G.D. Roy et al. Progress in Energy and Combustion Science 30(2004)545-672 mpensates for the initial energy increase, so that the detonation velocity is virtually independent of the initial temperature. In line with this logic, the temperature of detonation products increases only slightly with the initial temperature(Fig 2b). An important parameter such as the detonation pressure(Fig. 2c)decreases with temperature because the pressure ratio is proportional to the initial fluid density. Due to dissociation, the molecular mass of detona- tion products decreases, however, insignificantly. At the low end, the initial pressure should not affect the detonation velocity, but at higher pressures the equilibrium in the reaction products is shifted towards polyatomic molecules, which lie at lower energy levels. Hence, reduced dissociation of the products increases slightly the detonation Fig 3. Detonation properties of homogeneous JP-10-air mixture velocity(Fig. 2a), temperature(Fig. 2b), and molecular btained by using thermodynamic code tEP [96,97: 1-dcj mass(Fig. 2d). Dimensionless detonation pressure is almost insensitive to the initial pressure(Fig. 2c). It should be noted that at very low initial pressures the detonation parameters pressure Pay/po(c), and molecular mass ua(d)on the initial e affected by losses to the walls of even quite wide tubes temperature To and pressure Po of a stoichiometric homo- (this effect is not taken into account in thermodynamic geneous iso-octane-air mixture [95]. The effect of the initial calculations of Fig. 2). All the features of Fig. 2 are temperature on the detonation velocity is insignificant confirmed by the measurements and are typical for (Fig. 2a). According to elementary considerations, the initial detonations of high hydrocarbons internal energy is just added to the reaction heat and an As JP-10 is considered as one of prospective fuels for ease in the initial temperature should slightly increase the PDE applications, Fig. 3 shows the calculated detonation detonation velocity. However, the actual influence of the properties of homogeneous JP-10-air mixture [96] that initial temperature on the detonation velocity is more are very similar to those presented in Fig. 1. The complex since due to dissociation the reaction heat drops as properties presented in Fig. 3 were obtained by usin the final temperature in the products rises. This partl thermochemical equilibrium code TEP [971 which does c2750 A Fig. 4. Predicted dependencies of (a)detonation velocity Dc.(b)temperature Tc, (c)dimensionless pressure Pcr/po, and(d)molecular mass uc of detonation products on the molar fraction of HP vapor a admixed to the stoichiometric homogeneous iso-octane-air(solid curves)andpressure pCJ=p0 ðcÞ; and molecular mass mCJ ðdÞ on the initial temperature T0 and pressure p0 of a stoichiometric homo￾geneous iso-octane–air mixture [95]. The effect of the initial temperature on the detonation velocity is insignificant (Fig. 2a). According to elementary considerations, the initial internal energy is just added to the reaction heat and an increase in the initial temperature should slightly increase the detonation velocity. However, the actual influence of the initial temperature on the detonation velocity is more complex since due to dissociation the reaction heat drops as the final temperature in the products rises. This partly compensates for the initial energy increase, so that the detonation velocity is virtually independent of the initial temperature. In line with this logic, the temperature of detonation products increases only slightly with the initial temperature (Fig. 2b). An important parameter such as the detonation pressure (Fig. 2c) decreases with temperature because the pressure ratio is proportional to the initial fluid density. Due to dissociation, the molecular mass of detona￾tion products decreases, however, insignificantly. At the low end, the initial pressure should not affect the detonation velocity, but at higher pressures the equilibrium in the reaction products is shifted towards polyatomic molecules, which lie at lower energy levels. Hence, reduced dissociation of the products increases slightly the detonation velocity (Fig. 2a), temperature (Fig. 2b), and molecular mass (Fig. 2d). Dimensionless detonation pressure is almost insensitive to the initial pressure (Fig. 2c). It should be noted that at very low initial pressures the detonation parameters are affected by losses to the walls of even quite wide tubes (this effect is not taken into account in thermodynamic calculations of Fig. 2). All the features of Fig. 2 are confirmed by the measurements and are typical for detonations of high hydrocarbons. As JP-10 is considered as one of prospective fuels for PDE applications, Fig. 3 shows the calculated detonation properties of homogeneous JP-10–air mixture [96] that are very similar to those presented in Fig. 1. The properties presented in Fig. 3 were obtained by using thermochemical equilibrium code TEP [97] which does Fig. 4. Predicted dependencies of (a) detonation velocity DCJ; (b) temperature TCJ; (c) dimensionless pressure pCJ=p0; and (d) molecular mass mCJ of detonation products on the molar fraction of HP vapor cA admixed to the stoichiometric homogeneous iso-octane–air (solid curves) and n-heptane–air (dashed curves) mixtures [95]. Fig. 3. Detonation properties of homogeneous JP-10-air mixture obtained by using thermodynamic code TEP [96,97]; 1—DCJ; 2—pCJ=p0; 3—TCJ=T0: 554 G.D. Roy et al. / Progress in Energy and Combustion Science 30 (2004) 545–672