[Rocketworkbench] Cpropep frozen perfomance calculations.

[<ghe...@ci...>]

Dear rocketworkbench-devel colleagues,

During frozen perfomance calculations with Cpropep using either Cpropep-Web
on line  or the recent  CpropepShell interfases I noticed  rather important
discrepancies with the values presented for the example given in NASA RP
1311, pages 163 -4, specially lower  throat and exit temperatures and throat
entropy. Surprisingly for me using Cpropep for frozen perfomance calculation
the obtained  entropy value at throat is lower than the  values at  chamber
and exit sections and not equal as should be the case for an isoentropic
expansion, regardless of equilibrium or frozen conditons, as illustrated in
the mentioned example of the NASA report.. This is not the case for shifting
perfomance calculations where all the values match very well the example
values with constant entropy values for all three sections and equal to the
cooresponding  values at  chamber and exit conditions for frozen conditions.
The input heat of formation data for the components used in Cpropep are
slightly different from those of the example, but seem to affect very little
the output data, at least for shifting perfomance. Please find attached
files with the calculation results. I hope someone can help to explain and
resolve the differences.

Gunterio Heineken
Buenos Aires, Argentina

 <<frozen_perform.htm>>  <<shift_perform.htm>>