流体力学复习资料及英文专有名词解释

1、Chapter 1 Fluid static流体静力学1. 连续介质假定（Continuum assumption） : The real fluid is considered as no-gap continuousmedia, called the basic assumption of continuity of fluid, or the continuum hypothesis of fluid.流体是由连续分布的流体质点（fluid particle）所组成，彼此间无间隙。它是流体力学中最基本的假定，1755年由欧拉提出。在连续性假设之下，表征流体状态的宏观物理量在空间和时间上都

2、是连续分布的，都可以作为空间和时间的函数。2. 流体质点（Fluid particle）: A fluid element that is small enough with enough moles to make sure that the macroscopic mean density has definite value is defined as a Fluid Particle宏 观上足够小，微观上足够大。3. 流体的粘性（ Viscosity） : is an internal property of a fluid that offers resistance to shea

3、r deformation. It describes a fluid's internal resistance to flow and may be thought as a measure of fluid friction.流体在运动状态下抵抗剪切变形的性质，称为黏性或粘滞性。它表示流体的内部流动阻力，也可当做一个流体摩擦力量。The viscosity of a gas increaseswith temperature, the viscosity of a liquid decreases with temperature.4.牛顿内摩擦定律Newton's la

4、w of viscositydz5. The dynamic viscosity 动力黏度）is also called absolute viscosity （绝对黏度）.The kinematic viscosity （运动黏度） is the ratio of dyn amic viscosity to den sity.v = 一P6. Compressibility （压缩性）： As the temperature is constant, the magnitude of compressibility is expressed by coefficient of volume

5、compressibility积压缩系数 ） K a relative variation rate （相对变化率）of volume per unit pressure.dV VdV2/瓷（m N dpVdpThe bulk modulus of elasticity （体积弹性模量）E is the reciprocal of coefficient of volumecompressibility K .dpdV7.流体的膨胀性（expansibility; dilatability）： The coefficient of cubical expansion （体积热膨胀 系数）a t

6、 is the relative variation rate of volume per unit temperature change.dV VdVVdT1 K,1 oC8. 表面张力Surface tension: A property resulting from the attractive forces betweenmolecules.c-单位长度所受拉力9. 表面力 Surface forceis the force exerted on the contact surface by the contacted fluidor other body. Its value is

7、proportional to contact area.作用在所研究流体外表面上与表 面积大小成正比的力。Stress （应力）is the surface force on per unit area.10. 质量力 Mass forceThe force acting on every fluid mass particle within the control body.Its value is proportional to its mass. Mass force is also known as body force作用在流体的每一个流体质点上，其大小与流体所具有的质量成正比。1

8、1. Euler Equilibrium Equations!欧拉平衡微分方程（分量式）1775 年1.:PPhysical Meaning:（虫,込込；：X，；：y ' :zareFor the fluid in equilibrium, surface force comp onents per mass fluid are equal to mass forcecomp onents per mass fluid. Pressure variati on rate in axes direct ionsequal to mass force components per unit

9、 volume in axes directions respectively（fx,fy,fz）12. constant-pressure Surface等压面）a surface that the pressure of every point in liquidis equal. Common constant-pressure surfaces are free liquid surface and interface of two unmixed fluids in equilibrium.平衡流体中压强相等的点所组成的平面或曲面。p = C 或 dp = 013. Pressure

10、 Distribution in the Static Fluid重力场中流体的平衡Conclusions:p = - ?gz C1. Pressure at a point in a static fluid un der gravity in creases lin early with depth.2. Pressure at a point in a static fluid un der gravity is equal to the sum of the pressure at the free surface and the fluid specific weight timin

11、g depth.3. constant-pressure surface in a static fluid under gravity is a horizontal plane.4. Exte nded: while the pressure at a point and the depth differe nee betwee n two points are known, the pressure at ano ther point can be calculated.14. Absolute pressure绝对压力）,Gage pressure相对压力，又称 表压力 ” ）,and

