阅读说明：本技术 一种基于最速降线的多翼离心通风机叶片设计方法 (Multi-wing centrifugal ventilator blade design method based on steepest descent line ) 是由 黄加禹 张凯 李海运 于 2019-09-29 设计创作，主要内容包括：本发明涉及一种基于最速降线的多翼离心通风机叶片的设计方法,用于多翼离心通风机中,包括叶片本体,其中,叶片本体横截面的吸力面一侧型线为最速降线,叶片本体横截面的压力面一侧型线为叶片本体吸力面的等距最速降线,叶片本体的横截面为叶片本体横截面的吸力面一侧型线的最速降线的等距轮廓,所述的速降线能够极大地减少气流在最速降线斜面上流动的阻力,该叶片能够在增加风量的前提下改善叶轮内气流流动,提高风机的效率。(The invention relates to a design method of a multi-wing centrifugal fan blade based on a steepest descent line, which is used in a multi-wing centrifugal fan and comprises a blade body, wherein the molded line on one side of a suction surface of the cross section of the blade body is the steepest descent line, the molded line on one side of a pressure surface of the cross section of the blade body is the equidistant steepest descent line of the suction surface of the blade body, the cross section of the blade body is the equidistant contour of the steepest descent line of the molded line on one side of the suction surface of the cross section of the blade body, the steepest descent line can greatly reduce the flowing resistance of airflow on the slope of the steepest descent line, and the blade can improve airflow flowing in an impeller on the premise of increasing the air volume and improve the efficiency of the fan.)

1. The utility model provides a blade based on slowest descent line, its characterized in that for among the multiple wing centrifugal fan, including blade body (1), wherein the molded lines of suction surface (3) one side of blade body (1) cross section is the slowest descent line, and the molded lines of pressure surface (2) one side of blade body (1) cross section is the equidistance slowest descent line of blade body (1) suction surface (3), and the cross section of blade body (1) is the equidistance profile of the slowest descent line of suction surface (3) one side molded lines of blade body (1) cross section.

2. The steepest descent based blade according to claim 1, characterized in that the inlet setting angle β of the steepest descent of the suction surface (3) in the blade body (1) is₁Is 80 degrees to 90 degrees, and the outlet installation angle beta of the steepest descent line of the suction surface (3) in the blade body (1)₂Is 160-170 degrees.

3. The steepest-descent-line-based blade of claim 1, wherein the blade profile is the steepest-descent line and the curve equation iswherein a is the inner diameter r of the impeller₁outer diameter r₂Has the relation ofTheta is the angle rotated by the rolling circle with the radius of a, and the value range of theta in the formula is (0, 2 pi).

4. The blade according to claim 1, characterized in that the linear distance of the most rapidly decreasing profile line suction surface (3) of the blade from the inlet to the outlet is

5. The steepest descent based blade according to claim 1, wherein the steepest descent curve equation for the blade body has a value of θ from the inlet to the outlet ofNamely, the length of the steepest descent line profile of the suction surface (3) in the blade body is 6 a.

6. The steepest descent line-based blade of claim 1, wherein the blade body cross-section is an equidistant profile of the steepest descent line of the profile line on the suction side of the blade body cross-section, the equidistant distance being taken as d.

7. The steepest descent line-based blade according to claim 1, comprising the steps of:

1) Determining the inner diameter r of the impeller₁Outer diameter r₂Through a and the inner diameter r of the impeller₁Outer diameter r₂Is a relational expression ofDetermining the rolling circle radius a of the steepest descent curve equation, wherein the theta value range isEstablishing a curve of a curve equation of the steepest descent curve, wherein the established curve is the molded line of the suction surface of the blade;

2) And (2) constructing blade pressure surface blade molded lines at equal intervals according to the blade suction surface molded lines designed in the step 1), and the equal distances d. After the cross section profile of the blade is constructed, the profile of the most-speed-reducing line blade is scaled according to the installation size of the blade on the multi-wing centrifugal fan, so that the fan volutes with different sizes can be matched.

Technical Field

The invention relates to a method for designing a multi-wing centrifugal fan blade, in particular to a method for designing a multi-wing centrifugal fan blade based on a steepest descent line.

Background

Centrifugal ventilators are widely used as a vane machine in mechanical and electrical equipment in various industries, such as: subway ventilation, building ventilation, air conditioning systems, and the like. The main structure of the device comprises a current collector, a bracket, a motor, a volute and an impeller. The most important part in the multi-wing centrifugal fan is an impeller, the impeller has the characteristics of more blades, larger curvature of the blades, larger inner and outer diameters of the impeller, shorter flow channels of blade channels and the like, the performance quality determines the working performance of the air conditioner, the working process is that a motor is directly connected to drive the impeller to rotate, and axially sucked gas is radially thrown out of the impeller from the center of the impeller under the action of centrifugal force. Due to the large amount of fan applications, the energy consumption is also large. Currently, with the problem of global energy shortage becoming more and more serious, people pay more and more attention to the problem of energy conservation and emission reduction. Therefore, the design of the high-efficiency fan has very important practical significance for saving energy.

