JP2007179501A - Thermal fluid simulation device, thermal fluid simulation method, thermal fluid simulation program, and storage medium recording the program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal fluid simulation method for shortening time for simulation calculation without deteriorating accuracy. <P>SOLUTION: A calculation condition used for simulation calculation is inputted (S1), a flow field and a temperature field in an initial state are simulation-calculated using the input calculation condition (S2), a velocity (surface fluid velocity) of a fluid contacting with the surface of a mobile object is calculated and set as a boundary condition (S3), a corrected heat conductivity is calculated based on the moving direction and moving speed of the mobile object (S4), the flow field and the temperature field are simulation-calculated using the surface fluid velocity and the corrected heat conductivity (S5), whether the balance calculation between the flow field and the temperature field reaches convergence or not (S6), and when it is not converged, the procedures S5 to S6 are repeated until the balance calculation reaches convergence. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention belongs to the field of engineering simulation, and relates to a thermofluid simulation apparatus, a thermofluid simulation method, a thermofluid simulation program, and a recording medium recording the thermofluid simulation program in a system including a moving object.

  Conventionally, in a thermofluid simulation in which a moving object and a flow field and a temperature field around the moving object are simulated in a system including a rotating or linearly moving object, a single calculation mesh (hereinafter, simply referred to as an object) is represented. A method is used in which a mesh is recreated at each calculation step accompanying the movement of an object.

  FIG. 8 is a diagram for explaining a conventional thermal fluid simulation method. FIG. 8 illustrates an example in which an object 1 having a circular planar shape rotates and uses a rotationally moving object 1 and a single mesh formed around the object 1. In the example of FIG. 8, the outside of the boundary 2 that separates the rotationally moving object 1 from the outside is gas. The mesh is formed so as to extend to the rotating moving object 1 and its surroundings, and an element number for identifying each element is assigned to each element constituting the mesh. In FIG. 8, the element number is represented by a circled number. Although element numbers are assigned to all individual elements constituting the mesh, only element numbers 1 to 12 are displayed in FIG. 8 to avoid complication.

  In general, in the thermal fluid simulation, a time series simulation is performed in which a certain time step is set and calculation is performed at each step. FIG. 8 also shows a time series simulation. FIG. 8A shows the state at a certain time step n, and FIG. 8B shows the next time step n + 1 after a predetermined time has elapsed from the time of FIG. 8A. The state in is shown.

  The predetermined time in the example of FIG. 8 is the time required for the rotationally moving object 1 to rotate and move by one mesh component in the clockwise direction indicated by the arrow 3. Therefore, when a predetermined time has elapsed and the state of FIG. 8A is shifted to the state of FIG. 8B, that is, when one calculation step is advanced, only the mesh formed on the rotationally moving object 1 is obtained. Becomes a mesh shifted clockwise by one element. This means that this is a new mesh in which the connection state between each element changes, and for simulation calculation, it is necessary to create a new mesh and solve a new equation corresponding thereto.

  Therefore, the conventional method has a problem that a large amount of calculation is required because a balance equation representing a mesh, that is, a state must be recreated at each step of the simulation calculation. Furthermore, since the time of the system to be simulated is divided into fine time steps and a transient response analysis is performed to balance the flow field and temperature field at each step, in order to obtain a stable state of the final system There is a problem that it is necessary to calculate all of the intermediate progress and requires a huge amount of calculation time.

  Another conventional technology of thermal fluid simulation uses multiple meshes, moves the mesh around the moving object independently of the other meshes, and flows at the connection boundary nodes of each mesh system at each calculation step. There is a simulation method to calculate while exchanging field information. However, in this prior art, it takes a lot of calculation time to search for mesh cells (elements) of other meshes to which the connection boundary node belongs, which is necessary when each mesh exchanges flow field information at the connection boundary node. There is a problem that the amount of calculation increases due to the movement of the object.

  In a conventional technique for solving such a problem, in a new calculation step, a search for the mesh cell number of the other mesh to which the connection boundary node of one mesh belongs is performed in advance, and a table referring to adjacent mesh cells in each mesh system is previously stored. There is one that is created and exchanged from the mesh cell to which the connection boundary node belongs in the previous calculation step and its adjacent mesh cell, and exchanges flow field information (see Patent Document 1).

  In the technique disclosed in Patent Document 1, the time required for searching for mesh cells can be shortened. However, in each new mesh including the searched mesh cells, a balance equation representing a state is created each time. Therefore, there remains a problem that the amount of calculation for solving the above problem is necessary, so that the reduction of the amount of calculation and the reduction of the calculation time are not yet achieved sufficiently.

