: General conservation of mass:min-mout=dmcy/dtmoutmindmcydpdvdtdtJcvP(V.n)dASmpV,dA=mnet-CSCSCSQp(V.n)dA=0pdV+atV The time rate of change of mass within thecontrol volume plus the net mass flow ratethroughthecontrolsurfaceisequaltozero1
• General conservation of mass: • The time rate of change of mass within the control volume plus the net mass flow rate through the control surface is equal to zero 11
p(V.n)dA=OpdV+at1CS: Splitting the surface into two parts: in and outdZpVndA-ZpdV+pV.dA=OdtinoutCvSAdZmpdV=mdtoULnCVdmcyZmmdtinout2
• Splitting the surface into two parts: in and out 12
Forsteadyflow process(稳流过程)：mcy=constantmj=2kg/sm2=3kg/sH业0ZZmmoutInCVSteady flowZiZm=mm=m+m=5kg/soutSteady flow (single stream):m=m2PiVAi=P2VA213
• For steady flow process(稳流过程): mcv=constant Steady flow Steady flow (single stream): 0 13