Rapid calculation method for tube pass sound transmission characteristics of heat exchanger

Abstract

The invention discloses a rapid calculation method for sound transfer characteristics of a heat exchanger tube pass, and relates to the technical field of ships, the method is based on a transfer matrix method, the heat exchanger tube pass is firstly divided into a plurality of structural units, and then a numerical simulation / analytical calculation / experimental test method is adopted to obtain a sound transfer matrix of each unit; and finally, matrix assembly is performed according to the overall structure and unit boundary conditions to form an overall transfer matrix, evaluation calculation of the heat exchanger tube pass sound transfer loss is achieved, and meanwhile quantitative analysis of sound transfer characteristics is facilitated. The method breaks through an acoustic vibration transmission analysis modeling technology of a heat exchange tube with shell pass fluid, solves the problem that a large-size heat exchanger with an acoustic-structure interaction effect is difficult to calculate by a numerical method, and can provide input for acoustic quantitative evaluation of a ship sea cooling pipeline system; and positive significance is achieved for low-noise design of the heat exchanger and improvement of ship sound stealth performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship, in particular to a quick calculation method of heat exchanger tube sound transmission characteristics. BACKGROUND

[0002] The heat exchanger is the core equipment of the ship cooling system, and the heat exchanger is installed in the sea pipeline, which has an important influence on the sound transmission of the sea pipeline, and further affects the sound radiation of the sea pipeline. At present, the research on the sound transmission characteristics of the heat exchanger tube is mostly carried out by numerical simulation or experimental test, but the cost of experimental test is high, and the cycle is long, the numerical simulation method needs large calculation resources for the heat exchanger with large size, complex structure and sound-solid coupling effect, and the simulation time is long, which is not conducive to engineering application. At present, there is a lack of a quick calculation method of heat exchanger tube sound transmission characteristics suitable for engineering application. SUMMARY

[0003] The present application relates to the technical field of ship, in particular to a quick calculation method of heat exchanger tube sound transmission characteristics.

[0004] The technical scheme of the present application is as follows:

[0005] A quick calculation method of heat exchanger tube sound transmission characteristics, comprising the following steps:

[0006] S1: According to the structure characteristics of the heat exchanger tube, the heat exchanger tube is divided into a plurality of structure units;

[0007] S2: Calculate the acoustic impedance characteristics or transfer matrix of each structure unit, and the acoustic impedance and the transfer matrix can be converted to each other;

[0008] S3: According to the overall structure form of the heat exchanger tube, the position relationship of each structure unit and the boundary condition between the units, the transfer matrix of all structure units is assembled to obtain the overall transfer matrix representing the relationship between the inlet and outlet variables of the heat exchanger tube;

[0009] S4: According to the relationship between the transfer matrix and the sound transmission loss, the sound transmission loss of the heat exchanger tube is calculated based on the overall transfer matrix. Further, the sound transmission characteristic parameter analysis can be carried out, and the influence law of each parameter on the sound transmission characteristics is mastered, which provides technical support for the noise control of the heat exchanger.

[0010] Further technical solutions are that in step S1, the divided structural unit should be mathematically analyzable, and for the structural unit that cannot be analyzed, the numerical simulation calculation or test method can be used to obtain the acoustic impedance characteristics or transfer matrix. On this basis, the number of divided units is required to be as small as possible to improve the calculation efficiency.

[0011] Further technical solutions are that in step S2, for regular structural units such as straight pipes and conical pipes, the acoustic impedance characteristics or transfer matrix can be calculated by corresponding mathematical models; for structural units that are difficult to be numerically analyzed but can be reasonably simplified, the structural units are divided into combined structural units with mathematical analysis models, for example, the end of the tube side of the heat exchanger can be simplified as a series structure of a straight pipe and a conical pipe model, and the acoustic impedance characteristics or transfer matrix of the unit is obtained by equivalent combination of the impedance characteristics or transfer matrix; for complex irregular structural units, the acoustic impedance characteristics or transfer matrix is obtained by numerical simulation or test method. It is worth noting that there is a mutual conversion relationship between the acoustic impedance and the transfer matrix, and the acoustic impedance calculated or tested can be converted into the transfer matrix.

