CN103761416B - Method for rapidly forecasting scattering sound field of underwater triangle corner reflector - Google Patents

Abstract

The invention discloses a method for quickly estimating the scattering sound field of an underwater triangular corner reflector, measuring the parameters of the triangular corner reflector and the sound source parameters, and calculating the scattered sound field after multiple scattering of a triangular surface: calculating the triangular surface at the receiving point the first scattering sound field; determine whether there is a first reflection intersection surface, and calculate the second scattering sound field of the first reflection intersection surface at the receiving point; determine whether there is a second reflection intersection surface, and calculate the second reflection intersection surface at the receiving point Three scattered sound fields; the first scattered sound field, the second scattered sound field, and the third scattered sound field are superimposed to obtain a scattered sound field after multiple scattering by a triangular surface. Using the same method to calculate the scattered sound field of the other two triangular surfaces after multiple scattering, and superimpose the scattered sound fields of the three triangular surfaces after multiple scattering to obtain the total scattered sound field of the triangular corner reflector. The invention provides a theoretical calculation method for the use of the triangular corner reflector, reduces calculation time and improves work efficiency.

Description

A method for rapidly estimating the scattering sound field of underwater triangular corner reflectors

technical field

The invention belongs to the field of underwater target sound scattering, and mainly relates to a method for estimating the scattering sound field of an underwater triangular corner reflector.

Background technique

The triangular corner reflector is composed of three mutually perpendicular equilateral right-angled triangular faces. The triangular corner reflector has the characteristic of having a larger target intensity in a larger space azimuth range, so it can be used as an acoustic reflector or an underwater acoustic marker, and can also be used as a standard reflector to calibrate the underwater target intensity, or as a Acoustic decoys and experimental targets that simulate the echo of underwater targets. At present, most of the methods for estimating the scattered sound field of corner reflectors are numerical calculation methods that require computer-aided software for grid division, which has a large amount of calculation and slow calculation speed. The existing fast calculation methods for the scattered sound field of triangular corner reflectors require The cutting algorithm using triangle intersection is more complicated.

Contents of the invention

The purpose of the present invention is to quickly calculate the scattering sound field of the triangular corner reflector, and propose a method for quickly estimating the scattering sound field of the underwater triangle corner reflector.

A method for quickly estimating the scattering sound field of an underwater triangular corner reflector, including the following steps:

Step 1, measuring the parameters of the triangular corner reflector and the sound source parameters, the parameters of the triangular corner reflector include the length of the right-angled side of the corner reflector, and the sound source parameters include the position of the sound source and the frequency of the sound wave;

Step 2, calculate the primary reflection mirror point P2 of the sound source point P1 relative to a triangular surface, and calculate the first scattered sound field of the triangular surface at the receiving point;

Step 3, the intersection line of the two triangular faces of the triangular reflector is the orthogonal axis, and it is judged whether the plane formed by the mirror image point P2 of the primary reflection and the two points on the hypotenuse of the triangular face has an intersection point with the orthogonal axis, and the existing intersection point is the axis At the upper intersection point D5, calculate the reflection intersection surface once according to the upper intersection point D5;

Step 4, calculating the two secondary reflection mirror points of the primary reflection mirror point P2 relative to the primary reflection intersecting surface, and calculating the second scattered sound field of the primary reflection intersecting surface at the receiving point;

Step 5, the intersection point of the straight line formed by connecting the mirror point of the secondary reflection and the point on the intersection surface of the corresponding primary reflection except the intersection point D5 on the axis and the apex of the corner reflector and the plane where the triangular surface of the corner reflector is located is the surface Up intersection point, when the intersection point on the surface exists, the secondary reflection intersecting surface is calculated according to the intersection point on the surface;

Step 6, calculating the third scattered sound field of the secondary reflection intersecting surface at the receiving point;

Step 7, superimposing and summing the first scattered sound field and the second scattered sound field to obtain the scattered sound field after multiple scattering by the triangular surface A;

Step 8: Repeat steps 2 to 7 to calculate the scattered sound field of the other two triangular surfaces of the triangular reflector after multiple scattering, and superimpose the scattered sound fields of the three triangular surfaces after multiple scattering to obtain the total scattered sound field of the triangular reflector .

