Ms. Amy F. Mielke Profile

Amy F. Mielke

Research Engineer at NASA Glenn Research Ctr

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Publications (2)

Proceedings Article | 18 August 2005 Paper

Molecular Rayleigh scattering diagnostic for measurement of high frequency temperature fluctuations

Amy Mielke, Kristie Elam

Proceedings Volume 5880, 58800K (2005) https://doi.org/10.1117/12.615415

KEYWORDS: Temperature metrology, Light scattering, Rayleigh scattering, Mirrors, Photon counting, Laser scattering, Scatter measurement, Scattering, Fabry–Perot interferometers, Molecules

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Proceedings Article | 31 August 2000 Paper

Approach for particle sizing using DPIV

Amy Mielke, Mark Wernet, Jaikrishnan Kadambi

Proceedings Volume 4076, (2000) https://doi.org/10.1117/12.397946

KEYWORDS: Particles, Charge-coupled devices, Light scattering, Sensors, Monte Carlo methods, Diffraction, Mie scattering, Computer simulations, CCD image sensors, Scattering

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Many industrial and fossil fuel energy processes involve two phase flows for mass transit. In order to improve and better understand these two phase flows, knowledge of both the droplet/particle size and spatial distribution are required. The useful diagnostic tools should be able to make in-situ measurements without disturbing the flow field so that undisturbed flow measurements can be obtained. This suggests the need for a novel non-intrusive optical technique that can provide instantaneous measurements of particle size and velocity at multiple spatial points in planar (2-D) fields. Digital Particle Image Velocimetry (DPIV) is being studied as a candidate technique for making these measurements. A Monte-Carlo simulation has been developed that simulates the PIV optical recording system and the electric field scattered from particles in the flow. The simulation incorporates diffraction and the variation in light sheet intensity across the depth of field of the optical system. The simulation also computes the Mie scattered electric fields and images these onto the CCD detector. For small size particles, diffraction effects of the optical system dominate the recorded particle image light intensity distribution on the CCD array, and precludes our ability to determine their size. However, for larger sized particles other effects become more dominant, such as the glare spots in optically clear particles. The simulation allows us to examine the Mie scattered electric field of the particles recorded on the CCD and use the higher order structure in the recorded images to determine particle size. A technique for sizing is proposed which uses the separation between two glare spots visible on the particle image to estimate the particle diameter. The results show that the input particle size distribution to the simulation can be reasonably reproduced using the proposed sizing technique. Analysis of experimental PIV images also demonstrated that this technique is capable of providing moderate accuracy particle size estimates.

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