12、 Vacuum真 空度）:表压力=绝对压力-大气压力 ；真空度=大气压力-绝对压力15. Fluid in Relative Equilibrium相对静止流体）Equation of constant-pressure surface等压面方程）:a）Uniform Linear Acceleration等加速度直线运动流体 ：a cos ： dy （asin 匚-g）dz 二 0b) Uniform Rotation about a Vertical Axis等 角速度旋转流体Chapter 2 basic equations of fluid mechanics16. 迹线 pathli

13、ne: the trace after a single particle travels in a field of flow over a period of time.流体质点的运动轨迹曲线dy空 dtu x,y,z,t v x, y, z,t w x, y,z,t17. 流线 streamline : a curve that show the direction of a number of particles at the sameinstant of time.某一时刻处处与速度矢量相切的空间曲线-瞬时性。dxdydzu(x,y,z,t)v(x,y, z,t) w(x,y,z,t

14、)18. Stream-tube(流管)Consider a closed curve(not streamline) in the flow field, then drawstreamlines through every point on it, so as to form a tube-shaping space whose walls are streamlines. This tube is called the stream-tube.在流场中任取一个有流体从中通过的圭寸 闭曲线，在曲线上的每一个质点都可以引出一条流线，这些流线簇围成的管状曲面称为流管。19. Tube-flow

15、 流束Fluid fulling the stream tube is called the tube-flow and the limit of atube-flow is a streamline.流管内的全部流体称为流束。20. Mini stream-tube 微小流束The stream tube with an infinitesimal section is said to bemini-stream tube. Streamline is the extreme case of mini-stream tube.截面无穷小的流 束。21. Total flow 总流Total

16、of countless mini-stream tubes is called total flow.包含流动中所有的微小流束。22. Cross section过水断面 )-The section is perpendicular to the direction of fluid flow. (suchas pipe flow and channel flow)与流束或总流流线dA, A成正交的断面。23. Discharge(流量)-Amount of fluid pass through a cross section per unit time (such as the secti

17、on in the channel or pipe)单位时间内通过某一过水断面的流体体积称为体积流量，简称流量。24. Mean velocity 断面平均流速 -The velocities of points on the same cross section in the total flow are different, so usually an average velocity is used instead of the real velocityover the cross section, this average velocity is called the mean ve

18、locity.25. Uniform flow 均匀流： is defined as uniform flow when in the flow field the velocity andother hydrodynamic parameters do not change from point to point at any instant of time （in which the cross section of each stream tube remains unchanged.流 场中每一空间点的 各运动参数（速度，压力）不随空间位置而变化。（v）= 026. Nonunifor

19、m flow 非均匀流：Flow such that the velocity varies from place to place at anyinstant.27. Steady flow 恒定流：the flow whose motion factors don' t change wi流场中所有的运动要素不随时间变化.28. Unsteady flow非恒定流：the flow that at least one of its motion factors changes with time.流场中至少有一个运动要素随时间变化29. One dimensional flow （

20、一元流动 ）-all main variables in the flow field can be completely specified by a single coordinate if the variation of flow parameters transverse to the mainstream direction can be neglected流 动参数只与一个坐标变量有关。30. Two dimensional flow（ 二元流动）-fluid motion factors are function of two space coordinates.流动参数与两个

21、坐标变量有关。31. Three-dimensional Flow （三元流动）:Fluid flow ' motion factors are functions of three space coordinates流动参数与三个坐标变量有关。32. System （系统）is a set of definite fluid particles selected in the interest of researcher.由确定的流体质点组成的流体团或流体体积V（t）。系统边界面S（t）在流体的运动过程中不断发生变化。反映了拉格朗日观点33. Control volume （控制体

22、CV）is defined as an invariably hollow volume or frame fixedin space or moving with constant velocity through which the fluid flows.相对于坐标系固 定不变的空间体积 V。是为了研究问题方便而取定的。反映了欧拉观点For a CV:1）its shape, volume and its cs can not change with time.2）it is stati onary in the coord in ate system. （in this book）3）