The centrifugal impeller is used as a core pneumatic component of the centrifugal fan and is a main transmission component for realizing energy conversion, loss generated at the impeller is also a main source of the loss of the whole fan, and the flow of the impeller can directly influence the work of a subsequent flow passage component. The design of the centrifugal impeller comprises the design of parameters such as the profile of the blade, the profile of the impeller disc and the profile of the cover, wherein the design of the profile of the blade has a great influence.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provides a design method of a multi-wing ventilator blade based on a steepest descent line, the blade can improve airflow flowing in an impeller on the premise of increasing air volume and improve the efficiency of a ventilator, and the specific content is as follows:

In order to achieve the above purpose, the method for designing a multi-wing ventilator blade based on the steepest descent line of the invention is used in a multi-wing centrifugal fan, and comprises a blade body, wherein the molded line on one side of the suction surface of the cross section of the blade body is the steepest descent line, the molded line on one side of the pressure surface of the cross section of the blade body is the equidistant steepest descent line of the suction surface of the blade body, the cross section of the blade body is the equidistant contour of the steepest descent line of the molded line on one side of the suction surface of the cross section of the blade body, and the steepest descent line can greatly reduce the resistance of airflow flowing on the slope of the steepest descent line.

Inlet mounting angle beta of the steepest descent line of the suction surface in the blade body₁Is 80 degrees to 90 degrees, and the installation angle beta of the outlet of the steepest descent line of the suction surface in the blade body₂Is 160-170 degrees.

The profile line of the blade is the steepest descent line, and the curve equation iswherein a is the inner diameter r of the impeller₁Outer diameter r₂Has the relation ofTheta is the angle rotated by the rolling circle with the radius of a, and the value range of theta in the formula is (0, 2 pi).

The linear distance from the inlet to the outlet of the most speed-reducing line profile of the blade is

The value of theta from the inlet to the outlet of the curve equation of the steepest descent line of the blade body isI.e. the length of the steepest descent profile in the blade body is 6 a.

The cross section of the blade body is an equidistant contour of the steepest descent line of the molded line on one side of the suction surface of the cross section of the blade body, and d is taken from the equidistant distance.

The invention relates to a design method of a multi-wing centrifugal fan blade based on a steepest descent line, which comprises the following steps of:

1) Determining the inner diameter r of the impeller₁Outer diameter r₂Through a and the inner diameter r of the impeller₁Outer diameter r₂Is a relational expression ofDetermining the rolling circle radius a of the steepest descent curve equation, wherein the theta value range isEstablishing a curve of a curve equation of the steepest descent curve, wherein the established curve is the molded line of the suction surface of the blade;

2) And (2) constructing blade pressure surface blade molded lines at equal intervals according to the blade suction surface molded lines designed in the step 1), and the equal distances d. After the cross section profile of the blade is constructed, the profile of the most-speed-reducing line blade is scaled according to the installation size of the blade on the multi-wing centrifugal fan, so that the fan volutes with different sizes can be matched.

The invention has the following beneficial effects:

1) According to the blade design method based on the steepest descent line, both the pressure surface and the suction surface of the blade body are in the shape of the steepest descent line during specific operation, the shape of the steepest descent line is better utilized, so that the resistance of gas is reduced, the pneumatic performance in a blade flow channel is improved, the radius of a rolling circle of a curve equation in the same blade body is determined by the inner diameter and the outer diameter of an impeller, the inlet angle and the outlet angle of the blade profile of the steepest descent line are determined according to a forward-bent blade shape design method of a multi-wing centrifugal fan, and the blade design method has stronger acting capacity than a forward-bent blade with the same inlet and outlet installation angle; therefore, the maximum static pressure and the maximum flow generated by the multi-wing centrifugal fan adopting the design method are higher than those of the traditional multi-wing centrifugal fan, and meanwhile, the speed from the gas inlet to the gas outlet is continuously increased due to the fact that the blade flow channel forms the accelerating flow channel, so that boundary layer separation and vortex generation in the blade channel are effectively inhibited, and the fan efficiency is improved.

Drawings

A better understanding of the present invention, and the advantages thereof, will be obtained by reference to the following detailed description when considered in conjunction with the accompanying drawings, which form a part hereof, and which are set forth to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, wherein:

FIG. 1 is a schematic diagram of a steepest descent curve equation;

FIG. 2 is a cross-sectional profile view of a bucket of the present invention;

FIG. 3 is a schematic view of a blade configuration according to the present invention;

FIG. 4 is a schematic structural view of a multi-winged centrifugal ventilator impeller for use in the present invention;

FIG. 5 is a schematic of a two-dimensional cross-sectional profile configuration of the present invention;

FIG. 6 is a schematic cross-sectional width view of a blade path of the present invention.

In the figure: 1 is the blade body, 2 is the blade pressure side, and 3 is the blade suction side.

