JP2004340487A - Performance simulating method and device for air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To estimate the air blowing performance of an air conditioner (HVAC) with high accuracy while inhibiting the increase of a calculation time. <P>SOLUTION: This performance simulating method of the air conditioner comprising a fan for supplying the air-conditioning air comprises the database corresponding to a type of the fan and having the data on a state of the flow at a fan outlet. This method comprises a process for inputting the type of the fan, a process for inputting an operating state of the fan of the input type, a process for selecting and outputting the data on the state of the flow at the fan outlet corresponding to the type of the fan, from the database, a process for inputting the selectively output data on the state of the flow at the fan outlet to a numerical value fluid analysis calculation as the input data, a process for executing the numerical value fluid analysis calculation on the basis of the input data, and a process for processing a result of the executed numerical value fluid analysis calculation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a simulation method and an apparatus for the same, and more particularly, to a simulation method and an apparatus for predicting a ventilation performance of an air conditioner (HVAC).
[0002]
[Prior art]
2. Description of the Related Art Computational fluid dynamics (CFD) has conventionally been used to predict the ventilation performance of a vehicle air conditioner (HVAC). FIG. 1 shows a CFD model of the configuration of the HVAC. The configuration of the HVAC 10 is roughly divided into a blower (a centrifugal blower or a cross flow blower) 1, a unit 2 including a heat exchanger and the like, and a duct 3 leading to an outlet.
When performing the HVAC CFD, adding a CFD model of the blower causes an increase in the calculation scale and the calculation time. In many cases, this is omitted and a uniform flow velocity is given as a boundary condition at the entrance of the HVAC. . However, since the velocity distribution is actually large at the outlet of the blower, the accuracy of calculation prediction may be significantly affected depending on the configuration of the HVAC. Therefore, conventionally, a method of adding a model diagram (A) of only the scroll of the blower has been adopted. At this time, the boundary condition on the inflow side gives a velocity component toward the centrifugal direction from the fan outer cylindrical surface (fan outlet) (FIG. 2B). In the case of such a method, the increase in calculation time is small because there is no fan portion, but the tendency of the speed distribution at the outlet of the blower is significantly different from that in the case where there is a fan, and the accuracy is not sufficient. When there is a fan, a swirling flow occurs in the scroll, but when there is no fan, such a flow does not occur (FIG. 3).
[0003]
The above problem will be described based on an actual calculation example.
FIG. 3 shows a comparative example of calculation results in the case of the model with a fan (case 1) and the model without a fan (case 2). The calculation is performed for the cross section “1” and the cross section “2” in the plan view of the duct portion including the centrifugal blower (fan) shown in FIG. FIGS. 3B and 3E of the section “1” show the state of the wind velocity distribution near the fan outlet, and FIGS. 3C, 3D, 3F, and 3G of the section “2” 9 shows a state of a wind velocity vector in a duct portion slightly downstream from a fan outlet. As described above, in the fanless model of Case 2, since the uniform flow velocity is given as the boundary condition at the entrance of the HVAC (ie, at the exit of the fan), the height (Z) direction of the duct in FIG. Indicates that the flow rate is constant. On the other hand, in the calculation based on the model with a fan in Case 1, assuming that there is a fan, the flow velocity changes in the direction of the height (Z) of the duct in FIG. The flow velocity is highest near the center, which indicates that the flow velocity distribution is mountain-shaped. It is considered that the velocity distribution of the section “1” in FIGS. 3B and 3E indicates the boundary condition of the calculation at the entrance of the HVAC. That is, it can be seen that the inlet boundary conditions of Case 1 and Case 2 are different in the flow velocity distribution in the height (Z) direction. (Here, the lines representing the wind speed distribution in FIGS. 3B and 3E do not accurately represent the magnitude of the wind speed, but mainly represent the wind speed distribution.)
