Thermo-Gas Dynamics of Hydrogen Combustion and Explosion

Measurement of Ignition Limits and Induction Times of Hydrogen–Air Mixtures Behind the Incident Shock Wave Front at Low Temperatures

“…Analysis of the presented data shows that the kinetic calculation with the use of the combustion mechanism [26] describes well the experimental points in the high-temperature region. Characteristic of this region is the minimum of the curve τ k = τ k (p) at low pressures with its subsequent sloping as the pressure is increased to 1-2 MPa [4], which is just observed in Fig. 5.…”

“…As a result of the thermal expansion in combustion, the apparent fl ame velocity S 1 (velocity with respect to the tube walls) exceeds ρ u /ρ b times the laminar burning velocity u l [4]. To calculate the expansion coeffi cient (ρ u /ρ b ), we can make use of the approximate relation…”

“…The process of low-temperature (T < 1000 K) ignition of the hydrogen-air mixture behind the refl ected shock wave front is realized as mild ignition [4,17] at which local fl ame kernels are formed near the walls and the rear fl ange of the shock tube [12,18]. The subsequent coalescence of fl ame kernels and the propagation of the formed combustion front into the nonreacted mixture determine the time of defl agration propagation of the fl ame τ d , which can be much shorter than the kinetic time of spontaneous ignition τ k at a given temperature, when the proceeding of the process is fully determined by the gasphase thermally equilibrium chemical reactions [19].…”

“…The ignition limits of combustible gaseous mixtures are an important characteristic of combustion and detonation processes. Most of the classical experimental works on determining the above limits in hydrogen-air mixtures were carried out under the conditions when the gaseous mixture was practically in the state of rest or moving with a low velocity [1][2][3][4]. The corresponding theoretical calculations were oriented to these experiments [5,6].…”

Supercomputer predictive modeling for ensuring space flight safety

“…In the present paper kinetic models developed based on methodology [15] will be used. The validation of these models were presented in [3] performed based on experimental investigations of ignition delay times being functions of pressure, temperature and mixture composition [16,17].…”