This work deals with the experimental study of a swirl two-phase gas-liquid flow in a horizontal vortex chamber with a tangential swirler. Particular attention is paid to the influence of void fraction on the characteristics of precessing vortex core (PVC), formed behind the outlet of the vortex chamber nozzle. It has been found out that the addition of a gas phase into the water flow produces a sharp decrease in the vortex precession frequency and a total pressure drop in the vortex chamber. With a further increase in the gas content, the frequency decreases gradually and the pressure drop varies slightly, increasing or decreasing depending on the liquid phase flowrate. Finally, the current research reveals the consistency of a change in integral characteristics of the flow, depending on the changes in the liquid and gas flow rates.