This applet computes the isentropic
flow relations.** Isentropic** means constant entropy,
which implies a **reversible** process from the Second
Law of Thermodynamics. As a gas (white area) is forced through a
tube (black outline), the gas molecules are deflected by the walls of
the tube. The properties of the gas will
change along the length of the tube depending on the speed, or
Mach number, of the gas.

The values of all the flow variables are related to one another through the
Mach number, as shown on a separate slide. Therefore,
selecting a value for any one variable determines the value of all the other
variables. In this applet, you can select a variable by using the choice button
labeled **Input Variable**. Directly below the selection, you can type in
the value of the selected variable. When you hit the** Enter** key, you will
see the output values change for the Mach number, the static to total pressure
ratio (p/pt), the static to total temperature ratio (T/Tt), the static to total
density ratio (rho/rhot), the area ratio (A/A*), the dynamic pressure ratio
(q/p), and the corrected airflow per area (wcor/A). The definitions of these
relations are given on a separate slide. Some of
the variables (like the area ratio) are double valued. This means that for the
same area ratio, there is a subsonic and a supersonic solution. The choice button
at the right top selects the solution is that is presented.

Go to...

- Beginner's Guide Home Page

*byTom
Benson
Please send suggestions/corrections to: benson@grc.nasa.gov *