CN103559341A - Drip irrigation small district hydraulic design method - Google Patents

Abstract

The invention relates to a drip irrigation small district hydraulic design method. The drip irrigation small district hydraulic design method firstly comprises putting forward a drip irrigation system flow deviation rate calculation formula which takes hydraulic deviation and irrigation emitter manufacturing deviation into consideration simultaneously, wherein given a drip irrigation system allowable flow deviation rate, the allowable hydraulic flow deviation rate of the drip irrigation small district can be obtained through back calculation according to the formula, and accordingly the allowable working head deviation of the drip irrigation small district can be determined; establishing working head deviation calculation formula on a single pipe (a capillary pipe or a branch pipe) under slopes of different types, reasonably distributing the allowable working head deviation of the drip irrigation small district on the capillary pipe and the branch pipe, and designing the capillary pipe and the branch pipe. According to the drip irrigation small district hydraulic design method, due to the fact that the irrigation emitter manufacturing deviation is considered, the design results of a drip irrigation project is closer to actual conditions, and the irrigation quality of the drip irrigation system is improved.

Description

A kind of drip irrigation community Hydraulic Design Method of pouring water

Technical field

The invention belongs to agricultural irrigation technology, relate to the method for designing of drip irrigation project, particularly a kind of drip irrigation community Hydraulic Design Method of pouring water.

Background technology

Flow deviation rate is one of important indicator of describing drip irrigation system irrigation quality, is also one of major parameter of drip irrigation project design.In drip irrigation project design, conventionally adopt the way of limited flow rate deviation ratio to guarantee system uniformity of irrigation water appilcation.The factor that affects flow deviation rate is a lot, variation just rising and falling as the temperature variation of the manufacture deviation of the blockage of the variation of douche working pressure, douche, douche, irrigation water and ground etc.In drip irrigation project design, only have as much as possible its influence factor is taken into account comprehensively, just can make drip irrigation project actual irrigation quality and design object approach to greatest extent.

At present, the existing < < slight irrigation engineering legislation > > (GB/T50485-2009) of China has only considered factor of hydraulic deviation when drip irrigation is poured water community the Hydraulic Design, not counting the impact of Manufacture variation, also there is a certain distance in drip irrigation project actual irrigation quality and the design object therefore designed.

Summary of the invention

The defect or the deficiency that for above-mentioned prior art, exist, the object of the invention is to, and a kind of drip irrigation community Hydraulic Design Method of pouring water is provided.

In order to realize above-mentioned task, the technical scheme that the present invention takes is:

The community Hydraulic Design Method of pouring water, is characterized in that:

First, set up the drip irrigation system flow deviation rate computing formula of simultaneously considering hydraulic deviation and Manufacture variation:

q _v＝(1+0 ^.3u ₁c _v)q _hv+2u ₁c _v （1）

In formula: q _vfor consider the community integrated flux deviation rate of pouring water of hydraulic deviation and Manufacture variation, unit: % simultaneously;

U ₁for obeying average, be 0, the random number of the normal distribution that standard deviation is 1;

C _vfor Manufacture variation coefficient;

Q _hvfor considering the cell flow deviation ratio of pouring water of hydraulic deviation, unit: %;

Secondly, according to the topographical elevation difference Δ H ' of conduit entrance and end and the ratio of conduit entrance to total friction loss Δ H of end, be Δ H '/Δ H, terrain slope is divided into the different type of three major types five microspecies, sets up respectively the working head deviation computing formula in single conduit under the dissimilar gradient:

1) the first type (Fig. 1): minimum working pressure power is at pipe end, i.e. Δ H '/Δ H≤0

$\mathrm{\&Delta;h}=(5.35\frac{Q^{1.852}}{d^{4.871}}-S_0)l---\left(2\right)$

In formula: Δ h is the working head deviation in single conduit, unit: m;

Q is conduit entrance flow, unit: L/s;

D is internal diameter of the pipeline, unit: cm;

S ₀for terrain slope;

L is duct length, unit: m;

2) Second Type: minimum working pressure power is in the middle of pipeline

1. the first of Second Type (Fig. 2): 0 < Δ H '/Δ H < 1

$\mathrm{\&Delta;h}=(5.35\frac{Q^{1.852}}{d^{4.871}}-S_0+0.15\frac{{S_0}^{1.54}{d}^{2.63}}{Q})l---\left(3\right)$