[0004]
In the case of the case 1 (model with fan) and the case 2 (model without fan), when the inlet conditions are different as described above, an example of calculating the flow downstream to some extent by calculation is shown in FIG. Probable result. The calculation results of this cross section “2” are shown as wind direction and wind speed distribution in FIGS. 3 (C) and 3 (D) and FIGS. 3 (F) and 3 (G). (The white dots in the figure indicate the wind velocity vectors that simultaneously represent the direction and magnitude of the wind at section “2”.) FIGS. 3 (C) and 3 (F) show the direction of the wind at section “2” with arrows. However, in case 2, the wind flows from above to below in the duct (and turns slightly clockwise). On the other hand, in the case 1, the wind is a calculation result of turning in the counterclockwise direction. As described above, it can be seen that the model with the fan (case 1) and the model without the fan (case 2) have completely opposite results with respect to the wind direction.
[0005]
Next, the calculation results for the wind speed distribution are shown in FIGS. 3 (D) and 3 (G). In case 2, the speed is low inside the duct (in the range of about 10 m / s to 15 m / s in this example), the speed gradually increases toward the outside of the duct, and is 25 to 28 m / s near the outside. Yes, the result is that the velocity increases in parallel from cross-section "2" from inside to outside as seen in FIG. 3 (G). On the other hand, in case 1, although the wind speed increases from the inside to the outside of the duct, the way of increase is a contour line, and the constant wind speed region surrounds the high-speed region of 28 m / s in the center of the outside of the duct. The result will change. Therefore, as can be seen by comparing FIGS. 3 (D) and 3 (G), with respect to the wind speed distribution, the calculation results differ considerably between the model with a fan (case 1) and the model without a fan (case 2). I understand.
[0006]
Further, there is a proposal regarding a simulation system of an air conditioner in the related art (for example, see Patent Document 1).
[Patent Document 1]
JP-A-2002-197125 (page 4)
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described circumstances, and has as its object to provide a method of accurately predicting the ventilation performance of an air conditioner (HVAC) while suppressing an increase in calculation time. It is therefore an object of the present invention to provide a method including a new modeling of a blower affecting the calculation time and the calculation accuracy and an apparatus for implementing the method.
[0008]
[Means for Solving the Problems]
According to the first aspect of the present invention, in order to achieve the above object, a method for simulating the performance of an air conditioner including a fan for supplying air for air conditioning is a database corresponding to the type of the fan, A database having data on the state of the flow. The method includes the steps of inputting the type of the fan, inputting the operating state of the fan of the type, and selecting data on the flow state of the fan outlet according to the type and operating state of the fan from the database. And outputting the selected and output fan exit flow state data as input data to the CFD calculation, executing the CFD analysis according to the input data, Processing the result of the executed computational fluid dynamics calculation.
[0009]
This configuration eliminates the need for the person performing the calculation of the computational fluid dynamics (CFD) model of the fan, reduces the calculation time, and improves the calculation accuracy. The period and man-hour for estimating the ventilation performance of the air conditioner (HVAC) can be greatly reduced.
[0010]
According to a second aspect of the present invention, in the first aspect, the database includes wind speed distribution data at a fan outlet.
According to the present embodiment, a mode is disclosed in which the contents of the data included in the database of the present invention are further embodied.
[0011]
According to a third aspect of the present invention, in the first aspect or the second aspect, the database includes a radial direction and a circular shape at a fan outlet corresponding to each type of the fan and an operation state of each fan. It is characterized by having wind speed vector data in each of a circumferential direction and a height (vertical) direction.
According to the present embodiment, a mode for further embodying the contents of the data provided in the database of the present invention is disclosed.
[0012]
According to a fourth aspect of the present invention, in any one of the first to third aspects, the fan is a centrifugal blower.
According to the present embodiment, an embodiment that further embodies the type of the fan is disclosed.
[0013]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the step of executing the numerical fluid analysis calculation is performed by general-purpose numerical fluid calculation software. .
According to the present embodiment, an embodiment that further embodies the procedure for executing the computational fluid dynamics calculation of the present invention is disclosed, and a more inexpensive embodiment is disclosed.
