A method, system and electronic device for determining helicopter rotor noise

Abstract

The application provides a method and system for determining helicopter rotor noise and an electronic device, relates to the technical field of noise value measurement, and obtains sound source information of a flow field where a helicopter rotor is located; determines a plurality of sound source terms of the flow field where the helicopter rotor is located according to the sound source information; determines physical receiving time of an observation point according to current sound emission time and a current sound source emission position; determines a plurality of observation point receiving sound pressures of each physical receiving time of the observation point, which are originated from the current sound source; and superimposes the observation point receiving sound pressures corresponding to a plurality of sound sources at the same physical receiving time to obtain the helicopter rotor noise at the corresponding physical receiving time. The physical receiving time of the observation point is corrected, the sound speed, the flow field speed and the mobility of the observation point are considered in the determination of the helicopter rotor noise, and the determination precision of the helicopter rotor noise is improved.

Description

Technical Field

[0001] This invention relates to the field of noise measurement technology, and in particular to a method, system and electronic device for determining helicopter rotor noise. Background Technology

[0002] The acoustic analogy method was proposed when studying the sound radiation problem in a small turbulent region (generally the surface of a moving object and the surrounding flow field) in an infinitely uniform fluid with constant sound speed and density. It has outstanding performance in predicting far-field noise and has important applications in the study of aircraft aerodynamic noise.

[0003] like Figure 1 As shown, solving for noise using the acoustic analogy method involves the following steps: 1) Obtaining sound source information in the flow field, including pressure, velocity, and density, as well as coordinate information including time and space; 2) Determining multiple sound source terms based on the sound source input information; 3) Determining the physical time of the observation point, obtaining the coordinates of the observation point at the physical time, and solving for the delay time using the Newton-Raphson iteration method to obtain the corresponding noise propagation time and sound source emission time; 4) Determining the propagation distance of the corresponding sound source term based on the sound source emission time, and obtaining the sound pressure value of the observation point at the physical time; 5) Repeating steps 3) and 4) for different sound source points, and integrating to obtain the sound pressure value of the observation point at the physical time.

[0004] It is known that in existing methods, the sound source emission time needs to be determined by inversely calculating the physical time of the observation point and the sound wave propagation time, and the noise propagation time is obtained by solving the delay time formula using Newton's iteration method. Therefore, the accuracy of the delay time formula solution determines the accuracy of the noise sound pressure. The noise propagation time is determined by the ratio of the propagation distance to the far-field sound speed. Existing acoustic analogy methods assume that noise propagates in a stationary air medium. When the helicopter rotor and tail rotor rotate, the surrounding flow field is agitated by the rotating blades and engine exhaust. Not only does the air medium itself have a large velocity, but the local sound speed also changes due to variations in air density and pressure. Therefore, the assumptions made by existing technologies regarding sound speed and air medium differ from the actual flow field of a helicopter and are difficult to consider variable sound speeds and flow field velocities. Furthermore, the sound source emission time obtained by solving the delay time formula is often inconsistent with the existing time points in the sound source set. Therefore, it is necessary to interpolate the sound source set in time to obtain the sound source information of the emission time. When the time points of the original sound source set are not dense enough, the interpolation method will also introduce errors. Summary of the Invention

[0005] The purpose of this invention is to provide a method, system, and electronic device for determining helicopter rotor noise, which can improve the accuracy of helicopter rotor noise determination.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A method for determining helicopter rotor noise, comprising:

[0008] Acquire sound source information of the flow field where the helicopter rotor is located; the sound source information includes sound speed and number of sound sources, as well as the sound source location and sound emission time when each sound source emits sound pressure.

[0009] Based on the sound source information, multiple sound source terms in the flow field where the helicopter rotor is located are determined;

[0010] Identify any sound source as the current sound source;

[0011] Determine the time of any sound emitted from the current sound source as the current sound time;

[0012] The location of the sound source at the current time of sound emission is defined as the current sound source emission location.

