Deflagration example Sample Clauses

Deflagration example. ‌ The effect of the computational domain boundaries was examined in hydrogen deflagration simulation. A hydrogen-air mixture of 29.7% by volume occupies an unconfined hemispherical volume of 20 m diameter. Explosion pressure was measured at 2.0, 3.5, 5.0, 6.5, 8.0, 18.0, 25.0, 35.0, 60.0 and 80.0 m from the ignition point which it was located at the center of the hemisphere. More details about the experiment may be found in (Xxxxxx et al. 2006). Various domain-sizes were studied in order to examine the impact on the results. The domain-sizes that were tested are presented in Table 12. At all exit planes (lateral, front, back and top) the non- reflecting type boundary conditions for the normal velocities is chosen, while for the parallel to the exit planes’ velocity components, zero gradient boundary conditions are applied. In Figure 18 the pressure at 5, 8, 35 and 80 m from the center of the hemisphere, for three different domain sizes are presented. We observe that the domain size has a significant impact on the results at the closest to the boundary sensor (80 m). At the other sensors, the extended domains affect the results only at the tail of the pressure-time curve. When the Domain 1 is used (200 x 200 x 100 m), the pressure fails to return to its initial value. Domains 2 and 3 (extended domains), however, reproduce this physical behaviour. Small differences between Domain 2 and 3 are observed only at the tail of the pressure-time curve at the last position (80 m). At that sensor, even the Domain 2 fails to restore the initial value of the pressure and the more extended Domain 3 is required. Table 12. Dimensions of the numerical domain Length (m) Width (m) Height (m) Figure 18: Pressure at 5, 8, 35 and 80 m from the center of the hemisphere, for three different domain sizes.