lect. notes #2.pdf - Isentropic Flow u25cf It is a...

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15 Isentropic Flow It is a one-dimensional steady flow; where applications are mainly in ducts DUCT flow is normally adiabatic, For short ducts (Nozzles & Diffusers), friction is small ..reversible We have ISENTROPIC FLOW (adiabatic reversible flow) Q:What are the features of Isentropic flow ?? General Features of Isentropic Flow Governing Equations: (1) (2) (3) (4) (5) T or hsohhPopVo=0Vs=soV p T a h Vo=0 PoToaohop,s&,shhstateofEquation2Vhhamicsthermodynoflaw12ostondssamicsthermodynoflaw2VAmconst mVA ContinuityspVaVMnumber Mach
16 Performance Curves of Isentropic Flow For given (fixed) values of so, po, equations (1) to (5) are used to draw these curves as such: Choose p such that p < poGet h, from equation (4) Get V from equation (1) Get Amfrom equation (3) Get M from equation (5) Distinction between subsonic & supersonic flows M V/Vcrit V Subsonic Supersonic maxAmAmcritical 0 p/po1 VdVhdEnergyflowisentropicfor dpdhdp-dhTdsmicsThermodyna
17 (a) (b) (c) (d) Equation (a) implies that (e) (f) Equations (e) & (f) lead to: (i)for subsonic speeds (M<1), (ii)For supersonic speeds (M>1), (iii)For sonic speeds (M=1), dpVM1AdA(c)flowisentropicfor apddp,222s0.0VdVAdAdconst mVA ContinuitydpdV1dpAdA(b)&)a(2flowinviscidfor equation sEuler'iswhich dVV-dpThermody &Energy flowssupersonic&subsonicboth for p,Vasi.e,0.0dpdV0.0dVdA,0.0dpdA0.0dVdA,0.0dpdA0.0

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