KR101869699B1 - Method and apparatus for fan simulation by flow analysis - Google Patents

Abstract

According to an embodiment of the present invention, a fan simulation method using a flow analysis includes: inputting a point data and a tester dimension by a user; Computing the point data to generate a shape of the pan and generating a tester from the tester dimensions; Generating a grating on the fan; Inputting a boundary condition for the fan to interpret the flow by the fan; And calculating a noise figure from the analysis, wherein the noise figure is proportional to the deviation of the pressure according to the position of the fan when the flow by the fan is in a steady state.

Description

METHOD AND APPARATUS FOR FAN SIMULATION BY FLOW ANALYSIS FIELD OF THE INVENTION [0001]

The present invention relates to a fan simulation method and a fan simulation apparatus, and more particularly, to a fan simulation method and a fan simulation apparatus through flow analysis and noise analysis.

Since the industrialization, products developed mainly in functions have been transformed into superior products with performance according to the demand of consumers demanding quality improvement. As a criterion for judging a good quality product, it is necessary to provide the air power which is most importantly considered, and the noise at that time should be the lowest.

For example, it is necessary to carry out a study on the noise of the flow noise. This is the case of an acoustic wind tunnel with an anechoic chamber in the Wind Tunnel which blows wind or an acoustic fan tester (Experimental Study). Because of the cost and expertise required by these expensive experimental equipment, it is impossible to produce excellent products with low noise design in general SMEs.

In particular, the fragrance-free wind tunnel equipment is expensive, and home appliance companies and SMEs can not afford to apply these technologies. The development process through experiments was a repetition of a process that first made a low-noise shape (prototype production) and then experimented with the situation similar to the actual situation. In the case of automobiles, it is a high-cost, low-efficiency structure that requires testing and building dozens of vehicles that are more than several hundreds of millions of dollars for real low-noise shapes. Research on household appliances requires research costs of hundreds of millions of won. It is performed only in some large corporations. Therefore, a low-cost, high-efficiency research process that can replace such a costly and inefficient research process is needed.

Korean Unexamined Patent Application Publication No. 2007-0097988 (Oct.

An object of the present invention is to provide a fan simulation method and a fan simulation apparatus capable of predicting the performance of a fan through flow analysis.

Other objects of the present invention will become more apparent from the following detailed description and the accompanying drawings.

According to an embodiment of the present invention, a fan simulation method using a flow analysis includes: inputting a necessary fluid date; Confirming the basic shape provided by the present invention for generating such a floating date; A point data generating step of plotting the basic shape; Computing the point data to generate a shape of the fan; Generating a grid for analysis that fits the pan; Inputting a boundary condition for the fan to interpret the flow by the fan; And calculating the fan efficiency and noise from the analysis, wherein the noise represents a quantitative noise having a unit (dB, dBA) or a noise figure which is a relative value of the noise, Is in proportion to the deviation of the pressure according to the position of the fan in the steady state.

The noise figure may be proportional to the deviation of the pressure at a predetermined position of the fan when the flow by the fan is in an abnormal state.

The interpreting step may include calculating the pressure and the velocity according to the position and the time of the fan with respect to the flow.

According to an embodiment of the present invention, a fan simulation apparatus through a flow analysis includes a fan design module to which point data and tester dimensions are input; A CAD module for calculating the point data input to the fan design module to generate a shape of a fan and generating a tester from the tester dimension; A grating module for generating a grating on the fan; A solving module for inputting a boundary condition for the fan and analyzing the flow by the fan; And a performance analysis module for calculating a noise figure from the analysis, wherein the performance analysis module calculates the noise figure in proportion to the deviation of the pressure according to the position of the fan when the flow by the fan is in a steady state.

The solving module may calculate a pressure and a velocity according to the position and time of the fan with respect to the flow.

The performance analysis module may calculate the noise figure in proportion to the deviation of the pressure at a predetermined position of the fan when the flow caused by the fan is in an abnormal state.

According to an embodiment of the present invention, the performance of the fan, that is, efficiency and noise can be predicted by simulation of the fan through the flow analysis.