A method for quickly estimating the scattering sound field of an underwater triangular corner reflector in the present invention may also include:

(1) Primary reflection mirror point:

${{\stackrel{<span\; class="notranslate">\; \&Right\; Arrow;</span>}{\mathrm{<span\; class="notranslate">\; Q</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Right\; Arrow;</span>}{\mathrm{<span\; class="notranslate">\; o</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&Right\; Arrow;</span>}{\mathrm{<span\; class="notranslate">\; k</span>}}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}$

in is the position coordinate vector of the primary reflection mirror point, Q ₁ is the sound source position coordinate vector, is the coordinate vector of the center point of the triangle face, is the primary reflected sound ray vector;

The first scattered sound field of the triangular surface at the receiving point:

in, is the acoustic scattering potential function, is the coordinate vector radius of the sound source, r _m is the coordinate vector radius of the receiving point, k is the wave number, is the z-direction component of the sound source coordinate vector, w _m0 is the z-direction component of the receiving point coordinate vector, N is the number of sides of the triangle, b _n is the position vector of the nth vertex of the triangle, and b _N+1 =b ₁ , Δb _n =b _n+1 -b _n , is the unit coordinate vector of the sound source, is the unit coordinate vector of the observation point, t _x and t _y are respectively and The sum of the components in the x and y directions.

(2) The intersecting surface of a reflection is determined by the position of the intersection point on the axis. The position of the intersection point on the axis is divided into two cases: (1) the distance between the intersection point on the axis and the vertex of the corner reflector is less than the length of the right-angled side of the corner reflector, and the intersection point on the axis The vertices of the sum angle reflector are respectively connected with the two vertices on the hypotenuse of the triangular surface to form two triangular surfaces, which are two intersecting surfaces of primary reflection. The length of the right-angled side, the two triangular surfaces corresponding to the intersection point on the axis are two primary reflection intersecting surfaces.

(3) The mirror point of the secondary reflection is:

${{\stackrel{<span\; class="notranslate">\; \&Right\; Arrow;</span>}{\mathrm{<span\; class="notranslate">\; Q</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Right\; Arrow;</span>}{\mathrm{<span\; class="notranslate">\; o</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&Right\; Arrow;</span>}{\mathrm{<span\; class="notranslate">\; k</span>}}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}$

in is the secondary reflection mirror point position coordinate vector, Q ₂ is the primary reflection mirror point position coordinate vector, is the coordinate vector of the center point of the intersecting surface of the primary reflection corresponding to the mirror point of the secondary reflection, is the secondary reflected sound ray vector;

The second scattering sound field of the first reflection intersecting surface at the receiving point:

in, is the acoustic scattering potential function, is the coordinate vector radius of the primary reflection mirror point, r _m is the coordinate vector radius of the receiving point, k is the wave number, is the z-direction component of the mirror point coordinate vector of one reflection, w _m0 is the z-direction component of the receiving point coordinate vector, N is the number of sides of the intersecting surface of one reflection, b _n is the position vector of the nth vertex of the intersecting surface of one reflection , and b _N+1 = b ₁ , Δb _n = b _n+1 -b _n , is the unit coordinate vector of a reflection mirror point, is the unit coordinate vector of the observation point, t _x and t _y are respectively and The sum of the components in the x and y directions.

