KR20150113581A - Element detecting mehtod for impeller of 2 step radial blower - Google Patents

Abstract

The present invention is to disclose an element detecting method of a two-step centrifugal blower. According to the present invention, a calculation grid of a tetrahedral grid which is an unstructured grid for rotational and irrotational areas is formed. A momentum equation is deducted by converting a governed equation of each of the grids by using an MFR technique of a rotary coordinate system according to computational fluid dynamics. A tetrahedral flow is interpreted by using a k-ω SST (shear-stress transport) tetrahedral flow after separating the drawn momentum equation. The verification for an interpretation technique of the flow is executed based on a comparison of the measured flow coefficient and pressure coefficient. Therefore, the two-step centrifugal blower wherein performance and efficiency are improved is provided by manufacturing the two-step centrifugal blower which is optimized based on the flow interpretation technique using the MFR technique by the more precise computational fluid dynamics.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of detecting an element of an impeller for a two-stage centrifugal blower,

The present invention relates to a method for detecting an element of an impeller for a two-stage centrifugal blower for medical use, and more particularly, to a method for detecting an element of an impeller for a medical two-stage centrifugal blower, The present invention relates to a method for detecting an element of an impeller for optimum design through flow analysis to improve performance and efficiency.

The blower is a machine that transfers the air by rotating the impeller. A blower with a pressure ratio of 1.1 or more and less than 2.0 is referred to as a blower. The blower is a fan in which the pressure ratio between the air inlet and the air outlet is less than 1.1. It is called a blower.

Generally, a blower is divided into a turbo type blower and a volumetric type blower, which increases the wind flow intensity using gas, particularly air. The double turbo blower is divided into an axial blower that obtains energy by the lifting force of the blades generated by the rotation of the rotary car, and a centrifugal blower that obtains energy by the centrifugal force. Among such blowers, the centrifugal blower generally has a suction port at the center of one side of the cylindrical main body, forms a discharge port on one side of the cylindrical surface, and has a blade rotating around an axis centered on the cylindrical main body inner cylinder, An impeller or the like. Thus, a plurality of small blades, which are small blades, are tilted to one side and pushed to the outside by sucking air into the center of a columnar impeller formed in the plurality of blades.

In the turbo type blower thus provided, due to various factors such as a sudden change of the main flow in the impeller, an asymmetry of the flow along the circumferential direction of the impeller, a pressure gradient around the tongue and a flow inside the scroll, The flow and efficiency of the fuel cell can not be predicted. In addition, there is a problem that it is impossible to design an efficient optimum impeller.

In order to solve the above-mentioned conventional problems, the present invention performs a three-dimensional flow analysis through the interior of the impeller, examines the effect on the performance range of the design parameters of the upper cap, the lower cap and the blade, In order to provide an element detecting method for a two-stage centrifugal blower, which can improve the performance and efficiency of an optimized turbo centrifugal blower based on a more precise flow analysis technique by designing an optimum impeller based on the present invention have.

Technical Solution According to an embodiment of the present invention,

A two-stage centrifugal blower for analyzing an internal flow of a ballowork disposed in a predetermined number of rotation regions for rotating the rotational force of the motor and sucking external mixed gas through an inlet and discharging the same through an outlet; The method comprising:

A design parameter setting step of setting a position, a radius, and an impeller width of an outlet set as a design variable;

A grid generating step of dividing a two-stage impeller, a case, and a blit into three blocks and constructing a predetermined number of calculation grids in an algebraic manner to perform a computational fluid analysis in a blower having a set design variable;

In order to calculate the three-dimensional partial differential equation of turbulent flow using the standard k-ω SST (Shear-Stress Transport) turbulence model, the momentum equations are computed from the hydrodynamic governing equations of each grid in the rotating coordinate system, A flow analysis step of deriving a coefficient and a pressure coefficient,

And an analysis result verification step of comparing the flow analysis result and the actual measurement result to verify the validity of the analysis method used in the flow analysis step.

Preferably, the lattice-

And a tetrahedral mesh (Tetra mesh), which is a non-aligned mesh of 5,300,000 which produces dense lattices at the interface of the impeller rotating at high speed and at the interface between the blades and the flow field junction inside the casing in a stationary state .

Preferably, the flow analysis step comprises:

In order to model the flow in the accelerating coordinate system, the multiple frame reference (MFR) method which simultaneously analyzes the rotational and stationary regions including the two-stage impeller, case, and blit To be executed.

