Optimization of diesel engine parameters using Taguchi method and design of evolution
The objective of this work is to optimize the control parameters of the direct injection (DI) single cylinder diesel engine with respect to NOx (Oxides of Nitrogen) and fuel emissions through experimental investigations and Taguchi method. A single cylinder 5.2 kW diesel engine was selected for this experiment. Five parameters such as clearance volume, valve opening pressure, nozzle-hole diameter, static injection timing and load torque were varied at four levels and the responses such as NOx emissions and fuel economy were recorded. The optimum values of the response variables could be predicted using S/N ratio and optimum combination of control parameters were specified. Results of confirmation tests showed good agreement with predicted results. Thus the relationship between the diesel engine operating parameters with NOx and b.s.f.c (brake specific fuel consumption) could be understood using Taguchi method of experimental design.
Investigation of diesel engine operating and injection system parameters for low noise, emissions, and fuel consumption using Taguchi methods
Abstract In order to optimize the performance of a small direct injection (DI) diesel engine with respect to noise, emissions, and fuel economy, an experimental investigation was undertaken using Taguchi methods. A single-cylinder 3.5 kW diesel engine was selected for performance tests at different levels of two operating parameters (speed and load) and six injection parameters of the engine (static injection timing, plunger diameter, nozzle valve opening pressure, nozzle hole diameter, number of nozzle holes, and nozzle tip protrusion). These controlled parameters were varied at two levels, and the resulting changes in responses were investigated, namely engine noise, combustion noise, smoke, brake specific fuel consumption (b.s.f.c.), and emissions of unburned hydrocarbons (HC), oxides of nitrogen (NO x ), and carbon monoxide (CO) were investigated. The optimum values of engine noise, combustion noise, smoke, emissions, and b.s.f.c. could be predicted using signal-noise (S/N) ratios, and a relevant combination of controlled input parameters was specified. Results of confirmation runs of the engine showed good agreement with the predicted quantities of interest based on Taguchi analysis. The relative importance of the controlled parameters to the above responses was evaluated in terms of the percentage contributions of the parameters using analysis of variance (ANOVA). The Taguchi method of experimental design was found to be robust and more cost effective for understanding the relationship between diesel engine parameters and noise, emissions, and b.s.f.c. than full factorial design.
Turbulent boundary layer wall‐pressure fluctuations downstream from an abrupt change in surface roughness
Spectra of wall‐pressure fluctuations beneath a turbulent boundary layer have been investigated immediately downstream from an abrupt change in surface roughness, from slightly rough to very rough. Over the measurable frequency band (400 Hz to 7 kHz), the spectra in the first 150 mm scale on wall variables. This indicates that the motions responsible for the pressure fluctuations measured in this region are very close to the wall. Farther downstream this scaling procedure breaks down. It is suggested that the initially thin internal layer behaves independently of the flow external to it until it has grown appreciably and only then interacts with the outer boundary layer. It was found that, for all frequencies measured, the dimensional spectral level decreases initially then rises to a maximum at 250 mm from the roughness change before decreasing once more. The position of the maximum is close to where the internal layer ceases to have a distinct edge.