(4) The intersecting surface of the secondary reflection is determined by the position of the intersection point on the surface. The intersection point of the straight line connecting the intersection point on the surface and the apex of the triangular corner reflector and the hypotenuse of the triangle on the plane where the intersection point on the surface is located is the intersection point on the hypotenuse, and the position of the intersection point on the surface There are two cases: (1) The distance from the intersection point on the surface to the vertex of the corner reflector is less than or equal to the distance from the intersection point on the hypotenuse to the vertex of the corner reflector. The triangular surface is the intersecting surface of secondary reflection; (2) the distance from the intersection point on the surface to the apex of the corner reflector is greater than the distance from the intersection point on the hypotenuse to the apex of the corner reflector, and the intersection point of the straight line connecting the intersection point on the axis and the intersection point on the surface and the hypotenuse is the upper intersection point of the second hypotenuse, and the surface formed by connecting the upper intersection point of the axis, the upper intersection point of the hypotenuse, the upper intersection point of the second hypotenuse, and the apex of the corner reflector is a secondary reflection intersection surface.

(5) The third scattered sound field at the receiving point of the secondary reflection intersecting surface:

in, is the acoustic scattering potential function, is the coordinate vector radius of the secondary reflection mirror point, r _m is the coordinate vector radius of the receiving point, k is the wave number, is the z-direction component of the coordinate vector of the secondary reflection mirror point, w _m0 is the z-direction component of the receiving point coordinate vector, N is the number of sides of the secondary reflection intersecting surface, b _n is the nth vertex of the secondary reflection intersecting surface , and b _N+1 = b ₁ , Δb _n = b _n+1 -b _n , is the unit coordinate vector of the mirror point of the secondary reflection, is the unit coordinate vector of the observation point, t _x and t _y are respectively and The sum of the components in the x and y directions.

Beneficial effects of the present invention:

1. There is no need to use other computer-aided design software such as ANSYS to model and divide the corner reflector, which simplifies the working procedure and reduces the workload.

2. No complex triangle intersection cutting algorithm is required, which reduces the computational complexity.

3. No panel division is performed, but the triangular reflective surface is used as a panel for calculation, which improves the calculation accuracy and calculation speed.

Description of drawings

Fig. 1 is a schematic diagram of a triangular corner reflector;

Fig. 2 is a schematic diagram of a reflection intersecting surface of a triangular corner reflector;

Fig. 3 is a schematic diagram of the secondary reflection intersecting surface of the surface intersection point on the triangular surface;

Fig. 4 is a schematic diagram of a secondary reflection intersecting surface whose intersection point is not on a triangular surface;

Fig. 5 is the flowchart of the method for rapidly estimating the scattering sound field of a triangular reflector;

Figure 6 is the calculation result of target strength at different azimuth angles

detailed description

The present invention will be described in further detail below in conjunction with accompanying drawings 1 to 6 and examples.

The first step is to set the parameters of the triangular corner reflector and the sound source. The parameter of the triangular corner reflector is the length of the right-angled side of the corner reflector, and the sound source parameters are the position of the sound source and the frequency of the sound wave.

In the second step, the three triangular faces that make up the triangular corner reflector are respectively marked as faces A, B, and C. Calculate the scattered sound field of the triangular surface A at the receiving point as shown in Figure 1 with the Gordon surface element integration method. The formula for calculating the triangular surface scattered sound field by the Gordon surface element integration method is as follows:

in, is the sound scattering potential function, r _q is the coordinate vector radius of the sound source, r _m is the coordinate vector radius of the receiving point, k is the wave number, w _q0 is the z direction component of the sound source coordinate vector, w _m0 is the z direction of the receiving point coordinate vector direction component, N is the number of sides of the surface element, b _n is the position vector of the nth vertex, and b _N+1 = b ₁ , Δb _n = b _n+1 -b _n , is the unit coordinate vector of the sound source, is the unit coordinate vector of the observation point, t _x and t _y are respectively and The sum of the components in the x and y directions.