2. the second of Second Type (Fig. 3): Δ H '/Δ H=1

$\mathrm{\&Delta;h}=0.37\mathrm{\&Delta;H}=1.98\frac{Q^{1.852}}{d^{4.871}}l---\left(4\right)$

3. the third (Fig. 4) of Second Type: 1 < Δ H '/Δ H < 2.852

$\mathrm{\&Delta;h}=0.15\frac{{S_0}^{1.54}{d}^{2.63}}{Q}l---\left(5\right)$

3) the 3rd type (Fig. 5): minimum working pressure power is in conduit entrance, i.e. Δ H '/Δ H >=2.852

$\mathrm{\&Delta;h}=(S_0-5.35\frac{Q^{1.852}}{d^{4.871}})l---\left(6\right)$

Set up single conduit import step calculation of pressure formula:

$h_0=\stackrel{\&OverBar;}{h}+0.74\mathrm{\&Delta;H}\stackrel{\&OverBar;}{+}0.5\mathrm{\&Delta;}{H}^{\&prime;}---\left(7\right)$

Wherein: $\mathrm{\&Delta;H}=5.35\frac{Q^{1.852}}{d^{4.871}}l---\left(8\right)$

ΔH′＝S ₀l （9）

In formula: h ₀for single conduit import step pressure, unit: m;

for the average working pressure in single conduit, unit: m;

Finally, the drip irrigation community the Hydraulic Design process of pouring water is as follows:

1) determine that the drip irrigation community of pouring water allows hydraulic flow deviation rate:

1. drip irrigation is poured water to community permissible flow deviation ratio as design standards, q _vget 0.2;

2. determine u ₁:

Known P, calculates u by following formula ₁:

$P=\frac{1}{\sqrt{2\mathrm{\&pi;}}}{\&Integral;}_{-\&infin;}^{u_1}{e}^{-\frac{x^2}{2}}\mathrm{dx}---\left(10\right)$

3. choose douche type, determine c _v;

4. utilize formula (1), according to u ₁and c _vvalue calculate the community of pouring water and allow hydraulic flow deviation rate q _hv;

2) determine that the drip irrigation community of pouring water allows working head deviation:

1. calculate the drip irrigation community of pouring water and allow working head deviation ratio:

$h_v=\frac{q_{\mathrm{hv}}}{x}(1+0.15\frac{1-x}{x}{q}_{\mathrm{hv}})---\left(11\right)$

In formula: h _vin order to pour water, community allows working head deviation ratio, unit: %;

X is douche flow stance index;

2. calculate the drip irrigation community of pouring water and allow working head deviation:

$\mathrm{\&Delta;}{h}_{(s,l)}=\stackrel{\&OverBar;}{h}{h}_v---\left(12\right)$

In formula: Δ h _{(s, l)}for the drip irrigation community of pouring water allows working head deviation, unit: m;

3) hollow billet the Hydraulic Design:

1. by Δ h _{(s, l)}1/2 as hollow billet working head deviation:

$\mathrm{\&Delta;}{h}_l=\frac{1}{2}\mathrm{\&Delta;}{h}_{(s,l)}---\left(13\right)$

In formula: Δ h _lfor hollow billet working head deviation, unit: m;

2. given hollow billet caliber, determine hollow billet laying length:

A, according to terrain slope, from formula (2)～formula (6), select corresponding formula to calculate hollow billet length;

B, according to field size and hollow billet length computation value, determine hollow billet laying length;

C, utilize the formula selected in the 2. step a in step 3) to calculate hollow billet working head deviation delta h _l;

3. the hollow billet import step head that utilizes formula (7) calculation requirement, the average working head of hollow billet equals douche design effort head;

4) the community the Hydraulic Design of pouring water:

1. according to hollow billet working head deviation delta h in the 2. step c in step 3) _lcalculated value, calculate arm working head deviation:

Δh _s＝Δh _(s,l)-Δh _l （14）

In formula: Δ h _sfor arm working head deviation, unit: m;

2. according to drip irrigation the pour water size of community and the design length of hollow billet, determine a length of tube;

3. according to terrain slope, from formula (2)～formula (6), select corresponding formula to calculate a bore;

4. according to the arm inner diameter values of calculating, in conjunction with commercial caliber, bore is propped up in design;

5. utilize the formula of selecting in the 3. step in step 4) to calculate arm working head deviation delta h _s;

6. check the hollow billet working head deviation delta h in the 2. c step in step 3) _larm working head deviation delta h in 5. step in calculated value and step 4) _scalculated value sum whether be less than the drip irrigation community of pouring water and allow working head deviation delta h _{(s, l)}value Δ h _s;

7. the arm import step head that utilizes formula (7) calculation requirement, the average working head of arm equals hollow billet import step head.

