Influence of Fuel Temperature on the Fuel Flux Coefficient for Small UAV Engines Carburetor

The variation of the environmental air temperature during a one-time-flight of modern 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.