[0013] Determine the physical reception time of the observation point based on the current sound emission time and the current sound source location;

[0014] Based on the sound source item, the sound pressure value originating from the current sound source at the observation point is determined to be the sound pressure received at the observation point at the physical reception time;

[0015] The physical reception time of each observation point is determined from the sound pressure received by multiple observation points of the current sound source;

[0016] The sound pressure received at observation points corresponding to multiple sound sources at the same physical reception time is superimposed to obtain the helicopter rotor noise at the corresponding physical reception time.

[0017] Optionally, the calculation formula for the sound source term is:

[0018]

[0019]

[0020] Where, p L (x,t) represents the load sound pressure, p T (x,t) represents the thickness sound pressure; x is the location of the observation point, t is the actual physical time at the observation point, π is pi, and c0 is the far-field sound velocity; f = 0 represents the sound source surface to be integrated, and s is the area of ​​the element; l is the force exerted by the load on the surface area of ​​the sound source surface on the local fluid. i Let x be the normal force exerted by the object's surface on the local fluid at the x-axis during the i-th iteration. i Components in direction, Let x be the normal force exerted by the object's surface on the local fluid at the x-axis during the i-th iteration. i Component l in direction i The derivative of l with respect to the sound source time τr Let x be the normal force exerted by the object's surface on the local fluid at the x-axis during the i-th iteration. i Component l in direction i Projection in the direction of sound propagation r is the distance between the sound source and the observation point. The unit vector in the direction from the sound source point to the observation point. The unit vector in the direction from the sound source point to the observation point. x-axis at the i-th iteration i Components in direction; M a M is the Mach number of the sound source relative to the observation point. ai M is the Mach number of the sound source point relative to the observation point. a Yu x i Components in the axial direction, M ar M is the Mach number of the sound source point relative to the observation point. a Yu x i Component M in the axial direction ai Projection in the direction of sound propagation; M is the Mach number of the sound source point relative to the observation point. a Yu x i Component M in the axial direction ai The derivative with respect to the sound source time τ; V n Let be the normal velocity of the sound source surface. V is the normal velocity of the sound source surface. n The derivative with respect to the sound source time τ; ρ0 is the density of the far-field fluid.

[0021] Optionally, determining the physical reception time of the observation point based on the current sound emission time and the current sound source location includes:

[0022] Let the iteration number i = 1;

[0023] The position of the observation point at the current sound emission time is the same as the position of the observation point receiving sound pressure at the 0th iteration.

[0024] Based on the current sound source location and the sound pressure location of the observation point during the (i-1)th iteration, determine the noise propagation time during the i-th iteration;

[0025] The location of the sound pressure received at the observation point during the i-th iteration is determined based on the noise propagation time during the i-th iteration.

[0026] The absolute value of the difference between the sound pressure position of the observation point at the i-th iteration and the sound pressure position of the observation point at the (i-1)-th iteration is the correction influence amount.

[0027] The determination result is obtained by judging whether the correction effect is less than the correction effect threshold;

[0028] If the judgment result is negative, the value of the iteration number i is increased by 1, and the process returns to the step "determine the noise propagation time at the i-th iteration based on the current sound source location and the sound pressure location of the observation point at the (i-1)th iteration".

[0029] If the judgment result is yes, then based on the current sound emission time and the noise propagation time at the i-th iteration, the sound pressure time received by the observation point at the i-th iteration is determined as the physical reception time of the observation point.

[0030] Optionally, the location of the observation point receiving the sound pressure during the i-th iteration is:

[0031] y i =y0+t 传,i ·v y ;

[0032] Among them, y i Let y0 be the position of the observation point receiving sound pressure during the i-th iteration, and t be the position of the observation point receiving sound pressure during the 0-th iteration. 传,i v is the noise propagation time during the i-th iteration; y The velocity of the observation point relative to the ground.

[0033] Optionally, the sound pressure reception time at the observation point during the i-th iteration is:

[0034] t i =τ+t 传,i ;

[0035] Among them, t i τ is the sound pressure time received at the observation point during the i-th iteration; τ is the current sound emission time; t 传,i Let be the noise propagation time during the i-th iteration.

[0036] Optionally, the noise propagation time during the i-th iteration is:

[0037]

[0038] Among them, t 传，i Δt represents the noise propagation time during the i-th iteration. j Let be the time required for the noise to travel through the j-th Δs distance; c j For the local speed of sound, v n,j Δs is the projection of the local air medium velocity in the propagation direction; Δs is the pre-selected discrete distance when the entire noise propagation path is discretized at equal intervals, and Δs does not exceed 0.01 times the total propagation distance s.

