Transient airflow in building drainage systems /
John Swaffield
- London: Spon Press, 2010.
- xxxv, 322 p.
1 Building drainage and vent systems, a traditional building service requiring an engineering analysis makeover? -- 1.1 The requirement for drainage and vent systems -- 1.2 Basic operational mechanisms within drainage and vent systems -- 1.3 Historic development of building drainage and vent systems -- 1.4 Air entrainment, annular flow and terminal velocity -- 1.5 Assessment of system water flows -- fixture and discharge unit approaches -- 1.6 Definition of airflow as unsteady, relationship to pressure surge theory -- 1.7 Time line for analysis techniques -- 1.8 Concluding remarks -- 2 Pressure transient propagation in building drainage and vent systems -- 2.1 Development of pressure transient theory -- 2.2 Building drainage and vent system pressure transient propagation -- 2.3 Wave speed -- 2.4 Development of the equations of continuity and momentum, leading to the Joukowsky equation -- 2.5 Transients generated by changes in flow velocity -- 2.6 Terminal system boundary condition reflections -- 2.7 Internal system boundary condition reflections -- 2.8 Simplification due to constant wave speed -- 2.9 Application to a building drainage and vent system vertical stack -- 2.10 Effect of variable wave speed on junction reflection and transmission coefficients -- 2.11 Trapped transient in branch -- 2.12 Principle of superposition of pressure waves -- 2.13 Trap seal reflection coefficient -- 2.14 Concluding remarks -- 3 Mathematical basis for the simulation of low amplitude air pressure transients in vent systems -- 3.1 Development of the general St Venant equations of continuity and momentum -- 3.2 Derivation of the St Venant unsteady flow equations in the special case of low amplitude air pressure transient propagation in building drainage and vent systems -- 3.3 Application of the Method of Characteristics to transform the St Venant equations into a total derivative form -- 3.4 Frictional representation within the St Venant equations -- 3.5 Boundary condition modelling -- 3.6 Transient driving functions -- 3.7 Traction forces acting on the air core within a building drainage and vent system -- 3.8 Concluding remarks -- 4 Simulation of the basic mechanisms of low amplitude air pressure transient propagation -- AIRNET applications -- 4.1 Drainage and vent system design and the simulation of the pressure regime in each common system type in response to multiple appliance discharge -- 4.2 Dependence of entrained airflow on appliance discharge, inflow position and restrictions to airflow entry due to blocked vent terminations or defective traps -- 4.3 Simulation of transients imposed on the drainage network by external changes in conditions -- 4.4 The simulation of stackbase surcharge -- 4.5 Modelling the effect of a surcharge in a stack offset -- 4.6 Frictional representation as affected by the rate of change of the local flow conditions -- 4.7 Discharging branch boundary condition and the effect of falling solids -- 4.8 Concluding remarks -- 5 Pressure surge as a source of system failure, leading to the development of control and suppression strategies -- 5.1 Consequence of transient propagation -- 5.2 Control of transients -- 5.3 Applications in building utility systems -- 5.4 Applications within building drainage and vent systems -- 5.5 Development of a low amplitude positive transient attenuator -- 5.6 Active and passive pressure transient.