Experimental Characterisation of a Vitiated Coflow Piloted Premixed Burner

This paper describes the first characterisation results of a new vitiated coflow piloted premixed burner that has been recently developed. The burner consists of a high velocity premixed central jet, piloted by a low velocity stoichiometric premixed pilot, surrounded by a large diameter hydrogen premixed vitiated coflow. The significance of the new burner is that in certain flow regimes the premixed central jet undergoes an extinction re-ignition process. It is proposed intense turbulent mixing at the nozzle outlet drives the initial extinction process, and re-ignition occurs downstream where turbulent mixing has decreased. With the coflow temperature equal to the adiabatic temperature of the central jet mixture, extinction is driven by pure shear and at lower coflow temperatures by a combination of shear and quenching. The burner layout and dimensions are reported together with coflow thermocouple profiling and burner regime diagram results.