A numerical simulation method for ship thermal characteristics

Abstract

The invention discloses a method for numerically simulating thermal characteristics of a ship. The method belongs to the field of thermal characteristic simulation, and specifically comprises the following steps: 1. dividing a hull model grid; 2. establishing a mathematical model of the thermal characteristics of the hull; 3. solving the thermal balance equation of the grid unit; 4. processing the numerical calculation result; assigning a temperature or heat flux density to each grid unit of the hull model to obtain the temperature or heat flux density distribution of the entire ship; the method for numerically simulating thermal characteristics of a ship proposed in the invention comprehensively considers the thermal influence of multiple factors such as direct solar radiation, scattered solar radiation, sky radiation, sea surface radiation, sea surface reflection, external radiation of the hull itself, external convection heat transfer and internal convection heat transfer on the hull, and can predict the temperature and heat flux density distribution of the outer surface of the hull in advance. Compared with most existing commercial software, the numerical simulation method proposed in the invention can obtain more accurate thermal characteristic calculation results.

Description

Technical Field

[0001] The invention belongs to the field of thermal characteristic simulation and relates to a method for numerical simulation of thermal characteristics of a ship. Background Art

[0002] In the prior art, all objects with a temperature higher than absolute zero will emit thermal radiation to the outside world. Thermal radiation is generated by the thermal motion of microscopic particles inside the object. According to the Stepan-Boltzmann law, when an object is regarded as a black body, its radiation force is proportional to the fourth power of its thermodynamic temperature. Therefore, the higher the temperature of the object, the stronger the radiation. The thermal radiation emitted by the object is composed of continuous electromagnetic waves of different wavelengths. Among them, electromagnetic waves with wavelengths in the spectrum range of 1.0 to 1000.0 μm are called infrared radiation. Infrared detection technology for infrared radiation has been widely used in guidance and target identification due to its good anti-interference and concealment.

[0003] When an object in a natural environment transmits infrared radiation outward, it will be selectively absorbed by various gases in the atmosphere (CO2, O3, H2O, etc.). Therefore, the intensity of infrared radiation will be greatly weakened when it reaches the detector. The absorption of infrared radiation by the atmosphere is related to the wavelength of the radiation. The infrared radiation in the bands of 1.0-3.0μm, 3.0-5.0μm and 8.0-14.0μm has a strong transmittance in the atmosphere and is easily captured by infrared detectors. When a ship is sailing at sea, it is affected by the external environment, such as the sun, sky, sea surface, etc., and its outer surface temperature will rise to a certain extent. The thermal radiation emitted by the hull surface is just in the band of 8.0-14.0μm. Therefore, studying the thermal characteristics of the ship surface is of great significance to its infrared stealth and infrared detection.

[0004] At present, most mainstream commercial software can only simulate the impact of unilateral factors (such as solar radiation) on the hull surface, and cannot consider the changes in the thermal characteristics of the hull surface under complex environments. Therefore, the present invention proposes a numerical simulation method for ship thermal characteristics, which can more comprehensively consider the thermal impact of background radiation such as the sun, sky and sea surface on the outer surface of the hull. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a method for numerical simulation of thermal characteristics of ships, which comprehensively considers the thermal influence of multiple factors in a complex environment on the surface of the hull, and can obtain more accurate thermal characteristics simulation calculation results.

[0006] Technical solution: The numerical simulation method of ship thermal characteristics described in the present invention has the following specific operation steps:

[0007] (1) Grid division of hull model;

[0008] (2) Establishment of mathematical model of hull thermal characteristics;

[0009] (3) Solving the heat balance equation of the grid unit;

[0010] (4) The numerical calculation results are processed to finally obtain the temperature or heat flux density distribution of the entire ship.

[0011] Furthermore, in step (1), the grid division of the hull model specifically includes: determining the orientation of the three-dimensional geometric model of the hull in the Cartesian coordinate system, and deriving the information of the grid units after gridding the model.

[0012] Furthermore, the three-dimensional geometric model of the hull is a model of the part of the hull above the waterline.

[0013] Furthermore, in step (2), the specific process of establishing the mathematical model of the thermal characteristics of the hull is as follows: by inputting the location of the ship, the current day and the physical properties of the hull, the specific environment of the ship is determined, and the heat flux density generated by direct solar radiation, scattered solar radiation, sky radiation, sea surface radiation, sea surface reflection, the hull's own external radiation, external convection heat transfer and internal convection heat transfer on each grid unit is calculated, and the thermal balance equation of each grid unit is established based on the calculated multiple heat flux densities.

