What is Fanno flow equation?
Flow in a constant area duct with friction and without heat transfers is described by a curve is known as Fanno line or Fanno curve. Weknow that, From continuity equation, Density ρ is a function of entropy and enthalpy.
Is Fanno flow adiabatic?
Fanno flow is the adiabatic flow through a constant area duct where the effect of friction is considered. Compressibility effects often come into consideration, although the Fanno flow model certainly also applies to incompressible flow.
What are the assumptions to be made for the Fanno flow?
1. One dimensional flow without friction and heat transfer 2. Constant area duct 3. Perfect gas with constant specific heats and molecular weights 4.
Why the velocity grows if the flow is subsonic in the Fanno line?
Solution: Friction increases the flow velocity in subsonic Fanno flow, but decreases the flow velocity in supersonic flow. These results may not be intuitive, but they come from following the Fanno line, which satisfies the conservation equations.
What are the characteristics aspects of Fanno flow?
The characteristic aspect of Fanno flow is its consideration of friction. The main assumptions associated with Fanno flow are: the flow is steady, one- dimensional, and adiabatic through a constant-area duct, and the fluid is an ideal gas with constant specific heats.
What is limiting Mach number for maximum enthalpy point in Rayleigh flow?
The Rayleigh flow model reaches maximum entropy at M = 1.0 For subsonic flow, the maximum value of H occurs at M = 0.845.
What is the equation for the Fanno flow?
Fanno flow equation: Continuity equation: dρ ρ + d∁ ∁ = 0 Perfect gas equation: dp p = dρ ρ + dT T By definition of Mach number: 1 M2 ∙ dM2 = 1 C2 ∙ dC2 − dT T Energy equation: dT T + γ_1 2 M2 ∙ dC2 C2 = 0 8.
Is the Fanno flow model reversible or irreversible?
For this model, the duct area remains constant, the flow is assumed to be steady and one-dimensional, and no mass is added within the duct. The Fanno flow model is considered an irreversible process due to viscous effects.
When does the Fanno line reach maximum entropy in the diagram?
In the diagram, the Fanno line reaches maximum entropy at H = 0.833 and the flow is choked. According to the Second law of thermodynamics, entropy must always increase for Fanno flow. This means that a subsonic flow entering a duct with friction will have an increase in its Mach number until the flow is choked.
How do you plot a Fanno line?
Figure 1 A Fanno Line is plotted on the dimensionless H-ΔS axis. The Fanno flow model begins with a differential equation that relates the change in Mach number with respect to the length of the duct, dM/dx. Other terms in the differential equation are the heat capacity ratio, γ, the Fanning friction factor, f, and the hydraulic diameter, Dh :