柴油机高原起动过程及火焰进气预热试验

In order to solve the cold start difficulty for diesel engines on the plateau，an experimental study on the effect of flame intake preheating on the starting performance of diesel engine at 5 km altitude was carried out on a plateau environmental test chamber. The results show that under the altitude of 5 km and the intake temperature of 303 K without intake preheating，the diesel engine falters in the speed range of 400—500 r/min at the coolant temperature of 303，318 and 333 K，respectively. At the coolant temperature below 318 K，the diesel engine falters for a longer time and even cannot go to idle condition. After analyzing，it is found that at 200 r/min，large amount of residual gases from the last cycle results in misfire. At 400 r/min，no misfire happens. When the engine speed goes above 500 r/min，the misfire cycle rate increases significantly due to the increased ignition delay period，leading to faltering at 400—500 r/min. Under the altitude of 5 km，when a flame intake preheating device was used and set its preheating power to 0.84 kW at 200 r/min and 400 r/min，1.25 kW at 600 r/min and 2.10 kW at 800 r/min，respectively，the misfire cycle rate drops to 0% across all speeds. Experimental results show that the flame-assisted intake preheating system used with a precise fuel control can effectively improve the starting performance of the diesel engine at plateau，reducing the engine starting time to within 4 s at the altitude of 5 km.