JP-A-4-319767

  An object of the present invention is to provide a thermal fluid simulation apparatus and a thermal fluid simulation method that can reduce the calculation time of simulation calculation without reducing accuracy.

  Another object of the present invention is to provide a thermal fluid simulation program for a computer to execute the thermal fluid simulation method and a computer-readable recording medium on which the thermal fluid simulation program is recorded.

The present invention relates to a thermal fluid simulation apparatus for performing simulation calculation for each step of a step in which a moving object and a flow field and a temperature field around the moving object are set in plural in a system including the moving object,
Calculation condition supply means for supplying calculation conditions used for simulation calculation;
Using the calculation conditions supplied from the calculation condition supply means, the moving object and the flow field and temperature field in the initial state around the object are simulated and calculated, and in steps other than the initial state, the thermal conductivity of the moving object is corrected. A simulation calculation means for simulating a moving object and a flow field and a temperature field around the moving object using the corrected thermal conductivity and the moving velocity of the fluid in contact with the surface of the moving object;
Based on the moving direction and moving speed of the moving object, multiply the thermal conductivity of the moving object by the correction coefficient to obtain the corrected thermal conductivity, and give the corrected thermal conductivity to the simulation calculation means. Means,
Based on the moving direction and moving speed of the moving object, the surface fluid velocity, which is the moving velocity of the fluid in contact with the surface of the moving object, is obtained, and the surface fluid velocity is set as a boundary condition between the moving object and the fluid. Fluid velocity calculation means to be given to the calculation means;
Calculation condition supply means, simulation calculation means, thermal conductivity correction coefficient calculation means, control means for controlling the operation of the fluid velocity calculation means,
A storage unit for storing simulation calculation results by the simulation calculation means;
A thermal fluid simulation apparatus comprising: display means for displaying a simulation calculation result by the simulation calculation means.

The present invention also includes a boundary condition correction data storage unit that stores experimentally or empirically determined values or techniques for correcting the surface fluid velocity,
The fluid velocity calculation means is
According to the surface characteristics of the moving object, the surface fluid velocity set as the boundary condition is corrected based on a value or a method stored in the boundary condition correction data storage unit corresponding to the surface characteristic of the moving object. .

Further, the present invention relates to a thermofluid simulation method for performing simulation calculation for each step of a step in which a moving object and a flow field and a temperature field around the moving object are set in a plurality in a system including the moving object,
A procedure for obtaining calculation conditions used in the simulation calculation;
A procedure for performing a simulation calculation of a moving object and a flow field and a temperature field in an initial state around the moving object using the obtained calculation conditions;
Based on the moving direction and moving speed of the moving object, a procedure for obtaining the corrected thermal conductivity by multiplying the thermal conductivity of the moving object by the correction coefficient;
A procedure for obtaining a surface fluid velocity, which is a velocity of fluid moving in contact with the surface of the moving object, based on the moving direction and moving speed of the moving object;
A thermal fluid simulation method comprising a simulation calculation of a moving object and a flow field and a temperature field around the moving object using the surface fluid velocity and the corrected thermal conductivity.

The present invention also relates to a thermal fluid simulation program used for simulation calculation for each step of a step in which a moving object, a flow field and a temperature field around the moving object, and a plurality of steps are set in a system including a moving object. There,
A procedure for obtaining calculation conditions used in the simulation calculation;
A procedure for performing a simulation calculation of a moving object and a flow field and a temperature field in an initial state around the moving object using the obtained calculation conditions;
Based on the moving direction and moving speed of the moving object, a procedure for obtaining the corrected thermal conductivity by multiplying the thermal conductivity of the moving object by the correction coefficient;
A procedure for obtaining a surface fluid velocity, which is a velocity of fluid moving in contact with the surface of the moving object, based on the moving direction and moving speed of the moving object;
A thermal fluid simulation program for causing a computer to execute a simulation calculation of a moving object and a flow field and a temperature field around the object using the surface fluid velocity and the corrected thermal conductivity.

  The present invention is also a computer-readable recording medium on which the thermal fluid simulation program is recorded.

  According to the present invention, for example, when a moving object is homogeneous and the structure of the object does not change even after the movement, and the object movement is periodic, the moving object and the flow field and temperature field around the object are calculated by simulation. In this case, the corrected thermal conductivity obtained by multiplying the thermal conductivity of the object by the correction coefficient corresponding to the moving speed only in the moving direction of the object is used, and the surface fluid velocity that is the moving velocity of the fluid on the moving object surface is obtained and moved. By considering the fluid motion by means of setting the boundary condition between the object and the fluid, the flow field and the temperature field can be calculated with high speed and high accuracy without creating a new mesh each time the object moves. Can do.

