| Hydraulic lifting dam is a new type of automatic lifting of the river dam,has the dual function of water retaining and discharge.The flow pattern of the hydraulic lifting dam is different from the traditional one,and the discharge capacity can not be calculated according to the traditional dam.In order to study the discharge characteristic of hydraulic lifting dam,the common 3m,4m and 5m of high dam hydraulic lifting dam as the prototype,a design of three fan high dam dam,according to the ratio of 1:30 to make the physical model in the organic glass sink for discharge test.Keep the two ends of the hydraulic lifting dam water retaining state for normal operation,the hole hydraulic lifting dam adjustment to various support angle(0 degrees,14 degrees,28 degrees,42 degrees,56 degrees,70 degrees),and then through the valve regulating flow,downstream water level respectively corresponding to different flow measurement.Influence of flow type,combined with the experimental data and theoretical knowledge of the hydraulic lifting dam leakage variation,flow coefficient calculation formula and flow coefficient factors,flow calculation methods are analyzed,main conclusions are drawn below:(1)Observation test shows that the hydraulic lifting dam mainly has three kinds of pattern in the collapse operation.A three fan hydraulic lifting dam are to maintain normal water retaining operation state,upstream flow,upstream water depth,water flow evenly flows from the top of hydraulic dam,the similar rectangle thin-wall weir weir.The other is a hydraulic lifting dam at both ends to maintain normal water retaining dam running in hole hydraulic lifting dam to adjust to different support angle(14 degrees,28 degrees,42 degrees and 56 degrees),upstream flow,water flow from the part between the hole and both ends of the hydraulic lifting dam dam cracks through a triangle.Part of the top through hole in hydraulic lifting dam,combined with the flow of the equivalent rectangle thin-wall weir and thin triangular weir.The last one is to keep the two ends of the dam for the normal operation of the state of water,the middle of the hydraulic lift dam collapsed flat bottom of the sink,the upstream flow directly from the middle of the set aside,similar to the width of the weir weir flow.(2)When the three hydraulic lift dams are in the normal operation of the water,The discharge coefficient m of hydraulic lifting dam has a good linear relationship with H0/P1,and increases with the increase of H0/P1.The discharge coefficient m is between 0.4 and 0.45.Similar to the rectangular weir,the flow can be calculated using the formula Q=mb(?).The flow coefficient can be calculated according to the empirical formula m=0.403+0.053H0/P1+0.0007/H0.Type H0 refers to the hydraulic lifting dam top head,P1 refers to the vertical height of water retaining dam hydraulic lifting.(3)When the two ends of the hydraulic lifting dam is in the normal running state of water retaining dam in the hole,slumping to various support angle,flow equivalent to thin triangular weir and rectangle thin-wall weir combination.The flow calculation formula can be used:where H is the pore water retaining dam hydraulic vertical height,HO head crest.C is a thin triangular weir flow coefficient,through the test data fitting out formula is:C=8.26cos ?-7.56sin ?,m=0.403+0.056H0/P1 were calculated according to the empirical formula,wherein P1 is a hydraulic lifting water retaining dam vertical height.The larger the supporting angle,the smaller the discharge coefficient of the same dam.Under the same support angle,the dam height is higher,the discharge coefficient m is smaller,and the range of change is smaller.(4)Both ends of the hydraulic lifting dam are in the normal water running state,and the flow pattern of the middle hole hydraulic lifting dam is close to the bottom of the organic glass sink,which is similar to that of the wide crested weir.The calculation of the flow can refer to the calculation of the width of the top weir flow formula.The flow coefficient m can refer to the empirical formula. |
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