Unified system for holographic measurement in fluid and solid mechanics: application of the system to volumetric flow measurement in an internal combustion engine

This paper reports holographic measurements of full-field 3D flows inside a production geometry 4-stoke internal combustion engine with extensive optical access through both the cylinder wall and the piston crown. The seeded flow is recorda at two instants as a reflection hologram of high numerical aperture. A purpose built holographic camera using a phase conjugate holographic optical element is used to compensate for the gross aberrations caused by imaging through a thick walled, glass cylinder. Fiber-optic, conjugate recognition and subsequent correlation of the complex amplitude recorded by the hologram facilitates sub- wavelength measurement of particle displacement without directional ambiguity. Preliminary measurements of the flow field within the cylinder at the bottom of the induction stroke are discussed. The results clearly show the potential of this technique to extract 3D velocity information in hostile environments.