The drip irrigation of the present invention community Hydraulic Design Method of pouring water, owing to considering Manufacture variation, can make drip irrigation project design result closer to actual conditions, improves drip irrigation system irrigation quality.

Accompanying drawing explanation

Fig. 1 to Fig. 5 is single conduit upward pressure distribution schematic diagram under five kinds of different even slope, wherein Fig. 1 is that the first type (pressure distribution type I) Fig. 2 is that (pressure distribution type II-a) Fig. 3 is the second type the second (pressure distribution type II-b) to the second type the first, Fig. 4 is the second type the third (pressure distribution type II-c), the third type of Fig. 5 (pressure distribution type III).

Below that the present invention is described in further detail in conjunction with the embodiments.

Embodiment

Applicant provides a kind of drip irrigation community Hydraulic Design Method of pouring water, and first proposes to consider the drip irrigation system flow deviation rate computing formula of hydraulic deviation and Manufacture variation simultaneously; Then for the dissimilar gradient, set up the working head deviation computing formula in single conduit (hollow billet or arm); On this basis, and then propose the drip irrigation community the Hydraulic Design process of pouring water.Specifically comprise:

First, set up the drip irrigation system flow deviation rate computing formula of simultaneously considering hydraulic deviation and Manufacture variation:

q _v＝(1+0.3u ₁c _v)q _hv+2u ₁c _v （1）

In formula: q _vfor consider the community integrated flux deviation rate of pouring water of hydraulic deviation and Manufacture variation, unit: % simultaneously;

U ₁for obeying average, be 0, the random number of the normal distribution that standard deviation is 1;

C _vfor Manufacture variation coefficient;

Q _hvfor considering the cell flow deviation ratio of pouring water of hydraulic deviation, unit: %.

Secondly, according to the topographical elevation difference Δ H ' of conduit entrance and end and the ratio (Δ H '/Δ H) of conduit entrance to total friction loss Δ H of end, terrain slope is divided into the different type of three major types five microspecies, as shown in Figures 1 to 5, set up respectively the working head deviation computing formula in single conduit under the dissimilar gradient:

1) first kind (Fig. 1, pressure distribution type I): minimum working pressure power is at pipe end, i.e. Δ H '/Δ H≤0

$\mathrm{\&Delta;h}=(5.35\frac{Q^{1.852}}{d^{4.871}}-S_0)l---\left(2\right)$

In formula: Δ h is the working head deviation in single conduit, unit: m;

Q is conduit entrance flow, unit: L/s;

D is internal diameter of the pipeline, unit: cm;

S ₀for terrain slope;

L is duct length, unit: m.

2) Second Type: minimum working pressure power is in the middle of pipeline

1. Second Type type the first (Fig. 2, pressure distribution type II-a): 0 < Δ H '/Δ H < 1

$\mathrm{\&Delta;h}=(5.35\frac{Q^{1.852}}{d^{4.871}}-S_0+0.15\frac{{S_0}^{1.54}{d}^{2.63}}{Q})l---\left(3\right)$

2. Second Type the second (Fig. 3, pressure distribution type II-b): Δ H '/Δ H=1

$\mathrm{\&Delta;h}=0.37\mathrm{\&Delta;H}=1.98\frac{Q^{1.852}}{d^{4.871}}l---\left(4\right)$

3. Second Type the third (Fig. 4, pressure distribution type II-c): 1 < Δ H '/Δ H < 2.852

$\mathrm{\&Delta;h}=0.15\frac{{S_0}^{1.54}{d}^{2.63}}{Q}l---\left(5\right)$

3) the 3rd type (pressure distribution type III): minimum working pressure power is in conduit entrance, i.e. Δ H '/Δ H >=2.852

$\mathrm{\&Delta;h}=(S_0-5.35\frac{Q^{1.852}}{d^{4.871}})l---\left(6\right)$

Set up single conduit import step calculation of pressure formula:

$h_0=\stackrel{\&OverBar;}{h}+0.74\mathrm{\&Delta;H}\stackrel{\&OverBar;}{+}0.5\mathrm{\&Delta;}{H}^{\&prime;}---\left(7\right)$

Wherein: $\mathrm{\&Delta;H}=5.35\frac{Q^{1.852}}{d^{4.871}}l---\left(8\right)$

ΔH′＝S ₀l （9）

In formula: h ₀for single conduit import step pressure, unit: m;

for the average working pressure in single conduit, unit: m.

