A method for determining the parameters of a propeller aircraft stiffened panel noise index

Abstract

The application specifically relates to a propeller airplane stiffened panel noise index parameter decomposition determination method, which comprises the following steps: step one, calculating the critical frequency of the stiffened panel; step two, calculating the sound transmission loss based on the critical frequency of the stiffened panel; step three, calculating the turbulent boundary layer noise on the surface of the stiffened panel; step four, calculating the near-field noise of the propeller distributed along the stiffened panel; step five, calculating the cabin noise of the propeller airplane by using the sound transmission loss of the stiffened panel, the turbulent boundary layer noise on the surface of the stiffened panel and the near-field noise of the propeller distributed along the stiffened panel; and step six, if the cabin noise of the propeller airplane cannot meet the cabin noise index requirement, adjusting the structure and material parameters of the stiffened panel, optimizing the structure and material parameters of the stiffened panel, and then performing steps one to five again until the cabin noise of the propeller airplane meets the cabin noise index requirement, so as to obtain the sound transmission loss of the stiffened panel and the structure and material parameters thereof.

Description

Technical Field

[0001] The present application belongs to the technical field of propeller aircraft stiffened wall panel design, and specifically relates to a method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels. Background Art

[0002] During the development of propeller aircraft, it is necessary to control the cabin noise.

[0003] The near-field noise of propeller aircraft mainly comes from the propeller. There are a large number of stiffened panels on propeller aircraft. In order to ensure that the cabin noise meets the index requirements, it is necessary to decompose the cabin noise index into the stiffened panels and determine the structure and material parameters of the stiffened panels. However, at present, there is a lack of efficient and feasible methods for this. In view of this, this application is proposed. Summary of the Invention

[0004] The purpose of this application is to provide a method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel, so as to guide the design of the stiffened wall panel during the aircraft development process.

[0005] The technical solution of this application is:

[0006] A method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel comprises:

[0007] Step 1: Calculate the critical frequency of the reinforced wall panel;

[0008] Step 2: Calculate the sound transmission loss based on the critical frequency of the stiffened wall panel;

[0009] Step 3: Calculate the turbulent boundary layer noise on the surface of the stiffened panel;

[0010] Step 4: Calculate the near-field noise of the propeller along the stiffened wall panel;

[0011] Step 5: Calculate the cabin noise of the propeller aircraft based on the sound transmission loss of the stiffened panel, the turbulent boundary layer noise on the surface of the stiffened panel, and the near-field noise of the propeller distributed along the stiffened panel;

[0012] Step 6: If the cabin noise of the propeller aircraft cannot meet the cabin noise index requirements, adjust the structure and material parameters of the stiffened wall panel, optimize the structure and material parameters of the stiffened wall panel, and repeat steps 1 to 5 until the cabin noise of the propeller aircraft meets the cabin noise index requirements, and obtain the sound transmission loss of the stiffened wall panel and its structure and material parameters.

[0013] According to at least one embodiment of the present application, in the above-mentioned method for determining the noise index parameters of the propeller aircraft reinforced wall panel, the reinforced wall panel structural parameters include the wall panel cross-sectional thickness h, the reinforcing rib height h r, rib width t, and center distance d between ribs.

[0014] According to at least one embodiment of the present application, in the above-mentioned method for determining the noise index parameters of the propeller aircraft reinforced wall panel, in step 1, the critical frequency of the reinforced wall panel is calculated, including the critical frequency f in the vertical direction of the wall panel. c1 , critical frequency f in the direction parallel to the wall panel c2 .

[0015] According to at least one embodiment of the present application, in the above-mentioned method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel, step 1 includes:

[0016]

[0017] in,

[0018] c is the speed of sound in air;

[0019] M S is the mass per unit area of ​​the wall panel;

[0020] B1 is the vertical bending stiffness of the wall panel.

[0021] According to at least one embodiment of the present application, in the above-mentioned method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel, step 1 includes:

[0022] M S =ρ W h[1+(h r / h)(t / d)];

[0023] in,

[0024] ρ W is the density of the siding material.

