STUDY THE PERFORMANCE OF MICROTUBE AS AN EMISSION POINT IN MICRO•IRRIGATION SYSTEM
BOSHRA LOUIZ BISHARA GIRGIS;
Abstract
Studies were conducted to investigate the performance of microtube as an emission point in microirrigation system. The first one was to study the hydraulics of microtube emitters, to get a suitable empirical equation for predicting discharge rates, depending on the data of the
experimental determination of these rates under different conditions. The second was to calculate the friction factor in polyethylene pipes applying Darcy-Weisbach equation. The third was to apply modeling techniques to form a simple model for designing single microirrigation lateral with the microtube as an emission device using the experimental data that was simulated the uniformity coefficient of water application.
The current investigation was carried out in Hydraulic National Lab of Agricultural Eng. Research Institute in Dokki, Giza. The first laboratory experiments were conducted to study the relationship between the parameters microtube diameter (d), microtube length (f), operating head
(p), lateral diameter (D) and microtube discharge (q) as estimated for turbulent flow conditions. A computer numerical analysis program (the least square method) was used to determine empirical equation (4.1) for flow rate ofmicrotube diameters 3.15 and 4.3 mm as follows:
q=kp"d'l"(d/D)' (4.1)
in which q =the discharge of the microtube (Lih); p =the pressure at entrance ofmicrotube (bar); d = the inside diameter of microtube (mm); I = the length of microtube emitter (m); D = the internal diameter oflateral (mm); and k, a, b, c, e =the constants. The values of constants k, a, b, c and e are given as 2.8, 0.62, 2.54, -0.26 and -0.5 respectively. The equation has correlated the observed values with a correlation coefficient of 0.92. The microtubes length about of meter or less affects the discharge values for microtube (3.15 and 4.3 mm), and increasing of microtube length decreases the values of discharge. Each microtube diameter and lateral diameter has its effect on the microtube discharge. Increasing the ratio between microtube diameter and lateral diameter decreases the values ofmicrotube discharge.
In the second laboratory experiments for evaluating the average friction factor, relative
roughness and absolute roughness, these values were found 0.039081, 0.0063 and 0.084 mm respectively for the lateral size of 13.35 mm. The average friction factor, relative roughness and absolute roughness values were found 0.039074, 0.0073 and 0.118 mm for the lateral size of
16.15 mm. The average friction factor, relative roughness and absolute roughness values were found 0.037328, 0.005 and 0.09 mm for the lateral size of 18.2 mm. The Reynolds number was
found to increase from 6376.8 to 16779.6 for the lateral size of 13.35 mm with increase in the flow velocity from 0.45 to 1.2 m/s. The Reynolds number was found to increase from 8971.6 to
21613.3 for the lateral size of16.15 mm with increase in the flow velocity from 0.523 to 1.26 m/s. The Reynolds number was found to increase from 11327.2 to 26947.8 for the lateral size of 18.2 mm with increase in the flow velocity from 0.586 to 1.39 m/s. The total range of Reynolds
number was found to be on the side of the turbulent range for the microirrigation lateral sizes of
13.35, 16.15 and 18.2 mm. The measured and calculated pressure drop is highest for small lateral diameter 13.35 mm and that with increasing of lateral diameter the measured and calculated pressure drop will decrease.
A computer model for designing single microirrigation lateral with the microtube as an emission device was constructed to evaluate the Christiansen's uniformity coefficient.
experimental determination of these rates under different conditions. The second was to calculate the friction factor in polyethylene pipes applying Darcy-Weisbach equation. The third was to apply modeling techniques to form a simple model for designing single microirrigation lateral with the microtube as an emission device using the experimental data that was simulated the uniformity coefficient of water application.
The current investigation was carried out in Hydraulic National Lab of Agricultural Eng. Research Institute in Dokki, Giza. The first laboratory experiments were conducted to study the relationship between the parameters microtube diameter (d), microtube length (f), operating head
(p), lateral diameter (D) and microtube discharge (q) as estimated for turbulent flow conditions. A computer numerical analysis program (the least square method) was used to determine empirical equation (4.1) for flow rate ofmicrotube diameters 3.15 and 4.3 mm as follows:
q=kp"d'l"(d/D)' (4.1)
in which q =the discharge of the microtube (Lih); p =the pressure at entrance ofmicrotube (bar); d = the inside diameter of microtube (mm); I = the length of microtube emitter (m); D = the internal diameter oflateral (mm); and k, a, b, c, e =the constants. The values of constants k, a, b, c and e are given as 2.8, 0.62, 2.54, -0.26 and -0.5 respectively. The equation has correlated the observed values with a correlation coefficient of 0.92. The microtubes length about of meter or less affects the discharge values for microtube (3.15 and 4.3 mm), and increasing of microtube length decreases the values of discharge. Each microtube diameter and lateral diameter has its effect on the microtube discharge. Increasing the ratio between microtube diameter and lateral diameter decreases the values ofmicrotube discharge.
In the second laboratory experiments for evaluating the average friction factor, relative
roughness and absolute roughness, these values were found 0.039081, 0.0063 and 0.084 mm respectively for the lateral size of 13.35 mm. The average friction factor, relative roughness and absolute roughness values were found 0.039074, 0.0073 and 0.118 mm for the lateral size of
16.15 mm. The average friction factor, relative roughness and absolute roughness values were found 0.037328, 0.005 and 0.09 mm for the lateral size of 18.2 mm. The Reynolds number was
found to increase from 6376.8 to 16779.6 for the lateral size of 13.35 mm with increase in the flow velocity from 0.45 to 1.2 m/s. The Reynolds number was found to increase from 8971.6 to
21613.3 for the lateral size of16.15 mm with increase in the flow velocity from 0.523 to 1.26 m/s. The Reynolds number was found to increase from 11327.2 to 26947.8 for the lateral size of 18.2 mm with increase in the flow velocity from 0.586 to 1.39 m/s. The total range of Reynolds
number was found to be on the side of the turbulent range for the microirrigation lateral sizes of
13.35, 16.15 and 18.2 mm. The measured and calculated pressure drop is highest for small lateral diameter 13.35 mm and that with increasing of lateral diameter the measured and calculated pressure drop will decrease.
A computer model for designing single microirrigation lateral with the microtube as an emission device was constructed to evaluate the Christiansen's uniformity coefficient.
Other data
| Title | STUDY THE PERFORMANCE OF MICROTUBE AS AN EMISSION POINT IN MICRO•IRRIGATION SYSTEM | Other Titles | دراسة أداء الأنبوب الدقيق كنقطة بث فى نظام الرى الدقيق | Authors | BOSHRA LOUIZ BISHARA GIRGIS | Issue Date | 2005 |
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