The Edlén empirical equations and the two-color method are the commonly used approaches to converting a length measured in air to the corresponding length in vacuum to eliminate the influence of the refractive in...The Edlén empirical equations and the two-color method are the commonly used approaches to converting a length measured in air to the corresponding length in vacuum to eliminate the influence of the refractive index of air. However, it is not well known whether the two-color method is superior to empirical equations in refractive index compensation. We investigated the uncertainties of these approaches via numerical calculations of their sensitivity coefficients of environmental parameters. On the basis of a comparison of their uncertainties, we found that in a 0% humidity environment, the two-color method had potential to provide greater measurement accuracy than the empirical equations.展开更多
A novel optical instrumentation system for flame characterization was developed and tested. The two-color system is capable of performing on-line measurement of flame and temperature distribution, providing temporal a...A novel optical instrumentation system for flame characterization was developed and tested. The two-color system is capable of performing on-line measurement of flame and temperature distribution, providing temporal and spatial characterization of the combustion process. In addition, the system has the advantage of being non-intrusive. The on-line measurement of temperature distribution on a methane-air combustor revealed some interesting characteristics. When air flow rate was kept constant, an increase in CH4 flow rate would enhance the combustion intensity and elevate the flame temperature. While under constant CH4 flow rate, the increase of air flow rate would lead the measured flame temperature first to increase and then decrease. The drop of temperature might partially be caused by the heat losses due to excessive air. However, with insufficient soot particles in the flame, the temperature could be under-evaluated.展开更多
文摘The Edlén empirical equations and the two-color method are the commonly used approaches to converting a length measured in air to the corresponding length in vacuum to eliminate the influence of the refractive index of air. However, it is not well known whether the two-color method is superior to empirical equations in refractive index compensation. We investigated the uncertainties of these approaches via numerical calculations of their sensitivity coefficients of environmental parameters. On the basis of a comparison of their uncertainties, we found that in a 0% humidity environment, the two-color method had potential to provide greater measurement accuracy than the empirical equations.
基金The author gratefully acknowledges the support of K.C.Wang Education Foundation, Hong Kong.
文摘A novel optical instrumentation system for flame characterization was developed and tested. The two-color system is capable of performing on-line measurement of flame and temperature distribution, providing temporal and spatial characterization of the combustion process. In addition, the system has the advantage of being non-intrusive. The on-line measurement of temperature distribution on a methane-air combustor revealed some interesting characteristics. When air flow rate was kept constant, an increase in CH4 flow rate would enhance the combustion intensity and elevate the flame temperature. While under constant CH4 flow rate, the increase of air flow rate would lead the measured flame temperature first to increase and then decrease. The drop of temperature might partially be caused by the heat losses due to excessive air. However, with insufficient soot particles in the flame, the temperature could be under-evaluated.