[0025] According to at least one embodiment of the present application, in the above-mentioned method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel, step 1 includes:

[0026] B1=EI / d;

[0027] in,

[0028] E is the elastic modulus of the siding material;

[0029] I is the moment of inertia of the T-axis of the wall panel.

[0030] According to at least one embodiment of the present application, in the above-mentioned method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel, step 1 includes:

[0031]

[0032] in,

[0033] B2 is the bending stiffness in the direction parallel to the wall panel.

[0034] According to at least one embodiment of the present application, in the above-mentioned method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel, step 1 includes:

[0035]

[0036] According to at least one embodiment of the present application, in the above-mentioned method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel,

[0037] In step 3, the noise cutoff frequency f is less than the critical frequency f in the vertical direction of the wall panel c1 When , the sound transmission loss TL of the stiffened panel is calculated as:

[0038] TL=TL n -5;

[0039] in,

[0040] TL n is the normal transmission loss of incident sound waves on the stiffened panel;

[0041] TL n =10log 10 (1 / a tn );

[0042] in,

[0043] a tn is the transfer coefficient of sound energy in the stiffened wall panel;

[0044]

[0045] in,

[0046] c1 is the speed of sound propagation in the reinforcement rib;

[0047] ρ1 is the density of the reinforcing rib material.

[0048] According to at least one embodiment of the present application, in the above-mentioned method for determining the noise index parameters of the propeller aircraft reinforced wall panel, in step 3, the noise cutoff frequency f is between the critical frequency f in the vertical direction of the wall panel c1 , critical frequency f in the direction parallel to the wall panel c2 When , the sound transmission loss TL of the stiffened panel is calculated as:

[0049] TL=TL n (f c1 )+10log 10 (η)+30log 10 (f / fC1 )-40log 10 [ln(4f / f C1 )]+10log 10 [2π 3 (f C2 / f C1 ) 1 / 2 ];

[0050] in,

[0051] TL n (f c1 ) is the noise cutoff frequency of the reinforced wall panel, f is the critical frequency f in the vertical direction of the wall panel c1 The sound transmission loss when

[0052] η is the damping coefficient of the panel material.

[0053] According to at least one embodiment of the present application, in the above-mentioned method for determining the noise index parameters of the propeller aircraft reinforced wall panel, in step 3, the noise cutoff frequency f is greater than the critical frequency f in the parallel direction of the wall panel. c2 When , the sound transmission loss TL of the stiffened panel is calculated as:

[0054] TL=TL n (f c2 )+10log10(η)+30log 10 (f / f C2 )-2;

[0055] in,

[0056] TL n (f c2 ) is the noise cutoff frequency of the reinforced wall panel, f is the critical frequency f in the parallel direction of the wall panel c2 The sound transmission loss at this time.

[0057] According to at least one embodiment of the present application, in the above-mentioned method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel, step three is specifically as follows:

[0058]

[0059] in,

[0060] TBL is the turbulent boundary layer noise on the surface of the stiffened panel;

[0061] τ w is the shear stress on the wall of the reinforced panel;

[0062] δ * is the displacement thickness of the turbulent boundary layer on the surface of the stiffened panel;

[0063] U0 is the flight speed.

[0064] According to at least one embodiment of the present application, in the above-mentioned method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel, step three includes:

[0065]

[0066]

[0067] in,

[0068] ρ is the air density;

[0069] Re δ Calculate intermediate parameters for shear stress on the wall of stiffened panels;

[0070] υ is the kinematic viscosity of air.

[0071] According to at least one embodiment of the present application, in the above-mentioned method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel, step three includes:

[0072]

[0073] in,

[0074] x0 is the distance between the reinforced wall panel and the front end of the nose.

