阅读说明：本技术 一种农业通风机叶片优化方法 (Method for optimizing blades of agricultural ventilator ) 是由 丁涛 李松 王朝元 施正香 孔维双 于 2020-11-20 设计创作，主要内容包括：本发明属于机械应用领域,具体涉及一种农业通风机叶片优化方法。所述方法包括S1、旋转域叶片轴向切片处理；S2、叶片周向涡量分析；S3、农业通风机叶片仿生凹槽设计。本发明的农业通风机叶片优化方法,能够提高农业通风机流量,能够显著提高农业通风机的通风能效3％左右。(The invention belongs to the field of mechanical application, and particularly relates to an optimization method for blades of an agricultural ventilator. The method comprises S1, axial slicing processing of the blades in the rotating field; s2, analyzing the circumferential vorticity of the blade; s3, designing bionic grooves of blades of the agricultural ventilator. The method for optimizing the blades of the agricultural ventilator can improve the flow of the agricultural ventilator and can obviously improve the ventilation efficiency of the agricultural ventilator by about 3%.)

1. A method for optimizing blades of an agricultural ventilator, which is characterized by comprising the following steps:

s1, axial slicing of the blades in the rotating domain;

the method comprises the following steps of (1) slicing the blades at intervals of a certain distance in the positive direction of the Z axis of a rotating shaft from the origin of a rectangular coordinate system where a fan impeller hub is located to obtain a plurality of sections of the blades; the rectangular coordinate system takes the center of the hub as the origin of coordinates, an X, Y axis is established from the plane where the hub is located, a Z axis is established perpendicular to the plane of the hub, and the positive direction of the Z axis is consistent with the outflow direction of the fan;

s2, analyzing the circumferential vorticity of the blade;

obtaining a circumferential vorticity distribution cloud picture of a plurality of sections of the blade according to the plurality of sections of the blade, thereby obtaining the position and the development trend of the circumferential vorticity of the fan blade;

s3, designing bionic grooves of blades of the agricultural ventilator;

s3.1, punching a groove on the surface of an initial blade on the surface of the blade close to the blade top, wherein the groove on the surface of the initial blade is in a circular arc shape taking a rotating shaft of the fan as a circle center and is provided with a groove inner diameter R1, a groove outer diameter R2 and a groove depth h; the stamping direction of the initial blade surface groove is from a blade suction surface to a blade pressure surface;

s3.2, repeating the steps S1-S2 to analyze the circumferential vorticity of the blade provided with the initial blade surface groove;

s3.3, if the area ratio of a first negative circumferential vorticity area in the middle of the blade or close to the blade top is larger than 1/20 multiplied by S, gradually increasing the inner diameter R1 and the outer diameter R2 of the groove according to a certain increase, and adjusting the groove on the surface of the blade; wherein the increase of the inner diameter R1 of the groove is 1/100 multiplied by R1, and the increase of the outer diameter R2 of the groove is 1/110-1/100 multiplied by R2; wherein S is the area of the suction surface of the blade and the unit is mm²R1 is the inner diameter of the groove in mm, R2 is the outer diameter of the groove in mm; and then repeating the steps S3.2-S3.3 until the area of the first negative circumferential vorticity area in the middle of the blade or close to the blade top is reduced by more than 10 in proportion to the area of the first negative circumferential vorticity area before first adjustment% and the moving distance of the first negative circumferential vorticity region to the blade root direction exceeds 1/30 XH compared with the moving distance before the first adjustment; h is the height of the blade, the unit is mm, the inner diameter R1 of the groove, the outer diameter R2 of the groove and the depth H of the groove on the surface of the blade at the moment are determined, and optimization of the blade is completed.

2. An agricultural ventilator blade optimisation method as claimed in claim 1 wherein in step S1, the blade is sliced perpendicular to the Z axis every 20 mm.

3. An agricultural ventilator blade optimization method according to claim 1, wherein the groove inner diameter R1 ═ 50% H and the groove outer diameter R2 ═ R1+ kH of the initial blade surface groove; wherein H is the height of the blade, and the unit is mm; k is a constant term, and k is 1/30-1/20.

4. An agricultural ventilator blade optimisation method as claimed in claim 1 wherein the groove depth h of the initial blade surface groove is the blade thickness in mm and does not change.

5. The method of optimizing an agricultural ventilator blade according to claim 1, wherein the method is capable of improving the ventilation energy efficiency of an agricultural ventilator by 3%.

