A series of experiments were performed to investigate the effect of ignition energy (E_ig) and hydrogen addition on the laminar burning velocity (S_u⁰), ignition delay time (t_delay), and flame rising time (t_rising) of lean methane−air mixtures. The mixtures at three different equivalence ratios (ϕ) of 0.6, 0.7, and 0.8 with varying hydrogen volume fractions from 0 to 50% were centrally ignited in a constant volume combustion chamber by a pair of pin-to-pin electrodes at a spark gap of 2.0 mm. In situ ignition energy (E_ig ∼2.4 mJ ÷ 58 mJ) was calculated by integration of the product of current and voltage between positive and negative electrodes. The result revealed that the S_u⁰ value increases non-linearly with increasing hydrogen fraction at three equivalence ratios of 0.6, 0.7, and 0.8, by which the increasing slope of S_u⁰ changes from gradual to drastic when the hydrogen fraction is greater than 20%. t_delay and t_rising decrease quickly with increasing hydrogen fraction; however, t_rising drops faster than t_delay at ϕ = 0.6 and 0.7, and the reverse is true at ϕ = 0.8. Furthermore, t_delay transition is observed when E_ig > E_ig,critical, by which t_delay drastically drops in the pre-transition and gradually decreases in the post-transition. These results may be relevant to spark ignition engines operated under lean-burn conditions.

Multi-purpose forest fire fighting vehicles include a combination of fire fighting equipment such as a high-pressure water pump, create corridor fire insulation cutting machine, vacuum and high wind speed bowling machine, extinguish the fire sandblast apparatus that is mounted on the URAL 4320 active three axles vehicle. When installing fire fighting equipment on vehicles, increases the load, affecting the vehicle's load distribution, angularity, and stability. Therefore, to ensure structural rigidity, the suspension system is redesigned to increase rigidity. However, alteration of the suspension stiffness will change the dynamic load acting on the chassis. This research presents the results of research on the influence of suspension stiffness on dynamic loads acting on the chassis of a multi-purpose forest fire fighting vehicle. The survey results showed that an increasing the suspension stiffness will increase the dynamic load acting on the chassis, and reduce the durability of the chassis in particular and the details of the vehicle in general. The research outcomes are the basis for evaluating the working life of the chassis in subsequent studies.

Multi-purpose forest fire fighting vehicle is produced in Viet Nam include a combination of fire fighting equipment such as high-pressure water pump, create corridor fire insulation cutting machine, vacuum and high wind speed bowling machine, extinguish the fire sand blast apparatus that is mounted active three axles vehicle. The paper presents how to determine the dynamic load acting on the chassis by 3D modeling method. The results of this study are the input parameters for assessing the durability of the chassis of multi-purpose forest fire fighting vehicle.