CH* Chemiluminescence Measurement in sooting Flames

In this work, a non-intrusive method is developed to measure the CH* chemiluminescence in a laminar non-premixed flame. In this method, a digital camera and optical band-pass filters are used. CH* chemiluminescence happens in a sharp band around 430 nm, but in the case of a soot formation in the flame, the resulting thermal radiation partly happens in the CH* chemiluminescence band. In this work, two other band-pass filters with central frequencies of 420 and 440 nm are used to estimate the thermal radiation of soot particles near 430 nm. Using this approximation, the effect of the thermal radiation of soot particles on CH* chemiluminescence is removed. Comparing the experimental results in this work with the numerical simulations show that the proposed method can effectively remove the soot thermal radiation when the soot concentration is low. However, as the soot concentration increases, resulting in enhanced thermal radiation, the accuracy of the method decreases.