[0014]
According to a sixth aspect of the present invention, in the method according to any one of the first to fifth aspects, a program for executing a performance simulation method is provided.
According to the present embodiment, an embodiment in which each procedure of the method of the present invention is embodied is disclosed.
[0015]
According to a seventh aspect of the present invention, there is provided an apparatus having the program according to the sixth aspect.
According to this embodiment, an embodiment that embodies an apparatus that can execute the method of the present invention is disclosed.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a method for simulating the performance of an air conditioner according to one embodiment of the present invention will be described in detail with reference to the drawings.
The present invention focuses on the wind speed distribution at the fan outlet, models (functions) the wind speed distribution from the fan outlet as data without adding a fan model, and assigns boundary conditions, thereby increasing the calculation load. , To improve the calculation accuracy.
A method of directly applying the fan outlet wind speed distribution as a boundary condition based on the calculation result of the fan with a fan can be considered, but since it is necessary to perform the blower calculation every time the fan type and operating conditions are changed, the method of the present invention is used. Then, the wind speed distribution characteristics can be obtained in advance by experiment or the like for each operating state of each fan type and converted into data, so that it can be commonly used for general purposes.
[0017]
In the present embodiment, the air conditioner (HVAC) 10 to be calculated is the air conditioner 10 having the configuration shown in FIG. 1 described above. Therefore, the air conditioner 10 includes a fan 1, a unit 2 including a heat exchanger and the like, and a plurality of ducts 3 leading to an outlet. In the present embodiment, the fan 1 is a centrifugal blower.
Since the fan outlet wind speed distribution of the centrifugal blower has a characteristic, this distribution is modeled (functionalized) and given as a boundary condition. FIGS. 4A to 4D schematically show the fan outlet wind speed distribution of the centrifugal blower. A fan of a centrifugal blower generally has a component R (U) in the centrifugal (radial) direction, a component θ (V) in the rotation direction, and a component Z (W) in the rotation axis direction (FIG. 4B )-(D)). A swirling flow is generated in the scroll by these vector components.
FIG. 4A is a three-dimensional view of the shape of a centrifugal fan (hereinafter referred to as a fan) 1 having a spiral shape, and as shown in FIG. A body including wings is provided. In general, the fan 1 sucks air from a central portion of the fan 1 and generates a flow of air in a centrifugal direction as shown in FIG. 4B, and the air flows through a duct 12 surrounding the fan 1 to discharge the air. Outflow from 11.
[0018]
FIG. 6 shows a wind speed vector at a fan outlet of a specific centrifugal blower. The example of the wind speed of each direction component which made rotation axis direction height a parameter with respect to the angle of a fan rotation direction is shown. These wind speed distributions are functionalized and given as inflow boundary conditions for computational fluid dynamics (CFD). The inflow condition of the CFD is such that each vector component is given as a function of the coordinates (position) of the fan in order to set the U, V, and W direction components. It is also known that these vector components vary depending on the shape of the fan and the operating condition of the blower (point on the performance curve of the fan, ie, the pressure exerted by the fan and the flow rate corresponding to the pressure). Therefore, the wind speed distribution characteristics in the operating state are obtained in advance for each type of fan, and are made into a database. If this database is created, it is possible to select boundary conditions for various combinations of fans and use them universally for general purposes.
[0019]
Here, FIGS. 5A, 5B and 6 will be described. FIG. 5A is a schematic plan view of the fan portion as viewed from above, showing that the fan is at the center, and the position of the fan outlet is shown in the figure. FIG. 5A shows an angular position (0, 90, 180, 270 degrees) at the fan outlet, and FIG. 5B shows a height position (0, 15, 30, 45 mm) at the fan outlet. ) Is indicated. The height position of 0 mm is the lower surface (bottom surface) of the fan. FIG. 6 shows an example of the flow velocity data at the fan outlet corresponding to the positions shown in FIGS. 5A and 5B. FIG. 6 shows ten lines. Each line shows the flow velocity at ten equally divided height positions from a height of 0 mm to 45 mm. As shown in FIG.