The mirror image point P2 of the primary reflection of the sound source P1 relative to the triangular surface A is obtained by using the mirror image method, as shown in Fig. 2 . The calculation formula of the mirror image method is as follows:

${\stackrel{<span\; class="notranslate">\; \&Right\; Arrow;</span>}{\mathrm{<span\; class="notranslate">\; Q</span>}}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\stackrel{<span\; class="notranslate">\; \&Right\; Arrow;</span>}{\mathrm{<span\; class="notranslate">\; o</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; |</span>{\stackrel{<span\; class="notranslate">\; \&Right\; Arrow;</span>}{\mathrm{<span\; class="notranslate">\; k</span>}}}_{\mathrm{<span\; class="notranslate">\; r</span>}}$

in is the position coordinate vector of the primary reflection image point of the sound source, Q is the position coordinate vector of the sound source, is the coordinate vector of the surfel center point, is the reflected sound ray vector.

The third step is to connect the reflection mirror point P2 with the points D2 and D3 to form a plane, and calculate the intersection point of the formed plane with the other two triangular surfaces or the intersecting axis on the axis according to the method of calculating the intersection point of a straight line and a plane in geometry D5. If there is no intersection, do not count. If there is an intersection point, when the distance between the intersection point D5 on the axis and the vertex of the corner reflector is less than the length of the right-angled side of the corner reflector, the intersection point D5 and the vertex D4 on the axis are respectively connected to the two vertices on the hypotenuse of the triangular surface to form a reflection intersection Surface M1 and primary reflection intersecting surface M2; when the distance between the intersection point D5 on the axis and the apex of the corner reflector is greater than the length of the right-angled side of the corner reflector, the other two triangular surfaces are respectively called primary reflection intersecting surface M1 and primary reflection intersecting surface M2.

The fourth step is to use the primary reflection mirror point P2 as the incident sound source, use the Gordon surface element integral method to calculate the scattered sound field of the primary reflection intersection surface M1 and the primary reflection intersection surface M2 at the receiving point, and use the mirror method to obtain the secondary reflection mirror point D6 and secondary reflection mirror point D7.

In the fifth step, the intersection point D8 of the straight line connecting point D6 and point D3 and the plane where the reflective surface of the corner reflector is located is called the surface intersection point. If there is no intersection, do not count. If there is an intersection point, ① calculate and obtain the intersection point D9 on the hypotenuse. When the distance from the point of intersection D8 on the surface to the vertex D4 of the corner reflector is less than or equal to the distance from the point of intersection D9 on the hypotenuse to the vertex D4 of the corner reflector, connect the vertex D4 of the corner reflector, the point of intersection D8 on the surface and the point of intersection D5 on the axis. The surface is called the secondary reflection intersection surface M3, as shown in Figure 3; ② When the distance from the intersection point D10 on the surface to the vertex D4 of the corner reflector is greater than the distance from the intersection point D11 on the hypotenuse to the vertex D4 of the corner reflector, calculate the intersection points on the axis respectively The straight line connecting D5 to the intersection point D10 on the surface, the straight line connecting the vertex D4 of the corner reflector to the intersection point D10 on the surface and the two intersection points D11 and D12 of the hypotenuse of the triangle surface are connected in turn D4, D5, D12, D11 to form a secondary reflection intersection Surface 18, as shown in Figure 4. The above-mentioned surface M3 and surface M4 are secondary reflection intersecting surfaces corresponding to the surface M1, and the secondary reflection intersecting surface corresponding to the surface M2 can be obtained by the same method.

The sixth step is to use the secondary reflection mirror point as the incident sound source, and use the Gordon surface element integration method to calculate the scattered sound field of the secondary reflection intersecting surface at the receiving point.

The seventh step is to superimpose and sum the scattered sound fields obtained from the above calculations to form a scattered sound field after multiple scattering by a triangular surface.

The eighth step, by repeating the above steps 2 to 7, calculate the scattered sound field after multiple scattering on the other two surfaces B and C on the corner reflector, and superimpose and sum all the calculation results to obtain the total scattered sound field of the corner reflector.

