Adaptive optics for IC-engine measurements

Abstract

The present paper is concerned with the development of miniaturized LDA-optical systems to produce small-size, optical velocity sensors that can be easily employed to measure flow velocities. Miniaturization is achieved by employment of graded index fibers to guide the incident laser beams to the optical head. The same sort of fibers are used to guide the collected scattered laser radiation back to the photodetector. In this way, the bulky parts of a conventional LDA-optical system can be placed and operated away from the test section. Small optical heads result that can be easily handled and traversed. Three different LDA-optical systems are described. Test measurements in pipe and channel flows are presented and first measurements in a fired internal combustion engine are provided to establish the correct functioning of the system.