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Basics of Fluid Mechanics, 2014a

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11.4. ISENTROPIC FLOW 387<br />

Static Properties As A Function <strong>of</strong> Mach Number<br />

1<br />

0.9<br />

0.8<br />

0.7<br />

0.6<br />

P/P 0<br />

ρ/ρ 0<br />

T/T 0<br />

0.5<br />

0.4<br />

0.3<br />

0.2<br />

0.1<br />

0<br />

0 1 2 3 4 5 6 7 8 9<br />

Mon Jun 5 17:39:34 2006<br />

Mach number<br />

Fig. -11.6. The stagnation properties as a function <strong>of</strong> the Mach number, k=1.4.<br />

is constant for the other. In the same vein, the stagnation density is constant through<br />

the flow. Thus, knowing the Mach number or the temperature will provide all that is<br />

needed to find the other properties. The only properties that need to be connected<br />

are the cross section area and the Mach number. Examination <strong>of</strong> the relation between<br />

properties can then be carried out.<br />

11.4.3 The Properties in the Adiabatic Nozzle<br />

When there is no external work and heat transfer, the energy equation, reads<br />

dh + UdU=0 (11.31)<br />

Differentiation <strong>of</strong> continuity equation, ρAU =<br />

continuity equation reads<br />

dρ<br />

ρ + dA A + dU U<br />

ṁ = constant, and dividing by the<br />

=0 (11.32)<br />

The thermodynamic relationship between the properties can be expressed as<br />

Tds= dh − dP ρ<br />

(11.33)<br />

For isentropic process ds ≡ 0 and combining equations (11.31) with (11.33) yields<br />

dP<br />

ρ<br />

+ UdU=0 (11.34)

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