[0075] According to at least one embodiment of the present application, in the above-mentioned method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel, step four is specifically as follows:

[0076] Based on the flight status of a propeller aircraft, a propeller near-field noise source model is constructed. The propeller diameter, power, thrust, number of blades, rotational speed, speed of sound, flight speed, ambient temperature, number of propellers, blade width at a radius of 0.8, distance between wingtip and wall panel, and air density are used as key parameters. The near-field noise ROR of the propeller distributed along the stiffened wall panel within the noise cutoff frequency range is obtained.

[0077] According to at least one embodiment of the present application, in the above-mentioned method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel, step five is specifically as follows:

[0078]

[0079] in,

[0080] SPL is the cabin noise of propeller aircraft.

[0081] This application has at least the following beneficial technical effects:

[0082] A method for decomposing and determining noise index parameters of propeller aircraft stiffened panels is provided. Based on an open-theory analysis of the sound transmission loss of propeller aircraft stiffened panels and the cabin noise under excitation by an external sound source, the cabin noise index is decomposed into the stiffened panels. Through iterative calculation of the sound transmission loss, structure, and material parameters of the stiffened panels, the sound transmission loss, structure, and material parameters of the stiffened panels that meet the cabin noise index requirements are finally obtained. This method is convenient and efficient and can guide the design of stiffened panels during the aircraft development process. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 Schematic diagram of a method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel provided in an embodiment of the present application;

[0084] Figure 2 It is a schematic diagram of the reinforced wall panel structure model provided in an embodiment of the present application.

[0085] In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. In addition, the drawings are only used for illustrative purposes and should not be understood as limiting this application. DETAILED DESCRIPTION

[0086] To make the technical solution and its advantages of this application more clear, the technical solution of this application will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described here are only some of the embodiments of this application and are only used to explain this application, not to limit this application. It should be noted that for ease of description, only the parts relevant to this application are shown in the accompanying drawings, and other relevant parts can refer to the general design.

[0087] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application should have the usual meanings understood by those skilled in the art in the field to which this application belongs. The words indicating orientation used in the description of this application are only used to indicate relative directions or positional relationships. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "include" used in the description of this application means that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0088] In addition, it should be noted that, unless otherwise clearly stipulated and limited, the words "installation", "connection" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0089] The embodiment of the present application provides a method for decomposing and determining noise index parameters of propeller aircraft stiffened panels based on theoretical analysis of the sound transmission loss of propeller aircraft stiffened panels and cabin noise under excitation of external sound sources, such as Figure 1 shown.

[0090] Step 1: Calculate the critical frequency of the stiffened wall panel.

[0091] The structural parameters of the reinforced wall panel mainly include the wall panel section thickness h, the reinforcing rib height h r , rib width t, and center distance d between ribs, the structural model of the stiffened wall panel is constructed as follows: Figure 2 shown.

[0092] The stiffness of the stiffened panel in the directions perpendicular to and parallel to the ribs is different, so there are critical frequencies in two directions, including the critical frequency f in the perpendicular direction of the panel. c1 , critical frequency f in the direction parallel to the wall panel c2 .

[0093]

[0094] in,

[0095] c is the speed of sound in air;

[0096] M S is the mass per unit area of ​​the wall panel;

[0097] B1 is the vertical bending stiffness of the wall panel.

[0098] M S =ρ W h[1+(h r / h)(t / d)];

[0099] in,

[0100] ρ W is the density of the siding material.

[0101] B1=EI / d;

[0102] in,

[0103] E is the elastic modulus of the siding material;

[0104] I is the moment of inertia of the T-axis of the wall panel.

[0105]

[0106] in,

[0107] B2 is the bending stiffness in the direction parallel to the wall panel.

[0108]

[0109] Step 2: Calculate the sound transmission loss based on the critical frequency of the stiffened wall panel.

[0110] The noise cutoff frequency f is less than the critical frequency f in the vertical direction of the wall panel c1 When , the sound transmission loss TL of the stiffened panel is calculated as follows:

[0111] TL=TL n -5;

[0112] in,

[0113] TL n is the normal transmission loss of incident sound waves in the reinforced panel.

