CN108644993B - Low flow resistance pipeline device capable of uniformly supplying air - Google Patents

Low flow resistance pipeline device capable of uniformly supplying air Download PDF

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CN108644993B
CN108644993B CN201810253219.0A CN201810253219A CN108644993B CN 108644993 B CN108644993 B CN 108644993B CN 201810253219 A CN201810253219 A CN 201810253219A CN 108644993 B CN108644993 B CN 108644993B
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pipeline
curved surface
tee joint
tee
calculating
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CN108644993A (en
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叶为标
李聪
聂昌达
徐顺生
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Xiangtan University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/02—Ducting arrangements
    • F24F13/0245—Manufacturing or assembly of air ducts; Methods therefor
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/14—Pipes

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Abstract

The invention discloses a low-flow resistance pipeline device for uniformly supplying air, which comprises a main pipeline, a tee joint and branch pipelines. The height of the cross section of the main pipeline along the airflow direction is gradually reduced so as to ensure that the air output of each branch pipeline is uniform; the surface of the junction of the inlet and the outlet of the tee joint is a curved surface, and the curved surface is in the form of an arc surface and is used for reducing the flow resistance in the main pipeline; the branch pipeline is used for discharging the airflow of the main pipeline from the branch pipeline after passing through the tee joint. The air supply pipeline device disclosed by the invention has the advantages of uniform air outlet and low flow resistance.