[0014] Furthermore, in step (3), the specific process of solving the heat balance equation of the grid unit is: solving the heat balance equation of each grid unit of the hull model to obtain the temperature value of each unit; the temperature value calculated for each unit at the kth minute of a certain day will be used as the input parameter of the k+1th minute, and so on to obtain the temperature value of each unit at different times in a day;

[0015] Among them, the net heat flux density value of each unit at the corresponding moment is obtained during the calculation process, and the fourth-order Runge-Kutta method is used to iteratively solve the heat balance equation of each grid unit at each moment.

[0016] Furthermore, in step (3), the processing of the numerical calculation results is specifically as follows: assigning a temperature or heat flux density to each grid unit of the hull model, and finally obtaining the temperature or heat flux density distribution of the entire ship.

[0017] Beneficial effects: Compared with the prior art, the numerical simulation method of ship thermal characteristics proposed in the present invention comprehensively considers the thermal influence of multiple factors on the hull, such as direct solar radiation, scattered solar radiation, sky radiation, sea surface radiation, sea surface reflection, the hull's own external radiation, external convection heat transfer and internal convection heat transfer, and can predict the temperature and heat flux density distribution on the outer surface of the hull in advance. Compared with most existing commercial software, the numerical simulation method proposed in the present invention can obtain more accurate thermal characteristic calculation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an operation flow chart of the present invention;

[0019] Figure 2 is a specific calculation flow chart of an embodiment of the present invention;

[0020] Figure 3 It is a schematic diagram of the grid unit division and specific orientation of the hull model in the present invention;

[0021] Figure 4 is a schematic diagram of the relative positions of the sun and the earth in an embodiment of the present invention;

[0022] Figure 5 Schematic diagram of the relative position of the sun and the ground in an embodiment of the present invention;

[0023] Figure 6 is a schematic diagram of solar radiation shielding between grid units in an embodiment of the present invention;

[0024] Figure 7 is a temperature distribution diagram of a ship surface at 12 noon on a certain day calculated in an embodiment of the present invention;

[0025] Figure 8 It is a net heat flux density distribution diagram of a ship surface at 12 noon on a certain day calculated in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to more clearly illustrate the technical solution of the present invention, the technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings:

[0027] like Figure 1 As shown, after the present invention meshes the hull model and obtains the information of the mesh units, a mathematical model of the thermal characteristics of the hull is established according to the physical parameters of the hull and the environment in which it is located; based on the thermal balance equation of each mesh unit, the C++ language is used for programming and solving, and finally the temperature and heat flux density distribution of the hull surface at different times of a day can be obtained.

[0028] The present invention discloses a method for numerical simulation of thermal characteristics of a ship, and a computer software system is written based on the method. After determining the direction of the hull in a Cartesian coordinate system, the position of the ship, the current day, the hull physical parameters and other related parameters are input into the written software system, and the temperature and heat flux density distribution of the hull surface at various times of a day can be output. The method takes into account the thermal influence of multiple factors such as direct solar radiation, scattered solar radiation, sky radiation, sea surface radiation, sea surface reflection, hull's own external radiation, external convection heat transfer and internal convection heat transfer on the hull, and the calculated result is more accurate.

[0029] The main numerical processes included in the method of the present invention are as follows:

[0030] Step 1: Mesh division of the hull model: determine the orientation of the 3D geometric model of the hull in the Cartesian coordinate system, mesh the model, and derive relevant information of the mesh units;

[0031] Step 2: Establishment of the mathematical model of the thermal characteristics of the hull: Input the relevant parameters such as the location of the ship, the current day and the physical parameters of the hull, determine the specific environment of the ship, calculate the heat flux density generated by direct solar radiation, scattered solar radiation, sky radiation, sea surface radiation, sea surface reflection, hull's own external radiation, external convection heat transfer and internal convection heat transfer on each grid unit, and establish the heat balance equation of each grid unit based on the calculated multiple heat flux densities;

[0032] Step 3: Solving the heat balance equation of the grid unit: The fourth-order Runge-Kutta method is used to iteratively solve the heat balance equation of each grid unit of the hull model to obtain the temperature value of each unit; the temperature value calculated for each unit at the kth minute of a certain day will be used as the inlet parameter of the k+1th minute, and so on to obtain the temperature value of each unit at different times of the day. The net heat flux density value of each unit at the corresponding time can also be obtained during the calculation process;

[0033] Step 4: Processing of numerical calculation results: Assign temperature or heat flux density to each grid unit of the hull model to obtain the temperature or heat flux density distribution of the entire ship.

