Optical methods for the study of flames in turbulent pre-mixed gas streams

Three optical methods for the investigation of flame processes in turbulent gases are described. All are based on ray deflexion by the steep refractive-index gradient occasioned by large temperature and composition changes across the flame front. This is utilized in three different optical systems designed (1) to give a measure of the randomness of orientation of the fluctuating flame front in any locality; (2) to delineate the instantaneous flamefront surface; and (3) to map time-mean deflexion (and hence optical path) distributions. Their purpose and use is discussed and illustrated by examples of the records obtained.