Description

Low flow resistance pipeline device capable of uniformly supplying air
Technical Field
The invention belongs to the technical field of air supply control of air conditioners, and particularly relates to a low-flow-resistance pipeline device for uniformly supplying air.
Background
With the development of society, the requirements of industrial science and technology and human life on environmental protection and energy conservation are gradually increased, and the natural ventilation can not meet the requirements of modern industry and human life. Uneven air supply in living areas leads to reduction of the comfort of people, and uneven air supply in industry affects production efficiency.
For the air supply pipeline, the air supply quantity depends on the static pressure of the air supply openings, and if the air supply quantity of each air supply opening is ensured to be uniform, the static pressure of each air supply opening is ensured to be the same, namely, the difference of the dynamic pressure between two adjacent air supply openings is equal to the sum of the friction pressure loss and the local pressure loss between the two air supply openings. For a general air supply pipeline, the cross section area of the general air supply pipeline along the main pipeline direction is generally constant, and the air supply quantity of each air supply opening cannot be ensured to be uniform by the air supply pipeline. In addition, along with the increase of the air supply distance, the air supply resistance along the main pipeline direction can be gradually increased, the dynamic pressure attenuation can be increased, and the nonuniformity of each air supply outlet can be increased.
The air supply pipelines adopted by many large markets, residences and factories cannot completely meet the requirement of uniform air supply. Accordingly, the prior art has yet to be developed and improved.
Disclosure of Invention
The invention aims to solve the technical problems of uneven air supply and large flow resistance in the prior art, and provides a low-flow-resistance pipeline device for uniformly supplying air.
The technical scheme adopted by the invention for solving the technical problem is as follows:
a low flow resistance pipeline device for uniformly supplying air comprises a main pipeline, a plurality of tee joints and a plurality of branch pipelines; the sections of the main pipeline and the branch pipelines are square or circular; the main pipeline is connected with the branch pipelines through a tee; the height of the cross section of the main pipeline along the airflow direction or the diameter of the main pipeline when the cross section is circular is gradually reduced; the tee joint is provided with four curved surfaces, wherein the curved surface 1 is a curved surface on the opposite side of an air outlet of the main pipeline, the curved surface 2 is a curved surface at the downstream of the air flow at the joint of the main pipeline and the branch pipeline, the curved surface 4 is a curved surface with an inclination angle at the upstream of the air flow at the joint of the main pipeline and the branch pipeline, and the curved surface 3 is a curved surface at one side of the branch pipeline and connected with the curved surface 4; the radius of tee bend curved surface 1 is 20.05D, and the radius of curved surface 2 is 0.2D, and the radius of curved surface 3 is 3.47D, and the radius of curved surface 4 is 8.4D, and wherein D is the hydraulic diameter of tee bend and the continuous cross section of trunk line, and D is the hydraulic diameter of tee bend and the continuous cross section of branch pipeline. The cross-sectional area of the tee joint is larger than that of the traditional tee joint; the size of the tee joint is designed according to the heights of the main pipeline and the branch pipelines; the cross sections of the branch pipelines are the same; the exit angle of the fluid in the pipe at each branch pipe is not less than 60 deg.
A low flow resistance pipeline device for uniformly supplying air, which takes a square section as an example, comprises the following steps:
step 1: determining physical parameters of the air supply fluid, including density and viscosity, and the material of the pipeline; calculating the volume flow rate of each air outlet according to the total volume flow rate of the pipeline and the required number of the tee joints;
step 2: calculating the air supply speed of each air outlet according to the volume flow rate required by each air outlet and the cross section area of the branch pipeline, and calculating the static pressure driving speed of the first tee joint according to the air supply speed; calculating the dynamic pressure driving speed of the first tee joint according to the total volume flow rate and the size of the cross section of the first tee joint along the direction of the main pipeline, and then calculating a transmission angle which is not less than 60 degrees;
and step 3: calculating the friction pressure loss and the local pressure loss between the first tee joint and the second tee joint; calculating the dynamic pressure of the second tee joint according to the calculated friction pressure loss, the calculated local pressure loss and the calculated dynamic pressure of the first tee joint; calculating the speed of the second three-way dynamic pressure drive according to the relation between the dynamic pressure and the speed of the dynamic pressure drive; calculating the size of the cross section of the second tee joint along the direction of the main pipeline according to the volume flow rate of the main pipeline flowing through the second tee joint and the dynamic pressure driving speed of the second tee joint, and calculating the height of the cross section of the second tee joint along the direction of the main pipeline;
and 4, step 4: and (3) calculating the height of each residual tee joint along the cross section of the main pipeline by using a method similar to the steps 2 and 3.
The design principle of the invention is as follows:
in one blast duct, the relationship of pressure at the i-th branch duct and the i +1 branch duct according to the conservation of pressure is expressed by the following formula (1):
Pd(i)+Ps(i)＝Pd(i+1)+Ps(i+1)+Pf(i-(i+1))+Pl(i-(i+1))(1)