  According to the present invention, it further includes a boundary condition correction data storage unit that stores experimentally or empirically obtained values or methods for correcting the surface fluid velocity, and the fluid velocity calculation means includes the surface of the moving object. According to the characteristics, the surface fluid velocity set as the boundary condition is corrected based on the value or method stored in the boundary condition correction data storage unit corresponding to the surface characteristic of the moving object. Here, the surface characteristics of the moving object include a material type of the moving object, a surface structure type of the moving object, a moving form, a moving speed, and the like. By correcting the surface fluid velocity set as the boundary condition according to the surface characteristics of the moving object, it is possible to perform simulation calculation with extremely high accuracy.

  Further, according to the thermal fluid simulation method of the present invention, the corrected thermal conductivity obtained by multiplying the correction coefficient according to the moving speed only in the moving direction of the object is used as the thermal conductivity of the object, and the movement of the fluid on the surface of the moving object is used. By calculating the surface fluid velocity, which is the velocity, and using it as the boundary condition between the moving object and the fluid, the flow field and temperature field can be calculated at high speed and with high accuracy without creating a new mesh each time the object moves. be able to.

  The present invention also provides a thermal fluid simulation program for causing a computer to execute the thermal fluid simulation method and a computer-readable recording medium on which the program is recorded. Therefore, the versatility of the thermal fluid simulation method is increased, and the thermal fluid simulation method can be easily executed in a short time by a computer.

  FIG. 1 is a block diagram showing a simplified configuration of a thermal fluid simulation apparatus 10 according to an embodiment of the present invention. The thermal fluid simulation apparatus 10 generally includes a calculation condition supply unit 11, a simulation calculation unit 12, a thermal conductivity correction coefficient calculation unit 13, a fluid velocity calculation unit 14, a control unit 15, a storage unit 16, and a display. And means 17. The thermal fluid simulation apparatus 10 is used for simulation calculation for each step of a step in which a moving object, a flow field around the object, and a temperature field are set in plural in a system including a moving object.

  The calculation condition supply unit 11 supplies the calculation condition used for the simulation calculation to the simulation calculation unit 12. In the present embodiment, the calculation condition supply means 11 relates to the shape data storage unit 21 in which data relating to the shape and simulation region of the moving object, the arrangement of the object and the mesh are stored in advance, and the substance around the moving object and the moving object. Physical property data storage unit 22 in which density, specific heat, thermal conductivity and the like, which are physical property data, are stored in advance, for example, the heat generation amount of the heat source, the moving direction and moving speed of the object, and the moving speed of the object to which simulation calculation can be applied. Calculation condition data such as a range and a time interval for repeatedly executing simulation calculations are stored in advance, a calculation condition data storage unit 23, a surface type of a moving object, a material type of the moving object, a surface structure type of the moving object, Experimental or empirical for correcting the surface fluid velocity, which will be described later, depending on the type of movement, movement speed, etc. A boundary condition correction data storage unit 24 the obtained data or methods are stored, configured to include an input unit 25 capable of inputting the data of the.

  The shape data storage unit 21, the physical property data storage unit 22, the calculation condition data storage unit 23, and the boundary condition correction data storage unit 24 are memory devices realized by, for example, a random access memory (RAM) or a hard disk drive (HDD). . Data stored in each of the shape data storage unit 21, the physical property data storage unit 22, the calculation condition data storage unit 23, and the boundary condition correction data storage unit 24 may be given from another computer, for example, from the input unit 25 It may be entered.

  The input unit 25 is an input device such as a keyboard. Each of the aforementioned data may be directly input to the simulation calculation means 12 from the input unit 25 according to the simulation calculation opportunity, or the shape data storage unit 21 and the physical property data storage unit 22 from the input unit 25 or another computer in advance. Alternatively, the calculation condition data storage unit 23 and the boundary condition correction data storage unit 24 may be input to each unit and read from each unit according to a simulation calculation opportunity.

  The simulation calculation means 12 is an arithmetic circuit realized by, for example, a large-scale integrated circuit (LSI). In this embodiment, the flow field calculation unit 26 that calculates the flow field by the Navier-Stokes equation and the temperature by the Poisson equation. And a temperature field calculation unit 27 for calculating the field.

