Time and frequency analyses of dual-fuel engine block vibration

A single-point time, frequency experimental analyses have been carried out to scrutinize the engine-block vibration of a LPG-diesel, dual-fuel engine. A liquefied petroleum gas (LPG) has been used as the main fuel in a diesel engine where diesel fuel has been used as a pilot fuel to ignite the gaseous fuel. The results of the dual-fuel engine vibrations are compared to the vibrations of base diesel engine as a benchmark. The engine cylinder head vibration has been measured at different engine operating conditions of load, speed, injection timing and compressions ratio. Fast-Fourier-Transform (FFT), Short Time Fourier Transform (STFT) and root mean square of vibration signal have been calculated for the vibration signal for both engines. It has been found that the dual-fuel engine exhibits less vibration than the diesel engine. Results show that the vibration of dual-fuel engine is distributed over a narrow range of frequencies compared with diesel engine. These results of low vibrational levels for the dual-fuel engines, as compared with the diesel engines under similar operating conditions, would encourage us to further investigate the potential of using dual-fuel engines for better environmental and mechanical performance.