Finally, the drip irrigation community the Hydraulic Design process of pouring water proposed as follows:

1) determine that the drip irrigation community of pouring water allows hydraulic flow deviation rate:

1. drip irrigation is poured water to community permissible flow deviation ratio as design standards, q _vget 0.2;

2. determine u ₁:

Known P, can calculate u by following formula ₁:

$P=\frac{1}{\sqrt{2\mathrm{\&pi;}}}{\&Integral;}_{-\&infin;}^{u_1}{e}^{-\frac{x^2}{2}}\mathrm{dx}---\left(10\right)$

3. choose douche type, can determine c _v;

4. utilize formula (1), according to u ₁and c _vvalue calculate the community of pouring water and allow hydraulic flow deviation rate q _hv;

2) determine that the drip irrigation community of pouring water allows working head deviation:

1. calculate the drip irrigation community of pouring water and allow working head deviation ratio:

$h_v=\frac{q_{\mathrm{hv}}}{x}(1+0.15\frac{1-x}{x}{q}_{\mathrm{hv}})---\left(11\right)$

In formula: h _vin order to pour water, community allows working head deviation ratio, unit: %;

X is douche flow stance index.

2. calculate the drip irrigation community of pouring water and allow working head deviation:

$\mathrm{\&Delta;}{h}_{(s,l)}=\stackrel{\&OverBar;}{h}{h}_v---\left(12\right)$

In formula: Δ h _{(s, l)}for the drip irrigation community of pouring water allows working head deviation, unit: m.

3) hollow billet the Hydraulic Design:

1. by Δ h _{(s, l)}1/2 as hollow billet working head deviation:

$\mathrm{\&Delta;}{h}_l=\frac{1}{2}\mathrm{\&Delta;}{h}_{(s,l)}---\left(13\right)$

In formula: Δ h _lfor hollow billet working head deviation, unit: m.

2. given hollow billet caliber, determine hollow billet laying length:

A. according to terrain slope, from formula (2)～formula (6), select corresponding formula to calculate hollow billet length;

B. according to field size and hollow billet length computation value, determine optimum hollow billet laying length;

C. utilize the formula of selecting in the 2. step a in step 3) to calculate hollow billet working head deviation delta h _l.

3. the hollow billet import step head that utilizes formula (7) calculation requirement, the average working head of hollow billet equals douche design effort head.

4) the community the Hydraulic Design of pouring water:

1. according to hollow billet working head deviation delta h in the 2. step c in step 3) _lcalculated value, calculate arm working head deviation:

Δh _s＝Δh _(s,l)-Δh _l （14）

In formula: Δ h _sfor arm working head deviation, unit: m.

2. according to drip irrigation the pour water size of community and the design length of hollow billet, determine a length of tube;

3. according to terrain slope, from formula (2)～formula (6), select suitable formula to calculate a bore;

4. according to the arm inner diameter values of calculating, in conjunction with commercial caliber, design optimum bore;

5. utilize the formula of selecting in the 3. step in step 4) to calculate arm working head deviation delta h _s;

6. check the hollow billet working head deviation delta h in the 2. step c in step 3) _larm working head deviation delta h in 5. step in calculated value and step 4) _scalculated value sum whether be less than the drip irrigation community of pouring water and allow working head deviation delta h _{(s, l)}value Δ h _s;

7. utilize the arm import step head of formula (7) calculation requirement.The average working head of arm equals hollow billet import step head.

It is below the specific embodiment that inventor provides.

With the cotton field of 0.45 hectare, design the drip irrigation community of pouring water for example.Douche nominal operation head 10m, rated flow 0.79L/h, douche flow formula q=0.25h ^0.5, Manufacture variation coefficient c _vbe 0.05, douche is in hollow billet equal intervals layout, and spacing is 0.3m.Hollow billet internal diameter 1.6cm, capillary pipe spacing 0.95m.Hollow billet is laid on level land, and arm is laid along slope, and the gradient is 1%.Require to determine drip irrigation pour water community hollow billet laying length, hollow billet import step head, length of tube and internal diameter and arm entrance head.

