Energy losses and pressure head changes at storm drain junctions

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dc.contributor.author Hare, Clive Michael
dc.date.accessioned 2010-06-25T00:19:10Z
dc.date.accessioned 2012-12-15T03:51:12Z
dc.date.available 2010-06-25T00:19:10Z
dc.date.available 2012-12-15T03:51:12Z
dc.date.issued 1980
dc.identifier.uri http://hdl.handle.net/2100/1098
dc.identifier.uri http://hdl.handle.net/10453/19987
dc.description New South Wales Institute of Technology. en
dc.description.abstract An investigation has been made of the magnitude of hydraulic losses produced by storm drain junction structures which connect pipes operating under f1owfull conditions. The study comprised three parts: (a) a literature review; (b) a study of losses associated with commercially available 'closed' pipe junctions; (c) an experimental study, using hydraulic models, to investigate the magnitude of losses at 'open' pit structures. A theoretical analysis was developed for closed pipe junctions. The theory was found to be adequate when checked against available experimental data. For pit junction structures, the experimental programme comprised thirty models covering an extensive range of geometric and hydraulic variables. The model studies indicated that maximum hydraulic efficiency is attained when the junction branch point is located on the downstream face of the pit. Data have been plotted for bend deflections angles of between 0° and 90°, and for upstream to downstream pipe diameter ratios within the range 0.55 to 1.00. Grate inlet flow and submergence have been identified as parameters affecting losses. Semi-empirical equations have been developed to account for junction losses when the branch point is located on the downstream face of the pit. Nomenclature The symbols used in this thesis are listed hereunder. Alphabetical subscripts have been used which conform to a standard format. The subscript 'u' refers to the primary upstream pipe. If more than one upstream pipe converges at a junction, the second such pipe is characterized by the subscript 'b' (branch or lateral pipe). The outfall pipe is identified by the subscript '0'. Notation a spacer length for compound mitre bend junction. Ab mean cross sectional area of the lateral pipe. Am mean cross section area of the model pipeline. Ao mean cross sectional area of the outfall pipe. Ap mean cross sectional area of the prototype pipeline. Ar model-prototype area ratio. Au mean eros's sectional area of the upstream pipe. B pit dimension (square in plan). Cb dimensionless total energy loss coefficient as defined by the difference between the lateral total energy line elevation and the downstream total energy line elevation when extrapolated linearly to the branch point of the junction, divided by the average downstream velocity head. Cu dimensionless total energy loss coefficient as defined by the difference between the upstream total energy line elevation and the downstream total energy line elevation when extrapolated linearly to the branch point of the junction, divided by the average downstream velocity head. Db mean diameter of the lateral pipe. Dm mean diameter of the model pipeline. Do mean diameter of the outfall pipe. Dp mean diameter of the prototype pipeline. Dr model-prototype diameter ratio. Fo Froude number in the outfall pipe. g acceleration due to gravity (9.81 m/s2 ). HGL Hydraulic Grade Line (or pressure line or piezometric head line). kb dimensionless pressure head change coefficient as defined by the difference between the lateral and downstream pressure line elevations when extrapolated linearly to the branch point of the junction, divided by the average downstream velocity head. ku dimensionless pressure head change coefficient as defined by the difference between the upstream and downstream pressure line elevations when extrapolated linearly to the branch point of the junction, divided by the average downstream velocity head. kw dimensionless pressure head change coefficient as defined by the difference between the water surface elevation in a pit junction and the elevation of the downstream pressure line when extrapolated linearly to the branch point of the junction, divided by the average downstream velocity head. Lm characteristic length in a model. Lp characteristic iength in a prototype. Lr scalar ratio of the model equal to the characteristic length of the model divided by the characteristic length of the prototype. Pb static pressure in the lateral conduit. Po static pressure in the main conduit. Pu static pressure in the upstream conduit. Qb mean discharge in the lateral pipe. Qg mean grate flow discharge through the pit grate inlet ~ mean discharge in the model pipeline. Qo mean discharge in the outfall pipe. Qp mean discharge in the prototype pipeline. Qr model-prototype discharge ratio. Qu mean discharge in the upstream pipe. R resultant force component acting at the junction x used in the impulse-momentum equation. S depth of water in a pit junction measured from pit invert elevation to water surface elevation (submergence). TEL Total Energy Line. Vb mean velocity in the lateral pipe. Vm mean velocity in the model pipeline. Vo mean velocity in the outfall pipe. Vp mean velocity in the prototype pipeline. Vr characteristic model-prototype velocity ratio. Vu mean velocity in the upstream pipe. pressure head change defining the difference between the water surface elevation in a junction pit and the elevation of the downstream pressure line when extrapolated linearly to the branch point of the junction. specific weight of a fluid. H available head. Hb total energy loss across a junction as defined by the difference between the lateral total energy line elevation and the downstream total energy line elevation when extrapolated linearly to the branch point of the junction. Hu total energy loss across a junction as defined by the difference between the upstream total energy line elevation and the downstream total energy line elevation when 'extrapolated linearly to the branch point of the junction. kp incremental pressure head change coefficient due to presence of a pit structure, over and above a theoretical solution ks incremental pressure head change coefficient due s to submergence effects, over and above a theoretical solution . P/Y change in pressure head as defined by the difference between an upstream pressure line elevation and the downstream pressure line elevation when extrapolated linearly to the branch point of the junction. p density of water (~ 1000 kg/m3 ). ab angle of lateral pipe deflection. eu angle of upstream pipe deflection. en
dc.language.iso en en
dc.title Energy losses and pressure head changes at storm drain junctions en
dc.type Thesis (M.E.) en


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