Biofuels in Aircraft Engines

Abstract

An exptl. study of the peculiarities of atomization of liq. fuels with different phys. properties has been carried out. It has been shown that the spray angle upon hydraulic spraying is mainly detd. by fluid viscosity, while remoteness of the point of the film decay from the exit section of the nozzle is detd. by the surface tension coeff. The effect of the properties of the liq. on the aerosol dispersity depends on the method of fluid crushing into droplets. In the case of the hydraulic atomization method without air supply, viscosity exerts the greatest impact on the dispersity of droplets. In the case of the centrifugal-pneumatic method (with the same order of magnitude of the velocity of liq. and air), the greatest impact is from the surface tension. In the pneumatic method of spraying, when the injection velocity of the fluid is lower than the velocity of air, the linear size of droplets is mainly detd. by the air flow irresp. of the properties of the liq., whereas Sauter's mean diam. depends also on the surface tension coeff. In the case of low gas-turbine engine operating modes and high viscosity fuels like biodiesel or biokerosene, the centrifugal-pneumatic atomization method is optimal, while the pneumatic method is optimal for high operating modes. For conducting of hot tests in aviation combustor, 11 embodiments of mixed liq. fuels were proved. The mixt. in a proportion of 40% of aviation kerosene, 20% of castor oil, 40% of ethanol had been chosen for the tests as the most uniform and well mixed, without deposition and stratification. Fire tests of the compartment of aviation combustion chamber with fossil fuel (kerosene TS-1) have shown comprehensible characteristics. In particular, wide side-altars of the stable combustion, assured firing of the combustion chamber, with uniform enough field of gas temp. on exit. The application of blended fuel (kerosene-ethanol-castor oil mixt.) results in worse combustion stability characteristics for aircraft engines when compared with kerosene. For biofuel use, it is necessary to provide a no. of actions for the modernization of conventional aviation combustion chambers. [on SciFinder(R)]