  The simulation calculation means 12 performs a simulation calculation of the moving object and the flow field and the temperature field in the initial state around the object using the calculation conditions supplied from the calculation condition supply means 11, and in steps other than the initial state, the calculation is performed. Data relating to the moving direction and moving speed of the object supplied from the condition supplying means 11 is output to the thermal conductivity correction coefficient calculating means 13 and the fluid velocity calculating means 14 and from the thermal conductivity correction coefficient calculating means 13. Using the corrected thermal conductivity obtained and the surface fluid velocity, which is the velocity of the fluid in contact with the surface of the moving object, obtained from the fluid velocity calculating means 14, the flow field and temperature field around the moving object and the moving object are simulated. calculate.

  The thermal conductivity correction coefficient calculation means 13 is an arithmetic circuit realized by an LSI or the like, and has a memory unit 13a. An arithmetic program is stored in the memory unit 13a in advance. The thermal conductivity correction coefficient calculation means 13 reads the calculation program from the memory unit 13a when the data related to the moving direction and moving speed of the moving object is given from the simulation calculation means 12, and according to the calculation program, the calculation of the moving object is performed. Set a coefficient to correct the thermal conductivity in the moving direction, and calculate the corrected thermal conductivity by multiplying the correction coefficient only for the thermal conductivity of the moving object in the moving direction. The calculation is performed and the calculation result is given to the simulation calculation means 12.

  Hereinafter, calculation of the corrected thermal conductivity in the thermal conductivity correction coefficient calculating means 13 will be described. First, the thermal conductivity of a moving object is decomposed into each component of a coordinate system, for example, an XY biaxial coordinate system for translation and an R-θ polar coordinate system for rotation. Next, it is confirmed that the moving speed of the moving object is within a predetermined range, and a correction coefficient for the moving direction resolved in the previous coordinate system is set. The set correction coefficient is multiplied only by the thermal conductivity related to the heat conduction in the moving direction, and the corrected thermal conductivity is calculated.

  This corrected thermal conductivity serves to contribute to the temperature averaging in the direction of movement of the object resulting from the thermal energy transfer. Therefore, it is desirable that the correction coefficient multiplied by the thermal conductivity is a number sufficiently larger than 1, for example, 100.

  The fluid velocity calculation means 14 is an arithmetic circuit realized by an LSI or the like, and has a memory unit 14a. An arithmetic program is stored in the memory unit 14a in advance. When data relating to the moving direction and moving speed of the object is given from the simulation calculating means 12, the fluid velocity calculating means 14 reads out the calculation program from the memory unit 14a, and the moving direction and moving speed of the moving object according to the calculation program. Is obtained as a boundary condition between the moving object and the fluid, and is given to the simulation calculation means 12.

  FIG. 2 is a diagram for explaining the relationship between the rotation of the moving object and the velocity of the fluid. For the problem of the moving object system, when the simulation calculation method using the conventional method of fixing the mesh is adopted, the movement of the object is eliminated and replaced with the problem of heat conduction. It is calculated without considering the influence of the motion on the fluid.

  However, in reality, a moving object affects the surrounding fluid due to the movement of the object. As shown in FIG. 2, when the object 31 rotates in the direction of the arrow 32, the fluid in contact with the outer peripheral surface of the rotating object 31 moves at the same speed and direction as the rotating object 31, and the surface of the rotating object 31 As the distance from, the velocity of the fluid decreases as indicated by the arrows 33a, 33b, 33c and the decreasing length. FIG. 2 shows that the surface fluid speed, which is the moving speed of the fluid in contact with the surface of the rotating object 31, is usually the motion speed of the rotating object 31.

  FIG. 3 is a flowchart for explaining a method of calculating the surface fluid velocity in the fluid velocity calculating means 14, FIG. 4 is a diagram showing an example of the surface fluid velocity in the rotating moving object, and FIG. 5 is the surface fluid velocity in the belt moving object. It is a figure which shows the example of.

  Hereinafter, a method for calculating the surface fluid velocity will be described with reference to FIGS. At the start, the operation switch of the thermal fluid simulation apparatus 10 is turned on, and each means and each part are in operation.

  In step a1, the fluid velocity calculation unit 14 reads the moving direction and movement velocity of the moving object from the simulation calculation unit 12. In procedure a2, a fluid mesh adjacent to the moving object is selected. The selection of the fluid mesh adjacent to the moving object can be performed by, for example, identifying the mesh that contacts the moving object in advance at the stage of creating the mesh by the mesh number or the like. The case of the rotationally moving object 41 shown in FIG. 4 will be described. A mesh represented by circled numbers 7 to 16 formed in contact with the outer peripheral surface 41 a of the rotationally moving object 41 is a fluid mesh in contact with the moving object 41. . In the example shown in FIG. 4, it can be seen that the fluid mesh in contact with the moving object 41 is other than the mesh represented by the circled numbers 7 to 16, but is omitted in FIG. 4 to avoid complication. Yes.