[0039] A system for determining helicopter rotor noise, comprising:

[0040] The sound source information determination module is used to obtain the sound source information of the flow field where the helicopter rotor is located; the sound source information includes the sound speed and the number of sound sources, as well as the sound source location and sound emission time when each sound source emits sound pressure.

[0041] The sound source item determination module is used to determine multiple sound source items in the flow field where the helicopter rotor is located based on the sound source information.

[0042] The current sound source determination module is used to determine any sound source as the current sound source;

[0043] The current sound time module is used to determine the sound time of any sound source at any given time as the current sound time.

[0044] The current sound source location module is used to determine the current sound source location at the current sound source time as the current sound source location.

[0045] The physical reception time determination module is used to determine the physical reception time of the observation point based on the current sound emission time and the current sound source location.

[0046] The first observation point received sound pressure determination module is used to determine the sound pressure value originating from the current sound source at the observation point at the physical reception time based on the sound source item.

[0047] The second observation point received sound pressure determination module is used to determine the sound pressure received by multiple observation points at each physical reception time of the observation point, which originates from the current sound source.

[0048] The helicopter rotor noise module is used to superimpose the sound pressure received at observation points corresponding to multiple sound sources at the same physical reception time, and then use the result as the helicopter rotor noise at the corresponding physical reception time.

[0049] An electronic device includes a memory and a processor, the memory storing a computer program, and the processor running the computer program to cause the electronic device to perform the method for determining helicopter rotor noise.

[0050] Optionally, the memory is a readable storage medium.

[0051] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0052] This invention provides a method, system, and electronic device for determining helicopter rotor noise. The method involves acquiring sound source information of the flow field where the helicopter rotor is located; determining multiple sound source terms in the flow field based on the sound source information; identifying any sound source as the current sound source; determining the emission time of any emission from the current sound source as the current emission time; determining the location of the current sound source at the current emission time as the current sound source emission location; determining the physical reception time of the observation point based on the current emission time and the current sound source emission location; determining the sound pressure value originating from the current sound source at the observation point at the physical reception time based on the sound source terms; determining the received sound pressure at multiple observation points originating from the current sound source for each physical reception time at the observation point; and superimposing the received sound pressures at observation points corresponding to multiple sound sources at the same physical reception time to obtain the helicopter rotor noise at the corresponding physical reception time. This invention improves the accuracy of helicopter rotor noise determination by correcting the physical reception time of the observation point, taking into account sound speed, flow field velocity, and the mobility of the observation point. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 Flowchart for solving noise using the acoustic analogy method in existing technologies

[0055] Figure 2 This is a flowchart of the method for determining helicopter rotor noise in Embodiment 1 of the present invention;

[0056] Figure 3 This is a schematic diagram of the method for determining helicopter rotor noise in Embodiment 1 of the present invention;

[0057] Figure 4 This is a schematic diagram of the noise propagation path correction principle in Embodiment 1 of the present invention. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The purpose of the present invention is to provide a method, system, and electronic device for determining helicopter rotor noise, which can improve the accuracy of helicopter rotor noise determination.

[0059] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] The acoustic analogy method, proposed by Lighthill, was used to study sound radiation in small turbulent regions (typically the surface of a moving object and its surrounding flow field) of an infinitely uniform fluid with constant sound velocity and density. It has demonstrated outstanding performance in predicting far-field noise and has important applications in aircraft aerodynamic noise research. Solving for noise using the acoustic analogy method generally involves the following steps:

[0061] 1) Obtain relevant input information of the sound source from the flow field, including pressure, velocity and density, which contain time and space coordinate information.

[0062] 2) Obtain each sound source term from the sound source input information according to the Farassat1A formula [Equation (1) and Equation (2)]; the Farassat1A formula is a formula proposed by Farassat (a person's name, transliterated as Farasat) to specifically solve the noise source term based on the idea of ​​acoustic analogy.

