STUDY OF FLAME AND WALL TEMPERATURE VISUALIZATION ON SPARK-IGNITED ENGINE ULTRALEAN COMBUSTION

This paper presents a unique approach for two-dimensional visualization and measurement of chamber wall temperatures in ultralean combustion engines. It also includes a three-dimensional measurement method for flame speed in the lean combustion of spark-ignited engines. Ultralean combustion, which is characterized by an air fuel ratio of more than 20, has proven to be effective for combustion improvements such as emission gas cleaning and thermal efficiency. However, combustion has inherent difficulties such as instability. Swirl is an effective method of stabilizing lean combustion. It is important from a combustion stability standpoint to understand the relationship between swirl and wall temperature and between swirl and flame. Wall temperature distribution and three-dimensional flame speed in ultralean combustion are clearly observable by use of the visualization method. The relationship between wall temperature distribution and three-dimensional flame speed is investigated.