تعيين ضريب افت موضعي اتصالات براي لوله هاي موجدار زهكشي ساخت داخل

Determination of Junction head Loss Coefficients for local corrugated Drainage Pipes

Substituting manhole structures in agricultural drainage and urban sewer networks where it is applicable* with simpler junctions at the connection of the lateral and collector would considerably improve the project economy. Such pipe fittings have been used in many countries and recently were manufactured and used in drainage and sewer networks in Iran. However, the hydraulic characteristics of these fittings and their influences on the discharge capacity of the network, which has a decisive rule in the design process, were yet to be known. In this research by construction a specific prototype-scale experimental setup the hydraulic characteristics of the thread-type and hand-made junctions were investigated and determined. Data were compiled for wide-ranging of longitudinal slopes and discharge ratios and the local head loss coefficients were determined and presented in dimensional and non-dimension plots. The possibility of proposing an average value for the coefficients for the ease of practical applications and their impacts on the predicted values were also investigated. The results indicated that the application of average coefficient values predicted the water surface profile reasonably. especially for higher discharge values which are usually considered in the design process. The application of the results of this research in conveyance capacity determination models could reduce the uncertainties of the design process and assist in choosing reasonable safety factors.