110
A. I. Lopato
Fig. 8.2 Predicted peak
pressure time history in the
computational domain
and increases gasdynamics parameters. The mixture with high pressure and temperature generates the combustion wave that propagates to the right and interacts with
the leading wave with its amplification. The formation of the overdriven DW takes
place at the time moment of about 50 µs that can be considered as the end of the
initial stage. After the initial stage, DW obtains the classical structure with LSW,
reaction zone and Taylor expansion wave. DW remains overdriven and then the transition from the overdriven to self-sustaining regime occurs. During the transition,
the velocity of DW exceeds the value of 1900 m/s. Note that the theoretical value
of the Chapman-Jouguet (CJ) velocity specified in [7] is equal to 1993 m/s. So, the
values of the CJ velocity are in good agreement with each other. As the detonation
approaches the CJ state (the time moment of about 240 µs), pulsations of the HF
mode begin to appear, as shown in Fig. 8.2. The pulsations of parameters are associated with the interaction between the combustion waves formed in the reaction zone
and LSW. The HF mode is characterized by a relatively small distance and change
in distance from DW front to the reaction zone. Further development of the pulsations leads to the transition from the HF mode to the HA one at the time of about
520 µs. As shown in Fig. 8.2, the signal of the pulsations in the HA mode is close
to periodic. Figure 8.3 shows the time evolution of temperature and density profiles
every 10 µs during the time interval 620–660 µs. The acceleration of the chemical
rates in the reaction zone enhances the rate of heat release. The formation of the
combustion wave occurs. The accelerating flame burns the mixture in the induction
zone releasing large amount of energy up to the collision of the combustion wave
with LSW. Thus, at this stage, the formed disturbance propagates toward DW front,
and the reduction of the induction zone occurs. The stage corresponds to the region
marked with a green dashed line in Fig. 8.2 and is referred to as an acoustic wave
cycle. The next considered stage corresponds to the time interval 660–700 µs. The
stage is marked with a blue dashed line in Fig. 8.2 and is called an entropy wave
A. I. Lopato
Fig. 8.2 Predicted peak
pressure time history in the
computational domain
and increases gasdynamics parameters. The mixture with high pressure and temperature generates the combustion wave that propagates to the right and interacts with
the leading wave with its amplification. The formation of the overdriven DW takes
place at the time moment of about 50 µs that can be considered as the end of the
initial stage. After the initial stage, DW obtains the classical structure with LSW,
reaction zone and Taylor expansion wave. DW remains overdriven and then the transition from the overdriven to self-sustaining regime occurs. During the transition,
the velocity of DW exceeds the value of 1900 m/s. Note that the theoretical value
of the Chapman-Jouguet (CJ) velocity specified in [7] is equal to 1993 m/s. So, the
values of the CJ velocity are in good agreement with each other. As the detonation
approaches the CJ state (the time moment of about 240 µs), pulsations of the HF
mode begin to appear, as shown in Fig. 8.2. The pulsations of parameters are associated with the interaction between the combustion waves formed in the reaction zone
and LSW. The HF mode is characterized by a relatively small distance and change
in distance from DW front to the reaction zone. Further development of the pulsations leads to the transition from the HF mode to the HA one at the time of about
520 µs. As shown in Fig. 8.2, the signal of the pulsations in the HA mode is close
to periodic. Figure 8.3 shows the time evolution of temperature and density profiles
every 10 µs during the time interval 620–660 µs. The acceleration of the chemical
rates in the reaction zone enhances the rate of heat release. The formation of the
combustion wave occurs. The accelerating flame burns the mixture in the induction
zone releasing large amount of energy up to the collision of the combustion wave
with LSW. Thus, at this stage, the formed disturbance propagates toward DW front,
and the reduction of the induction zone occurs. The stage corresponds to the region
marked with a green dashed line in Fig. 8.2 and is referred to as an acoustic wave
cycle. The next considered stage corresponds to the time interval 660–700 µs. The
stage is marked with a blue dashed line in Fig. 8.2 and is called an entropy wave