  In step a3, a surface fluid velocity, which is a moving velocity on the surface in contact with the moving object of the fluid mesh selected in step a2, is calculated. Hereinafter, the calculation of the surface fluid velocity in the rotating moving object 41 and the calculation of the surface fluid velocity in the belt moving object 42 will be described separately.

First, calculation of the surface fluid velocity in the rotationally moving object 41 will be described. When the movement of the moving object 41 is rotation and the movement direction is the rotation direction, the surface fluid velocity is calculated by the equation (1) or the equation (2) as a tangential velocity with respect to the rotation surface.
v0 · (r1-r2) / | r1-r2 | (1)
rω · (r1-r2) / | r1-r2 | (2)

  Here, v0 is the tangential velocity of the outer peripheral surface 41a in contact with the fluid of the rotationally moving object 41, r1 and r2 are the position coordinates in polar coordinates, r is the distance from the center of rotation, and ω is the angular velocity. It is.

Next, calculation of the surface fluid velocity in the case of the straight movement of the belt moving object 42 will be described. When the movement of the moving object 42 is a belt movement and the moving direction is a straight traveling direction, the surface fluid velocity is calculated as the velocity of the moving object 42 in the traveling direction by Equation (3). In equation (3), v0 is the belt speed, and p1 and p2 are position coordinates. In FIG. 5 as well, although the fluid mesh is represented by the circled numbers 52 to 62, only the mesh numbers of necessary portions are shown because the figure becomes complicated.
v0 · (p1p2) / | p1p2 | (3)

  In step a4, the boundary condition correction data storage unit 24 is searched, and there is data (referred to as boundary condition correction data) corresponding to the material type of the moving object or the surface structure type of the moving object used in the thermal fluid simulation. It is determined whether or not. When the determination result is affirmative and there is boundary condition correction data, the process proceeds to step a5. On the other hand, when the determination result is negative and there is no boundary condition correction data, the process proceeds to step a6, where the surface fluid velocity is corrected and set as the boundary condition.

  In procedure a5, the fluid velocity calculation means 14 reads the boundary condition correction data. The boundary condition correction data depends on what is collectively referred to as the surface characteristics of the moving object, such as the material type of the moving object, the surface structure type of the moving object, the type of movement (whether it is rotation or straight), the moving speed, etc. It is a value or method obtained experimentally or empirically stored in advance in the boundary condition correction data storage unit 24 so that the fluid velocity can be corrected.

  Here, it is as follows when an example is shown about the value or method calculated | required experimentally or empirically. For example, an object with various frictional resistances on the surface of an object, such as an object with a smooth surface such as plastic and a low frictional resistance, or an object with a high-viscosity substance with a highly viscous material such as gummed tape, is assumed as a moving object. Then, a fluid is allowed to flow at a constant flow velocity on the surface, the flow velocity of the fluid is measured, the effect of frictional resistance on the surface fluid velocity is confirmed, and registered in the boundary condition correction database.

  If the surface fluid velocity is expected to change due to the influence of the moving speed of the object, the data when the flow velocity is changed is also measured, and the degree of influence is also registered in the boundary condition correction database. The degree of influence obtained in this way is, for example, an influence degree of 0.995 when the flow rate is 10 m / second, an influence degree of 0.98 when the flow rate is 100 m / second, and the like.

  When a moving object substance is selected as the target for thermal fluid simulation, the surface fluid velocity is converted into the boundary condition correction data using the degree of influence as described above according to the frictional resistance of the surface of the substance and the moving speed of the moving object. Correct.

  In step a6, the fluid velocity calculation means 14 corrects the surface fluid velocity using the boundary condition correction data.

  In step a7, the surface fluid velocity is set as a boundary condition between the moving object and the fluid. This set boundary condition is given from the fluid velocity calculation means 14 to the simulation calculation means 12.

  Returning to FIG. 1, the control means 15 is a processing circuit provided with a central processing unit (abbreviated CPU), for example. Although not shown, the control unit 15 includes a storage unit that stores a program for controlling the overall operation of the thermal fluid simulation apparatus 10 in advance. The storage unit is realized by, for example, a read only memory (ROM). The control unit 15 controls the operations of the calculation condition supply unit 11, the simulation calculation unit 12, the thermal conductivity correction coefficient calculation unit 13, and the fluid velocity calculation unit 14 according to the program read from the storage unit. In the present embodiment, the control means 15 is formed integrally with the calculation condition supply means 11, the simulation calculation means 12, the thermal conductivity correction coefficient calculation means 13 and the fluid velocity calculation means 14.

