G D. Roy et al. Progress in Energy and Combustion Science 30(2004)545-672 not account for finite-rate chemical kinetics and assumes that all of the fuel is in a vaporized state Of importance is the effect of relatively small fuel additives(up to 20%)on the detonation parameters I is+3200F cla cipated that small additives can hardly influence the aracteristics of steady C detonation waves. Indeed thermodynamic calculations performed in Ref. [95] for the iso-octane-air and n-heptane-air mixtures with admixed hydrogen peroxide(HP) vapor (see Fig. 4) reveal a weak dependence of detonation velocity(Fig 4a), as well as temperature(Fig. 4b), pressure(Fig. 4c). and molecular mass(Fig. 4d) of detonation products on the molar fraction of the additive, a A great body of the experimental data on detonation parameters reveals that, for ove of mixtures and shapes of charges, the measured wave velocities and pressures are fairly well consistent with the ideal thermodynamic calculations. It should be emphasized that recorded pressure profiles exhibit intense oscillations and, therefore, a comparison of calculations with exper iment in this case is often uncertain to a large extent. Usually, in compliance with the thermal theory of detonation limits [98, deviations of the measured detonation wave velocities in mixtures with arrhenius [100] and computed 2 [101] gas temperatures bout 10% even for marginal detonations. However, there (a) and donatio stoichiometric C2H2-O2 re exceptions for special types of detonations heavily onditions temperature and pressul affected by energy and momentum losses in which heat d to c conditions: Tc= 3937K and release kinetics senses only little variations of the gas Pc:33.3 atm, respectively. rameters. These waves require special consideration One of the most important features of detonation waves (see Section 2.2.5). n homogeneous mixtures is the instability that results in Detonation parameters that are measured their essentially 3D and unsteady nature. A major feature of (intrinsically) integration over the duct cross-sect as density measured by absorption of X-rays) detonation wave propagation is shown in Fig. 6a and b Fig 6a shows a typical footprint of detonation on the sooted profiles subject to less pronounced oscillations [99]. The foil mounted on the tube wall [102 Fig 6b[103] in terms veraged density at the end of the zone where the reaction of a series of pressure maps at evenly spaced intervals. The keeps going and transverse waves are still intense is indeed consistent with thermodynamic calculations. Recent connection of the paths of triple points produces the cellular detailed measurements of temperature and pressure histories structure that has become a characteristic feature of gaseous behind a detonation front [1001, using advanced laser detonations. The dimensions of the cellular structure diagnostics, revealed that trends in measurements agree with longitudinal size b and transverse size a-are related to the simulations [101] although certain discrepancies in the properties of the material and the chemical reaction profiles are apparent(Fig. 5) nechanism. Long chemical reaction times or induction This certainly makes the ID ZNd theory very useful times correlate with large detonation cells even though it does not adequately describe peculiarities of The structure of most propagating detonations is usually the detonation wave structure. There are several reasons for much more complex than that shown in Fig. 6, sometimes the detonation parameters to deviate from ideal thermo there are substructures within a detonation cell. and dynamic calculations: wave instability, incomplete reaction sometimes the structures are very irregular. Moreover at the sonic(C)) plane (if it exists in multidimensional ome detonations exhibit essentially 3D structure [1041 waves), and momentum and energy losses. Therefore, a Ref. [104], detailed measurements of the detonation reasonably good agreement between the calculated and structure in a square-section tube were made. The measured detonation parameters is observed only in long schematics of transverse motion of front shocks in cases ducts of a diameter exceeding the limiting value. At short of 2D and 3D detonation structures are shown, respectively, distances from the initiator(of about 1 or 2 m)and in narrow in Fig. 7a and b ducts, the deviations can be quite significant as obvious even Modeling of detonation waves initiated and propagating from id calculations with finite reaction kinetics in real combustion chambers is an efficient method fornot account for finite-rate chemical kinetics and assumes that all of the fuel is in a vaporized state. Of importance is