Preferably, the MFR technique comprises:

The momentum equation included in the flow acceleration when calculating the governing equations in the rotational coordinate system satisfies the following equation (1).

.. 식 1

.. Equation 1

Preferably, the flow analysis step comprises:

)은 다음 식 2을 만족하고, 상기 운동량 방정식은 다음 식 3를 만족하는 것을 특징으로 한다.The governing equation in the rotational domain includes continuity and momentum equations, and the continuity equation (

) Satisfies the following equation (2), and the momentum equation satisfies the following equation (3).

… 식 2

... Equation 2

… 식 3

... Equation 3

Preferably, the momentum equation is discretized according to a predefined equation, and the momentum equation that is discretized is satisfied through Equation (4).

… 식 4

... Equation 4

Preferably, the flow analysis step comprises:

Further comprising deriving a flow coefficient and a pressure coefficient, which are analytical values, using a standard k-SST (Shear-Stress Transport) turbulence model using the discretized momentum equation, and the derived flow coefficient and pressure coefficient The following expressions (5) and (6) are satisfied.

… 식 5

... Equation 5

… 식 6

... Equation 6

는 회전수, 밀도, 체적 유량, 임펠러 디스크 직경, 및 정압 상승을 의미한다.here,

Means the number of revolutions, density, volumetric flow rate, impeller disc diameter, and static pressure rise.

According to an embodiment of the present invention, a computational grid for a tetrahedral grid is constructed for an unoriented grid for the rotating and non-rotated regions, and the governing equations for each grid are fluidly transformed using the MFR technique of the rotational coordinate system according to the computational fluid analysis The momentum equations are derived and the derived momentum equations are discretized. Then, the turbulent flow is analyzed using the k-ω SST (Shear-Stress Transport) turbulence model, and the flow analysis method The centrifugal blower with optimized performance is manufactured by using the flow analysis technique using the MFR technique according to the more accurate computational fluid analysis to provide a two-stage centrifugal blower with improved performance and efficiency .

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further understand the technical idea of the invention. And should not be construed as limiting.
1 is a sectional view showing a two-stage centrifugal blower to which an embodiment of the present invention is applied.
2 is a flowchart illustrating an element detection process of a two-stage centrifugal blower according to an embodiment of the present invention.
3 is a view showing a calculation grid in the element detection process of the two-stage centrifugal blower according to the embodiment of the present invention.
4 is a view showing centrifugal coordinate system and fixed coordinate system during the flow analysis of the element detection process of the two-stage centrifugal blower according to the embodiment of the present invention.
5 is a diagram showing an experimental measurement apparatus for verifying an analysis result of an element detection process of a two-stage centrifugal blower according to an embodiment of the present invention.
6 is a view showing experimental results and analytical results according to the analysis result verification of the element detection process of the two-stage centrifugal blower according to the embodiment of the present invention.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

FIG. 1 is a sectional view showing a configuration of an impeller for a two-stage centrifugal blower to which an embodiment of the present invention is applied. As shown in FIG. 1, a scroll (including an impeller 2, a blade 3, 4). That is, the two-stage centrifugal blower 1 for allowing the gas introduced into the inlet 5 formed on one flat side to flow out to the outlet formed on one side of the circumferential surface of the body 5, which is formed in a generally cylindrical shape, And an impeller 2 rotated about an axis formed at one side of the central portion of the impeller 2. At this time, the impeller 2 is formed with a plurality of blades 3 as a blade, and sucks and discharges the gas with strong suction force. The scroll 4 collects the gas discharged from the impeller 2 and sends it to the outlet of the scroll 4, and the shape of the scroll 4 can be represented by a predetermined exponential function. At this time, as the exponential function increases, the flow cross-sectional area due to the scroll expansion angle increases, and as a result, the flow velocity energy passing through the scroll is changed to the pressure energy. The narrowest gap between the impeller 2 and the scroll 4 is referred to as a blit 6 and the scroll 4 is defined by the distance between the impeller 2 and the impeller 2 in the circumferential position of the blit 6 Respectively. In the embodiment of the present invention, a series of processes for setting a plurality of design variables through a predefined exponential function is a well-known technique, and a detailed description thereof will be omitted.