[0012] The beneficial technical effects of the present application are:

[0013] The present application first divides the tube side of the heat exchanger into multiple acoustic units, then obtains the acoustic transfer matrix of each unit by numerical simulation / analytical calculation / test method, and finally assembles the matrix to form the overall transfer matrix according to the overall structure and unit boundary conditions, thereby converting the acoustic transfer problem of the tube side of the heat exchanger into a combination problem of the unit transfer matrix, which can realize the rapid evaluation and calculation of the acoustic transfer loss of the tube side of the heat exchanger, and is suitable for engineering application. In addition, the parameter influence law analysis can also be carried out based on the transfer matrix, which is beneficial to the low-noise design of the heat exchanger.

[0014] The present application derives the internal acoustic vibration transfer matrix of the internal heat exchange tube bundle section when the water medium exists on the inside and outside, characterizes the acoustic transfer of the internal heat exchange tube bundle section through a simple mathematical model, solves the problem of large numerical simulation calculation amount caused by the existence of acoustic-solid coupling effect, and improves the calculation efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a flow chart of the rapid calculation method of the acoustic transfer characteristics of the tube side of the heat exchanger provided by the present application;

[0016] Figure 2 is a schematic diagram of the unit division of the tube side of the heat exchanger provided by an embodiment of the present application;

[0017] Figure 3 is an equivalent diagram of the structure of the tube side of the heat exchanger provided by an embodiment of the present application;

[0018] Figure 4is a schematic diagram of heat exchange tube and fluid coupling provided by an embodiment of the present application;

[0019] Figure 5 is a schematic diagram of the size of the conical pipe provided by an embodiment of the present application;

[0020] Figure 6 is a schematic diagram of the size of the cross-section mutation unit provided by an embodiment of the present application;

[0021] Figure 7 is a schematic diagram of the division of the tube side unit of the heat exchanger provided by another embodiment of the present application;

[0022] Figure 8 is a numerical simulation model diagram of a complex structure unit provided by another embodiment of the present application;

[0023] Figure 9 is a schematic diagram of the connection boundary of each unit in the cross-section provided by another embodiment of the present application;

[0024] Figure 10 is a comparison diagram of the test results of the sound transmission loss of the tube side of the heat exchanger and the calculation results of the present application provided by another embodiment of the present application. DETAILED DESCRIPTION

[0025] The specific embodiments of the present application will be further described below in combination with the accompanying drawings.

[0026] Embodiment one:

[0027] Please refer to Figure 1 The present embodiment provides a fast calculation method for the sound transmission characteristics of the tube side of the heat exchanger, which includes the following steps:

[0028] S1: According to the structural characteristics of the tube side of the heat exchanger, the tube side of the heat exchanger is divided into multiple structural units. In this step, it is required that the divided structural units should be mathematically analyzable, and for the structural units that cannot be analyzed, the sound impedance characteristics or transmission matrix can be obtained by numerical simulation calculation or test. On this basis, it is required that the number of divided units is as small as possible to improve the calculation efficiency.

[0029] S2: Calculate the acoustic impedance characteristics or transfer matrix of each structural unit, and the acoustic impedance and the transfer matrix can be converted to each other. In this step, for regular structural units, their acoustic impedance characteristics or transfer matrix can be calculated analytically through corresponding mathematical models; for structures that are difficult to be numerically analyzed but can be reasonably simplified, they are divided into combined structural units with mathematical analytical models, and the acoustic impedance characteristics or transfer matrix of the units are obtained by equivalent impedance characteristics or transfer matrix of unit combination; for complex irregular structural units, their acoustic impedance characteristics or transfer matrix are obtained by numerical simulation or experimental testing method, and the numerical simulation method can be realized by acoustic simulation software, and the experimental testing method is carried out according to the standard of pipeline component acoustic impedance test.

