| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 95 === Abstract
Laminar flame speed is a combustion property of fuel. Laminar flame speed was used in combustor design, parameter of turbulence simulation, analysis of chemical reaction of combustion, fire suppressants research. This thesis designed an open-open tube which can maintain constant pressure and close system to measure flame speed of CH4/air mixtures with different equilibrium rations (0.8-1.2) and different pressure (1,2,3,5,atm)at initial temperature 300k.and discuss about flame propagation speed and flame stretch rate in tube.
To reduce error of measuring laminar flame speed, we developed an open-open tube system to measure laminar flame speed. This system included pressure wave damper, pressure absorber, gate valve which were used to maintain system in constant pressure during flame propagating .and photodiode, data acquisition sub system, counter, which were used to calculate flame propagation speed By analyzing photodiode signal, we can assume flame surface in tube is concave, then estimated flame area and laminar flame speed.
Flame propagation speed would change by influence of heat conduction, thermal radiation, buoyancy effect .The experimental data showed the flame propagation speed was very fast in front of observed point. It because of ignition energy is too high so increased flame propagation speed. Flame in tube would be stretched and flame surface became concave because of Thermal effect and buoyancy effect. In order to accurately measure laminar flame speed.We chose observed point which flame stretch rate was zero to estimate flame area and laminar flame speed.
At 1atm the resulting laminar flame speed meet laminar flame speed presented in literatures. We could estimate reaction order by experiments data, compared with reaction order estimate by simulation data. Result showed practicability of experiment system.
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