Technical Field

The invention belongs to the field of mechanical application, and particularly relates to an optimization method for blades of an agricultural ventilator.

Background

Modern greenhouse facility agriculture and livestock and poultry breeding are developed at a high speed, the requirement level of agricultural ventilation is continuously improved, and an agricultural ventilator is widely applied as important mechanical equipment in modern facility agriculture and livestock and poultry breeding. The operation characteristics of the agricultural ventilator are low pressure and large flow, and the problems of large flow loss, low ventilation energy efficiency and the like exist. Wuhong, Jianghoude, gas turbine compressor vorticity theory and analysis method [ J ] aviation dynamics report, 2013, 28(04): 903-; the research of 'Guo Relay wave, Ma Hongmai' influence of non-smooth blades on the aerodynamic performance of an axial flow fan [ J ]. engineering thermophysics, 2007,28(3) 406-.

At present, no report is found on bionic design of blades of agricultural ventilators combined with circumferential vorticity analysis.

Disclosure of Invention

In view of the above technical problems, an object of the present invention is to provide an agricultural ventilator blade optimization method, which locates a negative circumferential vorticity accumulation region of a fan blade by a vorticity analysis method, and designs a fan blade surface groove in a targeted manner, so that circumferential vorticity distribution on the fan blade surface can be controlled, and further, the surface pressure distribution and streamline distribution of the fan blade are affected, thereby achieving the purpose of improving fan ventilation energy efficiency and fan flow.

In order to achieve the purpose, the invention provides the following technical scheme:

an agricultural ventilator blade optimization method comprises the following steps:

s1, axial slicing of the blades in the rotating domain;

the method comprises the following steps of (1) slicing the blades at intervals of a certain distance in the positive direction of the Z axis of a rotating shaft from the origin of a rectangular coordinate system where a fan impeller hub is located to obtain a plurality of sections of the blades; the rectangular coordinate system takes the center of the hub as the origin of coordinates, an X, Y axis is established from the plane where the hub is located, a Z axis is established perpendicular to the plane of the hub, and the positive direction of the Z axis is consistent with the outflow direction of the fan;

s2, analyzing the circumferential vorticity of the blade;

obtaining a circumferential vorticity distribution cloud picture of a plurality of sections of the blade according to the plurality of sections of the blade, thereby obtaining the position and the development trend of the circumferential vorticity of the fan blade;

s3, designing bionic grooves of blades of the agricultural ventilator;

s3.1, punching a groove on the surface of an initial blade on the surface of the blade close to the blade top, wherein the groove on the surface of the initial blade is in a circular arc shape taking a rotating shaft of the fan as a circle center and is provided with a groove inner diameter R1, a groove outer diameter R2 and a groove depth h; the stamping direction of the initial blade surface groove is from a blade suction surface to a blade pressure surface;

s3.2, repeating the steps S1-S2 to analyze the circumferential vorticity of the blade provided with the initial blade surface groove;

s3.3, if the area ratio of a first negative circumferential vorticity area in the middle of the blade or close to the blade top is larger than 1/20 multiplied by S, gradually increasing the inner diameter R1 and the outer diameter R2 of the groove according to a certain increase, and adjusting the groove on the surface of the blade; wherein the increase of the inner diameter R1 of the groove is 1/100 multiplied by R1, and the increase of the outer diameter R2 of the groove is 1/110-1/100 multiplied by R2; wherein S is the area of the suction surface of the blade and the unit is mm²R1 is the inner diameter of the groove in mm, R2 is the outer diameter of the groove in mm; then, repeating the steps S3.2-S3.3 until the area of a first negative circumferential vorticity region in the middle of the blade or close to the blade top is reduced by more than 10 percent compared with the area of the first negative circumferential vorticity region before the first adjustment, and compared with the area before the first adjustment, the moving distance of the first negative circumferential vorticity region to the blade root direction exceeds 1/30 multiplied by H; h is the height of the blade, the unit is mm, the inner diameter R1 of the groove, the outer diameter R2 of the groove and the depth H of the groove on the surface of the blade at the moment are determined, and optimization of the blade is completed.

In step S1, the blade is sliced perpendicular to the Z-axis every 20 mm.

The inner diameter R1 of the groove on the surface of the initial blade is 50% H, and the outer diameter R2 of the groove is R1+ kH; wherein H is the height of the blade, and the unit is mm; k is a constant term, and k is 1/30-1/20.

The groove depth h of the groove on the surface of the initial blade is the thickness of the blade, and is not changed any more in mm.