Fig. 5 is a flowchart of a method for quickly estimating the scattering sound field of an underwater triangular corner reflector according to the present invention.

Set the sound wave frequency to 800kHz, and the length of the right-angled side of the triangular corner reflector is 0.1m. Under rigid boundary conditions, the target strength of the triangular corner reflector at different azimuths in space is calculated when the transceiver is combined, as shown in Figure 6.

Claims (6)

1. A method for quickly pre-estimating a scattering sound field of an underwater triangular reflector is characterized by comprising the following steps:

measuring parameters of a triangular angle reflector and parameters of a sound source, wherein the parameters of the triangular angle reflector comprise the length of a right-angle side of the angle reflector, and the parameters of the sound source comprise the position of the sound source and the frequency of the sound wave;

step two, calculating a primary mirror image point (P2) of a sound source point (P1) relative to a triangular surface, and calculating a first scattering sound field of the triangular surface at a receiving point;

step three, the intersection line of two triangular surfaces of the triangular reflector is an intersection axis, whether a plane formed by a primary reflector image point (P2) and two points on the bevel edge of the triangular surface has an intersection point with the intersection axis or not is judged, the existing intersection point is an on-axis intersection point (D5), and a primary reflection intersection surface is calculated according to the on-axis intersection point (D5);

step four, calculating a secondary mirror image point of the primary mirror image point (P2) relative to the primary reflection intersecting surface, and calculating a second scattering sound field of the primary reflection intersecting surface at the receiving point;

step five, connecting the image point of the secondary reflector and the point on the corresponding primary reflection intersecting surface except the intersection point (D5) on the axis and the vertex of the angle reflector to form a straight line, and taking the intersection point of the plane where the triangular surface of the angle reflector is located as the on-surface intersection point, and calculating the secondary reflection intersecting surface according to the on-surface intersection point when the on-surface intersection point exists;

calculating a third scattering sound field of the secondary reflection intersecting surface at the receiving point;

step seven, superposing and summing the first scattering sound field and the second scattering sound field to obtain a scattering sound field after triangular surface multiple scattering;

and step eight, repeating the step two to the step seven, calculating the scattering sound field after the other two triangular surfaces of the triangular reflector are scattered for multiple times, and superposing the scattering sound fields after the three triangular surfaces are scattered for multiple times to obtain the total scattering sound field of the triangular reflector.

2. The method for rapidly pre-estimating the scattering sound field of the underwater triangular reflector according to claim 1, wherein the primary mirror image point is:

${{\stackrel{\&RightArrow;}{Q}}_1}^{\&prime;}={\stackrel{\&RightArrow;}{O}}_1-\left|Q_1\right|{\stackrel{\&RightArrow;}{k}}_{r1}$

whereinIs a position coordinate vector, Q, of a primary reflection mirror point₁Is a vector of the coordinates of the sound source position,is a coordinate vector of the center point of the triangular surface,is the primary reflected sound ray vector;

a first scattered sound field of a triangular surface at a receiving point:

wherein, is a function of the acoustic scattering potential and,as the radial dimension of the sound source coordinate, r_mIs the coordinate vector diameter of the receiving point, k is the wave number,is the z-direction component, w, of the sound source coordinate vector_m0For the z-direction component of the received point coordinate vector, N is the number of sides of the triangular face, b_nIs the position vector of the nth vertex of the triangular face,and b is_N+1＝b₁，Δb_n＝b_n+1-b_n， Is a unit coordinate vector of the sound source,is a unit coordinate vector of the observation point, t_xAnd t_yAre respectivelyAndthe sum of the x-direction and y-direction components.

