An application of speckle-based background oriented schlieren for optical microcalorimetry

Quentin Michalski (1) , Julien Sotton (1) , Alain Claverie (1) , Marc Bellenoue (1)

1 PPrime [Poitiers] - Institut Pprime [UPR 3346]

The aim of the present study is to validate an experimental method of in-fluid enthalpy variation measurement by means of Speckle-based Background Oriented Schlieren (SBOS). The method applies on resolving the millijoule thermal-energy transfer to fluid induced by an electric discharge in air. Intensified camera is used to match the electric discharge exposure time constraint. Speckle is used as the reference pattern as it allows an easier access to high density pattern for subcentimetrics imaging. Geometrics optics principles are used to extract line of sight integrated index of refraction. Local density field is then computed through filtered back projection of Gladstone-Dale equation. The method is first validated in close experimental conditions provided by the density measurement of a millimeters-dimensions CO2 gaseous laminar jet. An analysis on the jet gives useful insights on noises sources and uncertainties of the method which is then transposed to the discharge. Results of enthalpy measurements are discussed.

Mots clés: Background Oriented Schlieren; Calorimetry; Spark; Ignition

Domaines: Milieux fluides et réactifs

Quentin Michalski, Julien Sotton, Alain Claverie, Marc Bellenoue. An application of speckle-based background oriented schlieren for optical microcalorimetry. 18th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics, Jul 2016, Lisbon, Portugal. ⟨hal-01468085⟩