[0063]

[0064]

[0065] Where, p L (x,t) represents the load sound pressure, p T (x,t) represents the thickness sound pressure; x is the location of the observation point, t is the actual physical time at the observation point, π is pi, and c0 is the far-field sound velocity; f = 0 represents the sound source surface to be integrated, and s is the area of ​​the element; l is the force exerted by the load on the surface area of ​​the sound source surface on the local fluid. i Let x be the normal force exerted by the object's surface on the local fluid at the x-axis during the i-th iteration. i Components in direction, Let x be the normal force exerted by the object's surface on the local fluid at the x-axis during the i-th iteration. i Component l in direction i The derivative of l with respect to the sound source time τ r Let x be the normal force exerted by the object's surface on the local fluid at the x-axis during the i-th iteration. i Component l in direction i Projection in the direction of sound propagation r is the distance between the sound source and the observation point. The unit vector in the direction from the sound source point to the observation point. The unit vector in the direction from the sound source point to the observation point. x-axis at the i-th iteration i Components in direction; M a M is the Mach number of the sound source relative to the observation point. ai M is the Mach number of the sound source point relative to the observation point. a Yu x i Components in the axial direction, M ar M is the Mach number of the sound source point relative to the observation point. a Yu x i Component M in the axial direction ai Projection in the direction of sound propagation; M is the Mach number of the sound source point relative to the observation point. a Yu x i Component M in the axial direction ai The derivative with respect to the sound source time τ; V n Let be the normal velocity of the sound source surface. V is the normal velocity of the sound source surface. n The derivative with respect to the sound source time τ; ρ0 is the density of the far-field fluid.

[0066] 3) Determine the actual physical time of the observation point, obtain the coordinates of the observation point at the actual time, and solve the delay time formula (Equation (3)) by Newton's iteration method to obtain the corresponding noise propagation time and sound source emission time;

[0067] t-τ-r(y,τ) / c0=0 (3)

[0068] In the formula, t is the real time, τ is the time when the sound source is emitted, r(y,τ) is the noise propagation distance, and y is the spatial position of the sound source at the time when the sound source is emitted, τ.

[0069] 4) Determine the corresponding sound source term and propagation distance based on the sound source time to obtain the sound pressure value at the observation point in real time;

[0070] 5) Repeat steps 3) and 4) for different sound source points, and integrate to obtain the sound pressure value of the observation point in real time.

[0071] The emission time of the sound source obtained by this method through the delay time formula is often inconsistent with the existing time points in the sound source set. Therefore, it is necessary to interpolate the sound source set in time to obtain the sound source information of the emission time. When the time points of the original sound source set are not dense enough, the interpolation method will also introduce errors. To address this, the present invention provides the following technical solution:

[0072] Example 1

[0073] like Figure 2 As shown, this embodiment provides a method for determining helicopter rotor noise, including:

[0074] Step 201: Obtain the sound source information of the flow field where the helicopter rotor is located; the sound source information includes the sound speed and the number of sound sources, as well as the sound source location and sound emission time when each sound source emits sound pressure.

[0075] Step 202: Determine multiple sound source terms in the flow field where the helicopter rotor is located based on the sound source information; the calculation formulas for the sound source terms are formula (1) and formula (2).

[0076] Step 203: Determine any sound source as the current sound source;

[0077] Step 204: Determine the sound emission time of any sound source as the current sound emission time;

[0078] Step 205: Determine the location of the current sound source at the current sound emission time as the current sound source emission location;

[0079] Step 206: Determine the physical reception time of the observation point based on the current sound emission time and the current sound source location; Step 206 includes:

[0080] Step 2061: Let the iteration number i = 1;

[0081] Step 2062: Obtain the position of the observation point at the current sound emission time as the position of the sound pressure received by the observation point at the 0th iteration;

[0082] Step 2063: Determine the noise propagation time in the i-th iteration based on the current sound source location and the sound pressure location of the observation point during the (i-1)th iteration;

[0083] The noise propagation time in the i-th iteration is:

[0084]

[0085] Among them, t 传，i Δt represents the noise propagation time during the i-th iteration. j Let be the time required for the noise to travel through the j-th Δs distance; c j For the local speed of sound, v n,j Δs is the projection of the local air medium velocity in the propagation direction; Δs is the pre-selected discrete distance when the entire noise propagation path is discretized at equal intervals. The selected value shall not exceed 0.01 times the total propagation distance s. Reducing the selected value can improve the calculation accuracy.

