Experimental Study On Hydraulic Characteristics Of Two-Teeth Block

The teeth pier energy dissipater is one energy dissipation way which achieve dissipation through creating maelstorms in water so as to consume water energy.This way has its own advantages on simple layout and high dissipation efficient.According to a number of studies relased by Shanxi Province Natural Science Fund Project in “The test study for hydraulic characteristic of tooth pier energy dissipatation,” this way meets discharge caoacity while enhacing energy dissipation rate compared with plug in a same area contraction ratio.Based on the research on single-stage teeth pier energy dissipation through physical model,analyzing the impacts on hydraulic characteristic form gap of secondary teeth pier and rotation angle of teeth angle,including pressure chaacteristics,dicharge capacity,energy dissipation characteristics and cavitation characteristics.The trial choose two same size tooth pier energy dissipation with 0.5 area contraction ratio and 4 tooth pier and set 5 gap(40cm,60 cm,80cm,100 cm,120cm)and 3rotation angle(0°,15°,30°),which in total 15 project,to began to physical model trial.We can draw conclusions within the flow range given by the trial.1.When the gap of the two-stage tooth pier from small to large,It will has a certain impacts on the pressure,discharge capacity,energy dissipation characteristics and cavitation characteristics when the gap of the two-stage tooth pier from small to large,but when the two pier gap increased to 100 cm after the time pressure,the flow coefficient,energy dissipation will gradually stabilized.2.The relative rotation angles of the two tooth pier can affect the pressure,discharge capacity,energy dissipation characteristics and cavitation characteristics.When the gap of the two-stage tooth pier is small,the change of the angle of the secondary tooth pier will cause the average pressure increase,and then the discharge capacity will be weakened while the energy dissipation rate will increase and the cavitation number will decrease;And when the gap between the two tooth piers gradually increases,the influence on time-average pressure,discharge capacity,energy dissipation rate and cavitation number will be weakened gradually after a change of the relative angle of the two tooth piers;when the gap of the two tooth is greater than 100 cm,the relative angle of the change pier is contributed little to the time-average pressure,discharge capacity,energy dissipation rate and the cavitation number.3.With the gap of teeth pier increased,the time-average pressure of the second teeth pier is obviously different.When the distance is 40 cm and angles in average,the time-average pressure coefficient is 3.8,the distance is 100 cm among three types rotation angles,the time-average pressure coefficient is 4.7times.The Indicating that the gap of teeth pier is small,the second velocitydistribution is not fully adjusted which closing to the state of the uniform flow.4.When the rotation angle is 0°,the pulsation pressure coefficient of the two tooth piers is close to each other,and the variation range of Cp is between 0.28 and 0.37.As the rotation angle increases,the ripple pressure coefficient of second teeth pier increases,and when the rotation angle is 30°,the increasing proportion decreases with the increase of the gap.5.When the Reynolds number is about 1.8×105,the flow rate is changed from the turbulent transition zone to the resistance squared region,and the flow coefficient increases with the Reynolds number in the turbulent transition zone.When the water is in the resistance squared region,the flow coefficient has nothing to do with the Reynolds number.6.The flow coefficient changes in the tested range of 0.37 to 0.47.It is about0.46 in the case of sufficient turbulence.In the turbulent transition zone,the larger the rotation angle is,the smaller the flow coefficient is.This effect decreases with the increase of the gap of the teeth pier.When the space is 40 cm,the flow coefficient of 30 degree rotation will fall 2.38% compared to that of non rotation.7.Compared with all the experimental schemes,it was found that the ratation of angel of teeth pier can greatly improve the energy dissipation rate when the gap of the teeth pier is small.The highest energy dissipation rate is tested when the teeth pier is 40 cm and the rotation angle is 30 degrees.That rate can reach a maximum of 82.6% in the test flow range When the distanceincreases 100 cm later,the energy dissipation rate did not change significantly with a recorded rate of nearly 69%.8.The energy dissipation rate can increase by 92% the discharge capacity reduce by 28% in the second stage energy dissipator compared with the single-stage energy dissipator.It is clear that the energy dissipation rate can be effectively increased under the premise of ensuring the discharge capacity.The experimental research findings about the second stage nergy dissipator will be extremely helpful to make further relevant research.