[0030] It is worth noting that there is a mutual conversion relationship between acoustic impedance and transfer matrix, and the acoustic impedance calculated or tested can be converted to transfer matrix.

[0031] S3: According to the overall structure form of the heat exchanger tube, the positional relationship of each structural unit and the boundary conditions between the units, the transfer matrix of all structural units is assembled to obtain the overall transfer matrix representing the relationship between the variables at the inlet and outlet of the heat exchanger tube.

[0032] S4: According to the relationship between the transfer matrix and the acoustic transmission loss, the acoustic transmission loss of the heat exchanger tube is calculated based on the overall transfer matrix. Further, the acoustic transmission characteristic parameter analysis can be carried out to master the influence law of each parameter on the acoustic transmission characteristics, and to provide technical support for noise control of the heat exchanger.

[0033] Taking the heat exchanger tube shown in Figure 2 as an example, the inlet and outlet of the heat exchanger tube are respectively opened on both sides of the tube, and step S1 specifically includes: according to the geometric form of the heat exchanger tube, the connection relationship of the components and the fluid motion direction, first, dividing the regular structural units with mathematical analytical models, such as the inlet section 1, the outlet section 2 and the internal heat exchange tube bundle section 3 in the heat exchanger tube, the mathematical analytical models of these three parts are all characterized by straight pipe models, and the internal heat exchange tube bundle section 3 is a parallel arrangement of multiple straight pipe models, so the inlet section 1, the outlet section 2 and the tube bundle section 3 can be divided into an independent structural unit respectively. Secondly, dividing the combined structural units which have no definite mathematical model but can be simplified, such as the inlet end 4 and the outlet end 5 of the heat exchanger tube, the end can be simplified as a series structure of straight pipe and conical pipe model, and the mathematical analytical models of straight pipe and conical pipe model are known. Finally, dividing the complex structural units which have no mathematical analytical model and cannot be simplified, and the equivalent diagram of the heat exchanger tube structure after division is shown in Figure 3 It is worth noting that on the basis of the above division criteria, the number of divided structural units should be configured to be minimized to improve the calculation efficiency.

[0034] In step S2, for units that can be countably analyzed, such as straight tubes and tapered tubes, the corresponding impedance models or transfer matrix models are introduced as follows:

[0035] (1) When calculating the transfer matrix of inlet section 1 and outlet section 2, the transfer matrix of the variables at both ends of the straight pipe is used as follows:

[0036]

[0037] Where, p 1,2 These are the sound pressure levels at the inlet and outlet ends of the straight pipe, respectively. 1,2 ρ is the vibration velocity at the inlet and outlet ends, ρ is the density of the medium inside the pipe, c is the sound velocity of the medium inside the pipe, l is the pipe length, k is the wave number, and i is the imaginary unit.

[0038] In reality, because the water medium inside the tubes is a heavy fluid, it is coupled with the pipe structure. Furthermore, the special feature of the heat exchange tubes is that the inside is the tube-side water medium, and the outside is the shell-side water medium; that is, there is a medium on both the inside and outside of the tubes. Figure 4 As shown. When calculating the acoustic impedance characteristics or transfer matrix of the internal heat exchange tube bundle section, considering the acoustic-structure interaction effect between the fluid inside and outside the tube and the tube, the variable transfer matrix at both ends of the straight tube is derived as follows:

[0039] V z (l)=T p V z (0) (1.2)

[0040] Among them, the variables at both ends of the straight pipe are The inlet and outlet of the straight pipe are V respectively. z | z＝0 =V z (0), V z | z＝l =V z (l), transfer matrix T p =W a (l)W a (0) -1 In the formula u z Let p be the axial displacement of the straight pipe, p be the sound pressure of the fluid inside the pipe, and u be the axial displacement of the straight pipe. f F represents the fluid displacement inside the pipe. z A is the axial force of the straight tube, l is the length of the heat exchange tube bundle section, and A is the axial force of the straight tube. p E is the cross-sectional area of ​​the pipe. * =ES is the corrected elastic modulus of the heat exchanger tube material, and E is the elastic modulus of the heat exchanger tube material. To account for the fluid bulk modulus correction due to the coupling between the internal and external media, K is the fluid bulk modulus;