wherein P isd(i)Represents the dynamic pressure, P, at the ith branch pipes(i)Denotes the static pressure at the i-th branch pipe, Pf(i-(i+1))Represents the friction pressure loss between the i-th branch pipe and the (i + 1) -th branch pipe, Pl(i-(i+1))The local pressure loss between the i-th branch pipe and the (i + 1) -th branch pipe is shown. To ensure the air quantity of each air outlet is uniform, P is requireds(i)＝Ps(i+1)Equation (1) can be simplified to equation (2):
Pd(i)-Pd(i+1)＝Pf(i-(i+1))+Pl(i-(i+1))(2)
for a steel pipe, the left value of equation (2) is much larger than the right value, so the cross-sectional area of the main pipe needs to be gradually reduced to ensure uniform air supply.
Compared with the prior art, the low flow resistance pipeline device with uniform air supply provided by the invention has the following advantages and beneficial effects:
(a) the cross section area of the tee joint can be increased by designing the surface of the tee joint into a circular arc-shaped curved surface, and the velocity gradient of the cross section in each direction can be reduced by increasing the cross section area of the tee joint, so that the air supply resistance of the pipeline is reduced. In addition, the cost can be saved by using the cambered surface technology.
(b) The height of the main pipeline of the pipeline along the cross section of the airflow direction is gradually reduced, and the static pressure at each branch pipeline is ensured to be the same, so that the exhaust air volume at each branch pipeline is the same, and uniform air supply is realized.
Drawings
Fig. 1 is a schematic view showing the structure of the air supply duct device of the present invention.
Fig. 2 is a front view of the supply air duct device of the present invention.
FIG. 3 is a schematic structural view of the tee of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and embodiments. The embodiment provides a pipeline device designed according to a design method of a low-flow resistance pipeline for uniformly supplying air, which is composed of a main pipeline 1, a plurality of branch pipelines 2 and a plurality of tee joints 3, as shown in figures 1 and 2. The height of the main pipeline 1 along the airflow direction is gradually reduced, and the shape of the tee joint 3 is designed according to the height of the main pipeline 1 along the airflow direction. In designing the piping arrangement, the following four steps are experienced:
step 1: determining the temperature T of the fluid at the inlet of the pipeline, the dynamic viscosity mu and the density rho of the fluid at the temperature, and determining the material of the pipeline; flow rate Q according to the total volume of the pipetThe required number n of the three-way pipe is used for calculating the volume flow rate Q of each air outlet0(ii) a Determining the distance L between two adjacent tees, the width W of the cross section at the inlet of the first tee and the height H1Each tee being along the width of the cross section of the branch conduitw, height h.
Step 2: the average velocity v of each tee along the branch line is determined by the following equations (3), (4)0：
Figure GDA0002590867170000031
S0＝w×h (4)
The velocity v of the hydrostatic drive at the first tee is determined by equation (5) belows1Where ψ represents a flow coefficient:
Figure GDA0002590867170000032
velocity v of dynamic pressure drive at the first three-wayd1Determined by the following formula (6), dynamic pressure Pd1Determined by the following equation (7):
Figure GDA0002590867170000033
Figure GDA0002590867170000034
the exit angle theta of the fluid at the first tee along the branch conduits is determined by the following equation (8), the exit angle theta being not less than 60 deg.:
Figure GDA0002590867170000035
and step 3: the volumetric flow rate Q of the fluid between the first tee and the second tee1-2Represented by the following formula (9):
Q1-2＝Q0×(n-1) (9)
frictional pressure loss P between the first tee and the second teef(1-2)Represented by the following formula (10):
Figure GDA0002590867170000036
wherein f represents the coefficient of friction resistance, L represents the distance between two adjacent tees, D1Representing the hydraulic diameter of the first tee along the cross section of the main conduit, ρ representing the density of the fluid in the conduit, vd1Indicating the speed of the dynamic pressure drive.
The coefficient of friction resistance f is expressed by the following formula (11), hydraulic diameter D1Represented by the following formula (12):
Figure GDA0002590867170000041
Figure GDA0002590867170000042
where e represents roughness, which can be determined according to the pipe material, Re represents reynolds number, which can be expressed by the following formula (13):
Figure GDA0002590867170000043
local pressure loss P between the first tee and the second teeL(1-2)Is determined by the following formula (14), wherein ζ1-2Represents the local drag coefficient between the first tee and the second tee:
Pl(1-2)＝Pd1×ζ1-2(14)
dynamic pressure P at the second teed2Can be calculated by the following equation (15):
Pd(1)-Pd(2)＝Pf(1-2)+Pl(1-2)(15)
velocity v of dynamic pressure drive at the second three-wayd2Can be calculated by the following equation (16):
Figure GDA0002590867170000044
height H of second tee joint along cross section of main pipeline2Can be calculated by the following equation (17):
Figure GDA0002590867170000045
and 4, step 4: and (3) calculating the height of each rest tee joint along the cross section of the main pipeline by adopting a method similar to the steps 2 and 3.
The structure of the tee joint is shown in figure 3: the three-way flow divider is provided with an inlet and two outlets, and four surfaces of the three-way flow divider are curved surfaces in the form of circular arcs. The radius of the curved surface 1 is 20.05D, the radius of the curved surface 2 is 0.2D, the radius of the curved surface 3 is 3.47D, and the radius of the curved surface 4 is 8.4D, wherein D is the hydraulic diameter of the cross section of the tee joint connected with the main pipeline, and D is the hydraulic diameter of the cross section of the tee joint connected with the branch pipeline. Angle theta1Is 80 DEG, angle theta2Is 2 deg..

