Soot volume fraction and velocity fields
at high-speeds in a turbulent flame
William L. Roberts
Submitted to OSA, Optics Letters 2019
The set-up: Extinction imaging and planar laser induced incandescence setup (PLII). The extinction setup consists of a pulsed LED going through 2 Fresnel lenses and a diffuser captured by an SA-Z fast camera. PLII was captured using an ICCD camera.
Soot is a natural byproduct of incomplete combustion and is detrimental to human health and the environment.
Previous experiments in simple canonical flames typically provide point or 2D measurements to support the development of improved soot models.
In this letter, we introduce a new diagnostic able to obtain instantaneous 3D soot volume fraction and with the potential to obtain instantaneous 3D velocity fields in a turbulent flame.
To achieve these results, extinction images were simultaneously acquired at three angles around the flame.
A specialized space-time tomographic method was used to reconstruct 3D velocity fields and 3D extinction coefficients.
From the local extinction coefficients, local soot volume fraction can be derived.
The reconstructed soot fields were compared to a single shot planar laser-induced incandescence (PLII) image of the soot field synchronized with the final extinction measurement.
Qualitative results between the image slice corresponding to the PLII shot were in good agreement with the corresponding tomographic reconstruction slice.
(a) 2D extinction images (DBIEI) obtained at 0°, 45°, and 90° with the simultaneous LII image obtained at 117°.
(b) 3d reconstruction of the extinction images with K multiplied by 100, and Velocity profile of the flame with units of pixels/frame.
Input 2d video (left) obtained at 0°, 45°, and 90° with the simultaneous LII image obtained at 117°, and reconstructed results (right)
(Left image) Normalized LII image taken at 117°. (Right image) Normalized tomographic reconstruction image slice at 117°.
Paper and supplementary
Paper [Coming soon]
Supplement [Coming soon]
Related Project [Space time tomography]