Detailed Description

The invention will be further illustrated by way of example with reference to the accompanying drawings. This example is merely illustrative, and the scope of the present invention is not limited by this example.

Research shows that in the process of moving an object from the same starting point to the same end point on a plane, due to the effect of viscous resistance on the object in the moving process, if the object moves from the same starting point to the same end point on the same plane along different paths, the time required by the object moving along the path of the steepest descent from the starting point to the end point is the shortest. The method shows that the object on the path reaches the maximum speed firstly in the process of moving the object along the steepest descent line. The centrifugal fan is designed based on the principle that the maximum speed of fluid can be reached in a short time in the flowing process of the fluid in the flow channel by using the mathematical model and adopting the design of the blades with the slowest speed reduction line, and the speed of the fluid is in an acceleration state in the process from the inlet to the outlet, so that the flowing condition in the flow channel can be better improved, and the efficiency of the centrifugal fan is improved.

Referring to fig. 2, 3 and 4, the steepest descent vane of the present invention is used in a multi-blade centrifugal fan, and includes a vane body 1, wherein a molded line on a side of a suction surface 3 of a cross section of the vane body 1 is a steepest descent line, a molded line on a side of a pressure surface 2 of a cross section of the vane body 1 is an equidistant steepest descent line of the suction surface 3 of the vane body 1, a cross section of the vane body 1 is an equidistant contour of the steepest descent line of the molded line on the side of the suction surface 3 of the cross section of the vane body 1, specifically, a molded line of the suction surface 3 of the vane body 1 is a curved line length when a value θ of a steepest descent curve equation is taken from 0 to 3/2 π, a molded line length of an impeller on the vane body 1 is a curved line length when a value θ of the steepest descent curve equation is taken from 0 to π, a molded line length of an impeller outlet side of the vane body 1 is a curved line length when a value θ is, the molded line of the pressure surface 2 of the blade body 1 is the fastest descending line formed by the molded line of the suction surface 3 with the equal distance d being 0.5 mm.

The suction surface 3 in the blade body 1 is steepest to fallinlet setting angle beta of the wire₁Is 80 degrees to 90 degrees, and the installation angle beta of the outlet of the steepest descent line of the suction surface 3 in the blade body 1₂160-170 deg., and in the example of fig. 5, the inlet setting angle beta of the steepest descent line of the suction surface 3₁is 84 degrees, and the outlet installation angle beta of the steepest descent line of the suction surface 3 in the blade body 1₂is 165 deg..

Referring to fig. 1, 3 and 5, the suction surface 3 and the pressure surface 2 of the blade body 1 are the steepest descent line, and the curve equation isWherein a is the inner diameter r of the impeller₁Outer diameter r₂has the relation ofTheta is the angle rotated by the rolling circle with the radius of a, and the value range of theta in the formula is (0, 2 pi). The linear distance from the inlet to the outlet of the fastest descending line molded line of the suction surface 3 of the blade body 1 isThe value of theta from the inlet to the outlet of the steepest descent curve equation of the blade body 1 isi.e. the length of the steepest descent profile line in the blade body 1 is 6 a. The cross section of the blade body 1 is an equidistant contour of the steepest descent line of the molded line on the suction surface 3 side of the cross section of the blade body 1, and the equidistant distance d is 0.5mm in the example.

The invention relates to a design method of a multi-wing centrifugal fan blade based on a steepest descent line, which comprises the following steps of:

1) Determining the inner diameter r of the impeller₁Outer diameter r₂through a and the inner diameter r of the impeller₁Outer diameter r₂Is a relational expression ofdetermining the rolling circle radius a of the steepest descent curve equation, wherein the theta value range isestablishing a curve of a curve equation of the steepest descent curve, wherein the established curve is the molded line of the suction surface 3 of the blade;

2) And (2) constructing blade molded lines of a blade pressure surface at equal intervals according to the 3 molded lines of the blade suction surface designed in the step 1), and keeping the equal intervals at the distance d. After the cross section profile of the blade is constructed, the profile of the most-speed-reducing line blade is scaled according to the installation size of the blade on the multi-wing centrifugal fan, so that the fan volutes with different sizes can be matched.

Referring to fig. 1 and 5, the molded line lengths of the suction surface 3 and the pressure surface 2 of the steepest descent blade are 3/4 of the original length of the steepest descent curve, and since the object can reach the maximum speed in the shortest time when moving on the steepest descent curve, in order to utilize the motion characteristic of the steepest descent curve as much as possible, the curve length in the steepest descent curve equation in fig. 1 may be taken as a part, so as to obtain the actual molded line of the steepest descent curve in the blade design, and then construct the complete profile shape of the steepest descent curve blade according to the design method of the uniform thickness blade.

Referring to fig. 6, the width of the cross section of the vane flow passage decreases from the inlet to the outlet, that is, the gas is accelerated when flowing in the flow passage, and thus the vortex in the vane flow passage can be effectively removed to improve the efficiency.

the above examples are only described to help understand the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.