[0034] Example

[0035] like Figure 2 As shown, the specific process of the embodiment of the present invention includes:

[0036] The hull orientation is determined in the Cartesian coordinate system, and the hull model is meshed to obtain the information of the mesh units; the mesh unit division of the hull model is as follows Figure 3 As shown, in this method, the positive direction of the x-axis of the Cartesian coordinate system is the due east direction, and the positive direction of the y-axis is the due north direction;

[0037] Input relevant parameters for the software to read and calculate, including: the latitude of the ship, the number of days in the year on the calculation day, ambient temperature, sea surface temperature, temperature inside the ship, hull material emissivity, specific heat capacity, density, thickness, external convection heat transfer coefficient and internal convection heat transfer coefficient.

[0038] Calculate various heat flux densities on the grid unit; the various heat flux densities include: direct solar radiation heat flux density, scattered solar radiation heat flux density, sky radiation heat flux density, sea surface radiation heat flux density, sea surface reflected heat flux density, hull self radiation heat flux density, external convection heat transfer heat flux density, and internal convection heat transfer heat flux density.

[0039] Specifically, the calculation process of each heat flux is as follows:

[0040] Before calculating the direct solar radiation heat flux density, first determine the spatial position of the sun, such as Figure 4 As shown, first, the relative position of the sun and the earth is determined by the solar declination angle δ and the solar hour angle ω. The solar declination angle δ is the angle between the sun's rays and the equatorial plane, and its calculation formula is:

[0041]

[0042] Among them, N represents the day in a year that the calculated day is;

[0043] The solar hour angle ω is the angle between the hour circle where the sun is in real time and the projection of the meridian circle on the equatorial plane. The solar hour angle ω is 0 at noon, positive in the afternoon and negative in the morning. The calculation formula is:

[0044] ω=(t-12)×15 (2)

[0045] Here, t is the solar time.

[0046] Furthermore, if Figure 5 As shown, the solar altitude angle α sun and the solar azimuth γ sun Determine the relative position of the sun and the ground, the solar altitude angle α sun It is the angle between the sun's rays and its projection on the horizon, and its calculation formula is:

[0047] sinα sun =sin L sinδ+cos L cosδcosω (3)

[0048] Wherein, L is the latitude of the area where the ship is located, with north latitude as positive and south latitude as negative;

[0049] According to equations (2) and (3), assuming that the solar altitude angle is 0, the solar time t' and t" at sunrise and sunset can be calculated:

[0050]

[0051]

[0052] Solar azimuth γ sun It represents the angle between the projection of the sun's rays on the ground plane and the south direction, with south to west as positive and south to east as negative. It can be calculated by the following formula:

[0053]

[0054]

[0055] When the sun's spatial position is determined, the direct solar radiation heat flux density q direct,i Calculation:

[0056]

[0057] Where i is the grid unit number; α is the absorption rate of the hull material; θ i I is the angle between the external normal of the grid unit and the direct direction of the sun; direct is the solar radiation intensity reaching the hull, which can be calculated by the following formula:

[0058] I direct =I0P m (9)

[0059] Where I0 is the solar constant, usually 1316W / m 2 ; P is the atmospheric transparency, which is generally 0.75; m is the atmospheric mass number, which can be calculated by the following formula:

[0060] m=[1229+(614sinα sun ) 2 ] 0.5 -614sinα sun (10)

[0061] When the solar time is between the sunrise time t' and the sunset time t", the direct solar radiation heat flux density q is calculated using formula (8) direct,i Calculate the direct solar radiation heat flux density q at other times direct,i All are taken as 0.