3. The method for rapidly pre-estimating the scattering sound field of the underwater triangular reflector according to claim 1, wherein the intersection plane of the primary reflections is determined by the position of the on-axis intersection point, and the position of the on-axis intersection point is divided into two cases: (1) the distance between the axial intersection point and the vertex of the angle reflector is smaller than the length of the right-angle side of the angle reflector, the axial intersection point and the vertex of the angle reflector are respectively connected with two vertexes on the bevel edge of the triangular surface to form two triangular surfaces which are two primary reflection intersection surfaces, and (2) the distance between the axial intersection point and the vertex of the angle reflector is larger than the length of the right-angle side of the angle reflector, and the two triangular surfaces corresponding to the axial intersection point are two primary reflection intersection surfaces.

4. The method for rapidly pre-estimating the scattering sound field of the underwater triangular reflector according to claim 1, wherein the secondary mirror image points are as follows:

${{\stackrel{\&RightArrow;}{Q}}_2}^{\&prime;}={\stackrel{\&RightArrow;}{O}}_2-\left|Q_2\right|{\stackrel{\&RightArrow;}{k_r}}_2$

whereinIs a position coordinate vector, Q, of a secondary reflection mirror point₂Is a position coordinate vector of the primary reflection mirror point,is a coordinate vector of the central point of a primary reflection intersecting surface corresponding to the image point of the secondary reflector,is the secondary reflected sound ray vector;

and a second scattered sound field of the primary reflection intersection surface at the receiving point:

wherein, is a function of the acoustic scattering potential and,is at a timeMirror image point coordinate radial, r_mIs the coordinate vector diameter of the receiving point, k is the wave number,is the z-direction component, w, of the primary mirror image point coordinate vector_m0Is the z-direction component of the coordinate vector of the receiving point, N is the number of sides of the primary reflection intersecting surface, b_nIs a position vector of the nth vertex of the primary reflection intersecting surface, and b_N+1＝b₁，Δb_n＝b_n+1-b_n， Is a unit coordinate vector of the primary mirror image point,is a unit coordinate vector of the observation point, t_xAnd t_yAre respectivelyAndthe sum of the x-direction and y-direction components.

5. The method for rapidly pre-estimating the scattering sound field of the underwater triangular reflector according to claim 1, wherein the intersection of the secondary reflections is determined by the position of an intersection point on the surface, the intersection point of a straight line connecting the intersection point of the surface and the vertex of the triangular angular reflector and the triangular oblique side on the plane where the intersection point of the surface is located is an intersection point on the oblique side, and the position of the intersection point on the surface is divided into two cases: (1) the distance from the intersection point on the surface to the vertex of the angle reflector is less than or equal to the distance from the intersection point on the inclined edge to the vertex of the angle reflector, and a triangular surface formed by connecting the vertex of the angle reflector, the intersection point on the surface and the intersection point on the shaft is a secondary reflection intersection surface; (2) the distance from the intersection point on the surface to the vertex of the corner reflector is greater than the distance from the intersection point on the oblique side to the vertex of the corner reflector, the intersection point of the straight line between the intersection point on the connecting shaft and the intersection point on the surface and the oblique side is the intersection point on the second oblique side, and the surface formed by the intersection point on the connecting shaft, the intersection point on the oblique side, the intersection point on the second oblique side and the vertex of the corner reflector is a secondary reflection intersection surface.

6. The method for rapidly pre-estimating the scattering sound field of the underwater triangular reflector according to claim 1, wherein the third scattering sound field of the secondary reflection intersection surface at the receiving point is as follows:

wherein, is a function of the acoustic scattering potential and,is the secondary reflector image point coordinate vector, r_mIs the coordinate vector diameter of the receiving point, k is the wave number,is the z-direction component, w, of the coordinate vector of the point of the secondary mirror_m0Is the z-direction component of the coordinate vector of the receiving point, N is the number of sides of the plane where the secondary reflections intersect, b_nIs a position vector of the nth vertex of the plane of intersection of the secondary reflections, and b_N+1＝b₁，Δb_n＝b_n+1-b_n， Is the unit coordinate vector of the secondary mirror image point,is a unit coordinate vector of the observation point, t_xAnd t_yAre respectivelyAndthe sum of the x-direction and y-direction components.