Non-equilibrium effects due to condensible products

Another non-equilibrium effect arises when the product composition contains a condensible substance. Solid propellant formulations based upon potassium perchlorate form solid potassium chloride and the acetylenic monopropellants upon decomposition form large quantities of carbon particles, as do very fuel-rich mixture ratios of hydrocarbon propellant systems. More recently metal and metal compounds have been used as fuels and form product oxides which are very high boiling point compounds that condense to varying degrees in the rocket chamber and nozzle. For example, estimates indicate that the normal boiling points of Li20, BeO, 

These boiling point temperatures of the metal oxides increase with pressure and thus can be seen to be appreciably greater than the corresponding equilibrium combustion chamber temperature of propellant systems. 

This problem of performance defects due to heat transfer and velocity lag when condensation is completed in the chamber is now treated. Very interesting limiting cases which have been detailed by Altman and Carter (5) are reviewed first. Then, the more general case of the effect of simultaneous heat transfer and velocity lag on nozzle performance is developed. 

Altman and Carter show that only very small particles ( 0.1 p ) have essentially no lag and that particles greater than 10 p lag considerably behind the gas velocity, even upstream of the nozzle. 

They treat the heat transfer problem in three parts  

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