[0062] The calculation of direct solar radiation heat flux density takes into account the mutual shading between grid cells, such as Figure 6 As shown, the calculation of the occlusion problem adopts the following method:

[0063] Let the center of the unit emit light in the opposite direction of the incident direction of the sun's rays, and use the analytical geometry method of finding the intersection of the straight line and the space unit to determine whether the unit is blocked by other units. If it is not blocked, the unit will be illuminated by the sun;

[0064] Solar diffuse radiation heat flux density q scatter,i The calculation formula is:

[0065] q scatter,i =αI scatter X sky,i (11)

[0066] Among them, I scatter is the intensity of solar diffuse radiation:

[0067]

[0068] X sky,i is the sky angle factor:

[0069]

[0070] in, is the angle between the grid unit and the horizontal plane;

[0071] Sky radiation heat flux density q sky,i The calculation formula is:

[0072]

[0073] Among them, σ is the blackbody constant, and its value is 5.67×10 -8 W / (m 2 ·K 4 );T air is the external environment temperature; sky is the sky equivalent long-wave radiation emissivity:

[0074]

[0075] Among them, P air For the external environment pressure, take one atmosphere, i.e. 101325Pa;

[0076] Sea surface radiation heat flux density q sea,i The calculation formula is:

[0077] q sea,i =αε sea σT sea 4 X sea,i (16)

[0078] Among them, ε sea is the sea surface emissivity, generally taken as 0.98; T sea is the sea surface temperature; X sea,i is the sea surface angle coefficient, and the calculation formula is as follows:

[0079]

[0080] Sea surface reflected heat flux density q reflect,i The calculation formula is:

[0081] q reflect,i =αI reflect X sea,i (18)

[0082] Among them, I reflectis the radiation intensity reflected from the sea surface, which can be calculated by the following formula:

[0083] I reflect =A E (I direct sinα sun +I scatter ) (19)

[0084] Among them, A E is the sea surface albedo, which is 0.082;

[0085] The radiation heat flux density of the hull itself q body,i The calculation formula is:

[0086]

[0087] Where ε is the emissivity of the hull material, ε = α; T i is the grid cell temperature;

[0088] External convection heat transfer heat flux q c_out,i The calculation formula is:

[0089] q c_out,i =h c_out (T i -T air ) (twenty one)

[0090] Among them, h c_out is the external convection heat transfer coefficient;

[0091] Internal convection heat transfer heat flux q c_in,i The calculation formula is:

[0092] q c_in,i =h c_in (T i -T in ) (twenty two)

[0093] Among them, h c_in is the internal convection heat transfer coefficient; T in is the internal temperature of the hull;

[0094] According to the calculated heat flux densities, the net heat flux density q on each grid unit can be obtained. i :

[0095] q i =q direct,i +q scatter,i +q reflect,i +q sky,i +q sea,i -q body,i -q c_in,i -qc_out,i (twenty three)

[0096] Finally, the heat balance equation for each grid cell is established:

[0097]

[0098] Where, ρ is the density of the hull material; c is the specific heat capacity of the hull material; b is the thickness of the hull material; t is the time in a day.

[0099] The fourth-order Runge-Kutta method is used to iteratively solve the heat balance equation of each grid unit of the hull model to obtain the temperature value of each unit. The temperature value of each unit calculated at the kth minute of a certain day is used as the inlet parameter of the k+1th minute. The temperature value of each unit at different times of the day is obtained in this way. The net heat flux density value of each unit at the corresponding time can also be obtained during the calculation process.

[0100] The heat balance equation is solved through C++ programming, and the temperature and net heat flux density information of each unit is output.

[0101] The temperature and net heat flux density are assigned to each grid unit of the hull and displayed in the form of a cloud map.

[0102] By changing the relevant parameters involved in the above formula, such as the latitude of the ship, the number of days in a year on the calculation day, ambient temperature, sea surface temperature, ship interior temperature, hull material emissivity, specific heat capacity, density, thickness, external convection heat transfer coefficient and internal convection heat transfer coefficient, etc., the thermal characteristics calculation results of the hull under different working conditions can be output.