Claims (3)

1. A low flow resistance pipeline device for uniformly supplying air is characterized by comprising a main pipeline, a tee joint and branch pipelines; the main pipeline and the branch pipelines are connected by the tee; the tee joint is provided with four curved surfaces, wherein the curved surface 1 is a curved surface on the opposite side of an air outlet of the main pipeline, the curved surface 2 is a curved surface at the downstream of the air flow at the joint of the main pipeline and the branch pipeline, the curved surface 4 is a curved surface with an inclination angle at the upstream of the air flow at the joint of the main pipeline and the branch pipeline, and the curved surface 3 is a curved surface at one side of the branch pipeline and connected with the curved surface 4; the cross sections of the main pipeline and the branch pipelines are square or circular; the design method of the low flow resistance pipeline device for uniformly supplying air comprises the following four steps:
step 1: determining physical parameters of the air supply fluid, including density and viscosity, and the material of the pipeline; calculating the volume flow rate of each air outlet according to the total volume flow rate of the pipeline and the required number of the tee joints;
step 2: calculating the air supply speed of each air outlet according to the volume flow rate required by each air outlet and the cross section area of the branch pipeline, and calculating the static pressure driving speed of the first tee joint according to the air supply speed; calculating the dynamic pressure driving speed of the first tee joint according to the total volume flow rate and the size of the cross section of the first tee joint along the direction of the main pipeline, and then calculating a transmission angle which is not less than 60 degrees;
and step 3: calculating the friction pressure loss and the local pressure loss between the first tee joint and the second tee joint; calculating the dynamic pressure of the second tee joint according to the calculated friction pressure loss, the calculated local pressure loss and the calculated dynamic pressure of the first tee joint; calculating the speed of the second three-way dynamic pressure drive according to the relation between the dynamic pressure and the speed of the dynamic pressure drive; calculating the size of the cross section of the second tee joint along the direction of the main pipeline according to the volume flow rate of the main pipeline flowing through the second tee joint and the dynamic pressure driving speed of the second tee joint, and calculating the height of the cross section of the second tee joint along the direction of the main pipeline;
and 4, step 4: and (3) calculating the height of each residual tee joint along the cross section of the main pipeline by using the method in the steps 2 and 3.
2. A duct apparatus with low flow resistance for uniform blowing according to claim 1, wherein the height of the cross section of said main duct in the direction of air flow is gradually reduced.
3. The piping arrangement with low flow resistance for uniform blowing according to claim 1, wherein the radius of the curved surface 1 of the tee is 20.05D, the radius of the curved surface 2 is 0.2D, the radius of the curved surface 3 is 3.47D, and the radius of the curved surface 4 is 8.4D, where D is the hydraulic diameter of the cross section where the tee is connected to the main piping, and D is the hydraulic diameter of the cross section where the tee is connected to the branch piping.
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CN109753760A (en) * 2019-02-27 2019-05-14 哈尔滨哈锅锅炉容器工程有限责任公司 A kind of blast cap drag computation method
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CN101963171A (en) * 2010-10-26 2011-02-02 西安建筑科技大学 T-shaped splitting/rectifying tee
CN203585656U (en) * 2013-10-16 2014-05-07 浙江中洁管道有限公司 Three-way union with low chocked flow coefficient
CN203678987U (en) * 2013-12-24 2014-07-02 南京航空航天大学 Cavity structure of multi-way pipe fitting hydraulic expansion mould
CN204062300U (en) * 2014-07-04 2014-12-31 河南联塑实业有限公司 A kind of 45 ° of skew Ts
CN104421558A (en) * 2013-08-21 2015-03-18 扬州成功金属制品有限公司 T-shaped pipe
CN107676563A (en) * 2017-09-22 2018-02-09 西安建筑科技大学 Lower resistance threeway component based on bionics plant branched structure

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101829648A (en) * 2010-05-13 2010-09-15 浙江工业大学 Semicircle and variable-section air duct of drying room of automotive body
CN101963171A (en) * 2010-10-26 2011-02-02 西安建筑科技大学 T-shaped splitting/rectifying tee
CN104421558A (en) * 2013-08-21 2015-03-18 扬州成功金属制品有限公司 T-shaped pipe
CN203585656U (en) * 2013-10-16 2014-05-07 浙江中洁管道有限公司 Three-way union with low chocked flow coefficient
CN203678987U (en) * 2013-12-24 2014-07-02 南京航空航天大学 Cavity structure of multi-way pipe fitting hydraulic expansion mould
CN204062300U (en) * 2014-07-04 2014-12-31 河南联塑实业有限公司 A kind of 45 ° of skew Ts
CN107676563A (en) * 2017-09-22 2018-02-09 西安建筑科技大学 Lower resistance threeway component based on bionics plant branched structure

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