| The low temperature water released by reservoirs has always been a severe issue,and the available solutions such as stop log gate intake and multi-level intake must be completed before the operation of the reservoir.As a temperature control scheme,the water-separating curtain(WSC)has advantages of convenient regulation and no hydropower loss.However,this novel engineering approach was investigated barely in the stage of numerical simulation,and lacked in measured data to evaluate the improvement effect.In this paper,a generalized reservoir model was established,and then the corresponding physical model experiments were conducted,of which the results proved the effectiveness of the WSC for the amendment to the temperature distribution of the released water.Simultaneously,by means of combining the experimental and simulative results after the application of WSC,the influence pattern on the released water temperature(RWT)was analyzed and the main research contents and achievements were as follows:(1)A generalized reservoir model was established for further simulation,and the prototypical temperature profiles of reservoirs was realized by way of heating the water body in stratification in the physical experiments.In order to figure out the influence on the RWT after the installation of WSC,multiple variations of immersed water depth,discharge quantity as well as temperature distribution were undertaken and analyzed.Simulation and experiment results both confirmed that the implementation of WSC could improve the RWT significantly.Under the Single thermocline temperature profile(S1 reservoir temperature profile),the RWT increased by 6.1~8.4?,and accordingly increased by 2.0~3.5? under Double thermocline temperature profile(S2 conditions).The RWT increased with the decrease of let-through depth,which led to a difference of 1.4? under the S1 temperature profile.The RWT rose up along with the increase of discharge quantity and was slightly affected by changing the elevation of water intake,which caused a difference less than 0.3?.(2)A hydrodynamic model simulating the three-dimensional water temperature distribution was established and validated by the measured results of physical model experiments.The numerical model was used to analyze the influence of various factors on the water temperature field,flow field and RWT.The results showed that the top of the WSC and its vicinity were the main flow zone of the released water body,therefore the change of immersed water depth would influence the mainstream belt so as to the RWT.The increase of discharge quantity would thicken the upstream high-velocity flow area and strengthen the traction effect on the upper thermal layer.The RWT is mainly related to the water temperature of the maximum contribution layer,the boundaries temperature of the mainstream belt and the discharge quantity,thus a formula was proposed to predict the RWT after the installation of WSC,which was validated by the numerical simulation results.(3)The hydraulic model test of Sanbanxi reservoir was carried out to simulate the water temperature profile in mid-May and mid-August.The experimental results indicated that the WSC could enhance the RWT by 3.1? and by 5.2? separately under the scenario of mid-May and mid-August.By comparing the formula-predicted results with the model experiment data of different scenarios,the maximum deviation was 0.35?,which confirmed the feasibility of the predictive formula and provided reliable a basis of the application of the WSC in the practical engineering. |
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