23、there may be the excha nge of mass and en ergy on the cs.34. Control surface 控制面：the surface area completely encloses the CV边界面 S 称为控制 面。：二 0.'z35. differential fop of continuity equation 微分形式的连续性方程ctexcyFor incompressible fluid.：Vx.：VzFor 2-D incompressible flowv+ = 0；x ：yPhysical meaning: The

24、net mass discharge entering the control volume is equal to the mass in creased in un it time due to the cha nge in den sity.Fit for: Steady flow, un steady flow, compressible and in compressible fluid, ideal fluid and real fluid.36. Integral form of continuity equation 积分形式的连续方程cP+ f P =¥ 8 -Ph

25、ysical meaning：在单位时间内，由于控制体内密度变化引起的质量变化量（增加量或减少量）与通过控制体表面的质量净流出量（流出与流入的质量差）之和等于零。37. Motion Differential Equation 运动微分方程For IDEAL FLOWp c-+-+-+-+-+p +p38. Bernoulli Equation伯努利方程(1) steady flow 定常流动(2) incompressible flow不可压缩(3) integration along a streamline沿流线积分(4) mass force is a potential force质

26、量力有势For streamline+ +PFor compressible flow in gravity fieldV22P2.22 . z hf2g2 fVi2Pizi2g1For compressible flow with fluid machinery in gravity fieldV12Pi2gV22P22gZ2 hfz(m) -the elevation height above datum surface 0-0, called the elevation head (位置水 头)p/( ?g)- rising height of fluid with unit weigh

27、t un der the acti on ofpressure P, called thepressure head(压力水头).u2/(2g)rising height of fluid with unit weight un der the action of velocity V , called the velocity head (速度水头),denoted as huhfthe lost mechanical energy from 1 to 2 points per unit weight fluidThe effective energy obtained after the

28、unit weight of the liquid flows through the pump.单位重量液体流经泵后获得的有效能量。Head of delivery扬程2 2H=21.g.Z2-Zi旳 2gThe sum of them is called thetotal head (总水头),denoted asH.HtPump power 泵功率:Pw = H tQFor the ideal-fluid total flow理想流体总流的伯努利方程2ZiV22gfor the real-fluid total flow实际流体总流的伯努利方程2gui22?g 2ghf39. momen

29、tum integral equation 动量积分方程For CV川"；V)dV卩 v(v n )dS =川 PfdV + pndSsum of the fluid momentum change in CV and the net outflow momentum in CS, is equal to the resultant force.Steady flow：働 P v(v n)dS =川 PfdV + f pndSSVS40. Moment-of-momentum integral equation 动量矩积分方程.:(r："v).:tdV乙(r v)珥v md

30、S ! (r f )dVS(r pn)dSVFor steady flow：乙s (r v)：(v n)dS珥r f)dVJr Pn)dSV流出动量矩cs -流入动量矩cs =合外力矩cv+cs41. Forces onbend(弯头)Fx QV2COS Vj (J - Pa)A -(卩2 - Pa)A2COSFy - -、Qv2 sin v - (p2 - pa) A sin42. fluid jets on deflector(导流板)R' = -'QMcosr -Vi) (pi - Pa)A -(P2 - Pa)A?cosRy = -PQvzSin日 -(P2 - Pa)

31、Asin43. Sprinkler(贲水器)角速度:V（1 叨2 2124Q(1 2)d2(ri2；)固定所需力矩M = 'Q(viv2)4'Q2(i J)JIChapter 3 Pipe Flow and Boundary Layer Theory!管 流和边界层概述)44. Laminar flow （层流）: In the fluid flow the fluid particles move along smooth path in layers without transverse velocity in the direction of main flow, one

32、 layer glides smoothly over an adjacent layer.45. Turbulent flow （紊流, 湍流）or Turbulence : If the fluid particles have a transverse velocity normal to the main flow direction, that leads to particles mixing up each other, with a violent transverse interchange of momentum. This is turbulent flow （紊流,湍流

