风能是可再生资源中目前发展最快的清洁能源,风力发电也是具有大规模开发和商业化发展前景的发电方式,近年来,我国风电产业规模逐渐扩大,已成为能源发展的重要领域,在风电技术发展方面,由于相同风速时发电功率的不同,我国目前正逐步采用变桨距控制风力发电机替代定桨距控制风力发电机,来提高风力发电的效率
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E.%3C%2Fmo%3E%3C%2Fmath%3E)
具体风速对应的功率如图乙所示,设甲图中风力发电机每片叶片长度为30m,所处地域全天风速均为
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E7.5%3C%2Fmn%3E%3Cmi%3Em%3C%2Fmi%3E%3Cmo%3E%2F%3C%2Fmo%3E%3Cmi%3Es%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,空气的密度为
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E1.29%3C%2Fmn%3E%3Cmi%3Ek%3C%2Fmi%3E%3Cmi%3Eg%3C%2Fmi%3E%3Cmo%3E%2F%3C%2Fmo%3E%3Cmsup%3E%3Cmi%3Em%3C%2Fmi%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmsup%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,圆周率
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3E%CF%80%3C%2Fmi%3E%3C%2Fmath%3E)
取
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E3.14%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,下列说法不正确的是( )
![](http://tikupic.21cnjy.com/7a/fd/7afdaf76a94a1c310a54e36e0d648c85.jpg)
- A、变桨距控制风力发电机将风能转化成电能的效率为
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E52%3C%2Fmn%3E%3Cmi%3E%EF%BC%85%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
- B、用变桨距控制风力发电机替换定桨距控制风力发电机后,每台风力发电机每天能多发电
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E7200%3C%2Fmn%3E%3Cmi%3Ek%3C%2Fmi%3E%3Cmi%3EW%3C%2Fmi%3E%3Cmo%3E%C2%B7%3C%2Fmo%3E%3Cmi%3Eh%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
- C、无论采用变桨距控制风力发电机还是定桨距控制风力发电机,每台发电机每秒钟转化的空气动能均为
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E7.69%3C%2Fmn%3E%3Cmo%3E%C3%97%3C%2Fmo%3E%3Cmsup%3E%3Cmrow%3E%3Cmn%3E10%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmn%3E5%3C%2Fmn%3E%3C%2Fmsup%3E%3Cmi%3EJ%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
- D、若煤的热值为
,那么一台变桨距控制风力发电机每小时获得的风能与完全燃烧45kg煤所产生的内能相当