Laser Doppler velocimeter for measurement of flows induced by flames propagating over condensed fuels
The primary process in the spread of fire along the surface of a condensed fuel is heat transfer from the burning region of the fuel to the material ahead of the flame. In the early stages of a fire, the two mechanisms by which this heat transfer occurs are conduction and convection ahead of the flame through the gas and fuel phases. The determination of the importance of the convective heat transfer can be ascertained only by accurate measurement of the fluid flow velocity and temperature fields near the flame front. Convective flows induced by spreading flames are characterized by low fluid velocities with changes in magnitude and direction accompanied by sharp temperature changes occurring over small distances. The bulk gas velocity induced by the flame frequently opposes the propagation. In liquids, there exists, as well, a liquid motion in the direction of the propagation of the flame. These characteristics make quantitative measurements of fluid velocities difficult using conventional techniques. With the advent of Laser Doppler Velocimeter (LDV) techniques, a non-perturbing means of making high resolution measurements of two-dimensional low velocity fields now exists. Thus, the possibility of determining the role of convective effects has become realizable.
- Research Organization:
- Princeton Univ., NJ (USA). Dept. of Aerospace and Mechanical Sciences
- OSTI ID:
- 5354488
- Report Number(s):
- AD-A-132155/3
- Country of Publication:
- United States
- Language:
- English
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