The impeller 2 of the two-stage centrifugal blower 1 formed in this way is designed so that the size of the portion where the blade 3 is formed is smaller than the component elements such as the inner radius d1, the outer radius d2, and the width b, . In other words, the two-stage centrifugal blower 1 shows a flow of the fluid that is sucked into one side of the three-dimensional shape and flows out to one side after being rotated along the circumferential surface.

The two-stage centrifugal blower (1) is composed of a series of hydraulic statistical techniques using flow analysis method and turbulence modeling based on the MFR technique of rotational coordinate system used in the computational fluid analysis, and results obtained through physical or numerical experiments Based numerical optimization technique.

That is, asymmetrical geometric shape in which the momentum of the main flow in the impeller 2 changes, the shape of the scroll 4 is the narrowest in the tread portion 6 and gradually increases in the circumferential direction, The asymmetry of the flow along the circumferential direction of the impeller and the very large pressure gradient around the blot 6 which is the narrowest part between the scroll 4 and the impeller 2 and the strong three- The shape of the two-stage centrifugal blower can be determined by the elements detected by, for example,

Therefore, the width of the impeller 2, which is an element detected by the element detection method of the two-stage centrifugal blower 1 by the numerical optimization design technique as described above, the radius and position of the blot 6, A two-stage centrifugal blower 1 to which an embodiment of the invention is applied is designed.

) 및 반경(

)을 선택하였고, 임펠러(2)에 대해서 폭(b)을 선택하고, 추가로 송풍기의 운전과 관련된 유량을 포함하는 설계 변수 설정 단계(100)와, 설정된 설계 변수를 가지는 블로워(1)에서 전산 유체 해석을 실행하기 위해 2단 임펠러, 케이스, 및 블루트를 세 블록으로 분할하여 대수적 방법으로 소정 수의 계산 격자를 생성하는 격자 생성 단계(200)와, 표준 k-ω SST(Shear-Stress Transport) 난류 모델을 사용하여 난류 유동의 운동량 방정식으로 계산하고자 각 격자의 유체역학적 지배 방정식들을 회전 좌표계로 변환하여 운동량 방정식을 연산하고, 연산된 운동량 방정식을 이산화하여 유량 계수 및 압력 계수를 도출하는 유동 해석 단계(300)와, 상기 유동 해석 단계(300)에서 사용된 해석 방법에 대한 타당성을 검증하기 위해 상기 유동 해석 결과인 유량 계수 및 압력 계수와 실측 결과인 유량 계수 및 압력 계수를 비교하는 해석 결과 검증 단계(400)를 포함한다.That is, the number of the blades 3 of the two-round centrifugal blower shown in Fig. 1 is 13, and the disk diameter is set to 2 stages including the two-stage impeller 2 fixed to 42 mm, the blade 3 and the scroll 4 The element detection method of the centrifugal blower 1 is a geometric design variable known to have a performance-sensitive effect. The position of the blot 6 relative to the scroll (4)

) And radius

) Designating the width (b) for the impeller (2), and further including a flow rate associated with the operation of the blower (1) A lattice generation step (200) of dividing a two-stage impeller, a case, and a blit into three blocks to generate a predetermined number of calculation gratings by an algebraic method to perform a fluid analysis, a standard k-ω SST (Shear-Stress Transport ) To calculate the momentum equation of the turbulent flow using the turbulence model, the hydrodynamic governing equations of each lattice are converted into the rotational coordinate system to calculate the momentum equation, and the flow equation to derive the flow coefficient and pressure coefficient by discretizing the calculated momentum equation In order to verify the validity of the analysis method used in step 300 and the flow analysis step 300, the flow coefficient and the pressure coefficient, which are the result of the flow analysis, And an analysis result verification step 400 for comparing the flow coefficient and the pressure coefficient as a result of the analysis.

3, the lattice generation step 200 includes the steps of: generating a dense lattice on the interface between the high-speed rotating impeller and the flow field junction inside the case in a stationary state, And a tetrahedral mesh, which is an unstructured mesh. 3 is a view showing a calculation grid of the two-stage centrifugal blower shown in FIG. 2. FIG. That is, as shown in FIG. 3, by applying a multi-block system constituting a calculation grid in an algebraic manner by dividing the two-stage impeller and the blades of the rotating region into the non-root three blocks of the scroll as the fixed region, (1) to perform the flow analysis for the complicated geometric shape.

Meanwhile, the flow analysis step 300 uses a rotational coordinate system (MFR) to analyze the three-dimensional flow according to the computational fluid dynamics, which converts the hydrodynamic governing equations, which can be expressed in the form of partial differential equations, into an algebraic equation, Frame Reference) technique.

