Influence of pressure and temperature on laminar burning velocity and Markstein number of kerosene Jet A-1: Experimental and numerical study

Abstract

Turbulent flames are utilised in almost all applications employing combustion. Thus, better understanding of the combustion process is the key for increasing the efficiency of fuel consumption and reducing the environmental footprint of future combustors. As the turbulent flame velocity depends on the laminar burning velocity and intensity of the turbulence, the laminar burning velocity can be considered as a crucial parameter for fuel characterisation. Since turbulent flame can be considered basically as wrinkled laminar flame (flamelet approach), the effect of stretch (caused by turbulence) on the flame propagation must also be considered. The Markstein number, which quantifies the response of a laminar flame to the stretch, can be employed for this purpose. Additionally, the Markstein number can be utilised as an indicator for laminar and turbulent flame front stability. The experimental data of the conventional liquid fuel – kerosene Jet A-1 – are scarce, especially at elevated pressure conditions. Identification of the parameters for elevated pressures is very important as such conditions are closer to real operational ones. Additionally, as the laminar velocity embodies fundamental information on the diffusivity, reactivity and exothermicity of a given mixture, it is often utilized for the validation of fuel reaction mechanisms.The combustion characteristics laminar burning velocity and Markstein number of kerosene Jet A-1 are investigated experimentally in an explosion vessel. For this purpose an optical laser method is employed based on the Mie-scattering of the laser light by smoke particles. Within this experimental study the influence of three crucial parameters: initial temperature, initial pressure and mixture composition on the burning velocity and Markstein number are investigated. The experiments are performed at five different pressures: 0.1, 0.2, 0.4, 0.6 and 0.8MPa; three different temperatures: 373, 423 and 473K; and for a range of equivalence ratios of 0.67–1.43. Along with the experiments, two different reaction mechanisms are used to evaluate their ability to predict the experimentally observed laminar burning velocities. The observed results are compared and discussed in detail.