[0041] A, B, D, and X above are simplified calculation terms, related to the heat exchanger tube material and dimensions, and are expressed as follows:

[0042]

[0043] where μ is the Poisson's ratio of the heat exchange tube material, R is the radius of the heat exchange tube, ρ is the density of the tube material, h is the tube wall thickness, and ω is the angular frequency. p ij (1) 1,2

[0044] wherein,

[0045]

[0046] wherein C1-C6 are calculation items expressed in a simplified form, and are related to the heat exchange tube material and size, and are respectively expressed as:

[0047] wherein T ij (1) is a matrix element representing the pressure and displacement of the fluid outside the tube acting on the outer wall of the heat exchange tube, λ 1,2 is a dimensionless wave number solution.

[0048] (2) The dimensions of the conical tube at each position are as shown in Figure 5 , and the variable transfer matrix of the conical tube at both ends is:

[0049]

[0050] wherein p 1,2 are the sound pressures at the inlet and outlet ends of the conical tube, u 1,2 are the vibration speeds at the inlet and outlet ends of the conical tube, ρ is the density of the medium in the tube, c is the sound speed of the medium in the tube, k is the wave number, and i is the imaginary unit. It should be noted that, whether it is the diverging conical tube as shown in Figure 5 (a) or the converging conical tube as shown in Figure 5 (b), the dashed part needs to be extended for calculation, and l=x1+x2 is the total length of the conical tube after extension, and r1 and r2 are the cross-sectional radii at the inlet and outlet ends of the conical tube.

[0051] In step S3, based on the known unit transfer matrix, the matrix assembly is performed according to the boundary conditions between units to form the overall transfer matrix representing the relationship between the inlet and outlet variables of the tube side of the heat exchanger. The boundary conditions between units include: the sound pressure and fluid mass velocity continuity conditions should be satisfied between units. When performing matrix assembly, the interface between the inlet and outlet end heads 4 and 5 of the tube side and the internal tube bundle section 3 can be regarded as a cross-section mutation unit, and the size of the cross-section mutation unit is as shown in Figure 6 , wherein s1 corresponds to the cross-sectional area close to the end of the tube bundle section, and s2 corresponds to the cross-sectional area close to the end of the tube side end head, and the transfer matrix of the variables at both ends of the cross-section mutation unit is:

[0052]

[0053] where p 1,2 are the sound pressure near the tube bundle segment end and near the tube side end, u 1,2 are the vibration velocity near the tube bundle segment end and near the tube side end, p is the density of the medium in the tube, and c is the sound velocity of the medium in the tube. It should be noted that the transfer matrix of the cross-section mutation unit has considered the parallel connection of multiple tube bundles.

[0054] In the embodiment, the overall transfer matrix of the variable relationship at the inlet and outlet ends of the tube side of the heat exchanger can be expressed as:

[0055]

[0056] The corresponding sound transmission loss can be calculated by the following formula:

[0057]

[0058] where T ij is the element in the i-th row and j-th column of the overall transfer matrix, N is the number of rows and columns of the overall transfer matrix, and TL is the calculated sound transmission loss of the tube side of the heat exchanger.

[0059] Embodiment Two:

[0060] The embodiment provides a fast calculation method for the sound transmission characteristics of the tube side of a heat exchanger. The implementation steps of the method are the same as steps S1-S4 provided in Embodiment One, and reference is made to Figure 1 . The difference is that the sound transmission characteristics calculation in this embodiment is taken as an example of the tube side of a shell-and-tube heat exchanger commonly used in ship engineering (the inlet and outlet of the tube side are located on the same side). In step S1, according to the actual structure of the shell-and-tube heat exchanger, the tube side of the heat exchanger is divided into five parts, including an inlet end head 6, an outlet end head 7, a backflow end head 8, and an internal heat exchange tube bundle segment, wherein the internal heat exchange tube bundle segment actually includes two parts 9 and 10 in opposite directions of fluid movement, as shown in Figure 7 .

