t RULES OF THUM FOR MECHANICAL liEH A manual of quick, accurate solutions to everyday mechanical engineering problems J. Edward Pope, Editor RULES OF THUMEI FOR MECHANICAL ENGINEERS Gulf Publishing Company Houston, Texas [...]... Drag OceanographicF o s lw 7 7 1 11 12 12 12 13 14 14 15 15 16 16 16 16 17 2 Rules of Thumb for Mechanical Engineers FLUID PROPERTIES Afluid is defined as a “substance that deforms continuously when subjected to a shear stress” and is divided into two categories: ideal and real A fluid that has zero viscosity, is incompressible,and has uniform velocity distribution is called an idealfluid... 0.75 2.30 4.30 21. oo 0 .1 7 4.50 6.40 9.50 1. oo 0.04 7.00 17 35 11 5 215 10 50 9 225 320 475 50 2 350 K = [I - (D1/D2)2]2 For sudden contractions in the pipeline from a larger diameter D2to a smaller diameter D1, the value of the loss coefficient is: The above relations should serve as guidelines Corrections should be made for enlargements and contractionsthat are gradual Use values of K for fittings whenever... number R,and E is the specific surface roughness of the pipe mterid.The Moody fiic- Ix I d 1x10' l x l d where E is in ft, Q is in cfs, L is in ft, v is in ft2/s, g is in ft/s2, and hf is in f&.lb/lb units IXloL I x 10 7 ReynoMsNumba R Figure 1 Friction factor vs Reynolds number lxld 10 Rules of Thumb for Mechanical Engineers ~~ lasses in Pipe Fittings and Valves In addition to losses due to friction in... v = JM (So - S)/S = J2gAh / 1 k c v +II S pressure p x + SO (a) Static tube and piezometer (b) Pitot tube total pressure pt (c) Pitot-static tube Figure 5 Pressure and velocity measurements 14 Rules of Thumb for Mechanical Engineers If the pitot probe is used in subsonic compressibleflow, the compressibleform of the stagnationpressure should be used: ( ; 1 y p t = p 1+ - By knowing the stagnation... diameter Gravitational constant Constant Name Avagadro's number Gas constant constant Bolkmann constant Speed of light in vacuum Stefan-Boltzmann constant latmpressure Value 6.02 216 9*1Om 53.3 6.62 619 6 '10 -34 1. 38062PlP 913 72300 1. 712 "lP 14 .7 Units Kmor ft-lb/lbml"F J.s JIK Wsec Btu/hr/sq.W~ psi Symbols feet pound mass hour or seconds ampere Fahrenheitor Rankine feeVsecs2 Wsec poundlcu ft sq feet cubic feet... slugs by dividing it by 32 .17 4 before using it in any consistent equation Because of the confusion between weight (lbf)and mass (lbm) units in the U.S inconsistent system, there is also a similar confusion between density and specific weight units It is, therefore, always better to resort to a consistent system for engineering calculations 4 Rules of Thumb for Mechanical Engineers FLUID STATICS Fluid... Maps Estimating Pressure Drop 19 19 19 21 22 22 23 23 24 26 26 Emissivity View Factors Radiation Shields 27 27 29 Finite Element Analysis Boundary Conditions 2D Analysis Transient Analysis Evaluating Results 29 29 30 30 31 18 33 33 36 38 40 42 42 42 46 48 Heat Transfer 19 INTRODUCTION This chapter will cover the three... spillway to diffuse most of the fluid kinetic energy, and also as an 13 effective way of mixing in a mixing chamber The Froude numbers F1and F 2for a rectangular channel section before and after the jump are related by: where the dimensionless Froude number F = V l c y The Froude number before the jump is greater than 1, and is less than 1 after the jump FLUID MEASUREMENTS Total energy in a fluid flow... 3), the relations are: Note that for a given specific head and flow rate, two different depths of h are possible The Froude n d e r V/(gh) specifies the f o characteristicsof the channel flow If it is lw less than unity, it is called subcritical, or tranquil, flow If it is more than unity, it is called supercritical, or rapid, flow 12 Rules of Thumb for Mechanical Engineers Flow Through a Siuice Gate... the above form is convenient for liquid problems, the following form is more convenient for gas flow problems: p+ $+ p = constant (9) Energy Equation The energy equation for steady fIow through a control volume is: where &eat is heat added per unit mass and Wshaft is the shaft work per unit mass of fluid 4 +-+u2 2 ~ ~ Momentum Equation The linear momentum equation states that the resultant force F acting . Drag 9 10 10 10 11 11 12 12 12 13 13 14 14 15 15 16 16 16 16 17 Introduction 19 Conduction 19 Single Wall Conduction 19 Composite Wall Conduction 21 V The. Performance Curves 98 Series and Parallel Pumping 99 Design Guidelines 10 0 Reciprocating Pumps 10 3 Compressors 11 0 Definitions 11 0 Compressors 11 1 Compressors 11 4. Stresses 15 7 Preloading 15 7 Special Loads 15 8 Effects of Speed 15 9 Lubrication 16 0 General 16 0 Oils 16 1 Greases 16 1 Rating and Life 15 2 Lubricant Selection 16 2