Specific design process is as follows:

1) determine design standards q _v=0.2;

2) P gets 0.6, according to formula (10), calculates u ₁be 0.253;

3) Manufacture variation coefficient c _v=0.05;

4) according to formula (1), can obtain: q _hv=0.174;

5) according to formula (11), can obtain: h _v=0.357;

6) get 10m, according to formula (12), can obtain: Δ h _{(s, l)}=3.57m;

7) according to formula (13), can obtain: Δ h _l=1.785m;

8) because the hollow billet laying gradient is 0, so selecting type (2) calculates hollow billet length:

$1.785=5.35\frac{{(\frac{0.79}{3600}\&times;\frac{l}{0.3})}^{1.852}}{{1.6}^{4.871}}l\&DoubleRightArrow;l=165m$

9) design hollow billet length 150m, propping up length of tube is 30m;

10) according to formula (2), calculate: Δ h _l=1.358m;

11) according to the hollow billet import step head of formula (7) calculation requirement, be 11m;

12) according to formula (14), calculate arm working head deviation: Δ h _s=2.212m;

13) arm is arranged along slope, and the gradient is 1%, so selecting type (3) calculates a bore:

$\begin{array}{c}2.212=30(5.35\frac{{(\frac{0.79}{3600}\&times;\frac{150}{0.3}\&times;\mathrm{Roundup}\left(\frac{30}{0.95}\right))}^{1.852}}{d^{4.871}}-0.01+0.15\frac{{0.01}^{1.54}{d}^{2.63}}{\frac{0.79}{3600}\&times;\frac{150}{0.3}\&times;\mathrm{Roundup}\left(\frac{30}{0.95}\right)})\\ \&DoubleRightArrow;d=3.795\mathrm{cm}\end{array}$

Therefore, arm design internal diameter is 4cm.

14) according to formula (3), calculate: Δ h _s=1.66m;

15）(Δh _l+Δh _s＝1.358+1.66＝3.018m)＜(Δh _(s,l)＝3.57m)；

16) according to formula (8), calculate arm friction loss: Δ H=1.919m, calculates the topographical elevation difference of arm import and end: Δ H '=0.3m according to formula (9);

17) according to the arm import step head of formula (7) calculation requirement, be 12.27m.

Claims (1)

1. the drip irrigation community Hydraulic Design Method of pouring water, is characterized in that:

First, set up the drip irrigation system flow deviation rate computing formula of simultaneously considering hydraulic deviation and Manufacture variation:

q _v＝(1+0.3u ₁c _v)q _hv+2u ₁c _v （1）

In formula: q _vfor consider the community integrated flux deviation rate of pouring water of hydraulic deviation and Manufacture variation, unit: % simultaneously;

U ₁for obeying average, be 0, the random number of the normal distribution that standard deviation is 1;

C _vfor Manufacture variation coefficient;

Q _hvfor considering the cell flow deviation ratio of pouring water of hydraulic deviation, unit: %;

Secondly, according to the topographical elevation difference Δ H ' of conduit entrance and end and the ratio of conduit entrance to total friction loss Δ H of end, be Δ H '/Δ H, terrain slope is divided into the different type of three major types five microspecies, sets up respectively the working head deviation computing formula in single conduit under the dissimilar gradient:

1) the first type: minimum working pressure power is at pipe end, i.e. Δ H '/Δ H≤0

$\mathrm{\&Delta;h}=(5.35\frac{Q^{1.852}}{d^{4.871}}-S_0)l---\left(2\right)$

In formula: Δ h is the working head deviation in single conduit, unit: m;

Q is conduit entrance flow, unit: L/s;

D is internal diameter of the pipeline, unit: cm;

S ₀for terrain slope;

L is duct length, unit: m;

2) Second Type: minimum working pressure power is in the middle of pipeline

1. the first of Second Type: 0 < Δ H '/Δ H < 1

$\mathrm{\&Delta;h}=(5.35\frac{Q^{1.852}}{d^{4.871}}-S_0+0.15\frac{{S_0}^{1.54}{d}^{2.63}}{Q})l---\left(3\right)$

2. the second of Second Type: Δ H '/Δ H=1

$\mathrm{\&Delta;h}=0.37\mathrm{\&Delta;H}=1.98\frac{Q^{1.852}}{d^{4.871}}l---\left(4\right)$