[0086] Step 2064: Determine the location of the sound pressure received at the observation point during the i-th iteration based on the noise propagation time during the i-th iteration;

[0087] The location of the observation point receiving the sound pressure during the i-th iteration is:

[0088] yi =y0+t 传,i ·v y ;

[0089] Among them, y i Let y0 be the position of the observation point receiving sound pressure during the i-th iteration, and t be the position of the observation point receiving sound pressure during the 0-th iteration. 传,i v is the noise propagation time during the i-th iteration; y The velocity of the observation point relative to the ground.

[0090] Step 2065: Determine the absolute value of the difference between the sound pressure position of the observation point at the i-th iteration and the sound pressure position of the observation point at the (i-1)-th iteration as the correction influence amount;

[0091] Step 2066: Determine whether the correction effect is less than the correction effect threshold to obtain the determination result; if the determination result is no, proceed to step 2067; if the determination result is yes, proceed to step 2068.

[0092] Step 2067: Increment the value of iteration number i by 1, and return to step 2063;

[0093] Step 2068: Based on the current sound emission time and the noise propagation time at the i-th iteration, determine the sound pressure time received by the observation point at the i-th iteration as the physical reception time of the observation point.

[0094] The sound pressure reception time at the observation point during the i-th iteration is:

[0095] t i =τ+t 传,i ;

[0096] Among them, t i τ is the sound pressure time received at the observation point during the i-th iteration; τ is the current sound emission time; t 传,i Let be the noise propagation time during the i-th iteration.

[0097] Step 207: Based on the sound source term, determine the sound pressure value originating from the current sound source at the observation point at the physical reception time as the sound pressure received at the observation point;

[0098] Step 208: Determine the physical reception time of each observation point from the sound pressure received by multiple observation points of the current sound source;

[0099] Step 209: The sound pressure received at observation points corresponding to multiple sound sources at the same physical reception time is superimposed and used as the helicopter rotor noise at the corresponding physical reception time.

[0100] like Figure 3 As shown, in this embodiment, the noise sound pressure at the observation point location is calculated according to the following steps:

[0101] Step 1) Obtain relevant input information of the sound source from the flow field, including pressure, velocity, density, etc. This information should include time and space coordinate information;

[0102] Step 2) Obtain the various sound source terms according to the Farasat1A formula (Equation (1) and Equation (2)). These sound source terms represent the sound pressure generated by different components of sound sources at the same location. They propagate through space to the observation point to form the received sound pressure at the observation point. Since the sound sources are distributed in different spatial locations, the sound source terms, i.e., the initial values ​​of sound pressure, of the same sound source at different times are different. Therefore, it is necessary to determine any two of the sound source emission time, noise propagation time, and the actual time at the observation point in order to obtain the instantaneous sound pressure of a certain sound source propagating to the observation point. By summing the sound pressures of all sound sources propagating to the observation point over time, the sound pressure at the observation point as a function of time is obtained.

[0103] Step 3) Determine the emission time and emission source of a sound source (called sound source A). Determine the propagation path based on the location of the sound source at the emission time and the location of the observation point. Obtain the noise propagation time by advancing at equal distances.

[0104] Step 4) If the observation point is in motion relative to the ground, correct the reception time and position of the observation point when the sound wave arrives based on the propagation time to obtain a new propagation path; the correction process is as follows: Figure 4 As shown.

[0105] Step 5) Repeat steps 3)-4) until the effect of the correction in step 4) on the observation point position is less than a limit (generally set to 0.01m or lower). Then determine whether the iteration has ended. The time t at the end of the iteration is... i This is the actual physical time received by the observation point.

[0106] |y i -y i-1 |<δ(y)

[0107] In the formula, δ(y) is the constraint for determining whether to stop repeating.

[0108] Step 6) After completing step 5), we obtain the sound pressure from sound source A at the emission time τ, which reaches the observation point at time t. Combining this with the sound source information obtained in steps 1) and 2), we can obtain the sound pressure and time at which the corresponding sound source reaches the observation point at time τ. By repeating steps 3), 4), and 5) for the same sound source at different emission times τ, we can obtain the time-varying sound pressure from sound source A at the observation point.

