内容有点多,因为我时间不够,没时间自己去翻译了,占用大家一点时间,帮帮忙给翻译一下这几段,如果时间不够的话就能翻多少算多少吧,谁翻的多并且正确的话分就给谁好了,如果能全翻,而且译的好能加多少分我给加多少分。。。。谢谢了!但是谢绝翻译软件翻译。。。
内容如下:
The tailrace is the channel into which the water is discharged after passing through the turbines. If the powerhouse is close to the stream, the outflow may be discharged directly into the stream, while in other situations there may be a channel of considerable length between the powerhouse and the stream. The tailrace has been a badly neglected feature in many hydroelectric designs. In many low- head plants more of the gross head might have been utilized at very low cost if some attention had been given to tailrace design.
An unlined tailrace may degrade, i.e., the tailwater elevation is lowered by scouring of the channel bottom. In some cases this process has proceeded to the point where the tailwater dropped below the top of the draft - tube outlet and reduced the efficiency of the turbine. To correct this, an overflow dam must be constructed in the tailrace channel to raise the tailwater elevation back to normal. Sometimes the tail-race channel may aggrade, in which case the tailwater elevation rises, with a resulting decrease in the gross head at the plant. This situation may arise where the spillway discharge is close to the tailrace and no adequate training wall is provided. If aggradation is excessive, it may be necessary to remove the material deposited in the tailrace by dredging or other means. In any case a knowledge of tailwater elevation at various flow rates is essential to the hydraulic design of the tailrace. In some instances hydraulic - model studies will give valuable information.
Draft tubes should be provided with an unwatering drain so they can be unwatered for repairs. A gate should be provided at the draft -tube outlet or, where there is a tailrace, stop logs or sectional steel gates may be used between the tailrace piers to shut off water from the draft tube during unwatering. A hoisting mechanism must be provided for the gates or stop logs.
The tailraces of underground powerhouses often present unique problems of hydraulic design. In some instances the draft tube discharges into a horizontal tunnel with a free water surface so that no surge tank is required. In other cases there is a tailrace - pressure tunnel with a regular surge tank. Often the downstream portion of the diversion tunnel can be used as the tailrace tunnel. Such is the case of the Oroville underground powerhouse in California where two 35 - ft (10.7 - m) diameter tunnels 2200 ft (670 m) long are provided.
都说了,谢绝翻译软件,一楼那位一点不通顺,得人工翻译的
另外,如果有时间,还有另外两部分,因为太长所有分三个问题问
第二部分见:http://zhidao.baidu.com/question/98204098.html
第三部分见:http://zhidao.baidu.com/question/98204874.html
谢谢各位了