NATURAL GAS BURNERS FOR DOMESTIC AND INDUSTRIAL APPLIANCES. APPLICATION OF THE PARTICLE IMAGE VELOCIMETRY (PIV) TECHNIQUE.

This contribution presents some examples of the application of Particle Image Velocimetry (PIV) technique to domestic appliances and small scale burners, with the aim of discussing relevant results together with problems encountered. Combustion efficiency and pollutants emissions of gas burners are strongly influenced by the fluid dynamics of the mixture in both premixed and non-premixed flames. For these reasons the Combustion Laboratory of Politecnico di Milano started using laser diagnostic techniques (LDV and PIV) many years ago. The first PIV application was on a premixed V-flame attached over a burner plate with rectangular twin slots, developed for domestic appliances. The autocorrelation of a double exposed photograph was used to define the 2-D velocity flow field and high spatial resolution was obtained with a 1:1 magnification and a zoom Nikkor objective. More recently, a cross-correlation CCD camera with a double pulse Nd-YAG laser was used to characterize high swirl flows under both non-reacting and reacting conditions. In the paper special emphasis will be given to the discussion of the most relevant results and the main problems encountered with PIV applications to the investigated cases.