2013 Review for Final Exam for Fluid Mechanics and Heat Transfer

1,Part 1 About the Final Examination,Types of Problems1) True or false or fill in the blanks or choose the correct answer (30 points)2) Calculations (70 points): Totally four problemsAll the problems are based on the Course Presentations 考试内容以课件有关内容为准, including all relevant examples in the textbook and exercises mentioned in the course presentations,2,PercentagesPart 1: Fluid Mechanics: Chapters 12 (50%)Part 2: Heat Transfer: Chapter 4 (35%)Part 3: Heterogeneous Flow and Separation: Chapter 3 (15%),3,Part 2Important Equations,4,(1.1-4),(1.1-5),(1.1-9),(1.1-12),5,Discussion：,(1) If one leg of U-tube manometer is connected to the point measured, and the other leg is open to the atmosphere, it can be used to measure the gauge pressure or vacuum of the fluid.,gauge pressure,vacuum,6,Question：If U-tube manometer is used in an inclined pipeline, what does the reading of the manometer mean? p1 - p2 = ?,7,（2）Inverted U-tube manometer倒U形压差计,Density of indicator指示剂 such as air is smaller than that of liquid measured.,A,B (air),8,(3) Calculation of liquid seal height 液封高度的计算,Function of liquid seal: gas will flow out if pressure inside the equipment is over the set one p（gauge pressure）.,liquid seal height:,Water,p,9,(4) Measurement of liquid level液位测量,10,(5) Level glass-tube for long distance liquid level measurement (远距离液位测量装置 ),The pipeline is full of nitrogen,Therefore,11,(1.2-3),(1.3-6),(1.3.5),12,(1.3-28),(1.3-27),13,(1.4-9),(1.4-9), =4f,(1.4-11),The equivalent diameter is 4rH,14,(1.4-17),(1.4-19),For laminar flow,(1.4-23),For turbulent flow, f (Fanning friction factor) is a function of both Re and the relative roughness相对粗糙度k/D.,15,(1.4-32),(1.4-34),Entrance header进口管: Kc= 0.4 (In Chinese textbook, 0.5) Entrance loss factor进口阻力系数Exit header出口管: Ke= 1 Exit loss factor出口阻力系数,16,Local velocity of the point where the impact tube is located,That is,(1.6-1),17,When precise measurements are to be made,(1.6-2),Where, C = 0.981.0,That is,(1.6-4),18,(1.6-9),(1.6-10),(1.6-11),19,Where V0=average velocity through orifice =ratio of orifice diameter to pipe diameter,(1.6-12),Co is the orifice coefficient孔流系数流量系数 and always determined experimentally.,And volumetric flow rate q is,Where q=volumetric flow rate So=area of orifice hole孔板小孔的面积,20,Volumetric flow rate,Rotameters - area meters,21,(2.2-2),(2.2-4),(2.2-5),22,(2.2-8),(2.2-9),23,head H varies with n2,power P varies with n3,capacity Q varies with n,24,The effects of impeller size on capacity, head and power,head H varies with D2,power P varies with D3,capacity Q varies with D,The effects of impeller dimension on capacity, head and power are similar with that of speed-Affinity laws相似律.,25,(2.2-34),The equation is known as system curve equation, or system-head curve equation管路特性曲线方程.,26,(3.2-16),27,（3.2-22）,If K2.6, Stockes law applies.,(3.2-16),if 68.9 K2360, Newtons law applies.,28,The minimum terminal velocity:,The minimum diameter of the particle which can be settled :,Q= volumetric flow rate of dust-laden gas,含尘气体的体积流量,29,The maximum capacity of the gravity settling chamber,重力降尘室的最大处理量（生产能力）,30,Filtration Operations-Basic Equations,31,单位过滤面积得到的滤液体积,The basic equation for Constant-pressure filtration恒压过滤方程式:,(3.4-19),(3.4-18),32,(3.4-26),The capacity of drum filter Q in m3/s is,(3.4-27),转筒过滤机的生产能力,33,In Continuous filtration, the resistance of the filter medium is generally negligible compared with the cake resistance. So in Eq.(3.4-27), Vm=0.,or,The capacity of drum filter Q in m3/s is,(3.4-28),34,For a shell-and leaf filter the flow rate of the wash liquid,(3.4-30),For a filter press the flow rate of washing,(3.4-33),(3.4-32),35,(4.2-9),The rate of heat flow through several resistances in series is,36,(4.2-14),(4.2-15),(4.2-16),(4.2-17),37,(4.3-6),38,Enthalpy balances in total condensers全凝器,(4.3-7),=latent heat潜热 of condensation of vapor,39,Enthalpy balances in total condensers全凝器,(4.3-8),40,(4.3-9),(4.3-10),41,(4.3-14),(When 1/2T 2 / T 110000，0.760,Use average fluid temperature when evaluating the fluid properties k, cp, and , (定性温度).,45,A better relationship for turbulent flow is known as the Sieder-Tate equation,(4.4-26),Equation(4.4-26) should not be used for Reynolds numbers below 6000 or for molten metals, which have abnormally low Prandtl numbers.,Where W = fluid viscosity under wall te