The use of confuser–diffuser nozzles in power machines enables efficient conversion of gas energy into mechanical work. However, traditional Laval, Venturi, and Vitoszynski nozzles are associated with shock wave formation, causing energy losses, noise, and structural loading. This study proposes innovative jet nozzles with an internal streamlined body that forms annular flow rather than a classical diffusor. A rational computational design methodology based on the Venturi effect criterion and equality of cross-sectional area variation laws was developed. A couple of configurations with spindle-toroidal and ellipsoidal streamlined bodies were generated analytically, studied numerically, and confirmed experimentally. Based on the SST turbulence model, CFD simulations for a compressible flow (air) show that the proposed designs reduce the pressure jump from 60 kPa (traditional nozzle) to 20 kPa for the spindle-toroidal configuration and eliminate it for the ellipsoidal configuration. The Reynolds number in the throat decreases by a factor of 2.6, reducing turbulence. The outlet velocity increases by 3.0% for the spindle-toroidal design, while the ellipsoidal nozzle provides expansion with slightly lower velocity but a smoother velocity profile. Experimental thrust measurements agree with simulations within 2.6–6.7%. The proposed designs enhance energy efficiency, reduce erosion and vibration, and enable adaptive flow control via axial displacement of the streamlined body.

Two-phase nozzles, in which the phase transition process takes place, can work in jet superchargers for various purposes, including jet thermal pumps (steam-water injectors) and thermal compressors. In such schemes of thermal transformers, the ejector performs the function of a preliminary compression stage in order to reduce the load on the compression of the working substance in the main compressor. The use of fluxes of boiling liquid as energy-efficient working fluids is inhibited due to the lack of a reliable description of the mechanism of their flow. Finding the dependence of the steam content on the pressure and temperature at the nozzle exit will make it possible to determine the variant of the initial parameters at which the overproduction of steam will be greatest. It is also worth determining the change in the velocity factor, as well as the change in the thrust of the nozzle in the studied range of parameters, in order to find out whether the pressure at the nozzle outlet is a determining factor when choosing the design parameters of the nozzles. The article proposes to investigate the boiling streams in such nozzles by the method of mathematical modeling using a model that takes into account the relaxation nature of vaporization. The study used a compressible two-phase medium model, a kinetic model of evaporation / condensation. The model also takes into account the dynamic and mechanical equilibrium of the process of evaporation-condensation. The calculations were performed using an Ansys CFX commercial CFD product. The value of the mean square relative error of pressure measurement does not exceed 0,119%. The average discrepancy between the obtained data between the mathematical model and the field experiment does not exceed 3%.