33、）or turbulence.46. Reynolds number雷诺数：is used to describe the characteristic of flow.厂WDVDRe =V47. Wetted perimeter （湿润长度）:The length of wall contacted with liquid.48. the hydraulic diameter （水力直径 ）Dh： The characteristic dimension of noncircular tube.49. Head Loses（能头损失，或水头损失 ）：the total energy loss

34、es per unit weight （单位重量流体所损失的机械能为能头损失（水头）,which due to the resistance between twosections of gradually varied flow.（流体流动，克服粘性内摩擦力，消耗机械能为热能.）50. Friction Loss沿程水头损失（“）:In the flow through a straight tube with constant cross section, the energy loss increaseslinearly in the direction of flow and the

35、loss is called friction loss （原因：粘性内摩擦力，以及与管壁的摩擦阻力）2Darcy-Weisbch 达西-韦斯巴赫）Equation: ,L vh 了 -人D 2g入:the coefficient of friction loss沿程阻力系数，与流态和壁面有关51. Local losses局部水头损失（hs） : When the shape of flow path changes, such as section enlargement and so on, it will give rise to a change in the distributio

36、n of velocity for the flow. The change results in energy loss, which is callenh inor lossor local loss 原因: 流速 急剧变化，流体质点剧烈撞击和摩擦.2尸vh =_ 2gZ : minor loss coefficientor local loss coefficient为局部阻力系数,与障碍物形式有关52. Head losses 总能量损失（hf=hx+hs）hf 八h4卩卜旧53. LAMINAR FLOW THROUGH CIRCULAR TUB圆管中的层流 Velocity dis

37、tribution in cross sectionP 22wDu（r）=4 l（r -r）-Ap2UmaxR4LDischarge dqv 二 udA = u（r）2二 rdrRqv 二 dqv 二：0 u（r）2二rdrf-（R20 4L42佥亠主Umax: Rqv =vA2二 v 二 RVR2 J%-r2 2二 rdr 二8U 24 : Dp128L比:R2* dAHagen-Poiseuille（哈根-泊肃叶）equation.Distribution of shear stress 切应力分布理二空rdr2L2壁面剪切力='：PR=8v w _2L ReF = dw2二 RL

38、蚩2二 RL -R2 ：p =8"护二 R2Lv2LR254. Head loss along the path 沿程能量（阻力）损失pressure drop压强损失»8匕.128严.32严=8屮十为二 R4d2R2Head loss水头损失:v二 gR128 Lqv4: gd32 Lv 8 Lv2 2"-gd gRthe coefficient of friction loss64 二 64vd RePower loss（功率损失）:W 二:?gh.qv = pqy = pAv2v二d48Lq；128Lq4: R4:The phenomenon that th

39、e physical parameter55. Pulsation Phenomenon （脉动现象） fluctuates around a certain average value is calleqpulsation phenomenon （脉动现象） u= u + u'where: u is time-average velocity （时均速度）;u' -the component of random fluctuating velocity脉动速度）.56. hydraulic smooth 水力光滑 ）:If viscous sublayer more than

40、 absolute roughness ; （ie. > ;）, the effect of ；for the core of turbulent flow is very little, namely, the influence of ； in the energy loss is very little.57. hydraulic rough 水力粗糙 ）:If viscous sublayer less than absolute roughness ； （ie. < ；）, the fluid particles with certain velocity impact

41、or crash the roughness projections of pipe wall, so the velocity of these particles changes radically. It causes eddy涡流）or vortex （漩 涡）locally. Meantime the influence is transferred to the core of turbulent flow. So ； plays an important role in the energy loss.58. Parallel lines 并联管路By a few simple

42、lines or tandem line which inlet side and outletpiping connected respectively.hf = hf! = hf2 41II11discharge Q = Q! Q2 L L59. Pipeline in series/ tandem lines（串联管路）：By a couple of different diameter ordifferent roughness pipe line.hf Qk + r鉴+送匚上+己2< d!丿2g 、 d2Total discharge Q 二 wA 二 v2 A 二 L L60

