Study On 3-D Numerical Simulation Of The Hydraulic Characteristics Of Lateral Intake With Two-Direction Flow

The intakes adopted in the pump storage plant have the characteristic of two-direction flow. As to the upper reservoir, under the powergenerating condition, it is used as inlet; while under the pumping condition, it is used as outlet. Situations in the lower reservoir are the opposite. In this paper, the hydraulic characteristics of lateral intake such as velocity distribution and head loss have been systematically studied using CFD method. The main contents and conclusions are as follows:(1)The effects of four different factors, the modeling range, mesh division, turbulence model and discretization scheme, on the computational results of the lateral intake with single pipe which run under the inflow condition have been investigated. The results show that, all of these factors have effect on the precision of the calculation. The selecting of the longitudinal modeling range plays a critical role on the success of the simulation. Results of different ranges distinguish to each other very obviously. If it is not sufficient, the results will be totally wrong. The longitudinal modeling range should at least contain the whole forebay, only in this way, can the computational results approach the experimental data. In general, under the condition of the longitudinal modeling range has been fixed, better results can be obtained by expanding a distance, which is two times of the diameter of the diversion tunnel, from the left and right border of the forebay to both sides in the transversal direction. However, continuing expanding the transversal modeling range can not bring great improvement to the results. In the process of mesh generating, the dimensions of the mesh should be decided properly. With the increasing of the number of the mesh element, the precision of the computational results become more and more high. However, not the denser the mesh density, the better the results.When the dense of the mesh achieve to some extent, the results can only be improved slightly. The results ofusing standard k—εmodel, RNG k—εmodel, realizable k—εmodel and RSM are all in good agreement with the experimental data, which shows that all the four turbulence models can be used in the numerical simulation of the inflow condition. It is also found that the results using second order upwind scheme and QUICK scheme are not better than the results obtained by means of first order accuracy discretization scheme. Therefore, not the higher the orders of the discretization scheme, the better the results.(2) The effects of four different factors mentioned above on the simulation results of the lateral intake with single pipe which runs under the outflow condition have also been investigated, and the conclusions are approximately the same compared with those under the inflow condition.(3)From two respects which include the reservoir modeling range and the diversion tunnel modeling range, the effect of modeling range on the computational results of inflow condition and outflow condition in the two lateral intakes arranged in parallel have also been investigated. Under the inflow condition, better results can be achieved under the condition that the longitudinal modeling range of the reservoir contains the whole forebay and the modeling range of the diversion has been selected properly. Neither expanding the modeling range of the reservoir nor increasing the length of the diversion tunnel being modeled can the results be further improved. As to the outflow condition, if the modeling range of the diversion tunnel is insufficient, no matter how to increase the modeling range of the reservoir, the results will hardly fit with the experimental results. Only when the modeling range of the diversion tunnel including the bending section, can the discrepancy be largely reduced.