[0061] In step S2, the internal heat exchange tube bundle segments 9 and 10 adopt the derived transfer matrix analytical model, as shown in formulas (1.2) and (1.3). The backflow end head 8 is divided into a complex irregular structure due to the complex internal fluid movement direction, and the sound impedance characteristics / transfer matrix are calculated by using a numerical simulation method, as shown in Figure 8 , wherein the different colors in the figure represent the sound pressure distribution.

[0062] In step S3, the sound pressure and fluid mass velocity continuity conditions should be met between the units, and the inlet end 6, the outlet end 7 and the return end 8 are also regarded as cross-section mutation units at the interfaces of the internal heat exchange tube bundle segments 9 and 10, respectively, as shown in Figure 9 The transfer matrix of the two ends of the cross-section mutation unit is calculated by using formula (1.5).

[0063] In step S4, the total transfer matrix representing the inlet and outlet variables of the tube is obtained by assembling the transfer matrices of the units, as follows:

[0064]

[0065] Wherein, P i , P o represent the inlet and outlet sound pressures of the tube, respectively, Q i , Q o represent the inlet and outlet fluid mass velocities of the tube, respectively, and T i (i = 1, 2, 3, 4, 5) is the transfer matrix of each unit.

[0066] Finally, the sound transfer loss of the shell-and-tube heat exchanger is calculated based on formula (1.7) according to the elements in the assembled total transfer matrix, as shown in Figure 10 The comparison chart of the test results of the sound transfer loss of the tube of the heat exchanger and the calculation results of the present application is shown in The change trend of the test results and the calculation results is consistent, and the results are similar, which verifies the feasibility of the calculation method of the present application. The calculation method can realize the rapid calculation and evaluation of the sound transfer characteristics of the tube of the heat exchanger, which is beneficial to engineering application.

[0067] The above two embodiments show that the present application breaks through the analytical modeling technology of the sound and vibration transfer of the heat exchange tube with shell-side fluid, solves the problem that the large-size heat exchanger with sound-solid coupling effect is difficult to calculate by numerical method, and provides input for the acoustic quantitative evaluation of the marine through-cooling pipeline system, which has a positive significance for the low-noise design of the heat exchanger and the improvement of the acoustic stealth performance of the ship.

[0068] The above only describes the preferred embodiments of the present application, and the present application is not limited to the above embodiments. It can be understood that other improvements and changes directly derived or thought by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A method for fast calculation of sound transmission characteristics in a tube side of a heat exchanger, characterized in that, The method comprises: dividing the tube side of the heat exchanger into multiple structural units according to the structural characteristics of the tube side of the heat exchanger; calculating the acoustic impedance characteristics or transfer matrix of each structural unit, and the acoustic impedance and the transfer matrix can be converted to each other; assembling the transfer matrices of all structural units according to the overall structural form of the tube side of the heat exchanger, the positional relationship of each structural unit and the boundary conditions between units, to obtain the overall transfer matrix representing the variable relationship at the inlet and outlet of the tube side of the heat exchanger; calculating the acoustic transmission loss of the tube side of the heat exchanger based on the overall transfer matrix according to the relationship between the transfer matrix and the acoustic transmission loss.

2. The method for quick calculation of acoustic transmission characteristics of a heat exchanger tube side according to claim 1, characterized in that, The division of the tube side of the heat exchanger into multiple structural units according to the structural characteristics of the tube side of the heat exchanger comprises: dividing the tube side of the heat exchanger into: a regular structural unit with a mathematical analytical model; a combined structural unit with a mathematical analytical model by reasonable structural simplification; a complex structural unit without a mathematical analytical model and cannot be simplified; the number of structural units is configured to be minimized to improve the calculation efficiency based on the above division criteria.

