The following is a brief description of all the inputs. The inputs for our example will be defined in the next few pages.
In the upper left hand side of the input screen, the following Physical Properties inputs are required for program execution:
- The Grain Diameter is the outside diameter of the rocket motor energetic grain.
- The Density is the density of the rocket motor grain.
- The Flame Temperature is the Adiabatic Flame Temperature of the rocket motor grain combustion products.
- The Molecular Weight is the Molecular Weight of the rocket motor grain combustion products.
- The Specific Impulse is the energy content of the rocket grain energetic.
- The Specific Heat Ratio is the Specific Heat Ratio (Pressure/Volume) of the propellant grain combustion products.
In the upper right hand side of the input tab are the Analysis Parameters.
- The Start Pressure is the initial pressure at which the motor grain performance will be assessed.
- The Stop Pressure is the final pressure at which the motor grain performance will be assessed.
- The Pressure Step is the pressure increment between the Start Pressure and Stop Pressure for the motor performance assessment.
In the lower right hand side of the input tab are the Burn Rate Parameters.
- The Burn Rate is the Burn Rate (mm/sec or in/sec) of the rocket motor grain.
- The Burn Rate Exponent is the burn rate exponent of the rocket motor grain.
- The Burn Time is the total time of rocket motor energetic burn.
- The Total Impulse is the thrust-time integral required of the rocket motor.
- The Efficiency is a scalar indicating what fraction of motor momentum loss during combustion will be converted into thrust. Values between 0.90 and 0.98 are typical for most nozzles. The user should start the design process with a value between 0.90 and 0.92 because it is a bit conservative and leaves some room for performance growth.
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