Figure 1 shows an unirradiated and an unirradiated fan tester.
Figures 2 and 3 are conceptual diagrams in accordance with an embodiment of the present invention.
4 shows a GUI according to an embodiment of the present invention.
5 shows a dimension input window of the pan and tester.
Figure 6 shows ring, hub and rotate zone dimensions.
Figure 7 shows shroud, motor, radiator and condenser dimensions.
Figure 8 shows the shroud and tester dimensions.
FIG. 9 shows an example of generating an octree.
FIGS. 10 and 11 show the result of generating a grid with the Octree shown in FIG.
12 shows a result image for report generation after analysis is completed.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention can be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments are provided to explain the present invention to a person having ordinary skill in the art to which the present invention belongs. Accordingly, the shape of each element shown in the drawings may be exaggerated to emphasize a clearer description.

In order to study the improvement of the performance of the fan when the designer develops the actual product, it is necessary to have a lot of professional knowledge and expensive experimental equipment, such as an antifreeze (mushroom pen tester), to make many mock-up products, The work had to be repeated. The present invention relates to a fan simulation method and a fan simulation method which can be easily carried out through an automated program constructed according to a professional analysis process using a CFD tool after a designer designs a test product to replace such an inefficient and costly research process .

In the present invention, when a designer inputs the point data of the fan and the dimensions of the tester through the fan design module, a fan and a tester are automatically created in the CAD program (CAD module) (CAD modeling). The generated file is used to generate a grid for analysis using the program. When the grid is created, the flow analysis is started using the boundary conditions input by the user and the basic fan analysis boundary conditions. Once the analysis is completed, a report will be automatically generated to analyze the analysis results.

In the present invention, when the designer inputs and executes the point data and the tester dimensions, the CAD of the fan and tester is automatically completed in the program. Depending on the point data of the fan, the dimensions of the rotate zone are automatically calculated and modeled and the ring and hub are automatically created. Also, the present invention proposes a basic model for the flow date required by the designer, and an operation for determining the shape of the basic model includes an euler fan turbomahinery equation, a velocity triangle, and mean line analysis ) Is used.

Therefore, if the designer inputs only the point data of the fan, the size of the tester, the dimensions of the radiator and the condenser, and the distance between the shroud, the radiator and the condenser, all other operations are automatically computed and modeled in the program.

One of the biggest reasons why it is difficult for an actual designer to interpret is the part about grid generation. The lattice is an important part of the analysis. Properly creating the lattice of the part important for the analysis evaluation increases the accuracy of the analysis. Grid generation therefore requires a lot of experience, requires a lot of time, and requires CFD expertise.

In the present invention, many lattices are generated through the lattice module with respect to the shape of the axial fan, and optimum conditions are secured based on this. The lattice is usually composed of Tetra, Hexa, Prism type, Prism lattice on the wall, Hexa lattice in the large space, and Tetra lattice in the space between the large space and the wall.

In the present invention, a method of generating a lattice is to make a rectangular cube as a whole region, and to make an important region as a small cube. Determining this size is important because the size of this single cube determines the size of the analysis grid. In particular, it is important to make the size of the cube even smaller, making the lattice size small and uniform, especially in the geometrically important areas such as the front and back of the fan.

The model for executing the flow analysis is completed when the above step is performed. In order to perform the flow analysis, the boundary conditions necessary for the analysis must be input (the solving module). Most of these boundary condition inputs are set to optimal conditions, so the designer can set the dt value by applying the inlet flow rate, fan rotation speed (RPM), and the rotation angle of the fan per 1 cycle without wasting any extra setup do.

- Enter the rotational speed of the fan

- Pressure compensation selection

- Enter convergence condition: Recommended to use initial value

- Select the turbulence model used in the analysis

- Total Analysis Cycle Setting

- Time per cycle (calculated by the number of revolutions of the fan and cycle / degree)

- If IAUDT is 0: dt value is used as time interval

- Courant number: can be entered directly or calculated automatically when given dt value

- Problem Type: Steady and Unsteady analysis is selected. When analyzing the fan problem, about 100 cycles are interpreted as Steady and then Unsteady is analyzed. Convergence is slightly faster and interpretation is more stable.

