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 [...]... measuring the volume of flow over a specific time Constant Temperature Bath Figure 8 Capillary tube viscometer Figure 9 Rotating viscometer 16 Rules of Thumb for Mechanical Engineers The shear stress z is a function of this torque T Knowing shear stress, the dynamic viscosity may be calculated from Newton’s law of viscosity Td = 2n~3ho OTHER TOPICS Unsteadv Flow Surre and Water Hammer Study of unsteadyflow... is 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... 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 maximum flow rate is given by: In the case of flow generatedwhen... EQUATIONS In derivations of any of the basic equations in fluids, the concept of control volume is used A control volume is an arbitrary space that is defined to facilitate analysisof a flow region It should be remembered that all fluid flow situations obey the following rules: 1 Newton’s Laws of Motion 2 The Law of Mass Conservation (Continuity Equation) 3 1st and 2nd Laws of Thermodynamics 4.Proper... It is basically a ratio of convection to conductance: hl N=k Heat transfer r e q k s circulation,therefore, the Grashof number (and heat transfer coefficient)will rise as the buoyancy forces increase and the viscous forces decrease 24 Rules of Thumb for Mechanical Engineers Correlations Heat transfer correlations are empirical relationships They are available for a wide range of configurations.This... 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 the cross-section of the... 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 statics is the branch of fluid mechanics that deals... density of a gas can be found from the ideul gas law: p = p/RT (1) where p is the absolute pressure, R is the gas constant, and T is the absolute temperature The density of a liquid is usually given as follows: The specific volume v, is the reciprocal of density: v, = l/p The specific weight y is the weight per unit volume: The specific gravity s of a liquid is the ratio of its weight to the weight of an... 4(7m214) m Cmss Section Circular pipe of diameter D Annular section of inside dia d and outside dia D Square duct with each side a Rectangular duct with sides a and b Elliptical duct with axes a and b Semicircle of diameter D Shallow flat layer of depth h =D and for a square duct of sides and flowing full, rh Dl4 (D - d)/4 a14 a/4 (abyK(a + b) Dl4 h PIPE FLOW In internal flow of fluids in a pipe or a duct,... 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 are treated as equivalent frictional . RULES OF THUMEI FOR MECHANICAL ENGINEERS Gulf Publishing Company Houston, Texas