INFLUENCE OF PIPE ANGLE ON BEDLOAD TRANSPORT IN AN INCLINED PIPE
摘要
A number of reservoirs in Nebraska have been retrofitted with sediment bypass systems to extend their lifespan. The bypass systems are best suited for rerouting sediment that travels as bedload since bedload is relatively easy to capture at reservoir inlets. Because of their size, the captured sediment particles sometimes travel as bedload in the bypass system as well. Studies have been done to quantify head losses in horizontal pipes with different water and sediment flow rates, and the results have been used to assess the practicality of bypass systems for specific prototypes. However, much less has been done to evaluate the performance of inclined pipes for bypassing sediment. Furthermore, little has been done to understand how bedforms influence head losses in the pipes. In order to better understand the behavior of sediment transport within pipes, an experimental apparatus was constructed to simulate a range of sediment loading rates, water flow rates, and pipe inclination angles. Three pressure taps with a spacing of 1.5 m were installed in the pipe at a location sufficiently downstream from the inlet. One section of the pipe was replaced with an acrylic pipe of equivalent internal diameter so that bedform shapes and sizes could be measured for different flow conditions. For each flow condition, the pressure drop in the pipe and the sediment transport rate are recorded over time. For coarse sediment, the inclination angle ofthe pipe and the sediment transport rate both have a strong influence on flow properties, and, thus, head losses in the pipe.