| The vibration characteristics of DICI engine fueled with biodiesel was researched by combining the external vibration signals of engine with the combustion in the cylinder. The waste cooking oil biodiesel mixed with common diesel by volume ratio of 10∶?90 (B10)was used as the test fuel, vibration experiments and pressure collections were carried out in common operation conditions. The vibration time spectrums were calculated by the proposed wavelet scale, the vibration power density spectrums were calculated by vibration power density and frequency, and the combustion heat release rates were calculated by the pressure in the cylinder. The results showed that after burning B10, the overall engine vibration frequency reduced from about 4 200 Hz to about 2 900 Hz, due to the high viscosity and low calorific value of biodiesel,which led to the weakening of combustion in the cylinder and the reduction of engine vibration.Biodiesel had more even distribution of the vibration throughout the frequency band, and would contribute to the improvement of human comfort and the extension of engine life. |
