3A - Fundamentals of Liquid Pipeline Hydraulics

Design disciplines: Hydraulics - mechanical - geotechnical - operations and maintenance disciplines are closely interrelated hydraulic--> pipeline route- pipe size- operating P and T- number of pump stations mechanical --> pipe material selection- pipe specifications - burial depth requirements geotechnical-->surface loads - water crossings - buoyancy control- geo-hazard management operations and maintenance --> control systems - operating tasks while maintaining integrity Flow dictated by three conservation laws - MASS - MOMENTUM - ENERGY 4 independent variable define hydraulic states - Pressure - temperature- flow rate - density 4 equations are required to relate 4 independent variables mass, momentum, energy and EOS are the 4 equations 1D form used to describe flow in pipeline mass conservation equation slide 6 3A cross sectional area can change due to P or T Cp has a large effect on acoustic speed of pressure wave? ( Cp is the specific heat capacity) momentum equation slide 7-8 3A first term force due to acceleration second term is force due to kinetic energy third term is force due to pressure difference fourth term is force due to gravitation fifth term is force due to friction on pipe darcy weisbach equation to calculate pressure drop due to friction frictional pressure drop linearly proportional to density and friction factor frictional pressure drop squarely proportional to velocity frictional pressure drop inversely proportional to pipe diameter equation for frictional pressure drop in slide 8 friction factor function of reynolds and pipe roughness 3 flow regimes --> laminar, critical, turbulent (partially turbulent & fully turbulent) Re=density x velocity x diameter/viscosity ratio of inertial forces to viscous forces Re increases with increase in velocity, density and diameter kinematic viscosity used more because independent of density laminar flow friction factor --> slide 9 critical flow 2400 laminar independent of pipe roughness partially turbulent depends on Re and pipe roughness fully turbulent depends on relative roughness JAIN'S approximation (use this)--> slide 11 Energy equation--> slide 12 first term is temperature change over time second term is temperature change due to net convection third term is change in rate due to expansion/compression forth term is heat flow due to conduction fifth term is the effect of work due to gravity sixth term is heat due to friction EOS defines relation between density, pressure, and temperature EOS --> Slide 13 Assumptions --> no chemical change takes place- single phase flow - steady state steady state: no significant change in pressure and flow remain constant parameters included in hydraulic design --> Slide 17