[0103] Taking the calculation of thermal characteristics of a ship as an example, the ship is sailing in the east direction, and the following parameters are entered into the program: the latitude of the ship is 32° north latitude, the current day is the 355th day of the year, the ambient temperature is 278.15K, the sea surface temperature is 277.15K, the internal temperature of the hull is 301.15K, the specific heat capacity of the hull material is 460J / (kg·K), the emissivity is 0.9, and the material density is 7850kg / m 3 , the material thickness is 0.012m, and the external convection heat transfer coefficient is 42W / (m 2 ·K), the internal convection heat transfer coefficient is 8W / (m 2 K); take the calculation result at noon as the display object, such as Figure 7-Figure 8 As shown; among them, Figure 7 is the temperature distribution on the hull surface at 12 noon, Figure 8 is the net heat flux density distribution on the hull surface at 12 noon; Figure 7 and Figure 8It can be seen that this method can intuitively display the thermal characteristic distribution of the ship's surface at a specified time.

[0104] In summary, the present invention proposes a method for numerical simulation of ship thermal characteristics. The relevant program is written in C++ language. The thermal effects caused by various external factors when the ship is sailing at sea are comprehensively considered, and more accurate thermal characteristics calculation results can be obtained.

[0105] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A method for numerical simulation of ship thermal characteristics, characterized in that: The specific steps are as follows: (1) Grid division of hull model; Specifically, the orientation of the three-dimensional geometric model of the hull in the Cartesian coordinate system is determined, and the information of the grid cells is derived after the model is meshed; (2) Establishment of mathematical model of hull thermal characteristics; The specific process is: by inputting the location of the ship, the current day and the physical parameters of the hull, the specific environment of the ship is determined, and the heat flux density generated by direct solar radiation, scattered solar radiation, sky radiation, sea surface radiation, sea surface reflection, external radiation of the hull itself, external convection heat transfer and internal convection heat transfer on each grid unit is calculated, and the heat balance equation of each grid unit is established based on the calculated multiple heat flux densities; (3) Solving the heat balance equation of the grid unit; The specific process is: solve the heat balance equation of each grid unit of the hull model to obtain the temperature value of each unit; the temperature value calculated for each unit at the kth minute of a certain day will be used as the inlet parameter for the k+1th minute, and so on to obtain the temperature value of each unit at different times of the day; Among them, the net heat flux density value of each unit at the corresponding time is obtained in the calculation process, and the fourth-order Runge-Kutta method is used to iteratively solve the heat balance equation of each grid unit at each time; (4) Processing of numerical calculation results to finally obtain the temperature or heat flux density distribution of the entire ship; Specifically, the temperature or heat flux density is assigned to each grid unit of the hull model, and finally the temperature or heat flux density distribution of the entire ship is obtained; The specific process includes: Determine the hull orientation in the Cartesian coordinate system, and obtain the information of the grid cells after meshing the hull model, with the positive direction of the x-axis of the Cartesian coordinate system being the due east direction and the positive direction of the y-axis being the due north direction; Input relevant parameters for the software to read and calculate, including: the latitude of the ship, the number of days in a year on the calculation day, ambient temperature, sea surface temperature, ship temperature, hull material emissivity, specific heat capacity, density, thickness, external convection heat transfer coefficient and internal convection heat transfer coefficient; Calculate various heat flux densities on the grid unit; the various heat flux densities include: direct solar radiation heat flux density, scattered solar radiation heat flux density, sky radiation heat flux density, sea surface radiation heat flux density, sea surface reflection heat flux density, hull radiation heat flux density, external convection heat transfer heat flux density, and internal convection heat transfer heat flux density; Before calculating the direct solar radiation heat flux density, the spatial position of the sun must be determined. First, the relative position of the sun and the earth is determined by the solar declination angle δ and the solar hour angle ω. The solar declination angle δ is the angle between the sun's rays and the equatorial plane. The calculation formula is: In the formula, N represents the day in a year that the calculated day is; The solar hour angle ω is the angle between the hour circle where the sun is in real time and the projection of the meridian circle on the equatorial plane. The solar hour angle ω is 0 at noon, positive in the afternoon and negative in the morning. The calculation formula is: ω=(t-12)×15 (2) Where, t is the solar time; By the sun altitude angle α sun and the solar azimuth γ sun Determine the relative position of the sun and the ground, the solar altitude angle α sun It is the angle between the sun's rays and its projection on the horizon, and its calculation formula is: sinα sun =sinLsinδ+cosLcosδcosω (3) Where L is the latitude of the area where the ship is located, with north latitude as positive and south latitude as negative; According to equations (2) and (3), assuming that the solar altitude angle is 0, the solar time t' and t" at sunrise and sunset can be calculated: Solar azimuth γ sun It represents the angle between the projection of the sun's rays on the ground plane and the south direction, with south to west as positive and south to east as negative. It is calculated by the following formula: When the sun's spatial position is determined, the direct solar radiation heat flux density q direct,i Calculation: Where i is the grid unit number; α is the absorption rate of the hull material; θ i I is the angle between the external normal of the grid unit and the direct direction of the sun; direct is the solar radiation intensity reaching the hull, calculated by the following formula: I direct =I0P m (9) Where I0 is the solar constant, usually 1316W / m 2 ; P is the atmospheric transparency, which is generally 0.75; m is the atmospheric mass number, which is calculated by the following formula: m=[1229+(614sinα sun ) 2 ] 0.5 -614sinα sun (10) When the solar time is between the sunrise time t' and the sunset time t", the direct solar radiation heat flux density q is calculated using formula (8) direct,i Calculate the direct solar radiation heat flux density q at other times direct,i All are taken as 0; The heat balance equation for each grid cell is established: Where ρ is the density of the hull material; c is the specific heat capacity of the hull material; b is the thickness of the hull material; t is the time in a day.