The method can improve the ventilation energy efficiency of the agricultural ventilator by 3%.

Compared with the prior art, the invention has the beneficial effects that:

1) the method for optimizing the blades of the agricultural ventilator can improve the flow of the agricultural ventilator.

2) The method for optimizing the blades of the agricultural ventilator can obviously improve the ventilation energy efficiency of the agricultural ventilator by about 3%.

Drawings

FIG. 1 is a schematic view of a rotational domain blade axial slicing process according to an embodiment of the present invention;

FIG. 2a is a cloud view of the distribution of the circumferential vorticity of the cross section of a blade Z0 according to an embodiment of the invention;

FIG. 2b is a cloud view of the distribution of the circumferential vorticity of the cross section of the blade Z1 according to the embodiment of the invention;

FIG. 2c is a cloud view of the distribution of the circumferential vorticity of the cross section of a blade Z2 according to an embodiment of the invention;

FIG. 2d is a cloud view of the distribution of the circumferential vorticity of the cross section of the blade Z3 according to the embodiment of the invention;

FIG. 2e is a cloud view of the distribution of the circumferential vorticity of the cross section of a blade Z4 according to an embodiment of the invention;

FIG. 2f is a cloud view of the distribution of the circumferential vorticity of the cross section of a blade Z5 according to an embodiment of the invention;

FIG. 3a is a schematic diagram of the inner and outer diameters of a blade groove according to an embodiment of the present invention;

FIG. 3b is a schematic view of the depth of the blade groove according to an embodiment of the present invention;

FIG. 4 is a schematic view of a blade groove design according to an embodiment of the present invention.

Wherein the reference numerals are:

1 blade Z3 section

2 blade Z0 section

3 first negative circumferential vorticity region

4 second negative circumferential vorticity region

5-blade top casing

6 leaf top

7 blade root

8 blade surface grooves

R1 groove inner diameter

R2 groove outside diameter

h depth of groove

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

An agricultural ventilator blade optimization method comprises the following steps:

s1, axial slicing of the blades in the rotating domain;

the circumferential vorticity is distributed in the whole rotating domain space, and the circumferential vorticity distribution around the blade can be clearly observed by performing axial slicing processing on the rotating domain by adopting software Tecplot 360 EX 2017R 3.

The method for processing the axial slices of the blades in the rotating domain comprises the following steps:

and (3) slicing the blades perpendicular to the Z axis every 20mm from the origin of a rectangular coordinate system where the fan impeller hub is located along the positive direction of the Z axis of a rotating shaft, wherein the section at the position where the Z is 0mm is defined as a Z0 section, the section at the position where the Z is 20mm is defined as a Z1 section, and the like, so that the sections from Z0 to Z5 are obtained. The sections shown in FIG. 1 are blade Z0 section 2 and blade Z3 section 1. The rectangular coordinate system uses the hub center as the origin of coordinates, X, Y axes are established from the plane of the hub, a Z axis is established perpendicular to the plane of the hub, and the positive direction of the Z axis is consistent with the outflow direction of the fan.

S2, analyzing the circumferential vorticity of the blade;

according to the sections Z0-Z5, the distribution cloud pictures of the circumferential vorticity of the sections Z0-Z5 of the blades are obtained, so that the position and the development trend of the circumferential vorticity of the fan blade are obtained.

As shown in fig. 2a to 2f, the blade circumferential vorticity distribution is shown by sections Z0 to Z5, each section comprising a blade middle and a first negative circumferential vorticity region 3 near the blade tip 6 and a second negative circumferential vorticity region 4 near the blade root 7. The analysis of the circumferential vorticity distribution cloud charts of the Z0-Z5 sections shows that:

as shown in fig. 2a, when Z is 0mm (Z0), in the second negative circumferential vorticity region 4 near the root 7, there is a small amount of concentrated negative circumferential vorticity; in the middle of the blade and the first negative circumferential vorticity region 3 near the tip 6, there is a peak region of negative circumferential vorticity.

As shown in fig. 2b, when Z is 20mm (Z1), the negative circumferential vorticity of the second negative circumferential vorticity region 4 close to the blade root 7 tends to gather; in the first negative circumferential vorticity region 3 in the middle of the blade and near the blade tip 6, the peak region of the negative circumferential vorticity tends to move in the direction of the blade tip 6.

