The influence of jet medium disturbance on combustion of hydrogen-doped natural gas in low temperature environment

Ambient winds, obstructions or the operation of mechanical devices can induce turbulent disturbances in the flow field of hydrogen-doped natural gas combustion. The effects of the initial turbulent environment formed by two types of jet medium, N2 and compressed air (CA), on the combustion characteristics of Natural Gas-H2-Air mixtures at about 0 °C are investigated by combining experiments and dynamic simulations for the flow field. While at Pjet (jet intensity) = 0.6 MPa, the XN2 (Molar fraction of nitrogen) in the flow field of the N2 jet increases by 0.39 % in comparison with the CA jet. The jet enhances the flame instability of the gas mixture by inducing turbulent disturbances, which in turn increases the frequency of flame cell splitting. The Pmax (Peak overpressure) and τ (The time required to reach the peak overpressure) of mixtures show an increasing trend with rising P0 (initial pressure)when Pjet < 0.4 MPa. For the N2 jet medium, the k (Turbulent kinetic energy) of the flow field at the moment of ignition is higher than 1.25 m2/s2 when Pjet > 0.4 MPa, and the inerting effect gradually dominates, this phenomenon is more significant at higher P0.. The I (The impulse accumulation during the combustion)shows an increasing initially and then decreasing trend and reaches the maximum decreasing rate when Pjet increases from 0.4 MPa to 0.5 MPa. With the increase of Pjet to 0.6 MPa, the introduction of jet has an inhibiting effect on the Pmax, which is reduced by 5.12 % compared with the static conditions. The research results can provide important reference for the safe use of hydrogen-doped natural gas and quantitative analysis of combustion risks in low-temperature environments.