Study On Influence Of Hydraulic Characteristics For Differentarea Reduct Ration On Tooth Pier Energy Dissipation

This paper combined with the “Experimental Study on hydrauliccharacteristics of tooth block energy dissipater”, on the basis of the previousstudies, the adjustment and the optimization of test scheme, Its carried out fivedifferent area contraction ratio（0.375、0.44、0.5、0.56and0.625）of tooth blockenergy dissipater and plug energy dissipater through physical model test. Usingthe high precision pressure sensor with DOP3010velocity measurements werecarried out for a total of ten groups working in different flow pressure andvelocity. The discharge capacity, energy dissipation, pressure characteristics andflow characteristics of five kinds of tooth block energy dissipater are analyzed.At the same time, compared the two kinds of energy dissipater flow capacity,energy dissipation and fluctuating pressure variation, reached the followingconclusions:1.The area contraction ratio has decisive functions to the flow capacity oftooth block energy dissipater. As the area contraction ratio increases the flowcapacity is strengthened. The area contraction ratio increased from0.375to0.625, the flow coefficient increases from0.4to0.95.2.As the area contraction ratio increases, the corresponding head losscoefficient decreases. The area contraction ratio increased from0.375to0.625,the head loss coefficient decreased from5.848to1.063.3.The energy dissipation ratio decreases with the increase of the areacontraction ratio in the same flow. he energy dissipation ratio increases with the increase of flow. In the experimental observation range, the maximum energydissipation of schemeA1is up to78%.4.The flow has no effect on the pressure along the pipeline of five kinds oftooth block energy dissipaters which have different area contraction ratio. Thevariation of time average pressure of five kinds of different area contraction isbasically the same along the flow direction. It began to decrease in the placebefore the dental import0.2D. The five groups all reached the minimum value at-0.2D, then began to recover and then tended to be stable. The greater the areacontraction ratio is, the shorter the length of recovery is, the lower dimensionlesspressure is. Decreasing amplitude of time average pressure for all schemesdecrease. The area contraction ratio increased from0.375to0.625, decreasingamplitude of time average pressure from19.83kPa to1.46kPa.5.The fluctuating pressure variation of five different area contraction ratioalong the pipeline is basically same. It is basically stable and the dimensionlessCp is basically same in the teeth of pier section. Near the teeth of pier section, itgrows at the beginning, then it will reduce until that it is stable. The greater thearea contraction ratio is, the shorter the length of recovery is, maximum value ofpulsation pressure coefficient is decrease, the maximum value of pulsationpressure coefficient forA1is0.67.6.The flow of five groups of inlet section and the outlet section is basicallyrectangular distribution. The flow close to the wall is relatively small. Thedistance of center position of upper and lower0.4D is basically the same.Motion in dental section import and export in velocity direction is disorder.7.Comparing the tooth block energy dissipater and plug dissipater, in thesame area contraction ratio, plug energy flow coefficient is better than that oftooth block type， The flow coefficient of plug energy dissipater more0.013~0.036than that of tooth block type energy dissipater。8.In the area contraction ratio, tooth block type energy dissipater ratio is better than that of plug energy dissipater, The energy dissipation ratio of toothblock type energy dissipater more0.70%~2.68%than that of plug energydissipater。...