Caracterização e testes de tubo de choque para análise de combustão com injeção de combustível

Abstract

A burning process in a combustion chamber of an internal combustion engine is very important to know the maximum temperature of the gas, the combustion speed and time delay ignition of fuel air mixture. The automotive industry has invested considerable amounts of resources in simulations and numerical modeling in order to obtain relevant information about the processes in the combustion chamber and then extract the maximum engine performance, control emissions and in formulating new fuels. This work aimed at general construction and instrumentation of a shock tube for measuring the fuel ignition delay time. Specific objectives determined the reaction raté and delay time of ignition Diesel S25, ethanol with 5 % additive enhancer cetane number, B100 biodiesel and Diesel reference. The results were correlatéd with the number of cetane fuels and compared with the times of known delays ignition of Diesel and biodiesel. A shock tube is a metal tube in which a gas at low pressure and high pressure gas are separatéd by a diaphragm. This diaphragm when it breaks on predetermined conditions produces shock waves that move from the high pressure chamber known as the compression chamber or Driver for low pressure chamber known as Driven or expansion chamber. Were obtained in testing the speed of propagation of shock waves incident and reflected. It is measured ignition delay times of ethanol additive, Diesel S25, Diesel reference and biodiesel B100. It was concluded that the delay time of ethanol with 5% additive was at least twice that of the delay time Diesel S25. The delay time of biodiesel B100 was approximatély four times greatér than the time delay Diesel S25. The delay time of the Diesel reference was smaller than the S25. Should not use the fuel additive ethanol and B100 biodiesel as substitutes for Diesel compression ignition engines without any major changes in engines. The times of delays ignition of these fuels are at least three to four times larger than the time delay of the Diesel reference. This could cause serious malfunctions of engines being necessary to make changes in the construction of them, for example, increased compression ratio.