Rules of Thumb for Mechanical Engineers 2010 Part 1 pdf

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... the ratio of inertial force to weight: This is particularly important in pipe flows and aircraft model studies The Reynolds number also characterizesdifferent flow regimes (laminar, turbulent, and the transition T i number is useful in the design of spillways, weirs, chanhs nel flows, and ship design 8 Rules of Thumb for Mechanical Engineers Weber Number Weber number is the ratio of inertial forces t... Values for Common Fittings Type of Fitting K L$D 45-degree elbow 90-degree bend Diaphragm valve, open Diaphragm valve, half open Diaphragm valve, X open Gate valve, open Gate valve, half open Globe valve, wide open Globe valve, half open Tee junction Union and coupling Water meter 0.35 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. .. 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 and static pressures, and also the static temperature, the mach number at that point can also be found: q ' ( y - 1 ) M = Via = VI^ Rate Measurement Flow... the rate of change of linear momentum inside the control volume plus the net exchange of linear momentum from the control boundary Newton’s second law is used to derive its form: F=-= (mv) L p v d V + cs pw.dA dt (1 1) Moment -of- Momentum Equation The moment -of- momentumequation is obtained by taking the vector cross-product of F detailed above and the position vector r of any point on the line of action,... This phenomenon is often used at the bottom of a 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... 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 a piping system, there are also losses associated with flow through valves and fittings These are called minor losses, but must be accounted for if the system has a lot of such fittings These... parameters are of great value in fluid mechanics Reynolds Number Reynolds number is the ratio of inertial forces to viscous forces: between the two) through a critical value For example, for the case of flow of fluids in a pipe, a fluid is considered turbulent if R is greater than 2,000 Otherwise, it is taken to be laminar A turbulent flow is characterized by random movement of fluid particles Froude... Fluids 11 OPEN-CHANNEL FLOW Study of open channels is important in the study of river flow and irrigation canals The mechanics of flow in open channels is more complicated than that in pipes and ducts because of the presence of a free surface Unlike closed conduit flow, the specificroughessfactor E for open-channel flows is dependent on the hydraulic state of the channel The flow is called uniform if... 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 maximum flow rate is given by: In the case of flow generatedwhen a sluicegate that retains water in areservoir is partiaUy raised (Figm 4), . 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. 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. 16 Unsteady Flow. Surge. and Water Hammer 16 Boundary Layer Concepts 16 Lift and Drag 16 Oceanographic Flows 17 Pipes in Parallel 10 1 2 Rules of Thumb for Mechanical