A Comparative Study of Turbulent Premixed Flames Propagating Past Repeated Obstacles

Abstract

This paper presents a comparison of the overpressures and pressure gradients obtained in turbulent premixed flames of liquified petroleum gas (LPG), compressed natural gas (CNG), and hydrogen propagating past solid obstacles. The fuel-air mixture is initially at rest and is ignited at the base of a vented chamber. For each fuel a total of eighteen configurations are studied here with various permutations of three baffles plates and an obstacle with a square cross section providing a blockage ratio of either 0.24 or 0.5. High speed laser induced fluorescence from OH (LIF-OH) imaging is also performed at a repetition rate of 5kHz providing new measurements of the evolution of the flame front along the middle section of the chamber. It is found that for all fuels the peak pressure as well as the rate change of pressure increases not only with increasing blockage ratio induced by the increasing blockage ratio, but also with decreasing separation between successive baffles. The peak pressure and its rate of ch...