That is, the MFR technique, which is mainly used in the rotating region, is represented by a rotational coordinate system and a fixed coordinate system as shown in FIG. Where is the position vector of the rotational coordinate system, and ??? represents the angular velocity. 4 is a view showing a rotation coordinate system and a fixed coordinate system for the computational fluid analysis of the two-stage centrifugal blower.

Then, if the rotational coordinate system of the two-stage centrifugal blower 1 is defined, the rotating boundary layer is fixed relative to the rotational coordinate, so that the rotating boundary layer moves at the same speed as the coordinate system.

When the governing equations are computed in the rotational coordinate system, the acceleration of the flow is increased by the additionally indicated term in the momentum equation, and the left side term of the momentum equation satisfies the following equation (1).

식 1

Equation 1

)과 상기 운동량 방정식으로 나타낼 수 있으며, 연속 방정식(

)은 다음 식 2를 만족하고 운동량 방정식(

)은 다음 식 3을 만족한다.Then, the flow field in the rotating region is expressed by the continuity equation (

) And the momentum equation, and the continuous equation (

) Satisfies the following equation (2) and the equation of momentum (

) Satisfies the following equation (3).

.. 식 2

.. Equation 2

..식 3

.. Equation 3

And, the momentum equation is discretized and the discretized momentum equation satisfies the following equation (4).

..식 4

.. Equation 4

Thereafter, in the flow analysis step 300, flow modeling is performed using a standard k-ω SST (Shear-Stress Transport) turbulence model. Here, the k-ω SST turbulence model is the most suitable model for the analysis of flow separation.

In this flow analysis step 300, the flow coefficient and the pressure coefficient for determining the performance characteristics of the two-stage centrifugal blower are derived from the computational fluid dynamics analysis, and the derived flow coefficient and the pressure coefficient are expressed by the equations (5) and Satisfies.

.. 식 5

.. Equation 5

.. 식 6

.. Equation 6

는 회전수, 밀도, 체적유량, 임펠러 디스크직경, 정압상승을 의미한다.Here,

Means the number of revolutions, density, volumetric flow rate, impeller disk diameter, and static pressure rise.

In order to verify the validity of the analytical result obtained in the flow analysis step 300, the element detection method of the two-stage centrifugal blower according to the embodiment of the present invention uses a flow analysis result and an experimental measurement device, And an analysis result verification step 400 to be compared.

In the analysis result verification step 400, as shown in FIG. 4, the experimental measurement apparatus is implemented by a method of measuring the flow rate of rapeseed oil filled in a circular pipe having a pipe diameter of 50-120 mm. That is, when the fluid is installed in the pipe through which the fluid flows, the static pressure difference between the upstream side and the downstream side is correlated with the flow rate in the pipe. Therefore, the flow rate can be calculated using the static pressure difference. And the flow rate is derived based on the expansion correction coefficient of the gas.

) 및 혼합 가스 팽창 보정 계수(

)는 다음 식 7 및 8을 각각 만족하고, 질량 유량(

)은 다음 식 9를 만족한다.The effluent coefficient (

) And the mixed gas expansion correction coefficient (

Satisfy the following equations (7) and (8), respectively, and the mass flow rate

) Satisfies the following expression (9).

… 식 7

... Equation 7

… 식 8

... Equation 8

…. 식 9

... . Equation 9

), 유출 계수(

), 조임 지름비(

), D에 관한 레이놀즈 수(

), 오리피스 관의 상류면에서 상류쪽 압력 취출구까지의 거리를 관로의 지름으로 나눈 계수(

), 오리피스관의 하류면에서 하류쪽 압력 취출구까지의 거리를 관료의 지름으로 나누 계수

)를 의미한다. 다만

일 때

의 계수는 0.039 이다.Here, the volume flow rate (

), Effluent coefficient (

), Tightening diameter ratio (

), The Reynolds number for D (

), A coefficient obtained by dividing the distance from the upstream surface of the orifice pipe to the upstream pressure outlet by the diameter of the pipe (

), The distance from the downstream side of the orifice tube to the downstream side pressure outlet is divided by the diameter of the bureaucracy

). but

when

Is 0.039.

FIG. 5 is a graph showing the experimental results obtained through the experimental measurement device in the analysis result verification step 400 of FIG. 2, and shows the experimental results of holding 35000 RPM.

