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

Abstract

SYNOPSIS A v e r s a t i l e computer-based t e s t i n g and d a t a a c q u i s i t i o n f a c i l i t y d e v e l o p e d t o improve t h e speed and a c c u r a c y o f e n g i n e r e s e a r c h work i s d e s c r i b e d . ( f ) An i n c r e a s e i n t h e speed and a c c u r a c y a t which tests a r e performed.

Internal Combustion Engine Indicating Measurements

“…The strong influence of the pressure derivative on the energy release rate was recognized by several authors (Marzouk & Watson, 1976;Woschni, 1965;Krieger & Borman, 1966). Despite this, indicating measurements usually aim obtaining the in-cylinder pressure, even when combustion diagnosis is the major objective.…”

“…In the mid-seventies, when analog-to-digital converters were included in the instrumentation, multipurpose and of-less-complexity experimental sets became available (Benson & Pick, 1974;Ficher & Macey, 1975;Marzouk & Watson, 1976). From this time, the signal from instrumentation amplifiers has been digitalized and stored in a computer, allowing further manipulation via software.…”

“…These temperature changes modify the sensitivity of the piezoelectric element and impose thermal stresses in the diaphragm and in the sensor housing, generating spurious forces that act on the quartz element and cause additional distortion of the signal provided by the transducer. The inaccuracy due to these effects receives the name of temperature drift (Marzouk & Watson, 1976).…”

“…Despite this, indicating measurements usually aim obtaining the in-cylinder pressure, even when combustion diagnosis is the major objective. As a rule, this task is carried out using a piezoelectric transducer polarized by a charge amplifier (Brown, 1976;Marzouk & Watson, 1976;Benson & Pick, 1974;Lancaster et al, 1975;Lapuerta et al, 2000;Benson & Whitehouse, 1983). The preference for this practice can be attributed to the legacy of the mechanical indicators, which were created especially for pressure measuring, as well as to the importance of knowing the in-cylinder pressure for calculating the indicated work or for characterizing the thermodynamic state of the working fluid.…”

“…A reference to such an approach can be found in the work of Marzouk & Watson (1976) who processed the analog signal from a charge amplifier by an electronic differentiator. While avoiding the numerical differentiation of pressure data, these authors did not obtain satisfactory results for the pressure variation rate, underestimating its peak value during the premixed combustion.…”