燃油温度对化油器燃油流量系数的影响

摘要

The variation of the environmental air temperature during a one-time-flight of modem small UAVs can be up to 80 ℃.To achieve an optimal air to fuel (A/F) and flight efficiency to cost (F/C) ratios, the fuel viscosity-temperature characteristics of UAV engines are studied.With resort to calculation and experimental methodologies, viscosity-temperature properties between -40℃ ～ + 40℃ of the UAV engines utilizing pure gasoline or blended fuel are explored regarding to their influences on the fuel flux coefficient at different carburetor metering jets.It is demonstrated that in our UAV engines, the carburetor fuel flux coefficient can be approximately changed by 10 percent when the fuel temperature varies with 80℃.As a result, fluctuation of fuel viscosity should be taken into account to evaluate the carburetor fuel flux coefficients.%现代小型无人机一次飞行过程中大气温度变化量可以达到80℃左右.为追求发动机合理的空燃比和飞行效费比,测量了燃油粘度-温度特性,并利用计算及试验法,研究了小型无人机发动机使用纯汽油或混合油温度在-40℃～+40℃条件下,其粘度-温度特性对化油器各量孔燃油流量系数的干扰力度.研究结果表明,当燃油温度变化量在80℃范围内时,化油器燃油流量系数变化量在10%左右,即燃油温度(粘度)的变化对各量孔流量系数的影响不容忽略.