Investigation of the energy dissipation and aeration effect of different types of baffle blocks in free surface flows

Selecting the shortest route of open channels provides an economical solution in water transport systems. In an open channel route where the elevation difference is high, extremely flow velocities are not desired. Drop structures or energy-dissipating blocks are placed at certain distances to the base of the channel to dissipate the velocity and thus the kinetic energy of the flow. Energy dissipater blocks reduce the energy of the flow and at the same time aerate the flow, allowing harmful gases in the water to pass into the atmosphere and oxygen in the atmosphere into the water. Energy dissipater blocks are widely used in river improvement works, waste water systems, rainwater collection channels, agricultural irrigation systems, inclined chutes. In this thesis, the energy dissipation and oxygenation effects of new block types have six different geometries were experimentally and numerically investigated. Tests were carried out according to six different chute angles and six different discharge per unit channel width, and the results were compared and discussed. The effect of energy dissipater blocks on Oxygen Transfer Efficiency (OTE) was investigated experimentally. In addition, using the Computational Fluid Dynamics (CFD) method, the energy dissipating and other flow properties of the blocks were numerically-analyzed in 3D numerical domain. The compatibility of the results of the analysis with the experimental data was discussed with graphics and numerical simulations. The energy dissipation and OTE values of the blocks differed for different chute angles and unit flow discharges. Type-1 and Type-6 blocks showed the best performance at high chute angles. It was observed that the block types proposed in this thesis generally have good energy dissipation and oxygenation performance.