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 CYCLE-TO-CYCLE VARIABILITY
This paper summarises an investigation of the cycle-to-cycle variation in diesel engine cylinder pressure trace. A multi-channel, high-speed PC based data logger was developed and used to measure the cylinder pressure, crank angle, and fuel needle lift position over 50 consecutive cycles. A joint test programme was conducted by University of New Orleans (UNO) graduate students at the US Merchant Marine Academy's (USMMA) Engineering laboratory. The measurements were made over a 4-year period using a single cylinder test engine and later the 12-cylinder MV Kings Pointer propulsion engine. The study showed the cycle-to-cycle variation is influenced by the engine rev/min, injection timing, and compression ratio. It was found that the commonly adopted cycle-to-cycle variation in maximum cycle pressure may not reveal the variation in the cylinder output. In some cases the variation in ignition delay from fuel injection gave a better estimate. These trends were evident from the analysis of the 925 hp 12-cylinder MV King Pointer engine cylinder pressure measurements. A procedure for scaling the single cylinder engine results to full scale propulsion engine is presented. Comparison of the single cylinder and scaled propulsion engine results show reasonable agreement for the cycle-to-cycle variation in cylinder output.
Reid on Hypotheses and the Ether; A Reassessment
In recent years historians of science have come to see that Thomas Reid’s Essays on the Intellectual Powers of Man had a profound impact on the development of British methodological thought in the late-eighteenth and early-nineteenth centuries. Larry Laudan has argued that Reid was “the first major British philosopher to take Newton’s opinions on induction, causality, and hypotheses seriously”; and that Reid was thereby instrumental in changing the character of British methodological discourse in the Enlightenment.(1) Geoffrey Cantor has examined in detail the influence of Reid’s critique of ether theories and hypotheses in the Essays on leading protagonists in the nineteenth-century debates surrounding the wave theory of light,(2) and Richard Olson has traced the origins of the scientific style of British physics in the Victorian period to the writings of Reid and other Common Sense philosophers. (3) As well as delineating Reid’s influence, Laudan, Cantor, and Olson have attempted to identify the problems to which he addressed himself in articulating his methodology, and they have analysed with some care the internal structure of his methodological views. Thanks to the work of these historians, therefore, we have a fairly comprehensive picture of Reid’s methodology and its fortunes in the nineteenth century.