[0114] TL n =10log 10 (1 / a tn );

[0115] in,

[0116] a tn is the transfer coefficient of sound energy in the stiffened wall panel.

[0117]

[0118]

[0119] in,

[0120] c1 is the speed of sound propagation in the reinforcement rib;

[0121] ρ1 is the density of the reinforcing rib material.

[0122] The noise cutoff frequency f is between the critical frequency f in the vertical direction of the wall panel c1 , critical frequency f in the direction parallel to the wall panel c2 When , the sound transmission loss TL of the stiffened panel is calculated as follows:

[0123] TL=TL n (f c1 )+10log 10 (η)+30log 10 (f / f C1 )-40log 10 [ln(4f / f C1 )]+10log 10 [2π 3 (f C2 / f C1 ) 1 / 2 ];

[0124] in,

[0125] TL n (f c1 ) is the noise cutoff frequency of the reinforced wall panel, f is the critical frequency f in the vertical direction of the wall panel c1 The sound transmission loss when

[0126] η is the damping coefficient of the panel material.

[0127] The noise cutoff frequency f is greater than the critical frequency f in the direction parallel to the wall panel c2 When , the sound transmission loss TL of the stiffened panel is calculated as follows:

[0128] TL=TL n (f c2 )+10log10(η)+30log 10 (f / f C2 )-2;

[0129] in,

[0130] TL n (f c2 ) is the noise cutoff frequency of the reinforced wall panel, f is the critical frequency f in the parallel direction of the wall panel c2 The sound transmission loss at this time.

[0131] Step 3: Calculate the turbulent boundary layer noise on the surface of the stiffened panel.

[0132]

[0133] in,

[0134] TBL is the turbulent boundary layer noise on the surface of the stiffened panel;

[0135] τ w is the shear stress on the wall of the reinforced panel;

[0136] δ * is the displacement thickness of the turbulent boundary layer on the surface of the stiffened panel;

[0137] U0 is the flight speed.

[0138]

[0139]

[0140] in,

[0141] ρ is the air density;

[0142] Re δ Calculate intermediate parameters for shear stress on the wall of stiffened panels;

[0143] υ is the kinematic viscosity of air.

[0144]

[0145] in,

[0146] x0 is the distance between the reinforced wall panel and the front end of the nose.

[0147] Step 4: Calculate the near-field noise of the propeller distributed along the stiffened wall panel.

[0148] Based on the flight status of a propeller aircraft, a propeller near-field noise source model is constructed. The propeller diameter, power, thrust, number of blades, rotational speed, speed of sound, flight speed, ambient temperature, number of propellers, blade width at a radius of 0.8, distance between wingtip and wall panel, and air density are used as key parameters. The near-field noise ROR of the propeller distributed along the stiffened wall panel within the noise cutoff frequency range is obtained.

[0149] Step 5: Calculate the cabin noise of the propeller aircraft based on the sound transmission loss of the stiffened wall panel, the turbulent boundary layer noise on the surface of the stiffened wall panel, and the near-field noise of the propeller distributed along the stiffened wall panel.

[0150]

[0151]

[0152] in,

[0153] SPL is the cabin noise of propeller aircraft.

[0154] Step 6: If the cabin noise of the propeller aircraft cannot meet the cabin noise index requirements, adjust the structure and material parameters of the stiffened wall panel, optimize the structure and material parameters of the stiffened wall panel, and repeat steps 1 to 5 until the cabin noise of the propeller aircraft meets the cabin noise index requirements. The sound transmission loss of the stiffened wall panel and its structure and material parameters are obtained as design indicators for the stiffened wall panel.

[0155] In a specific example, the wall panel section thickness h=3mm, the reinforcing rib height h r =3mm, rib width t = 2mm, rib center distance d = 10mm, the mass per unit area of ​​the panel M is calculated S , the moment of inertia I of the T-shaped center axis of the wall panel.

