电大流体力学期末总复习小抄参考.doc

专业好文档期末总复习一、 选择题1. 堰流流量Q与堰上全水头H0的关系是（ ）。 （a）1/2次方的关系 (b) 1次方的关系（c）3/2次方的关系 (d) 2次方的关系2理想流体与实际流体的主要区别在于( )。(a) 是否考虑粘滞性 (b) 是否考虑易流动性 (c) 是否考虑重力特性 (d) 是否考虑惯性3 在均质孔隙介质中,渗流流速u与水力坡降J的几次方成比例 ( )。（a）1/2次方 (b) 1次方（c）3/2次方 (d) 2次方4对于实际流体,总水头线是（ ）的线。（a）沿程下降。 （b）沿程升高。 （c）沿程可升可降。 （d）沿程不升不降。二、判断题判断下列说法是否正确。若正确在括号内划，否则划。1动能修正系数与断面流速分布有关。（ ）2临界雷诺数的大小与流体的性质无关。（ ）3长短是指管道几何长度长的管道。（ ） 4谢齐（Chezy）公式适用于紊流粗糙区。 （ ） 5按程沿程阻力系数的变化规律,尼古拉滋试验曲线分为三个区。（ ） 6对于以重力为主导因素的流动，可按佛劳德准则进行模型设计。（ ）三、简答题 1. 等压面是水平面的条件有那些？2. 流体静压强的有那两个特性？3. 明渠均匀流有那些特性？4. 说明描述流体运动的两种方法（拉格朗日法与欧拉法）的主要区别。四、绘图题 1. 绘出下面图中平面上相对压强分布图。2. 绘出下面图中曲面上的压力体图。五、计算题 1. 在封闭水箱中，（如图），压力表读数为4.9KN/m2，求A点和水面压强。2圆形有压涵管穿过路基，管长，管径，上下游水位差，管路沿程阻力系数，局部阻力系数：进口，弯管，水下出口，求通过流量？ 3宽为1m的矩形闸门AB，倾角45°，水深，求作用于闸门上的静水压力和作用点。 参考答案一、选择题1.（c）2 (a)3 (b)4（a）二、判断题 1（）2（）3（） 4（） 5（） 6（）三、简答题 答:同一介质连续质量力只有重力。答:（1）流体静压强方向垂直且指向受压面。 （2）流体静压强大小与受压面方位无关。3. 答: （1）过流断面面积、水深沿程不变。（2）过流断面平均流速、流速分布不变。（3）底坡线、总水头线、水面线三线平行。（4）沿水流方向重力分量与摩擦力平衡。4.答: 拉格朗日法描述的是质点系法，跟踪流体质点，研究其在空间的运动规律；欧拉法是在空间设点，描述任意空间位置上流体质点的运动规律。四、绘图题 （略）五、计算题 1. 解： （1）A点的压强： （2）水面压强：2 解：（绘出上下游过流断面1-1、2-2）因为河道较宽，忽略上下游流速的影响，以下游水面为基准面列能量方程： 流速： 通过流量：3解：（1）绘出闸门上下游的压强分布图 （2）闸门上的合力 （3）闸门上的合力作用中心（对闸门下端之矩） 合力作用中心距闸门下端垂直距离为。 4解：（1）求Fr （2）判断急流还是缓流因为所以该水流是缓流 期末总复习(2)一、选择题在下列命题中选择出正确的说法，添在括号内。1. 流体中粘性摩擦力的大小与（ ）无关。(a) 两流层间速度差 (b) 流体种类(c) 流层的接触面积 (d) 接触面压力2理想流体与实际流体的主要区别在于( )。(a) 是否考虑粘滞性 (b) 是否考虑易流动性 (c) 是否考虑重力特性 (d) 是否考虑惯性3. 均匀流特征不包括（ ）。 （a）流线平行 (b) 过流断面上符合静水压强分布 (c) 流速及流速分布流程不变 (d) 流速缓慢4. 圆管层流中断面平均流速等于管中最大流速的（ ）。 （a）1/2 （b） 1/3 （c） 2/3 （d） 1/4二、判断题 1恒定流一定是均匀流。 （ ） 2静压强大小与受压面方位无关。 （ ） 3无论流体作何种运动，水平面都是等压面。 （ ） 4真空压强是指没有大气存在时的压强。 （ ） 5总流伯努利能量方程只适用于恒定流。 （ ） 6动量修正系数与速度平方成正比。 （ ）三、简答题 1. 写出流场中流体质点加速度的表达式，并说明其各项的意义。2. 试根据尼古拉兹试验,说明紊流各区沿程阻力系数与和的关系。3. 薄壁小孔口恒定自由出流，流量Q与孔口全水头H0是几次方的关系？4. 写出明渠均匀流形成的条件？四、绘图题 1. 绘出下面图中平面上相对压强分布图。2. 绘出下面图中曲面上的压力体图。五、计算题 1 如图所示，一端封闭的容器中装有水，求A，B，C三点的相对压强。2. 水泵系统如图，管径，流量为，吸水管与压水管的总长为30m，沿程阻力系数；吸水管设有带阀门的莲蓬头，所有弯头，两水面高差，求水泵扬程。（22分）3有一矩形底孔闸门，高，宽，上游水深，下游水深，求作用于闸门上的静水压力和作用点。（16分）4检验不可压缩流体运动是否存在？（10分） 期末总复习(2)参考答案一、选择题1.（d）2(a)3.（d）4.（a）。 二、判断题 1（） 2（） 3（） 4（） 5（） 6（）三、简答题 （每小题 3分，共12分）1. 答: 以上三式中等号右边第一项、表示在每个固定点上流速对时间的变化率，称为时变加速度（当地加速度）。等号右边的第二项至第四项之和、是表示流速随坐标的变化率，称为位变加速度（迁移加速度）。因此，一个流体质点在空间点上的全加速度应为上述两加速度之和。答: (1) 紊流光滑区（2） 紊流过渡区（3） 紊流粗糙（阻力平方）区 答: Q与H01/2成比例。4 答: （1）恒定流。（2）长直棱柱形渠道，糙率不变。（3）无支流汇入、流出。（4）渠道顺坡。四、绘图题 （答略）2. 绘出下面图中曲面上的压力体图。（答略）五、计算题 1. 解： （1）A点的相对压强： （2）B点的相对压强： （3）C点的相对压强： 2. 解：（1）管中流速 （2）列1-1到2-2能量方程（10分） (3)求扬程 （8分） 3解：（1）绘出闸门上下游的压强分布图 （2）闸门上的合力 （3）闸门上的合力作用中心（对闸门下端之矩）上游压强分布图上底边长上游压强分布图下底边长下游压强分布图上底边长下游压强分布图下底边长 合力作用中心距闸门下端为。或直接用解析法求解。4解：（1）不可压缩流体连续方程 （2）方程左面项 （2）方程左面=方程右面，符合不可压缩流体连续方程，故运动存在。 