As shown in fig. 2c, when Z is 40mm (Z2), it can be seen that the second negative circumferential vorticity region 4 near the blade root 7 continues to move toward the blade tip 6; the middle part of the blade and the negative circumferential vorticity peak area of the first negative circumferential vorticity area 3 close to the blade top 6 continuously move towards the direction of the blade top 6.

As shown in fig. 2d, the second negative circumferential vorticity region 4 near the blade root 7 decreases when Z is 60mm (Z3); the middle part of the blade and the first negative circumferential vorticity peak area of the negative circumferential vorticity area 3 close to the blade top 6 move greatly towards the direction of the blade top 6.

As shown in fig. 2e,2f, when Z is 80, 100mm (Z4, Z5), the second negative circumferential vorticity region 4 near the blade root 7 continues to decrease; the negative circumferential vorticity peak region of the blade middle and the first negative circumferential vorticity region 3 near the blade tip 6 slowly decreases until vanishing.

Comprehensive analysis shows that the circumferential vorticity distribution cloud pictures of the sections can clearly show the position and the development trend of the circumferential vorticity of the fan blade, and provide guidance for the design of a subsequent groove scheme.

S3, designing bionic grooves of blades of the agricultural ventilator;

from the angle of increasing the gain of the total pressure flow, the negative peak area with high circumferential vorticity should be close to the blade root 7 as much as possible, so that the negative contribution of the negative peak area to the total pressure flow is reduced, and the energy efficiency of the fan is improved. The gradient distribution of the disturbance speed of the boundary of the blade can be effectively changed by arranging the blade groove, so that the negative circumferential vorticity area is induced at the vortex core more quickly, the evolution and development of the boundary circumferential vorticity area are controllable, and the aim of controlling the negative circumferential vorticity area to move towards the direction of the blade root 7 is fulfilled. The specific process is as follows:

s3.1, punching a groove on the surface of the initial blade close to the blade top 6, wherein the groove on the surface of the initial blade is in a circular arc shape taking a rotating shaft of the fan as a circle center and is provided with a groove inner diameter R1, a groove outer diameter R2 and a groove depth h as shown in fig. 3a and 3 b; the stamping direction of the initial blade surface groove is from a blade suction surface to a blade pressure surface, the inner diameter R1 of the groove is 50% H, and the outer diameter R2 of the groove is R1+ kH; wherein H is the height of the blade, and the unit is mm; k is a constant term, and k is 1/30-1/20; the groove depth h of the initial blade surface groove is equal to the blade thickness in mm and is not changed any more.

S3.2, repeating the steps S1-S2 to analyze the circumferential vorticity of the blade provided with the initial blade surface groove;

s3.3, if the area ratio of a first negative circumferential vorticity area in the middle of the blade or close to the blade top is larger than 1/20 multiplied by S, gradually increasing the inner diameter R1 and the outer diameter R2 of the groove according to a certain increase, and adjusting the groove on the surface of the blade; wherein the increase of the inner diameter R1 of the groove is 1/100 multiplied by R1, and the increase of the outer diameter R2 of the groove is 1/110-1/100 multiplied by R2; wherein S is the area of the suction surface of the blade and the unit is mm²(ii) a Then, repeating the steps S3.2-S3.3 until the area of a first negative circumferential vorticity region in the middle of the blade or close to the blade top is reduced by more than 10 percent compared with the area of the first negative circumferential vorticity region before the first adjustment, and compared with the area before the first adjustment, the moving distance of the first negative circumferential vorticity region to the direction of the blade root 7 exceeds 1/30 multiplied by H; h is the height of the blade, the unit is mm, the inner diameter R1 of the groove, the outer diameter R2 of the groove and the depth H of the groove on the surface of the blade at the moment are determined, and optimization of the blade is completed.

For the blade surface groove 8 of the embodiment, the distribution positions of the middle part of the blade, the first negative circumferential vorticity region 3 close to the blade top 6 and the second negative circumferential vorticity region 4 close to the blade heel 7 are comprehensively considered, the absolute value of the negative circumferential vorticity gathering region close to the blade top 6 is large, and plays a negative leading role in the running and performance of the fan, so the blade surface groove is designed in the region close to the blade top 6 to control the negative circumferential vorticity region close to the blade top 6 to move towards the blade root 7.

FIG. 4 is a schematic view of an embodiment of a vane surface groove design. The stamping direction of the groove 8 on the surface of the blade is from the suction surface of the blade to the pressure surface of the blade, the inner diameter R1 of the groove is 480.8mm, the outer diameter R2 of the groove is 508.1mm, and the depth h of the groove is 5mm of the thickness of the blade.