43、. Boundary Layer边界层：The fluid particles on a solid boundary must adhere to粘着，附着） the solid wall in spite of （不论）the Reynolds number Re in the flow. The velocity of fluid near the boundary varies rapidly in a steep （陡的）velocity gradient （速度梯度 ）outward normal to the wall where the fluid has a zero vel

44、ocity. The velocity gradient sets up （产生） shear force near the boundary and for this reason the effect of viscosity can not be neglected in the region. This region called Boundary layer.The larger the Reyno Ids nu mber is, the thinner the boun dary layer is.Chapter 4 Orifice Outflow and gap flow孔 口出

45、流与缝隙流动 ）61. Thin-walled orifice （薄壁孔口 ） : l/d 一2 ,the edge thickness slightly effects the jet flow,and only minor loss was considered, the contracted section located at d/2 after the hole.62. Thick-walled orifice厚壁孔口 ）: 2 l/d_4 , also named long orifice长孔口 ）/nozzle（管嘴）.63. big orifice（大孔口）with the h

46、eight.The edge thickness distinctly effects the jet flow, and the flow was first contracted and then diffused until contacting the wall. Both frictional loss and minor loss should be considered.:H/dv=10, the head, pressure, velocity on the section will be changed64. small orifice （小孔口）： H/ d>10,

47、the head, pressure, velocity on the section will NOT be changed with the height.65. free outflow （自由出流）:the jet flows into atmosphere directly, the pressure on the contracted section was BAR, pc=pa.66. submerged outflow （淹没出流）：the jet flows down to the water.67. Contracted section 收缩断面： the streamli

48、nes were contracted after the hole, and the section reached the minimum at d/2, which was the contracted section C.68. contraction coefficient 收缩系数： the ratio between the contracted section area and theCc = Ac/A：1hole area, labeled asCc :69. The discharge calculation of steady free flow in orifice 孑

49、L口恒定自由出流流量计算Vc = , .、2gH =CV . 2gHCv is the velocity coefficient 流速系数2velocity distribution udp z2dx亠C|Z亠C2u max zzzh/2P8lLdischargeqvh二BadzB巾2Lh20 （hz-z ）dzBh3 p12LQ = Av： = ACcCv=：2gH - AC”：2gHC = C C discharge coefficient 流量系数rc v固定平板间的缝隙流动70. gap flow between stationaryaverage velocity12Spressur

50、e loss -p =_Bh371. gap flow between relatively moved parallel plates具有相对运动的两平行平板间的流动velocityu =2：（hz-z2）-U z hqBh3 ：pUBhdischarge%= 12此_ 2压差与平板运动方向相同取正号；方向相反取负号72. gap flow between concentric cylinders 同心圆环间的缝隙流动.jrdhAp ndUhdischarge qv 124L 一 2Chap. 5 Similitude and Dimensional Analysis相似理论和量纲分析73.

51、 The three similarities are essential conditions of Dynamic Similitude of Fluid Motion（流动 相似）,in which, at any time, all the parameters of the model and prototype are in the same ratio throughout the entire flow field. Dynamic Similitude of Fluid Motion（流动相似） includes Geometric similarity 几何相似,Kinem

52、atic similarity 运动相似,and Dynamic similarity 动力相似;Geometric similarity 几何相似 is the basic and the most obvious requirement; Kinematic similarity 运动相似 is the result; Dynamic similarity 动力相似 is the conditions.dynamic similarity includes kinematic similarity, while kinematic similarity includes geometric

53、 similarity. Hence, ratios of force, time and length are same under dynamic similarity, and other quantities are also equal.动力相似包括运动相似，而运动相似又包 括几何相似。所以动力相似包括力、时间和长度三个基本物理量相似。两系统的其它物 理量由它们决定，也必然相似。The initial conditions（初始条件）and boundary conditions（边界条件）also must be coincident for dynamic similitude of fluid flow except above three similarities