Combustion noise radiation during the acceleration of a turbocharged diesel engine operating with biodiesel or n-butanol diesel fuel blends

In the current study, experimental tests were conducted on a turbocharged truck diesel engine in order to investigate the mechanism of combustion noise radiation during various accelerations and for various fuel blends. With this aim, a fully instrumented test bed was set up in order to capture the development of key engine and turbocharger parameters. Apart from the baseline diesel fuel, the engine was operated with a blend of diesel with either 30 vol % biodiesel or 25 vol % n-butanol. Analytical diagrams are provided to explain the behaviour of combustion noise radiation in conjunction with the cylinder pressure, the pressure rise rates, the frequency spectrum and the turbocharger and governor-fuel pump responses. The blend of diesel fuel with n-butanol exhibited the highest noise emissions throughout each of the transient tests examined, with differences up to 4 dBA from those with neat diesel operation. On the other hand, the biodiesel blend was found to behave marginally noisier than neat diesel oil but without a clear trend established throughout the transient events.