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Time-Average Measurement of Velocity, Density, Temperature, and Turbulence Velocity Fluctuations Using Rayleigh and Mie Scattering (CAT#: STEM-ST-0075-YJL)

Introduction

A combined Rayleigh and Mie scattering technique has been developed to measure velocity, density, temperature, and turbulence velocity fluctuations in sparsely seeded, high-speed gas flows, and was used to make measurements in a 25.4 mm diameter free jet facility, which operates at subsonic and supersonic flow conditions. This measurement technique is useful for obtaining critical information for validation of computational fluid dynamics (CFD) codes. The non-intrusive technique is attractive to researchers studying high speed and heated flows where the environment is too harsh for intrusive instruments like hotwires, which disturb the flow and can only be applied to low temperature subsonic flows.




Principle

Mie scattering is defined as the type of scattering in which the diameter of the particle is the same or more than the wavelength of the radiation. Mie scattering gives a generalized solution for a system where a scattering of light takes place by a homogenous spherical medium. And this medium should have a refractive index different from that of the medium through which the light is traversing.
Unlike Rayleigh scattering, Mie scattering is not a physically independent phenomenon rather, it is a solution to Maxwell's equations for situations where the phase of the incident angle can change within the dimension of the scattering particles. Mie scattering is more commonly known as Mie solution, and it is named after Gustav Mie, a German physicist.
Mie scattering is also known as aerosol particle scattering, takes place in the atmosphere below 1,500 feet. In Mie scattering, the diameter of the spherical particles through which the light is scattered is approximately equal to the wavelength.

Applications

Mie scattering occurs in a variety of applications, including atmospheric science, cancer detection and treatment, metamaterials, and parasitology. Another application is the characterization of particles by optical scattering measurements.

Procedure

1. Sample preparation
2. Measurement by scattering detection instrument
3. Data analysis

Materials

Mie scattering measurement system