High-Temperature LDV Seed Particle Development
High-Temperature LDV Seed Particle
Physical Sciences Inc.
PO Box 3100
Andover, MA 01810
Michael B. Frish (508-475-9030)
LeRC -- NAS3-25284
To perform laser Doppler velocimetry (LDV) in the gas flows of aerospace propulsion
systems, light scattering particles able to withstand the harsh ambient environment
are needed. This project explored the feasibility of manufacturing mono-disperse,
heat-resistant particles having diameters of 0.05 to 0.5 m which can be seeded into
the flow. The technique employs a pulsed, CO2 laser to decompose gases flowing in
a supersonic nozzle, resulting in vapor products which condense, polymerize, or react
to form carbonaceous or silicon particulates which are prevented from agglomerating.
The particles generated were collected, evaluated for size and shape by electron
microscopy, and checked for agglomeration.
In Phase I, a small-scale feasibility study, non-agglomerated, nearly mono-disperse
carbonaceous spheres, typically 100 to 500 nm in diameter, were made by pyrolysis
of ethylene with a pulsed laser. It is expected that, by pyrolysis of other gases
or gas mixtures, this process or a similar one can be made to yield a multitude of
different particle compositions and sizes that can be selected as required to suit
specific LDV seeding applications.
Potential Commercial Application:
Potential Commercial Application: Applications include LDV seeding and the commercial
ceramics or abrasive materials manufacturing field where mono-disperse, non-agglomerated
powders having particle diameters ranging from tens to thousands of nanometers are