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The gas flow is isentropic. The gas flow is constant. The gas flow is along a straight line from gas inlet to exhaust gas exit. The gas flow behavior is compressible. There are numerous applications where a steady, uniform, isentropic flow is a good approximation to the flow in conduits.
In fluid dynamics, an isentropic flow is a fluid flow that is both adiabatic and reversible. That is, no heat is added to the flow, and no energy transformations occur due to friction or dissipative effects. For an isentropic flow of a perfect gas, several relations can be derived to define the pressure, density and temperature along a streamline.
For isentropic processes, the Cauchy number may be expressed in terms of Mach number. The isentropic bulk modulus K s = γ p {\displaystyle K_{s}=\gamma p} , where γ {\displaystyle \gamma } is the specific heat capacity ratio and p is the fluid pressure.
For isentropic flow, density can be expressed as a function only of enthalpy = (), which in turn using Bernoulli's equation can be written as = (). Since the flow is irrotational, a velocity potential ϕ {\displaystyle \phi } exists and its differential is simply d ϕ = v x d x + v y d y {\displaystyle d\phi =v_{x}dx+v_{y}dy} .
If a near supersonic flow experiences an area contraction, the velocity of the flow will decrease until it reaches the local speed of sound, and the flow will be choked. This is the principle behind the Kantrowitz limit: it is the maximum amount of contraction a flow can experience before the flow chokes, and the flow speed can no longer be ...
The analysis of gas flow through de Laval nozzles involves a number of concepts and assumptions: For simplicity, the gas is assumed to be an ideal gas. The gas flow is isentropic (i.e., at constant entropy). As a result, the flow is reversible (frictionless and no dissipative losses), and adiabatic (i.e., no heat enters or leaves the system).
In aerodynamics, the Prandtl–Meyer function describes the angle through which a flow turns isentropically from sonic velocity (M=1) to a Mach (M) number greater than 1. The maximum angle through which a sonic ( M = 1) flow can be turned around a convex corner is calculated for M = ∞ {\displaystyle \infty } .
An isentropic process is customarily defined as an idealized quasi-static reversible adiabatic process, of transfer of energy as work. Otherwise, for a constant-entropy process, if work is done irreversibly, heat transfer is necessary, so that the process is not adiabatic, and an accurate artificial control mechanism is necessary; such is ...