3. The method for quick calculation of acoustic transmission characteristics of a heat exchanger tube side according to claim 2, characterized in that, The calculation of the acoustic impedance characteristics or transfer matrix of each structural unit comprises: for the regular structural unit and the combined structural unit, the acoustic impedance characteristics or transfer matrix is calculated directly according to the mathematical analytical model thereof; for the complex structural unit, the acoustic impedance characteristics or transfer matrix is obtained by numerical simulation or test method.

4. The method for quick calculation of acoustic transmission characteristics of a heat exchanger tube side according to claim 2, characterized in that, The regular structural unit comprises the inlet and outlet sections and the internal heat exchange tube bundle section in the tube side of the heat exchanger, and the mathematical analytical model of the inlet and outlet sections and the internal heat exchange tube bundle section is characterized by a straight pipe model; The combined structural unit comprises the end of the tube side of the heat exchanger, which is simplified as a series structure of a straight pipe and a conical pipe model.

5. The method for quick calculation of acoustic transmission characteristics of a heat exchanger tube side according to claim 4, characterized in that, When calculating the acoustic impedance characteristics or transfer matrix of the internal heat exchange tube bundle section, the straight pipe two-end variable transfer matrix derived by considering the acoustic solid coupling effect of the fluid inside and outside the pipe and the pipe is: V z (l) = T p V z (0) Wherein, the straight pipe both ends variable is The straight pipe import, export end respectively is V z | z＝0 = V z (0), V z | z＝l = V z (1), transfer matrix T p = W a (1) W a (0) -1 ; u z is the axial displacement of the straight tube, p is the acoustic pressure of the fluid in the tube, u f is the displacement of the fluid in the tube, F z is the axial force of the straight tube, l is the length of the heat exchange tube bundle, A p is the cross-sectional area of the tube, E * is the corrected elastic modulus of the heat exchange tube material, K * is the fluid bulk modulus considering the coupling correction of the medium inside and outside the tube; wherein C1to C6are simplified expressions of the calculation terms, related to the heat exchange tube material and dimensions; λ 1,2 is the dimensionless wave number solution.

6. The method for quick calculation of acoustic transmission characteristics of a heat exchanger tube side according to claim 5, characterized in that, E * = ES; E is the modulus of elasticity of the heat exchange tube material, Wherein, K is the fluid bulk modulus; A, B, D, X are the calculation items of simplified expression, which are related to the material and size of the heat exchange pipe; μ is the Poisson's ratio of the heat exchange pipe material, R is the radius of the heat exchange pipe, T ij (1) To represent the matrix elements of the pressure and displacement of the fluid acting on the outer wall of the heat exchange pipe, ρ p is the density of the pipe material, h is the pipe wall thickness, and ω is the angular frequency.

7. The method of claim 1-4, wherein, The boundary conditions between units comprise: the interface between the end of the tube side of the heat exchanger and the internal heat exchange tube bundle section is regarded as a cross-section mutation unit, and the transfer matrix of the two-end variables of the cross-section mutation unit is: where p 1,2 are the sound pressures near the tube bundle segment end and near the tube side end, respectively, u 1,2 are the vibration velocities near the tube bundle segment end and near the tube side end, respectively, s 1,2 are the cross-sectional areas near the tube bundle segment end and near the tube side end, respectively, p is the density of the medium in the tube, and c is the sound velocity of the medium in the tube.

8. The method of claim 1-4, wherein, The boundary conditions between units further comprise: the acoustic pressure and fluid mass velocity continuous conditions are satisfied between units.

9. The method for rapid calculation of acoustic transmission characteristics of a heat exchanger tube side according to claim 1, characterized in that, The expression of the relationship between the transfer matrix and the acoustic transmission loss is: Among them, T ij is the element in the i-th row and j-th column of the overall transfer matrix, N is the number of rows and columns of the overall transfer matrix, and TL is the calculated acoustic transmission loss of the heat exchanger tube side.

10. The method for rapid calculation of acoustic transmission characteristics of a heat exchanger tube side according to claim 3, characterized in that, The numerical simulation method is realized by acoustic simulation software, and the test method refers to the standard for testing the acoustic impedance of pipeline components.

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