[0109] Step 7) Perform steps 3)-6) on all sound sources to obtain the time-varying sound pressure received by the observation point from different sound sources. Add the sound pressures from different sound sources to obtain the sound pressure at the observation point in real time.

[0110] Example 2

[0111] In order to execute the method corresponding to Embodiment 1 above and achieve the corresponding functions and technical effects, a system for determining helicopter rotor noise is provided below, including:

[0112] The sound source information determination module is used to obtain sound source information of the flow field where the helicopter rotor is located; the sound source information includes sound speed and number of sound sources, as well as the sound source location and sound emission time when each sound source emits sound pressure.

[0113] The sound source term determination module is used to determine multiple sound source terms in the flow field where the helicopter rotor is located based on the sound source information.

[0114] The current sound source determination module is used to determine any sound source as the current sound source;

[0115] The current sound time module is used to determine the sound time of any sound source at any given time as the current sound time.

[0116] The current sound source location module is used to determine the current sound source location at the current sound source time as the current sound source location.

[0117] The physical reception time determination module is used to determine the physical reception time of the observation point based on the current sound emission time and the current sound source location.

[0118] The first observation point received sound pressure determination module is used to determine the sound pressure value originating from the current sound source at the observation point at the physical reception time based on the sound source item.

[0119] The second observation point received sound pressure determination module is used to determine the sound pressure received by multiple observation points at each physical reception time of the observation point, which originates from the current sound source.

[0120] The helicopter rotor noise module is used to superimpose the sound pressure received at observation points corresponding to multiple sound sources at the same physical reception time, and then use the result as the helicopter rotor noise at the corresponding physical reception time.

[0121] Example 3

[0122] This embodiment provides an electronic device, including a memory and a processor. The memory stores a computer program, and the processor runs the computer program to enable the electronic device to perform a method for determining helicopter rotor noise as described in Embodiment 1.

[0123] The memory is a readable storage medium.

[0124] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0125] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method of determining the noise of a helicopter rotor, characterized in that, The method comprises the following steps: acquiring sound source information of a flow field where a helicopter rotor is located; the sound source information comprises sound speed and sound source quantity, and sound source sound emission position and sound emission time of each sound source when emitting sound pressure; determining a plurality of sound source terms of the flow field where the helicopter rotor is located according to the sound source information; determining any sound source as a current sound source; determining sound emission time of one-time sound emission of the current sound source as current sound emission time; determining a position of the current sound source at the current sound emission time as current sound source sound emission position; determining physical reception time of an observation point according to the current sound emission time and the current sound source sound emission position; determining sound pressure value of the observation point at the physical reception time and originating from the current sound source as observation point received sound pressure according to the sound source terms; determining a plurality of observation point received sound pressures of the observation point originating from the current sound source at each physical reception time; superimposing the observation point received sound pressures corresponding to a plurality of sound sources at the same physical reception time to obtain helicopter rotor noise at the corresponding physical reception time.

2. A method of determining the noise of a helicopter rotor according to claim 1, characterized in that, The calculation formula of the sound source terms is as follows: in, For load sound pressure, For thickness sound pressure; Location of the observation point The actual physical time at the observation point. Pi For far-field sound speed; Denotes the surface of the sound source to be integrated. The area of ​​the unit; The force exerted by the load on the surface area of ​​the sound source on the local fluid. The normal force exerted by the object's surface on the local fluid at the x-axis during the i-th iteration. Components in direction, The normal force exerted by the object's surface on the local fluid at the x-axis during the i-th iteration. Components in direction Relative to the time of the sound source The derivative of The normal force exerted by the object's surface on the local fluid at the x-axis during the i-th iteration. Components in direction Projection in the direction of sound propagation ; The distance between the sound source and the observation point. The unit vector in the direction from the sound source point to the observation point. The unit vector in the direction from the sound source point to the observation point. x-axis at the i-th iteration Components in direction; The Mach number of the sound source relative to the observation point. The Mach number of the sound source relative to the observation point. At Components in the axial direction, Mach number of the sound source relative to the observation point At Components in the axial direction Projection in the direction of sound propagation; , The Mach number of the sound source relative to the observation point. At Components in the axial direction Relative to the time of the sound source The derivative; Let be the normal velocity of the sound source surface. Normal velocity of the sound source surface Relative to the time of the sound source The derivative; The density of the fluid in the far field is given.

