Study Of Trapezoidal Labyrinth Weir Optimal Design Based On The Efficient And Safe Utilization

In the arid northern region, phenomenon of water shortage is very serious, and water shortage has become an important bottleneck restricting urban development. As the arid areas main surface water in northwest, rainwater is the main source for water using. It mainly concentrates in the main food season with high peak and big inflow. If we can accumulate the main flood season rain-flood to the reservoirs,and then use it to solve the problem of water shortage during the dry season, the economic benefits will be very obvious. Labyrinth weir can increase the reservoir hennessy capacity and improve the reservoirs discharge capacity that has been built, and the effect is remarkable. As a practical and efficient special weir, labyrinth weir can largely improve the reservoirs and hydropower stations water storage capacity and discharge capacity without changing the weir weight, which is very suitable for the discharge structure that need to improve reservoir flood storage capacity and discharge capacity with the limited weir weight with low maintenance fee, and simple management which is more suitable for medium and small reservoirs. The main methods for labyrinth weir research currently are physics experiments, achievements on using numerical simulation to solve labyrinth weir problems are power. Besides, how to propose certain basic design principles and then establish models based on the analysis of labyrinth weir discharge capacity currently is still an empty. Therefore, we simulate labyrinth weir discharging flow state, discharge capacity with FLUENT. Then propose a standardized method for engineering design based on the analysis of labyrinth weir discharge capacity currently.(1)In the paper, turbulence model was applied to simulate the turbulent overflow of labyrinth weirs, PISO was used for pressure- velocity coupling, and VOF method was used to track for free surface based on unsteady calculation method. We simulated water flow regime of labyrinth weir with different water head by air-water multiphase flow models. The result shows that the computational results are to fit in with experimental data. The main factors affecting the labyrinth weir discharge capacity is napping interference. With the increasing of the nappe interference and scope, labyrinth weir discharge capacity decreasing. Increased sidewall angle can reduce the degree of napping interference intensity and the scope.(2)To simulate labyrinth weir discharge capacity with different sidewall angles and water levels, turbulence model was adopted, SIMPLE method was used for pressure-velocity coupling on steady calculation method. The result shows that the computational results are to fit in with experimental data, verified that labyrinth weir discharging capacity has a relationship with sidewall angle and water head vs weir height, and numerical simulation can be widely used to solve Hydraulic characteristics problems.(3)On the basis of the labyrinth weir discharge capacity analysis, we use non-linear programming method to study the relationship between weir height and sidewall angle by keeping the controlling water level constantly. We make the regular discharging of the labyrinth weir, one cycle palace longitudinal length smaller than the length of spillway control section, the safety of flood discharging as constraints, and make increasing the weir crest elevation to the highest as objective function to set up a model, optimize and compute the model. The results showed that when we kept the controlling water level constantly, the weir height was reducing with the sidewall angle increasing within the labyrinth weir normal discharging. After using the method optimizing labyrinth, We find that when the dam elevation is determined by normal water level, using labyrinth weir can reducing the check water level or design water level, and improve the flood control standard. When the dam elevation is determined by check water level or design water level, using labyrinth weir not only can ensure the flood discharge safely, but also improve the reservoir flood storage capacity.(4)using trapezoidal labyrinth weir to youhe reservoir and Maobaguan reservoir with increasing water storage capacity, the results show that the optimal method is reasonable and labyrinth weir has an advantage in solving water shortage of northeast arid problem.