2. A method for numerical simulation of ship thermal characteristics according to claim 1, characterized in that: The calculation of direct solar radiation heat flux density takes into account the mutual shading between grid cells. The calculation of the shading problem adopts the following method: Let the center of the unit emit light outward in the opposite direction of the incident direction of the sun's rays, and use the analytical geometry method of finding the intersection of a straight line and a space unit to determine whether the unit is blocked by other units. If not, the unit will be illuminated by the sun.

3. A method for numerical simulation of ship thermal characteristics according to claim 1, characterized in that: Solar diffuse radiation heat flux density q scatter,i The calculation formula is: q scatter,i =αI scatter X sky,i (12) In the formula, I scatter is the intensity of solar diffuse radiation: X sky,i is the sky angle factor: In the formula, is the angle between the grid unit and the horizontal plane.

4. A method for numerical simulation of ship thermal characteristics according to claim 1, characterized in that: Sky radiation heat flux density q sky,i The calculation formula is: Where σ is the blackbody constant, and its value is 5.67×10 -8 W / (m 2 ·K 4 );T air is the external environment temperature; sky is the sky equivalent long-wave radiation emissivity: Where P air As the external environment pressure, take one atmosphere, that is, 101325Pa.

5. A method for numerical simulation of ship thermal characteristics according to claim 1, characterized in that: Sea surface radiation heat flux density q sea,i The calculation formula is: q sea,i =ae sea σT sea 4 X sea,i (17) In the formula, ε sea is the sea surface emissivity, generally taken as 0.98; T sea is the sea surface temperature; X sea,i is the sea surface angle coefficient, and the calculation formula is as follows:

6. A method for numerical simulation of ship thermal characteristics according to claim 1, characterized in that: Sea surface reflected heat flux density q reflect,i The calculation formula is: q reflect,i =αI reflect X sea,i (19) In the formula, I reflect is the radiation intensity reflected from the sea surface, calculated by the following formula: I reflect =A E (I direct sinα sun +I scatter ) (20) In the formula, A E is the sea surface albedo, and its value is 0.

082.

7. A method for numerical simulation of ship thermal characteristics according to claim 1, characterized in that: The radiation heat flux density of the hull itself q body,i The calculation formula is: q body,i =εσT i 4 (21) Where ε is the emissivity of the hull material, ε = α; T i is the grid cell temperature; External convection heat transfer heat flux q c_out,i The calculation formula is: q c_out,i =h c_out (T i -T air ) (22) In the formula, h c_out is the external convection heat transfer coefficient; Internal convection heat transfer heat flux q c_in,i The calculation formula is: q c_in,i =h c_in (T i -T in ) (23) In the formula, h c_in is the internal convection heat transfer coefficient; T in is the internal temperature of the hull; According to the calculated heat flux densities, the net heat flux density q on each grid unit can be obtained. i : q i =q direct,i +q scatter,i +q reflect,i +q sky,i +q sea,i -q body,i -q c_in,i -q c_out,i (24)。 8. A method for numerical simulation of ship thermal characteristics according to claim 1, characterized in that: Solve the heat balance equation through C++ programming and output the temperature and net heat flux density information of each unit; The temperature and net heat flux density are assigned to each grid unit of the hull and displayed in the form of a cloud map.

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