3. A method of determining the noise of a helicopter rotor according to claim 1, characterized in that, The determination of the physical reception time of the observation point according to the current sound emission time and the current sound source sound emission position comprises the following steps: setting iteration number i = 1; acquiring a position of the observation point at the current sound emission time as observation point received sound pressure position at the 0th iteration; determining noise propagation time at the ith iteration according to the current sound source sound emission position and the observation point received sound pressure position at the (i-1)th iteration; determining observation point received sound pressure position at the ith iteration according to the noise propagation time at the ith iteration; determining absolute value of a difference between the observation point received sound pressure position at the ith iteration and the observation point received sound pressure position at the (i-1)th iteration as a correction influence; judging whether the correction influence is less than a correction influence threshold to obtain a judgment result; if the judgment result is no, increasing the iteration number i by 1 and returning to the step of determining noise propagation time at the ith iteration according to the current sound source sound emission position and the observation point received sound pressure position at the (i-1)th iteration; if the judgment result is yes, determining observation point received sound pressure time at the ith iteration as the physical reception time of the observation point according to the current sound emission time and the noise propagation time at the ith iteration.

4. A method of determining the noise of a helicopter rotor according to claim 3, characterized in that, The observation point received sound pressure position at the ith iteration is as follows: ； wherein, is the observed sound pressure position at the i-th iteration, is the observed sound pressure position at the 0-th iteration, is the noise propagation time at the i-th iteration; is the velocity of the observed point relative to the ground.

5. A method of determining the noise of a helicopter rotor according to claim 3, characterized in that, The observation point received sound pressure time at the ith iteration is as follows: ； wherein, is the observed sound pressure time at the observation point for the i-th iteration; is the current sound emission time; is the noise propagation time for the i-th iteration.

6. A method of determining the noise of a helicopter rotor according to claim 3, characterized in that, The noise propagation time at the ith iteration is as follows: ； in, Let be the noise propagation time during the i-th iteration; For noise to pass through the j-th Time required to reach the destination; For the local speed of sound, This is the projection of the local air velocity in the direction of propagation. The pre-selected discrete distance is used to discretize the entire noise propagation path at equal intervals. No more than the total transmission distance 0.01 times.

7. A system for determining the noise of a helicopter rotor, characterized in that it comprises: The method comprises the following steps: a sound source information determination module is configured to acquire sound source information of a flow field where a helicopter rotor is located; the sound source information comprises sound speed and sound source quantity, and sound source sound emission position and sound emission time of each sound source when emitting sound pressure; a sound source term determination module is configured to determine a plurality of sound source terms of the flow field where the helicopter rotor is located according to the sound source information; a current sound source determination module is configured to determine any sound source as a current sound source; a current sound emission time module is configured to determine sound emission time of one-time sound emission of the current sound source as current sound emission time; a current sound source sound emission position module is configured to determine a position of the current sound source at the current sound emission time as current sound source sound emission position; a physical reception time determination module is configured to determine physical reception time of an observation point according to the current sound emission time and the current sound source sound emission position. A first observation point received sound pressure determination module is configured to determine, according to the sound source term, a sound pressure value of the current sound source at the observation point at the physical reception time as the observation point received sound pressure. A second observation point received sound pressure determination module is configured to determine a plurality of observation point received sound pressures of the current sound source at each physical reception time of the observation point. A helicopter rotor noise module is configured to superimpose the observation point received sound pressures corresponding to the plurality of sound sources at the same physical reception time to obtain the helicopter rotor noise at the corresponding physical reception time.

8. An electronic device, comprising: The electronic device comprises a memory and a processor, the memory is configured to store a computer program, and the processor is configured to run the computer program to enable the electronic device to perform the helicopter rotor noise determination method in any one of claims 1 to 6.

9. The electronic device of claim 8, wherein, The memory is a readable storage medium.

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