The solution to the conservation equations that describe conditions for incident and reflected shocks is most conveniently obtained in terms of assigned temperature before and after shock.   Therefore, theoretical values for shock parameters, such as velocities and gas compositions, are generally found tabulated as functions of assigned temperatures (or temperature ratios).   However, in shock tube experiments shock velocities rather than temperatures ratios are generally known, thus requiring interpolation for purposes of comparison.   It is therefore useful to have a calculating scheme that calculates shock properties in terms of assigned velocities.   This is the scheme used by CEA.

Definitions, nomenclature, and analysis are discussed in NASA RP-1311, 1994, chapter 7.   Example 7 illustrates the use of this CEA application.   The example comes from NASA RP-1311, 1996.   Note that the variables representing the initial conditions are subscripted "1", incident shock variables are subscripted "2", and reflected shock variables are subscripted "5".

REACTANTS
The reactants listed in the Reactant dataset are for the initial gaseous composition (only gases are allowed).

OPTIONS
User selects the desired options:

• Calculate Incident Shock Tube Parameters   - inc
• Calculate Reflected Shock Tube Parameters   - ref
• Assume Equilibrium Compositions    - eq
• Assume Frozen Compositions   - fr
• Print Intermediate Output   - deb

UNITS
Units may be selected for initial temperature T₁: Kelvin (default); Rankine; Celsius; and Fahrenheit.   Also for initial pressure P₁: bar (default); atm; psia; and mmHg.   In each case, the selected unit applies to all values listed in the associated tables.   The user has the choice of assigning initial velocities u₁ or Mach numbers.   The unit for velocity is m/s.

ASSIGNED INITIAL VALUES
Up to eight initial assigned values may be listed in each of the tables and they correspond to each other one to one.   If no temperatures are given, each value is assumed to be the same as the assigned temperature given to the initial reactants.   If the number of values for T₁ or P₁ is less than the number of values for u₁ or Mach₁ , then the missing values will be assumed to be the same as the last value listed.

Use the ENTER, RETURN, or TAB key or click on the next empty cell after each table entry.

HELP
The Help button displays the help menu for the Shock tube(shock) Problem.

SAVE
The Save button saves the data and returns to the Problem dataset.

RESET
The Reset button resets the data to the default settings.