Analysis of Auto-Ignition in a Compression Machine Using Two-Wired Thermocouples 18ICES/023
Authors
Seung-Hwan Choi - Chiba University
Yasuo Moriyoshi - Chiba University
Takafumi Tsunekawa - Chiba University
Young-June Chang - Pusan National University
Abstract
In order to examine the auto-ignition phenomenon, which plays an important role in HCCI and knock phenomenon, information on local gas temperature in combustion chamber is one of the most important factors. Thermocouple is useful to measure local gas temperature even in the vicinity of wall. However, a traditional thermocouple is not adaptable to measure the in-cylinder gas temperature due to slow response. The issue of response can be overcome by two-wired thermocouple. The two-wired thermocouple is consisted of two thermocouples in different diameter and it is possible to determine the time constant using the raw data from each thermocouple. In this study, measurements such as local gas temperature inside a constant-volume combustion chamber, pressure and visualization were achieved under with and without auto-ignited conditions. As a result, negative temperature coefficient was found to mostly affect auto-ignition in this experimental condition. To discuss more in engine-like conditions, RCM (Rapid Compression Machine) was designed and built. As a preliminary result, local gas temperature inside the combustion chamber under compression without combustion was measured to examine the accuracy of two-wired thermocouple.