  The storage unit 16 is a calculation result storage unit 16 that stores a thermal fluid simulation calculation result by the simulation calculation unit 12, and is a memory device realized by, for example, a random access memory (RAM) or a hard disk drive (HDD).

  The display means (display unit) 17 for displaying the simulation calculation result by the simulation calculation means 12 is a display device having a screen capable of displaying an image, such as a cathode ray tube (CRT) or a liquid crystal display (LCD). The display means 17 may be provided with a printer or the like for recording the thermal fluid simulation calculation result on recording paper or the like.

  FIG. 6 is a flowchart for explaining a thermal fluid simulation method performed using the thermal fluid simulation apparatus 10 shown in FIG. With reference to FIG. 6, the operation of the control means 15 relating to the execution of the thermal fluid simulation method will be described. In many cases, the thermal fluid simulation is performed on a three-dimensional space, but here, in order to facilitate the description, a case of a two-dimensional space will be described. The principle and effect of the simulation are the same regardless of whether they are two-dimensional or three-dimensional.

  At the start of the procedure S0, each switch of the thermal fluid simulation device 10 is turned on and is in an operable state.

  In step S <b> 1, various conditions necessary for the simulation calculation of the thermal fluid, that is, the simulation calculation of the flow field and the temperature field around the moving object are input from the input unit 25. The input conditions include, for example, the shape model of the moving object, the moving direction and moving speed of the moving object, the physical property values of the moving object and the substance around the moving object, various boundary conditions, and the heat generation conditions such as the heat generation amount of the heat source, convergence Conditions, simulation calculation step intervals, and the like. These calculation conditions are stored in advance in the shape data storage unit 21, the physical property data storage unit 22 and the calculation condition data storage unit 23 from the input unit 25 or another host computer, and the stored data is read out. Also good.

  In step S2, the flow field and the temperature field in the initial state are calculated using the input calculation conditions, and the field balance result in the initial state is calculated.

  In step S3, based on the moving direction and moving speed data of the moving object given from the simulation calculating means 12, the fluid velocity calculating means 14 performs the surface fluid as described in the description of FIGS. Calculate the speed. Further, the surface fluid velocity is corrected from the boundary condition correction data stored in advance in the boundary condition correction data storage unit 24 according to the surface characteristics of the moving object, and the calculation result is set as the boundary condition between the moving object and the fluid. The surface fluid velocity which is this boundary condition is given to the simulation calculation means 12.

  In step S4, based on the moving direction and moving speed data of the moving object given from the simulation calculating means 12, the thermal conductivity correction calculating means 13 sets a correction coefficient, and calculates the corrected thermal conductivity related to the moving direction of the moving object. Calculate. The calculated corrected thermal conductivity is given to the simulation calculation means 12.

  In step S5, the flow field and the temperature field in the next step are calculated using the surface fluid velocity and the corrected thermal conductivity. The simulation calculation in this procedure takes into account the surface fluid velocity set as the boundary condition by the fluid velocity calculation means 14 without creating a new mesh, and the corrected thermal conductivity with respect to the heat conduction in the moving direction of the moving object. Is a normal thermal fluid simulation except that is used to calculate a balance equation between a flow field and a temperature field.

  In step S6, it is determined whether or not the calculation of the flow field and temperature field executed in step S5 has converged. If the convergence has not been reached, the process returns to step S5, and the subsequent procedures are repeated until the calculation of the flow field and the temperature field converges. If it is determined that the convergence has been reached, the process proceeds to the end of step S7, and the simulation calculation is terminated.

  FIG. 7 is a diagram showing an example of the thermal fluid simulation shown in the flowchart of FIG. In FIG. 7, the moving object 51 is illustrated as an object whose planar shape has an annular shape and rotates and moves in the direction of the arrow 52 around the center of the circle.

  The outside of the moving object 51 is an atmospheric space. The atmospheric space faces the moving object 51 and is provided with two regions along the outer periphery of the moving object 51, that is, a heating region 53 and a heat dissipation region 54. A heater 55 is provided in the heating region 53 so as to face the moving object 51. When the moving object 51 rotates in the direction of the arrow 52 and passes through the heating region 53, the moving object 51 is heated by being given thermal energy by the heater 55. On the other hand, a heat source is not provided in the heat radiation area 54, and the part heated by the heating area 53 of the moving object 51 passes through the heating area 53 and reaches the heat radiation area 54, and radiates heat to the atmosphere.

