Influence of pressure and temperature on explosion characteristics of n-hexane/air mixtures

Abstract

N-hexane is an important alternative fuel for aviation kerosene in recent years. In this study, experiments of n-hexane in air at various initial temperatures of 353–393 K, initial pressures of 60–100 kPa and equivalence ratio of 0.7–1.7 were carried out in a cylindrical vessel with central ignition. The pressure histories and outward propagations of the spherical flame in the explosion process were recorded by the pressure sensor and Schlieren system, respectively. Explosion characteristics including the explosion pressure Pmax, the maximum rate of pressure rise (dP/dt)max and laminar burning velocity U1 were obtained and analyzed. Results show that all explosion parameters strongly depend on the n-hexane/air ratio, initial pressures and temperatures. The explosion pressure Pmax and maximum rate of pressure rise (dP/dt)max raise with the increase in initial pressure and decrease in temperature. However, the dimensionless explosion pressure Pmax/P0 remains constant with an increased initial pressure. Furthermore, the n-hexane/air flame propagation characteristics were investigated and the Markstein length were studied. The unstretched flame propagation speed S1 and laminar burning velocity U1 share the similar variation tendency with equivalence ratios, and they are increased with the increase of initial temperatures and decrease of pressures.