Some Problems in Diesel Engine Research with Special Reference to Computer Control and Data Acquisition

Abstract

SYNOPSIS A versatile computer-based testing and data acquisition facility developed to improve the speed and accuracy of engine research work is described. The role of computer-aided technology is illustrated through the discussion of two quite separate problems. Fuel burning rates (heat release diagrams) are the most basic measurement of combustion, yet highly sophisticated equipment and techniques are required to obtain accurate rate diagrams. The problem is illustrated through the derivation of heat release data by analysis of averaged and smoothed cylinder pressure diagrams from naturally aspirated and turbocharged diesel engines. Techniques developed for transducer mounting, choice of sampling interval, data-logging, processing, smoothing, etc. are presented. During transient conditions (e.g. sudden load chnages) a turbocharged diesel engine moves through operating regimes not normally encountered in steady state operation. Although empirical models have been used to prodict the transient response of these engines, only high-speed data-logging of many engine parameters during a transient will permit the development of more basic models. A fully instrumented turbocharged diesel engine has been run (under computer control) through a series of dynamic tests comprising load and speed demand changes, plus combinations of the two. The use of a computer controlled system allowed transients to be re-enacted with a very high order of accuracy following engine design changes. The high-speed data logging system enabled basic data, such as fuel burning rates, to be obtained for each cycle during the transient.