[0156] The wall panels and reinforcement ribs are made of aluminum alloy, the material density is W=ρ1=2700kg / m3, material elastic modulus E=70000MPa, material damping coefficient η=0.3, speed of sound propagation in the reinforcement rib c1=5000m / s, propeller aircraft cruising altitude 5km, speed of sound in the air on both sides of the panel c=320m / s, the bending stiffness of the panel in the vertical direction B1, the bending stiffness of the panel in the parallel direction B2, and the transfer coefficient of sound energy in the reinforced panel a are calculated. tn , sound wave incident normal transmission loss TL of reinforced wall panel n , and then the sound transmission loss TL of the stiffened wall panel is obtained.

[0157] The propeller aircraft flight speed U0 = 0.7 Ma, the distance between the stiffened panel and the front end of the nose x0 = 5 m, and the air viscosity υ = 2.8 × 10-5 are selected to calculate the turbulent boundary layer noise TBL on the stiffened panel surface.

[0158] With propeller diameter, power, thrust, number of blades, rotation speed, speed of sound, flight speed, ambient temperature, number of propellers, blade width at 0.8 radius, distance from wingtip to wall panel, and air density as key parameters, a propeller near-field noise source model is constructed, and the near-field noise ROR of the propeller distributed along the stiffened wall panel is obtained.

[0159] The propeller aircraft cabin noise SPL is calculated based on the sound transmission loss of the stiffened wall panel, the turbulent boundary layer noise on the surface of the stiffened wall panel, and the near-field noise distributed by the propeller along the stiffened wall panel. If the cabin noise index is not met, the stiffened wall panel structure and material parameters are adjusted and optimized. The above process is repeated until the propeller aircraft cabin noise SPL meets the cabin noise index requirements. The sound transmission loss TL of the stiffened wall panel and its structure and material parameters are obtained. Among them, the structural material of the stiffened wall panel can specifically include the wall panel section thickness h, the reinforcing rib height h r , rib width t, center distance d between ribs, etc. The material parameters of the stiffened wall panel specifically include the density, elastic modulus, moment of inertia and other aspects of the structure.

[0160] The above-mentioned disclosed method for decomposing and determining the noise index parameters of the propeller aircraft stiffened wall panel is based on an open-theory analysis of the sound transmission loss of the propeller aircraft stiffened wall panel and the cabin noise under the excitation of an external sound source. The cabin noise index is decomposed into the stiffened wall panel. The sound transmission loss of the stiffened wall panel and its structural and material parameters are iteratively calculated to finally obtain the stiffened wall panel sound transmission loss and its structural and material parameters that meet the cabin noise index requirements. This method is convenient and efficient and can guide the design of stiffened wall panels during the aircraft development process.

[0161] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or replacements to the relevant technical features, and the technical solutions after these changes or replacements will fall within the scope of protection of the present application.

Claims

1. A method for decomposing and determining noise index parameters of a propeller aircraft reinforced wall panel, characterized in that: include: Step 1: Calculate the critical frequency of the reinforced wall panel; Step 2: Calculate the sound transmission loss based on the critical frequency of the stiffened wall panel; Step 3: Calculate the turbulent boundary layer noise on the surface of the stiffened panel; Step 4: Calculate the near-field noise of the propeller along the stiffened wall panel; Step 5: Calculate the cabin noise of the propeller aircraft based on the sound transmission loss of the stiffened panel, the turbulent boundary layer noise on the surface of the stiffened panel, and the near-field noise of the propeller distributed along the stiffened panel; Step 6: If the cabin noise of the propeller aircraft cannot meet the cabin noise index requirements, adjust the structure and material parameters of the stiffened wall panel, optimize the structure and material parameters of the stiffened wall panel, and repeat steps 1 to 5 until the cabin noise of the propeller aircraft meets the cabin noise index requirements, and obtain the sound transmission loss of the stiffened wall panel and its structure and material parameters.

2. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 1, characterized in that: The structural parameters of the reinforced wall panel include the wall panel section thickness h, the reinforcing rib height h r , rib width t, and center distance d between ribs.

3. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 2, characterized in that: In step 1, the critical frequencies of the stiffened panels are calculated, including the critical frequencies f in the vertical direction of the panels. c1 , critical frequency f in the direction parallel to the wall panel c2 .

4. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 3, characterized in that: In step one: in, c is the speed of sound in air; M S is the mass per unit area of ​​the wall panel; B1 is the vertical bending stiffness of the wall panel.

5. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 4, characterized in that: In step one: M S =ρ W h[1+(h r / h)(t / d)]; in, ρ W is the density of the siding material.

6. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 5, characterized in that: In step one: B1=EI / d; in, E is the elastic modulus of the siding material; I is the moment of inertia of the T-axis of the wall panel.

7. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 6, characterized in that: In step one: in, B2 is the bending stiffness in the direction parallel to the wall panel.

8. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 7, characterized in that: In step one:

9. The method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel according to claim 8, characterized in that: In step 3, the noise cutoff frequency f is less than the critical frequency f in the vertical direction of the wall panel c1 When , the sound transmission loss TL of the stiffened panel is calculated as: TL=TL n -5; in, TL n is the normal transmission loss of incident sound waves on the stiffened panel; TL n D10log 10 (1 / a tn )4 in, a tn is the transfer coefficient of sound energy in the stiffened wall panel; in, c1 is the speed of sound propagation in the reinforcement rib; ρ1 is the density of the reinforcing rib material.

10. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 9, characterized in that: In step 3, the noise cutoff frequency f is between the critical frequency f in the vertical direction of the wall panel c1 , critical frequency f in the direction parallel to the wall panel c2 When , the sound transmission loss TL of the stiffened panel is calculated as: TL=TL n (f c1 )+10log 10 (n)+30log 10 (f / f C1 )-40log 10 [ln(4f / f C1 )]+10log 10 [2π 3 (f C2 / f C1 ) 1 / 2 ]; in, TL n (f c1 ) is the noise cutoff frequency of the reinforced wall panel, f is the critical frequency f in the vertical direction of the wall panel c1 The sound transmission loss when η is the damping coefficient of the panel material.

11. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 10, characterized in that: In step 3, the noise cutoff frequency f is greater than the critical frequency f in the direction parallel to the wall panel c2 When , the sound transmission loss TL of the stiffened panel is calculated as: TL=TL n (f c2 )+10log10(η)+30log 10 (f / f C2 )-2; in, TL n (f c2 ) is the noise cutoff frequency of the reinforced wall panel, f is the critical frequency f in the parallel direction of the wall panel c2 The sound transmission loss at this time.

12. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 11, characterized in that: Step three is as follows: in, TBL is the turbulent boundary layer noise on the surface of the stiffened panel; τ w is the shear stress on the wall of the reinforced panel; δ * is the displacement thickness of the turbulent boundary layer on the surface of the stiffened panel; U0 is the flight speed.

13. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 12, characterized in that: In step three: in, ρ is the air density; Re δ Calculate intermediate parameters for shear stress on the wall of stiffened panels; υ is the kinematic viscosity of air.

14. The method for decomposing and determining noise index parameters of a propeller aircraft stiffened wall panel according to claim 13, characterized in that: In step three: in, x0 is the distance between the reinforced wall panel and the front end of the nose.

15. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 14, characterized in that: Step 4 is as follows: Based on the flight status of a propeller aircraft, a propeller near-field noise source model is constructed. The propeller diameter, power, thrust, number of blades, rotational speed, speed of sound, flight speed, ambient temperature, number of propellers, blade width at a radius of 0.8, distance between wingtip and wall panel, and air density are used as key parameters. The near-field noise ROR of the propeller distributed along the stiffened wall panel within the noise cutoff frequency range is obtained.

16. The method for decomposing and determining noise index parameters of propeller aircraft stiffened wall panels according to claim 15, characterized in that: Step 5 is as follows: in, SPL is the cabin noise of propeller aircraft.

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