[0020]
FIG. 6 shows the flow velocity at the fan outlet, as described above, and the data obtained by experiments in the radial (R) direction, the circumferential (θ) direction, the height (W) direction, etc. For each angle (horizontal axis: 0 to 360 degrees) as a parameter. The values of the graph shown in FIG. 6 are an example of the data of the flow velocity at the fan outlet included in the database. As shown in FIG. 6, in general, the flow velocity vector component at the fan outlet varies considerably widely depending on the angular position and the height position, and it can be seen that the flow velocity vector component is not uniform as in the prior art.
[0021]
FIGS. 8 (A) to 8 (G) are drawings for comparison similar to the drawings of FIGS. 3 (A) to 3 (G), and FIGS. 8 (B) to 8 (D) show models with a fan ( 8 (E) to 8 (G) show the results obtained using the method of the present invention (Case 3), and show a comparison between these two methods. . FIG. 7 is a schematic three-dimensional view of the centrifugal blower (fan) according to the present embodiment, and shows that the flow velocity vector, which is the inflow boundary condition for calculation, has components in the respective directions of R, θ, and W. ing. FIG. 8A is a drawing similar to FIG. 3A, and FIGS. 8B to 8G show calculation results at the positions of the cross section “1” and the cross section “2”, respectively. The cross-section “1” and the cross-section “2” are at the same position as in FIG. FIGS. 8B to 8D are the same (data) as the calculation results of the model with a fan shown in FIGS. 3B to 3D, and FIG. 8 (C) and (D) show the wind direction and the wind speed distribution at the cross section “2”, respectively.
[0022]
FIGS. 8 (E) to 8 (G) show the change in the height direction of the flow velocity at the fan outlet at section “1” and the wind direction and wind velocity distribution at section “2”, respectively, obtained according to the present invention. 8 (B) and 8 (E), FIG. 8 (C) and FIG. 8 (F), FIG. 8 (D) and FIG. 8 (G) are close approximations, respectively, and the method of the present invention (Case 3) ) Indicates that the calculation result approximates the calculation result using the model with fan (case 1).
When the method of the present invention shown in FIG. 8 is used, the same wind speed distribution as in the case where the fan model exists is given as the inflow boundary condition, so that both the flow and the speed distribution in the scroll are equivalent to the case where the fan model is added. It is possible to give the calculation accuracy of Furthermore, the calculation time was about し て compared with the case where the fan model was provided.
[0023]
FIG. 9 shows the flow of the procedure of the method for simulating the performance of the air conditioner according to the embodiment of the present invention. In the present embodiment, an apparatus for performing the method may be a computer.
In the flow of FIG. 9, in step 1 of S1, a fan type to be calculated and the above-mentioned fan operation state (specific value of the flow rate corresponding to the pressure of the fan) are input to the computer. Proceeding to step 2 of S2, in S2, data of the flow velocity distribution at the fan outlet corresponding to the data input in S1 is selected from the database of the storage device of the computer. Next, the process proceeds to step 3 of S3, and the flow velocity distribution data at the predetermined fan outlet selected and output from the database is input to the calculation program.
[0024]
Further, the process proceeds to step 4 of S4, where a computational fluid dynamics (CFD) calculation is executed to calculate a pipe resistance in a necessary duct, a flow distribution in each outlet, and the like. Then, in step 5 of S5, processing of the CFD calculation result, such as a graphical display, is performed.
The CFD calculation in Step 4 may be performed using a general-purpose program. In step 3, a plurality of input data (flow velocity distribution data at the outlet of the fan) is selected, and in step 4, the calculation is repeatedly performed to obtain a plurality of calculation results. In step 5, a plurality of CFD calculation results are processed. May be. The above procedure is summarized as follows. Wind speed distribution characteristics for each fan type and operating state are obtained in advance by experiment or calculation, and the speed distribution is replaced with a function based on geometry. This is registered as a database. When performing the HVAC calculation, the fan shape to be used and the operating state are selected from this database. Based on the selected condition, subroutine input data for giving the inflow boundary condition is written out from the database. The HVAC CFD calculation is performed using this subroutine.
