Experimental Investigation on Effect of Compression Ratio, Injection Pressure and Engine Load on Cyclic Variations in Diesel Engine Using Wavelets

Higher cycle to cycle variations in combustion results in adverse effects on efficiency, power, drivability, and emissions. Present study investigates the effect of compression ratio, injection pressure and engine load on cycle-to-cycle combustion variations in a diesel engine using statistical methods and wavelets. Cycle to cycle variations of different combustion parameters are analyzed using continuous wavelet transform. Experiments are conducted on a diesel engine at constant engine speed at different engine loads for three compression ratios and injection pressures (170, 200 and 220 bar). Combustion parameters are calculated from measured cylinder pressure data for 2000 consecutive engine cycles. Wavelet power spectrum and global wavelet spectrum is used to analyze the variations in combustion parameters. Highest cycle to cycle variability is found for compression ratio 16 at no load condition. Cyclic variations are more prominent for total heat release in comparison to maximum cylinder pressure and indicated mean effective pressure.