Mass flux, mass fraction and concentration of kerosene droplets have been measured by a phase-Doppler instrument in a swirl-stabilized burner during inert and reacting flow. In the reacting flow, the flame was supported by natural gas added through the fuel stalk, while the kerosene was added to and atomized by the combusting air. The bulk mean velocity of the combustion air was 30.4 m/s, corresponding to a Reynolds number of 30,000, and the swirl numbers were 0.48 and 0.29, respectively, upstream and downstream of the kerosene injection. The equivalence ratios were 0.45 and 2.11 for the natural gas and the kerosene, respectively. The results show that the minimum swirl necessary for flame stability caused fuel to centrifuge from the region of combustion, so that only 8 kW of energy could be released out of the available 37.4 kW of the kerosene fuel. An important conclusion is that an optimum swirl number will exist with every atomization and burner arrangement of a liquid-fuelled flame and will be different from that associated with the corresponding gas-fuelled flame. The measurement techniques appropriate to regions where the flow instantaneously reverses are described and the existence of large droplets, which moved towards the injector inside the recirculation zone and supplied fuel to the base of the flame, are explained in terms of a "fountain effect" based on the mean drag between the gas phase and the droplets. Sources of uncertainties of the mass flux and concentration measurements with the phase Doppler instrument are considered in detail.