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2.Theprocessofenergytransformationinhydraulicgearmachines
Formula(2.5)showsthattheoreticaltorqueM
gt,assumingconstantspecificdeliveryq
g
changesindirectproportiontoloadingofthepumpp
g.Hence,Figure2.5bshows
thecharacteristicsoftheoreticaltorqueM
gtoftheidealpumpdependingonloadp
g,
namelyM
gt±f(p
g).Thecharacteristicisastraightlinecomingfromthebeginning
ofthecoordinatesystem.
Fig02050Characteristicsofthepump.
a)theoreticaldeliveryQ
gtandrealdeliveryQ
g,b)theoreticaltorqueM
gtandrealtorqueM
g,
c)volumetricefficiencyn
vg,hydraulic-mechanicalefficiencyn
h–mg,totalefficiencyn
g
Figure2.4bpresentstheenergybalancefortherealpump.Thefigureshowsthat
thestreamindicatingtheoreticaldeliveryQ
gtisreducedbythevalueofvolumetric
lossQand,consequently,ontheoutletofthepump,realdeliveryQ
gisgenerated.
Thevolumetriclossdependsontheleakageoftheworkingfluidthroughtheclear-