Kohlenstoff‐Sandwich: Nach der Polymerisation eines pyrrolhaltigen Tensids zwischen zwei Siliciumoxidschichten (siehe Bild; Pyrrolringe in Rot) und anschließendem Carbonisieren und Entfernen der Siliciumoxidtemplate entstehen ausgedehnte Graphen‐Monoschichten. Unter milden Bedingungen sind so μm‐große, reine Graphen‐Schichten im Gramm‐Maßstab zugänglich.

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Propylene oxide (PO) is widely used in fuel-air explosives and pulse detonation engines. Based on computational fluid dynamics, the effects of ignition position, initial pressure, and mass concentration on the explosion characteristics of the PO/air mixture were studied by using a 20 L spherical container. The results showed that the ignition position had a significant effect on the flame structure. When the fuel cloud was ignited at the center, the flame structure experienced spherical, elliptical, and tulip shapes. The explosion time first decreased and then increased with the increase of ignition position, while the maximum explosion pressure decreased correspondingly. The maximum explosion pressure and the temperature had an inverted "U" correlation with concentration at normal pressure. However, the overpressure was insensitive to concentration in the negative pressure condition. The maximum flame temperature showed different flame behaviors under different initial negative pressures and cloud concentrations. This study provides a theoretical basis for understanding the explosion behaviors of PO/air mixture with different ignition positions and initial vacuum pressures, which is of great significance in preventing explosion accidents.

Fuel-air cloud explosions or detonations are often affected by initial ambient conditions. A two-dimensional (2D) semi-confined model was established to study the effects of the inflowing air temperature and initial temperature of the combustor on the explosion process of isopropyl nitrate (IPN)/air mixture. The results showed that at different initial temperatures (1000-3000 K), the first peak pressure (P 1 ) and second peak pressure (P 2 ) decreased with the increase in initial temperature; the maximum flame temperature (2338-3534 K) increased with the increasing initial temperature; the explosion pressure and temperature had the opposite trends with the initial temperature, indicating that the oxygen content in the combustor had a greater impact on the explosion pressure, while the initial temperature had a more significant effect on the flame temperature. Under different incoming air temperatures (1000-3000 K), the flame temperature (~2700 K) of the two-phase explosion had a small difference at the incoming temperature of � 2500 K, signifying that the airflow temperature (< 3000 K) and the oxygen content in air jointly dominated the flame temperature; the flame temperature was 3100 K at the incoming temperature of 3000 K, which was about 300 K higher than other incoming flow temperatures, indicating that the flame temperature was more sensitive to the incoming air temperature (� 3000 K). At 600 m/s airflow, the explosion parameter curves at the inflow temperatures of 300 K and 600 K were compared, and the critical inflow temperature of the explosion process was also investigated.

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Purpose The reaction dynamics of combustible clouds at high temperatures and pressures are a common form of energy output in aerospace and explosion accidents. The cloud explosion process is often affected by the external initial conditions. This study aims to numerically study the effects of airflow velocity, initial temperature and fuel concentration on the explosion behavior of isopropyl nitrate/air mixture in a semiconstrained combustor. Design/methodology/approach The discrete-phase model was adopted to consider the interaction between the gas-phase and droplet particles. A wave model was applied to the droplet breakup. A finite rate/eddy dissipation model was used to simulate the explosion process of the fuel cloud. Findings The peak pressure and temperature growth rate both decrease with the increasing initial temperature (1,000–2,200 K) of the combustor at a lower airflow velocity. The peak pressure increases with the increase of airflow velocity (50–100 m/s), whereas the peak temperature is not sensitive to the initial high temperature. The peak pressure of the two-phase explosion decreases with concentration (200–1,500 g/m3), whereas the peak temperature first increases and then decreases as the concentration increases. Practical implications Chain explosion reactions often occur under high-temperature, high-pressure and turbulent conditions. This study aims to provide prevention and data support for a gas–liquid two-phase explosion. Originality/value Sustained turbulence is realized by continuously injecting air and liquid fuel into a semiconfined high-temperature and high-pressure combustor to obtain the reaction dynamic parameters of a two-phase explosion.

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