Font Size: a A A

Theory And Precise Sprinkling Irrigation For The Complete Fluidic Sprinkler

Posted on:2010-08-30Degree:DoctorType:Dissertation
Country:ChinaCandidate:X Y ZhuFull Text:PDF
GTID:1103360278472038Subject:Fluid Machinery and Engineering
Abstract/Summary:PDF Full Text Request
This project was supported by the National High-tech Research and Development Program (Grant No. 2006AA100211)—"Light-duty Irrigation System for Variable Sprinkling".The complete fluidic sprinkler, a new type of water-saving product, which depends on the theory of Coanda effect to accomplish the function of direct-spraying, stepping and reversing, was originally invented in China. We have had the intellectual property and have owned several correlative patents. The sprinkler has several advantages, such as easy-constructed, low loss of energy, low price and so on. For such new products, research was not deep enough now. Systematic research for the complete fluidic sprinkler has high academic value and practical significance. First, the working principle and characteristics were introduced. Combined with theoretical analyses, experimental tests and numerical simulation, the theory of the complete fluidic sprinkler and the technology of the precise sprinkling irrigation were systematically investigated. The main contents and innovations in this dissertation were as follow:1. After fifty-four tests, design method of the complete fluidic sprinkler was put forward firstly. An orthogonal array with four factors and three levels was selected to carry out the experiments. The relationships between the main sprinkler structure parameters were obtained: the influencing factors in decreasing order of importance for stepped frequency are contractive angle, water fetching angle, offset length and working area; the influencing factors for stepped angle are offset length, contractive angle, water fetching angle and working area in decreasing order of importance. The important structure parameters were confirmed as follow, the size of base circle is determined by the type of the sprinkler. Design method for water inlet and air inlet were the same. 14 and 30 degrees were defined for contractive angle and water fetching angle respectively. The equation of offset length and base circle relationship as well as the equation of working area and base circle were established using the method of quadratic regression analysis.2. Some kinds of new type of fluidic sprinklers were developed, including the continuous operated fluidic sprinkler, the outside signal fluidic sprinkler, the three section fluidic sprinkler and the twice wall-attachment fluidic sprinkler. Their structure and working principle were described respectively. An orthogonal array with five factors and four levels was selected to carry out the experiments for the continuous operated fluidic sprinkler. An orthogonal array with four factors and there levels was selected to carry out the experiments for the outside signal fluidic sprinkler. The best values of their structure parameters were confirmed after the experiments.3. The formula for calculating the mechanics characteristics of the complete fluidic sprinkler was summarized up. The performance parameters for the complete fluidic sprinkler and impact sprinkler were contrasted by experiments. The results demonstrated that the adjustable range of stepping angle and frequency for the complete fluidic sprinkler was much bigger than that of the impact sprinkler. To enlarge the scope of working pressure for the complete fluidic sprinkler, the turning angle was added in the effuser. It can increase the intrinsic driving moment for the sprinkler. The important structure parameters for the turning angle effuser included the angle and arm of force. Experiments were carried out based on seven effusers of different turning angles or arms of force. It can be seen from the results that the testing value agreed well with the theoretical analysis. Turning angle positively influenced the stepping angle and uniformity coefficient, while negatively influenced the stepping frequency. Turning arm of force positively influenced the stepping angle, and negatively influenced the wetted diameter.4. Mathematical model for the inner flow of the complete fluidic sprinkler was established using computational fluid dynamics. The FLUENT was used to numerical simulate the inner flow of the sprinkler. When turning angle was 2 or 5 degree for the effuser, the relationships between driving force, transfer driving force and flux were calculated by numerical simulation. The average deviation of the results between theoretical analysis and numerical simulation was less than 5 percent. Computational fluid dynamics method was applied to calculate the stepping frequency, the lean-wall position and the relationship between flux and working pressure. The simulated results agreed well with the experimental results.5. The theoretical study of variable irrigation for the complete fluidic sprinkler was carried out. The boundary equations of rectangular irrigated area were developed. The relationships between wetted diameter, working pressure and operated time were simulated using the MATLAB programe. The activity pieces to achieve rectangular irrigation for the complete fluidic sprinkler were designed. The irrigated water distribution was measured and the three-dimensional water distribution picture was drawn. The frequency control technology was brought into the sprinkler irrigation system. Energy consumption analysis was carried out for the variable-rate irrigated system. The data was tested and collected using the virtual instrument technology. The results demonstrated that rectangular irrigation can be achieved both by mechanical activity pieces designing and frequency control technology. It supplied theoretical foundation of variable rate irrigated sprinkler for the future. 6. Combination irrigation for the complete fluidic sprinkler was studied firstly. The MATLAB was used to analyze the data of water distribution. The data can be made visible in multidimensional orientation as a result. It was proved to change the radial data into net data conveniently and reliably. And three-dimensional water distribution pictures for sprinkler and combined sprinklers were drawn. According to the tested data, the total water depth of net point was calculated using superposition method. Then the combined uniformity coefficient of the complete fluidic sprinkler was simulated in different combined spacing. After the simulation, combined spacing coefficient was chosen by 1.2 in the rectangular combination, and 1.5 in the triangular combination. The average uniformity coefficient can be 82.4% and 85.7% respectively. A case study shows that the MATLAB is reliable for simulating water distribution in sprinkler irrigation.7. Series of PXH sprinklers were manufactured into plastic sprinklers, but there were still some problems. After field experiments, six respects were put forward to improve the working conditions. There were two important respects that must be improved. First, the match of hollow shaft and connected case must be revised. Second, the two fluorine circle should be movable fitted. After the resolved schemes, the reliability of field operation was increased and the PXH complete fluidic sprinklers could be put into mass production.
Keywords/Search Tags:complete fluidic sprinkler, precise sprinkling, variable spraying, unit sprinkling, numerical simulation, orthogonal experiment
PDF Full Text Request
Related items