FIGURE 5-6. Variation of exhaust gas composition at nozzle exit with pressure ratio at a fixed mixture ratio and for shifting equilibrium. For frozen equilibrium the composition would be the same as in the chamber, as shown in Fig. 5-2.

tion of exit pressure or pressure ratio for a fixed value of chamber pressure. Table 5-9 shows how the composition is shifted during expansion in the nozzle and how several of the species present in the chamber have disappeared at the nozzle exit. These three tables show theoretical results calculated on a computer; some of the thermodynamic properties of the reactants and reaction products probably do not warrant the indicated high accuracy of five significant figures which are obtained from the computer. In the analysis for chemical ingredients of this solid propellant, approximately 76 additional reaction products were considered in addition to the major product species. This includes, for example, CN, CH, CCI, Cl, NO, and so on. Their calculated mole fractions were very small and therefore they have been neglected and are not included in Table 5-8 or 5-9.

Calculations of this type are useful in estimating performance (Is, c*, CF, e, etc.) for a particular chamber pressure and nozzle exit pressure, and knowledge of the gas composition, as indicated by the previous figures and tables, permits a more detailed estimate of other design parameters, such as gas-film properties for heat transfer determination, radiation characteristics of the flame inside and outside the thrust chambers, and the acoustic characteristics of the gases. Performance data calculated for hybrid propellants are presented briefly in Chapter 15.

oo TABLE 5-5. Theoretical Performance of Liquid Rocket Propellant Combinations



Mixture Ratio

Average Specific Gravity

Chamber Temp. (K)

Chamber c*


SD! (kg/mol)

Is (sec)

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Project Management Made Easy

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