  As shown in FIG. 7, the heated portion 51 a of the moving object 51 that has absorbed the thermal energy at the position facing the heater 55 in the heating region 53 moves to the heat dissipation region 54 by rotational movement, and then the heating region 53 again. Until it reaches the position it faces, heat is transferred to the atmosphere to dissipate heat and lower the temperature.

  When the moving object 51 continues to rotate and the previous heated portion 51a reaches the heating region 53 again, the temperature rises by absorbing heat energy again. When the moving object 51 is rotating at a certain rotational speed, all of the heat energy absorbed in the heating area 53 cannot be radiated to the air, and the temperature before being heated in the heating area 53 cannot be lowered. Then, the heating region 53 is heated again. Thus, since the heat energy is absorbed again while leaving a part of the heat energy absorbed when passing through the previous heating region 53, the total amount of heat of the heated portion 51a increases compared to the previous time. The temperature will also be higher than during the previous heating.

  As the moving object 51 continues to rotate, thermal energy is accumulated, and the heated part 51a of interest is heated to a higher temperature. However, the amount of heat released from the heated part 51a to the atmosphere is as follows. It increases in proportion to the temperature difference between the temperature of 51a and the atmosphere. Therefore, when the temperature of the heated portion 51a rises to a certain level, the heat energy absorbed from the heater 55 in the heating region 53 becomes equal to the heat energy dissipated into the atmosphere in the heat dissipation region 54, and the temperature changes. Disappear. The heat energy radiated into the atmosphere moves by heat due to natural convection and convection associated with the movement of the object 51, and matches the ambient temperature. This state in which the heat energy input / output system is saturated is hereinafter referred to as a steady state. Since this phenomenon that reaches the steady state occurs in any part of the moving object 51, the temperature of the rotating moving object 51 is averaged in the rotation direction.

  In the thermal fluid simulation of the present invention, the corrected thermal conductivity that is increased by multiplying the correction coefficient is used only for the thermal conductivity related to the heat transfer in the rotational movement direction indicated by the arrow 52 of the moving object 51. Thermal energy transfer is facilitated. As a result, the temperature distribution of the moving object 51 is averaged only in the rotation direction, and the balance of the temperature field is calculated under the condition that the heat energy transfer in the rotation direction is promoted. By calculating the flow based on the surface fluid velocity and natural convection obtained by the fluid velocity calculation, it is possible to represent the steady state of the actual phenomenon, that is, to obtain the saturation state of the system by steady analysis. Thereafter, the balance calculation is repeated, and the simulation calculation ends when the balance calculation finally reaches convergence.

  As described above, according to the thermal fluid simulation apparatus and method of the present invention, when performing the thermal fluid simulation calculation in the system including the moving object, the simulation calculation is performed without moving the mesh. In addition to making the balance calculation unnecessary, the surface fluid velocity, which is the velocity of the fluid in contact with the moving object, is used as the boundary condition, and the influence of the fluid on the surface in contact with the moving object is incorporated into the calculation, thereby reducing the time required for the thermal fluid simulation calculation. The accuracy can be improved.

  The present invention also records a thermal fluid simulation program for causing a computer to operate as a thermal fluid simulation apparatus, that is, a thermal fluid simulation program for causing a computer to execute the procedure of the flowchart shown in FIG. 6, and a thermal fluid simulation program. A computer-readable recording medium is provided.

  As a recording medium for recording the thermal fluid simulation program, for example, a ROM or the like provided in the control means 15 described above can be cited. Further, the recording medium may be a medium that is provided with a program reading device as an external device and is inserted into the reading device to be read.

  When an externally read type recording medium is used in the thermal fluid simulation apparatus 10, a thermal fluid simulation program is read from the recording medium by the reading apparatus, and the read thermal fluid simulation program is not included in the control means 15. The program is downloaded to the illustrated program storage unit and executed. It is assumed that the download program is stored in the storage unit of the control unit 15 in advance.

Recording media that can be read by a reader include magnetic tapes such as cassette tapes, magnetic disks such as flexible disks, compact disks (CDs), digital versatile disks (DVDs), mini disks (MDs), and magneto optical disks (MOs). ) And other optical or magneto-optical recording media, integral circuit (IC) cards (including memory cards), optical cards, mask ROMs that carry a fixed program including semiconductor memory,
Erasable Programmable Read Only Memory (EPROM), Electrically Erasable
Examples thereof include Programmable Read Only Memory (EEPROM) and flash ROM.