In the present embodiment, a series of procedures is formed as a program and executed by a computer.
[0025]
Next, effects and operations of the above embodiment will be described.
The following effects can be expected by the method and apparatus for simulating the performance of an air conditioner according to one embodiment of the present invention.
-The person performing the calculation does not need the man-hour for creating the CFD model of the fan.
・ The calculation time can be shortened and the calculation accuracy can be improved.
-The period and man-hour for estimating the HVAC ventilation performance can be greatly reduced.
[0026]
The above embodiment is an example of the present invention, and the present invention is not limited by the embodiment, but is defined only by matters described in the claims. It is feasible.
[Brief description of the drawings]
FIG. 1 is an illustrative three-dimensional view showing an outline of a CFD model of a duct system of a general vehicle air conditioner.
FIG. 2 is a three-dimensional view of a scroll model of a blower used in the prior art (FIG. 2A), and a schematic plan view showing a constant wind speed distribution at the outlet of the blower (fan) (FIG. 2). (B)).
FIG. 3 is a drawing showing a difference in calculation results (in the section “1” and the section “2”) between the calculation of the model with a fan and the calculation of the model without a fan.
FIG. 4 is a three-dimensional view of the centrifugal blower (FIG. 4A), and the flow velocity distribution at the fan outlet is shown by R (FIG. 4B), θ (FIG. 4C), This is schematically shown in the W (FIG. 4D) direction.
FIG. 5 is a plan view (FIG. 5 (A)) and a side sectional view (FIG. 5 (B)) for specifying a position at a fan outlet.
FIG. 6 shows an example of flow velocity distribution data at a fan outlet included in the database of the present invention.
FIG. 7 is a schematic three-dimensional view of a centrifugal blower (fan) portion as an object of the embodiment of the present invention, wherein flow velocity vectors as inflow boundary conditions for calculation are R, θ, and W, respectively. Has a component in the direction of.
FIG. 8 is a diagram illustrating a difference (or similarity) between the calculation result (in the section “1” and the section “2”) between the calculation of the model with a fan and the calculation according to the embodiment of the present invention; 4 is a drawing corresponding to FIG.
FIG. 9 is a flowchart showing a procedure of an embodiment of the method of the present invention.
[Explanation of symbols]
1 ... Blower (fan)
2 Unit 3 Duct 10 Air conditioner

Claims (7)

In a method for simulating the performance of an air conditioner including a fan for supplying air for air conditioning, the method includes:
A database corresponding to the type of the fan, the database including data on a flow state at a fan outlet;
Inputting the type of the fan;
Inputting the operating status of the type of fan;
A step of selecting and outputting data on the flow state of the fan outlet according to the type and operating state of the fan from the database,
A step of inputting the selected and output fan outlet flow state data to the CFD calculation as input data,
Performing a numerical fluid analysis calculation according to the input data,
Processing the result of the executed computational fluid dynamics calculation,
A method for simulating the performance of an air conditioner, comprising: 2. The performance simulation method according to claim 1, wherein the database includes wind speed distribution data at a fan outlet. The database includes wind speed vector data in a radial direction, a circumferential direction, and a height (vertical) direction at a fan outlet corresponding to the type of each fan and the operation state of each fan. The performance simulation method according to claim 1. The device according to any one of claims 1 to 3, wherein the fan is a centrifugal blower. The performance simulation method according to any one of claims 1 to 4, wherein the procedure of performing the computational fluid dynamics calculation is performed by general-purpose computational fluid dynamics software. A method comprising a program for executing the performance simulation method according to claim 1. An apparatus comprising the program according to claim 6.

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