Engineering Mechanics Fluid Mechanics Week 1 Chapter 1
- Slides: 28
Engineering Mechanics Fluid Mechanics (Week 1) Chapter 1 Introduction Hsin-Yuan Miao, Ph. D. Assistant Professor Department of Mechanical Engineering National Kaohsiung University of Applied Science 415 Chien-Kung Road, Kaohsiung, 80778, Taiwan R. O. C. TEL : 886 -7 -381 -4526 ext. 5351 FAX : 886 -7 -3831373 Mobile : 886 -937 -215 -638 E-MAIL : kenymiao@cc. kuas. edu. tw http: //www 2. kuas. edu. tw/prof/kenymiao/index. html
Chapter 1: Introduction ---1. 1 Some Characteristics of Fluids What is “Fluid”? (water, oil, air)(contiuum連體) ------is based on how materials deform under the action of an external load. A fluid is defined as a substance that deforms continuously when acted on by a shearing stress of any magnitude. (flow). A shearing stress is created whenever a tangential force acts on a surface When common solids such as steel or other metals are acted on by a shearing stress, they will initially deform (usually a very small deformation), but they will not continuously deform (flow). What is “rheology”(流變學)? (slurries, tar, putty, toothpaste)
Shearing Stress
Chapter 1: Introduction ---1. 2 Dimensions, Dimensional Homogeneity, and Units A system for describing these characteristics both qualitatively (定性 )and quantitatively (定量). The qualitative aspect serves to identify the nature, or type, of the characteristics (such as length, time, stress, and velocity) The quantitative aspect provide a numerical measure of the characteristics. (units) Primary quantities---lenth(L), time(T), mass(M), temperature(θ) Secondary quantities---area=L 2, velocity=LT-1, density=ML-3, F=MLT-2, σ=FL-2=ML-1 T-2 And see page 3, Table 1. 1
Dimensionally homogeneous (因次均一性) 方程式的各項應具有相同的因次 1。For example of Velocity V = V 0 + at LT-1 = LT-1 + LT-1 2。For example of gravity D = 16. 1 t 2 ------ constant=LT-2 » D = ½ g t 2 ------g = 32. 2 ft/s 2, 9. 8 m/s 2 。restricted homogeneous ? 。general homogeneous ? 1. 2. 1 System of Units – BG, SI
Chapter 1: Introduction ---1. 3 Analysis of Fluid Behavior 1. 3 Classification of Fluid Flow 1 Viscous versus Inviscid 2. Internal versus External 3. Compressible versus Incompressible 4. Laminar versus Turbulent 5. Natural (unforced) versus Forced 6. Steady versus Unsteady 7. One-, Two-, Three-Dim.
Chapter 1: Introduction ---1. 4 Measure of Fluid Mass and Weight 1. 41 Density 密度 1. 42 Specific weight 比重量 1. 43 Specific gravity 比重 1. 4. 1 Density 密度 (sluds/ft 3, kg/m 3) = ρ (rho) =is defined as its mass per unit volume. = used to characterize the mass of a fluid system. = 不同流體,其值變化極大 = 但對單一流體,隨壓力與溫度之變化極小(氣 則不然)
Chapter 1: Introduction ---1. 4 Measure of Fluid Mass and Weight Figure 1. 1 Density of water as a function of temperature
Chapter 1: Introduction ---1. 4 Measure of Fluid Mass and Weight 1. 4. 2 Specifics Weight (lb/ft 3, N/m 3)(比重量) = γ (gamma) = is defined as its weight per unit volume. = is related to density through the equation γ= ρg = is used to characterize the weight of the system. 1. 4. 3 Specific Gravity(沒單位) = SG = is defined as the ratio of the density of the fluid to the density of water at some specified temperature. = SG = ρ/ ρH 2 O 4ºC ρHg = (13. 55)(1. 94 slugs/ft 3) = 26. 3 slugs/ft 3 ρHg = (13. 55)(1000 kg/m 3) = 13. 6 x 103 kg/m 3 Hg 20 ºC SG= 13. 55
Chapter 1: Introduction ---1. 5 Ideal Gas Law Gas are highly compressible in comparison to liquid. 氣體密度的改變直接引起壓力和密度的變化。 P = ρRT Ideal Gas Law(近液化狀態時不合用) 只要不要接近液化狀況,在正常狀態下的氣體,其行為可以此方程 描述 P = absolute pressure 絕對壓力 ρ = the density 密度 R = a gas constant氣体常數(視氣体種類及分子量而定) T = the absolute temperature 絕對溫度
Chapter 1: Introduction ---1. 5 Ideal Gas Law 絕對壓力 = 錶壓力 + 大氣壓力(靜壓) Gage pressure 14. 7 psi, 101. 33 kpa 相對於 單位: BG: lb/ft 2 (psf), lb/in 2 (psi) SI: N/m 2 (Pa) 例:大氣壓 14. 696 psi, 101. 33 kpa For example. . 胎壓 = 30 psi 絕對壓力 = 30 + 14. 7 = 44. 7 psi
Chapter 1: Introduction ---1. 6 Viscosity μ = � 對黏度 = 動力黏度(dynamic viscosity) =黏度(為斜率且呈線 受流體種類而定,且受溫度影響 性) 牛頓流體 Figure 1. 3 Linear variation of shearing stress with rate of shearing strain for common fluids
Chapter 1: Introduction 1. 9 Surface Tension γπR 2 h=2πRσcosθ h = 2σ cosθ/γπR Figure 1. 4 Effect of capillary action in small tubes. (a) Rise of column for a liquid that wets the tube. (b) Free-body diagram for calculating column height. © Depression of column for a nonwetting liquid
- Fluid kinematics example
- Kinematic viscosity symbol
- Chapter 8 fluid mechanics
- Fluid mechanics chapter 3
- Fluid mechanical
- Fluid mechanics chapter 8 solutions
- Week by week plans for documenting children's development
- Is synovial fluid extracellular fluid
- Fluid statics deals with fluid at rest
- Fluid statics deals with
- Transcellular fluid
- Solute definition
- Hypoosmotic
- Movement of body fluids
- Shifting dullness procedure
- Force system in mechanics
- Statics chapter 2
- Statics chapter 4
- Engineering mechanics (9th) edition chapter 12 problem 30p
- A crane
- Equazioni navier stokes
- Loss of head due to sudden contraction of pipe *
- Total head equation
- Dimensionless groups in fluid mechanics
- Reynolds number units
- Fluid mechanics pdhpe
- Non dimensional numbers
- Dimensionless groups in fluid mechanics
- Energy equation fluid mechanics