It is a block diagram which simplifies and shows the structure of the thermal fluid simulation apparatus 10 which is one Embodiment of this invention. It is a figure explaining the relationship between rotation of a moving object, and the speed of a fluid. 4 is a flowchart for explaining a surface fluid velocity calculation method in a fluid velocity calculation means 14. It is a figure which shows the example of the surface fluid velocity in a rotationally moving object. It is a figure which shows the example of the surface fluid velocity in a belt moving object. It is a flowchart explaining the thermal fluid simulation method performed using the thermal fluid simulation apparatus 10 shown in FIG. It is a figure which shows the example of the thermal fluid simulation shown to the flowchart of FIG. It is a figure explaining the conventional thermal fluid simulation method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Thermal fluid simulation apparatus 11 Calculation condition supply means 12 Simulation calculation means 13 Thermal conductivity correction coefficient calculation means 14 Fluid velocity calculation means 15 Control means 16 Storage part 17 Display means 21 Shape data storage part 22 Physical property data storage part 23 Calculation condition data Storage unit 24 Boundary condition correction data storage unit 25 Input unit 26 Flow field calculation unit 27 Temperature field calculation unit

Claims (5)

In a thermal fluid simulation apparatus for performing simulation calculation for each step of a step in which a moving object and a flow field and a temperature field around the moving object are set in a plurality in a system including the moving object,
Calculation condition supply means for supplying calculation conditions used for simulation calculation;
Using the calculation conditions supplied from the calculation condition supply means, the moving object and the flow field and temperature field in the initial state around the object are simulated and calculated, and in steps other than the initial state, the thermal conductivity of the moving object is corrected. A simulation calculation means for simulating a moving object and a flow field and a temperature field around the moving object using the corrected thermal conductivity and the moving velocity of the fluid in contact with the surface of the moving object;
Based on the moving direction and moving speed of the moving object, multiply the thermal conductivity of the moving object by the correction coefficient to obtain the corrected thermal conductivity, and give the corrected thermal conductivity to the simulation calculation means. Means,
Based on the moving direction and moving speed of the moving object, the surface fluid velocity, which is the moving velocity of the fluid in contact with the surface of the moving object, is obtained, and the surface fluid velocity is set as a boundary condition between the moving object and the fluid. Fluid velocity calculation means to be given to the calculation means;
Calculation condition supply means, simulation calculation means, thermal conductivity correction coefficient calculation means, control means for controlling the operation of the fluid velocity calculation means,
A storage unit for storing simulation calculation results by the simulation calculation means;
A thermal fluid simulation apparatus comprising: display means for displaying a simulation calculation result by the simulation calculation means. A boundary condition correction data storage unit that stores experimentally or empirically determined values or techniques for correcting the surface fluid velocity,
The fluid velocity calculation means is
According to the surface characteristics of the moving object, the surface fluid velocity set as the boundary condition is corrected based on a value or a method stored in the boundary condition correction data storage unit corresponding to the surface characteristic of the moving object. The thermal fluid simulation apparatus according to claim 1. In a thermal fluid simulation method for performing simulation calculation for each step of a step in which a moving object and a flow field and a temperature field around the moving object are set in a plurality in a system including the moving object,
A procedure for obtaining calculation conditions used in the simulation calculation;
A procedure for performing a simulation calculation of a moving object and a flow field and a temperature field in an initial state around the moving object using the obtained calculation conditions;
Based on the moving direction and moving speed of the moving object, a procedure for obtaining the corrected thermal conductivity by multiplying the thermal conductivity of the moving object by the correction coefficient;
A procedure for obtaining a surface fluid velocity, which is a velocity of fluid moving in contact with the surface of the moving object, based on the moving direction and moving speed of the moving object;
A thermal fluid simulation method comprising a simulation calculation of a moving object and a flow field and a temperature field around the moving object using the surface fluid velocity and the corrected thermal conductivity. A thermal fluid simulation program used for simulation calculation for each step of a step in which a moving object and a flow field and a temperature field around the moving object are set in a plurality in a system including a moving object,
A procedure for obtaining calculation conditions used in the simulation calculation;
A procedure for performing a simulation calculation of a moving object and a flow field and a temperature field in an initial state around the moving object using the obtained calculation conditions;
Based on the moving direction and moving speed of the moving object, a procedure for obtaining the corrected thermal conductivity by multiplying the thermal conductivity of the moving object by the correction coefficient;
A procedure for obtaining a surface fluid velocity, which is a velocity of fluid moving in contact with the surface of the moving object, based on the moving direction and moving speed of the moving object;
A thermal fluid simulation program for causing a computer to execute a simulation calculation of a moving object and a flow field and a temperature field around the moving object using the surface fluid velocity and the corrected thermal conductivity. A computer-readable recording medium on which the thermal fluid simulation program according to claim 4 is recorded.

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