FIG. 6 is a graph showing the experimental results obtained through the experimental measurement device and the flow analysis results obtained in the flow analysis step 300 in the commentary result verification step 400 of FIG. 2. The MFR of the three- The results of the numerical simulation are shown in Fig.

According to an embodiment of the present invention, a computational grid for a tetrahedral grid is constructed for an unoriented grid for the rotating and non-rotated regions, and the governing equations for each grid are fluidly transformed using the MFR technique of the rotational coordinate system according to the computational fluid analysis The momentum equations are derived and the derived momentum equations are discretized. Then, the turbulent flow is analyzed using the k-ω SST (Shear-Stress Transport) turbulence model, and the flow analysis method , The two-stage centrifugal blower which is optimized based on the flow analysis technique using the MFR technique according to the more accurate computational fluid analysis is manufactured to provide a two-stage centrifugal blower with improved performance and efficiency.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied in the form of a program form which may be performed via a variety of computing means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and configured for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

We constructed the computational grid of the tetrahedron lattice which is the unstructured lattice for the rotating and the non-rotating lattice. The governing equations of each lattice were transformed by using the MFR technique of the rotating coordinate system according to the computational fluid analysis to derive the momentum equation, By simulating the turbulent flow using the k-ω SST (Shear-Stress Transport) turbulence model after the equations are discretized and verifying the analytical technique of the flow based on the comparison of the measured flow coefficients and pressure coefficients, We propose a two-stage centrifugal blower that improves the performance and efficiency by manufacturing the optimized two-stage centrifugal blower based on the flow analysis technique using the MFR technique according to the more accurate computational fluid analysis. It can bring about great improvement in the accuracy and reliability of operation and further in performance efficiency. It is an industrial invention that is possible because it is not only possible to market or operate a respirator for medical use, but also to be practically and practically possible.

Claims (7)

A two-stage centrifugal blower for analyzing an internal flow of a ballowork disposed in a predetermined number of rotation regions for rotating the rotational force of the motor and sucking external mixed gas through an inlet and discharging the same through an outlet; The method comprising:
A design parameter setting step of setting a position, a radius, and an impeller width of an outlet set as a design variable;
A grid generating step of dividing a two-stage impeller, a case, and a blit into three blocks and constructing a predetermined number of calculation grids in an algebraic manner to perform a computational fluid analysis in a blower having a set design variable;
In order to calculate the three-dimensional partial differential equation of turbulent flow using the standard k-ω SST (Shear-Stress Transport) turbulence model, the momentum equations are computed from the hydrodynamic governing equations of each grid in the rotating coordinate system, A flow analysis step of deriving a coefficient and a pressure coefficient,
And an analysis result verification step of comparing the flow analysis result and the measurement result to verify the validity of the analysis method used in the flow analysis step. 2. The method of claim 1,
And a tetrahedral mesh (Tetra mesh), which is a non-aligned mesh of 5,300,000 which produces dense lattices at the interface of the impeller rotating at high speed and at the interface between the blades and the flow field junction inside the casing in a stationary state Wherein the element detection method of the two-stage centrifugal blower is characterized. 3. The method according to claim 2,
In order to model the flow in the accelerating coordinate system, the multiple frame reference (MFR) method which simultaneously analyzes the rotational and stationary regions including the two-stage impeller, case, and blit Wherein the step of detecting the element of the two-stage centrifugal blower comprises: 4. The method of claim 3,
Wherein the momentum equation included in the flow acceleration when computing the governing equations in the rotational coordinate system satisfies the following Equation (1): " (1) "

.. Equation 1 5. The method according to claim 4,
The governing equation in the rotational domain includes continuity and momentum equations, and the continuity equation (

) Satisfies the following equation (2), and the momentum equation satisfies the following equation (3): " (3) "

... Equation 2

... Equation 3 6. The method of claim 5, wherein the momentum equation is discretized according to a predefined equation and the discretized momentum equation is satisfied by the following equation (4).

... Equation 4 7. The method of claim 6,
Further comprising deriving a flow coefficient and a pressure coefficient, which are analytical values, using a standard k-SST (Shear-Stress Transport) turbulence model using the discretized momentum equation, and the derived flow coefficient and pressure coefficient The following expression (5) and (6) are satisfied.

... Equation 5

... Equation 6
here,

The number of revolutions, density, volumetric flow, impeller disc diameter, and static pressure rise.

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