Errors in measuring the temperature of turbulent flames by optical methods

Conclusions

• 1. The resultant discrepancies between temperatures of turbulently burning homogeneous mixtures which are measured by optical methods (the conversion method and the infrared method) and temperatures measured by other methods can be satisfactorily explained by theoretical considerations of the nature of temperature averaging by optical methods, if we assume that, in the combustion zone, the temperature fluctuates according to the law

  $$\bar T = T_2 P_2 + T_1 \left( {1 - P_2 } \right).$$

• 2. The fact that higher adiabatic combustion temperatures are obtained along the flame jet axis, where the combustion is complete for mixture compositions with α ≶ 0.8–1.1, can be explained by fluctuations of the mixture composition in time; however, it must be assumed that a considerable degree of inhomogeneity (P₂ is present in this case.

• 3. The above analysis shows that, in principle, the actual temperature can be calculated with respect to measured optical temperature values.