the effect of relatively small fuel additives (up to 20%) on the detonation parameters. It is anticipated that small additives can hardly influence the characteristics of steady CJ detonation waves. Indeed, thermodynamic calculations performed in Ref. [95] for the iso-octane–air and n-heptane–air mixtures with admixed hydrogen peroxide (HP) vapor (see Fig. 4) reveal a weak dependence of detonation velocity (Fig. 4a), as well as temperature (Fig. 4b), pressure (Fig. 4c), and molecular mass (Fig. 4d) of detonation products on the molar fraction of the additive, cA: A great body of the experimental data on detonation parameters reveals that, for overwhelming majority of mixtures and shapes of charges, the measured wave velocities and pressures are fairly well consistent with the ideal thermodynamic calculations. It should be emphasized that recorded pressure profiles exhibit intense oscillations and, therefore, a comparison of calculations with exper￾iment in this case is often uncertain to a large extent. Usually, in compliance with the thermal theory of detonation limits [98], deviations of the measured detonation wave velocities in mixtures with Arrhenius reaction kinetics from those calculated do not exceed about 10% even for marginal detonations. However, there are exceptions for special types of detonations heavily affected by energy and momentum losses in which heat release kinetics senses only little variations of the gas parameters. These waves require special consideration (see Section 2.2.5). Detonation parameters that are measured involving (intrinsically) integration over the duct cross-section (such as density measured by absorption of X-rays) exhibit profiles subject to less pronounced oscillations [99]. The averaged density at the end of the zone where the reaction keeps going and transverse waves are still intense is indeed consistent with thermodynamic calculations. Recent detailed measurements of temperature and pressure histories behind a detonation front [100], using advanced laser diagnostics, revealed that trends in measurements agree with simulations [101] although certain discrepancies in the profiles are apparent (Fig. 5). This certainly makes the 1D ZND theory very useful even though it does not adequately describe peculiarities of the detonation wave structure. There are several reasons for the detonation parameters to deviate from ideal thermo￾dynamic calculations: wave instability, incomplete reaction at the sonic (CJ) plane (if it exists in multidimensional waves), and momentum and energy losses. Therefore, a reasonably good agreement between the calculated and measured detonation parameters is observed only in long ducts of a diameter exceeding the limiting value. At short distances from the initiator (of about 1 or 2 m) and in narrow ducts, the deviations can be quite significant as obvious even from 1D calculations with finite reaction kinetics. One of the most important features of detonation waves in homogeneous mixtures is the instability that results in their essentially 3D and unsteady nature. A major feature of detonation wave propagation is shown in Fig. 6a and b. Fig. 6a shows a typical footprint of detonation on the sooted foil mounted on the tube wall [102], Fig. 6b [103] in terms of a series of pressure maps at evenly spaced intervals. The connection of the paths of triple points produces the cellular structure that has become a characteristic feature of gaseous detonations. The dimensions of the cellular structure— longitudinal size b and transverse size a—are related to the properties of the material and the chemical reaction mechanism. Long chemical reaction times or induction times correlate with large detonation cells. The structure of most propagating detonations is usually much more complex than that shown in Fig. 6, sometimes there are substructures within a detonation cell, and sometimes the structures are very irregular. Moreover, some detonations exhibit essentially 3D structure [104]. In Ref. [104], detailed measurements of the detonation structure in a square-section tube were made. The schematics of transverse motion of front shocks in cases of 2D and 3D detonation structures are shown, respectively, in Fig. 7a and b. Modeling of detonation waves initiated and propagating in real combustion chambers is an efficient method for Fig. 5. Measured 1 [100] and computed 2 [101] gas temperatures (a) and pressures (b) for detonation of stoichiometric C2H4 –O2 mixture at normal conditions. Peaks on temperature and pressure curves correspond to CJ conditions: TCJ ¼ 3937 K and pCJ ¼33.3 atm, respectively. G.D. Roy et al. / Progress in Energy and Combustion Science 30 (2004) 545–672 555