3. the third of Second Type: 1 < Δ H '/Δ H < 2.852

$\mathrm{\&Delta;h}=0.15\frac{{S_0}^{1.54}{d}^{2.63}}{Q}l---\left(5\right)$

3) the 3rd type: minimum working pressure power is in conduit entrance, i.e. Δ H '/Δ H >=2.852

$\mathrm{\&Delta;h}=(S_0-5.35\frac{Q^{1.852}}{d^{4.871}})l---\left(6\right)$

Set up single conduit import step calculation of pressure formula:

$h_0=\stackrel{\&OverBar;}{h}+0.74\mathrm{\&Delta;H}\stackrel{\&OverBar;}{+}0.5\mathrm{\&Delta;}{H}^{\&prime;}---\left(7\right)$

Wherein: $\mathrm{\&Delta;H}=5.35\frac{Q^{1.852}}{d^{4.871}}l---\left(8\right)$

ΔH′＝S ₀l （9）

In formula: h ₀for single conduit import step pressure, unit: m;

for the average working pressure in single conduit, unit: m;

Finally, the drip irrigation community the Hydraulic Design process of pouring water is as follows:

1) determine that the drip irrigation community of pouring water allows hydraulic flow deviation rate:

1. drip irrigation is poured water to community permissible flow deviation ratio as design standards, q _vget 0.2;

2. determine u ₁:

Known P, calculates u by following formula ₁:

$P=\frac{1}{\sqrt{2\mathrm{\&pi;}}}{\&Integral;}_{-\&infin;}^{u_1}{e}^{-\frac{x^2}{2}}\mathrm{dx}---\left(10\right)$

3. choose douche type, determine c _v;

4. utilize formula (1), according to u ₁and c _vvalue calculate the community of pouring water and allow hydraulic flow deviation rate q _hv;

2) determine that the drip irrigation community of pouring water allows working head deviation:

1. calculate the drip irrigation community of pouring water and allow working head deviation ratio:

$h_v=\frac{q_{\mathrm{hv}}}{x}(1+0.15\frac{1-x}{x}{q}_{\mathrm{hv}})---\left(11\right)$

In formula: h _vin order to pour water, community allows working head deviation ratio, unit: %;

X is douche flow stance index;

2. calculate the drip irrigation community of pouring water and allow working head deviation:

$\mathrm{\&Delta;}{h}_{(s,l)}=\stackrel{\&OverBar;}{h}{h}_v---\left(12\right)$

In formula: Δ h _{(s, l)}for the drip irrigation community of pouring water allows working head deviation, unit: m;

3) hollow billet the Hydraulic Design:

1. by Δ h _{(s, l)}1/2 as hollow billet working head deviation:

$\mathrm{\&Delta;}{h}_l=\frac{1}{2}\mathrm{\&Delta;}{h}_{(s,l)}---\left(13\right)$

In formula: Δ h _lfor hollow billet working head deviation, unit: m;

2. given hollow billet caliber, determine hollow billet laying length:

A, according to terrain slope, from formula (2)～formula (6), select corresponding formula to calculate hollow billet length;

B, according to field size and hollow billet length computation value, determine hollow billet laying length;

C, utilize the formula selected in the 2. step a in step 3) to calculate hollow billet working head deviation delta h _l;

3. the hollow billet import step head that utilizes formula (7) calculation requirement, the average working head of hollow billet equals douche design effort head;

4) the community the Hydraulic Design of pouring water:

1. according to hollow billet working head deviation delta h in the 2. step c in step 3) _lcalculated value, calculate arm working head deviation:

Δh _s＝Δh _(s,l)-Δh _l （14）

In formula: Δ h _sfor arm working head deviation, unit: m;

2. according to drip irrigation the pour water size of community and the design length of hollow billet, determine a length of tube;

3. according to terrain slope, from formula (2)～formula (6), select corresponding formula to calculate a bore;

4. according to the arm inner diameter values of calculating, in conjunction with commercial caliber, bore is propped up in design;

5. utilize the formula of selecting in the 3. step in step 4) to calculate arm working head deviation delta h _s;

6. check the hollow billet working head deviation delta h in the 2. step c in step 3) _larm working head deviation delta h in 5. step in calculated value and step 4) _scalculated value sum whether be less than the drip irrigation community of pouring water and allow working head deviation delta h _{(s, l)}value Δ h _s;

7. the arm import step head that utilizes formula (7) calculation requirement, the average working head of arm equals hollow billet import step head.

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