embedded nacelle air intake is 0.65D to 1.15D, where D is the engine inlet diameter.

10. The nested nacelle design method for scaled-down flight testing according to claim 9, characterized in that, In step S5, the shape of the embedded nacelle inlet is either circular or two elliptical segments.

11. The nested nacelle design method for scaled-down flight testing according to claim 10, characterized in that, In step S6, the embedded nacelle lip profile includes an inner lip profile and an outer lip profile. Both the inner and outer lip profiles are designed using 1 / 4 hyperellipse parameters, and the hyperellipse equation is: ； Where a is the major semi-axis of the hyperellipse, b is the minor semi-axis of the hyperellipse, and n is the control parameter.

12. The nested nacelle design method for scaled-down flight testing according to claim 11, characterized in that, In step S7, the ratio of the X-direction length of the inflection point of the embedded nacelle diffuser section from the starting point of the diffuser section to the X-direction length of the entire diffuser section is used as a design control parameter.

13. The nested nacelle design method for scaled-down flight testing according to claim 12, characterized in that, In step S8, the embedded nacelle outer cover profile includes the front section and the rear section of the outer cover.

14. The nested nacelle design method for scaled-down flight testing according to claim 13, characterized in that, The slenderness ratio of the rear section of the outer cover, the shrinkage ratio of the rear section of the outer cover, and the rear edge angle of the outer cover are used as the design control parameters for the rear section of the outer cover.

15. The nested nacelle design method for scaled-down flight testing according to claim 14, characterized in that, In step S9, the minimum cross-sectional area A of the airflow channel between the inner nacelle and the outer nacelle is... min Conditions met: ； in, These are flow control parameters.

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