- Select the equation to be used in the analysis.

- window for entering the properties of the working fluid.

- Select whether the working fluid is imcompressible or compressible.

In this step, a lattice is generated and each boundary condition is input and analysis is performed. The interpretation is done on an NI-based supercomputer.

After completion of the CFD analysis, a post-process function such as checking the drawing and checking the flow for the report is also performed automatically (performance analysis module). The designer can look at these drawings to determine if the design is well done, if the design is wrong, and where to fix it. The relative velocities at each blade section show whether the flow passes well along the blade section or if separation occurs. Also, by looking at the pressures at the front and back of the blade, you can see that the fans are efficient and that each blade operates consistently and efficiently. You can see how the flow past the fan flows by looking at the distribution of velocity and pressure at the cross-section where the fan is cut vertically. As a result, the designer can obtain various information by viewing each picture, and can apply this information to the next design to develop a better performance fan.

Performance analysis is based on the above report. Performance analysis is based on noise, efficiency, and flow uniformity, and noise and efficiency are considered as important factors.

Noise is understood to be due to pressure changes, and is assessed in terms of volume through the noise figure. The noise figure is in two forms and is based on the (standard) deviation of the pressure depending on the position of the blade in steady state and the (standard) deviation of the pressure according to the individual position in the abnormal state.

Through the flow analysis described above, the flow is defined as pressure and velocity and is defined as p = (x, y, z, t) and v = (x, y, z, t) Can be defined. In this case, the steady-state flow can ignore the time t since p = (x, y, z) and v = (x, y, z) It can be deformed. Here, the (standard) deviation of the pressure according to the positional change (x, y, z) can be grasped, and the relative amount of noise according to the point data input first can be evaluated.

That is to say, the point data is the individual position of the blade, which is located on the static pressure surface (where the wing force is generated) and the negative pressure surface (where the wing is lifted) divided by the curved shape of the blade The reason for the difference in pressure depending on the position of the blades is that the pressure is differently distributed due to the speed difference between air flowing above and below the wing of the static pressure side and the negative pressure side.
In the present invention, it is found that when the pressure difference is uniform in the steady state, the noise is lowered, and when the pressure difference is non-uniform, the noise is largely generated and the pressure difference value between the static pressure surface and the negative pressure surface distributed in each wing is calculated The standard deviation was calculated as a noise figure.
Here, the noise figure is a measure of the magnitude of the noise, which is a measure of the magnitude of the noise.

This method simplifies the calculation by eliminating one variable for time t, thereby greatly shortening the time required for noise evaluation. However, since the above evaluation reflects only the steady-state flow and the abnormal flow is overlooked, it can not be seen as an absolute numerical value, and it is impossible to evaluate whether or not the optimum performance is over unless the abnormal flow is overlooked. Therefore, in the process of completing the design through the above performance evaluation, the flow of the abnormal state should be reflected, and the flow of the steady state can only provide the comparison standard.

In the other way, the (standard) deviation of the pressure with respect to the individual position in the abnormal state can be grasped, and thus the relative amount of noise according to the initial input point data can be evaluated.

In addition, efficiency is evaluated based on steady-state flow, and is defined as the product of pressure and flow divided by torque and angular velocity.

Although the present invention has been described in detail by way of preferred embodiments thereof, other forms of embodiment are possible. Therefore, the technical idea and scope of the claims set forth below are not limited to the preferred embodiments.

Claims (6)

The basic design is made, the basic design is changed by the design variables to create the shape of the fan, the grid for analyzing the flow field to the fan is created, the boundary condition for the fan is inputted, A simulation method of a fan for designing by determining whether a value obtained by an analysis is suitable,
The flow analysis,
A pressure difference between a static pressure surface and a negative pressure surface flowing above and below each of the blades of the fan in a steady state is calculated and the noise figure is calculated through the standard deviation of the pressure difference value delete delete delete delete delete

Images