Characterization of Cycle-to-Cycle Variations in Conventional Diesel Engine Using Wavelets

Higher cycle-to-cycle variations in combustion engines lead to efficiency losses, engine roughness, lower power output, and higher exhaust emissions. Cycle-to-cycle variations in combustion engines are typically characterized by several techniques such as statistical method, symbol sequence statistics, chaotic methods, and wavelet analysis. Each strategy for cyclic variation characterization has its benefits and limitations depending on the application. Wavelet transform has a potential to analyze non-stationary signal in time domain as well as frequency domain simultaneously. This strategy has better temporal and spectral resolution; thus, wavelet analysis can be used to analyze the periodicities as well as magnitude of variations in the engine combustion cycles. This chapter presents the characterization of cycle-to-cycle variations in conventional diesel engine using statistical technique as well as wavelet technique. Cyclic variations in various combustion parameters (such as indicated mean effective pressure, total heat release rate, and peak pressure) are discussed in diesel engine operated at different operating conditions with diesel as well as butanol/diesel blends. Typically, cyclic variations in indicated mean effective pressure, peak pressure, and total heat release rate are found higher at lower engine loads and decrease with increase in engine load.