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Chen, Chiun-Hsun

Publications and source records attributed to Chen, Chiun-Hsun.

2 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Size and shape of solid fuel diffusion flames in very slow speed flows

The influence of very low speed forced flows on the size and shape of a diffusion flame adjacent to a solid fuel slab is studied experimentally and theoretically. Velocities in the range of 1.5 to 6.3 cm/s and O2 mole fractions (in the O2/N2 atmosphere) in the range of 0.15 to 0.19 were tested. The flames moved farther from the fuel surface as the flow velocity was reduced and closer to the sample as the O2 concentration was lowered. A corresponding theoretical model was solved using a two-dimensional Navier-Stokes system with a one-step finite-rate chemical reaction and surface radiative loss.

Chen, Chiun-Hsun↗
NASA NTRS1986

Diffusion flame extinction in slow convection flow under microgravity environment

A theoretical analysis is presented to study the extinction characteristics of a diffusion flame near the leading edge of a thin fuel plate in slow, forced convective flows in a microgravity environment. The mathematical model includes two-dimensional Navier-Stokes momentum, energy and species equations with one-step overall chemical reaction using second-order finite rate Arrhenius kinetics. Radiant heat loss on the fuel plate is applied in the model as it is the dominant mechanism for flame extinguishment in the small convective flow regime. A parametric study based on the variation of convective flow velocity, which varies the Damkchler number (Da), and the surface radiant heat loss parameter (S) simultaneously, is given. An extinction limit is found in the regime of slow convective flow when the rate of radiant heat loss from fuel surface outweighs the rate of heat generation due to combustion. The transition from existent envelope flame to extinguishment consists of gradual flame contraction in the opposed flow direction together with flame temperature reduction as the convective flow velocity decreases continuously until the extinction limit is reached. A case of flame structure subjected to surface radiant heat loss is also presented and discussed.

Chen, Chiun-Hsun↗