Winger Tuivasa-Sheck, who scored two tries in the Kiwis' 20-18 semi-final win over England, has been passed fit after a lower-leg injury, while Slater has been named at full-back but is still recovering from a knee injury aggravated against USA.Both sides boast 100% records heading into the encounter but Australia have not conceded a try since Josh Charnley's effort in their first pool match against England on the opening day.Aussie winger Jarryd Hayne is the competition's top try scorer with nine, closely followed by Tuivasa-Sheck with eight.But it is recently named Rugby League International Federation player of the year Sonny Bill Williams who has attracted the most interest in the tournament so far.The Kiwi - with a tournament high 17 offloads - has the chance of becoming the first player to win the World Cup in both rugby league and rugby union after triumphing with the All Blacks in 2011."I'd give every award back in a heartbeat just to get across the line this weekend," said Williams.The (lack of) air up there Watch mCayman Islands-based Webb, the head of Fifa's anti-racism taskforce, is in London for the Football Association's 150th anniversary celebrations and will attend City's Premier League match at Chelsea on Sunday."I am going to be at the match tomorrow and I have asked to meet Yaya Toure," he told BBC Sport."For me it's about how he felt and I would like to speak to him first to find out what his experience was."Uefa has opened disciplinary proceedings against CSKA for the "racist behaviour of their fans" during City's 2-1 win.Michel Platini, president of European football's governing body, has also ordered an immediate investigation into the referee's actions.CSKA said they were "surprised and disappointed" by Toure's complaint. In a statement the Russian side added: "We found no racist insults from fans of CSKA." Baumgartner the disappointing news: Mission aborted.The supersonic descent could happen as early as Sunda.The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.They blew it in 2008 when they got caught cold in the final and they will not make the same mistake against the Kiwis in Manchester.Five years ago they cruised through to the final and so far history has repeated itself here - the last try they conceded was scored by England's Josh Charnley in the opening game of the tournament.That could be classed as a weakness, a team under-cooked - but I have been impressed by the Kangaroos' focus in their games since then.They have been concentrating on the sort of stuff that wins you tough, even contests - strong defence, especially on their own goal-line, completing sets and a good kick-chase. They've been great at all the unglamorous stuff that often goes unnoticed in the stands but not by your team-mates.It is as though their entire tournament has been preparation for the final.In Johnathan Thurston, Cooper Cronk, Cameron Smith and either Billy Slater or Greg Inglis at full-back they have a spine that is unmatched in rugby league. They have played in so many high-pressure games - a priceless asset going into Saturday.The Kiwis are a lot less experienced but winning a dramatic match like their semi-final against England will do wonders for their confidence.They defeated Australia in the Four Nations final in 2010 and the last World Cup, and know they can rise to the big occasion.13