The article presents a new gas-dynamic mixer a closed-type one. The structure of a two-phase flow generated by the mixer, the disperse phase velocity diagram, the size and concentration of drops are experimentally investigated. Pulsation characteristics of a disperse phase are calculated. The mixer ensures the operation of a system that produces high-concentration two-phase gas-droplet streams for various values of consumption and pressure of working fluids. It is established, that, thanks to the presence of air in a two-phase working fluid the liquid is accelerated in the initial part of the stream and then it is decelerated. It should be noted that the stream under consideration is a polydisperse one: there are sites of very small particles which the optics practically does not resolve, and there are very large drops. The results of dispersion measurements using different methods are in close agreement. It is also experimentally established that the maximum pulsations take place at the nozzle outlet and there are local minima in the two-phase stream.