Modeling the Characteristics During the Flow of a Subcooled Liquid Out of Geometrically Similar Laval Nozzles

• Published in: Journal of engineering physics and thermophysics Vol. 97; no. 5; pp. 1296 - 1312
• Main Authors: Mil′man, O. O., Goldin, A. S., Shifrin, B. A., Perov, V. B., Ptakhin, A. V., Krylov, V. S., Kondrat′ev, A. V.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.09.2024; Springer Nature B.V
• Subjects: Classical Mechanics; Complex Systems; Engineering; Engineering Thermodynamics; Entrances; Heat and Mass Transfer; Industrial Chemistry/Chemical Engineering; Jet thrust; Mixtures; Nozzles; Outflow; Pressure dependence; Temperature dependence; Thermodynamics; Throats; Turbines; efficiency; Laval nozzle; flow-rate coefficient; throat; expansion ratio; temperature; velocity coefficient; pressure; reactive force; steam–water mixture
• ISSN: 1062-0125; 1573-871X
• DOI: 10.1007/s10891-024-03003-z

To design hydrosteam turbines of the Segner-wheel type, it is necessary to have reliable characteristics of a Laval nozzle with a large expansion ratio when water strongly subcooled to a saturation temperature is fed to the nozzle. The authors have given a review of a number of works on determining the flow-rate coefficient μ and the coefficient of velocity ϕ when water subcooled to a saturation temperature flows out of Laval nozzles. The complexity of the process of outflow of a steam–water mixture has been noted, which is dependent on the relation of the temperature and pressure at entry into the nozzle, pressure behind the nozzle and the nozzle expansion ratio, and the configuration of the entrance region. Experimental data have been given on blowdowns of geometrically similar nozzles with measuring the jet thrust and determining the flow-rate and velocity coefficients. It has been shown that the linear dimensions of the nozzle throat do not influence μ when a constant relation of the length of the throat to its diameter is observed. The velocity coefficient during the outflow of a boiling liquid depends on the linear dimensions of the expanding section of the nozzle, i.e., testing of geometrically similar nozzles do not ensure a correct determination of φ. It has been shown that the nozzles' efficiency must be compared in the design regime when the pressure on the exit section is equal to the pressure in the chamber where the steam–water mixture flows. Analysis results will be useful for calculating and designing a reaction hydrosteam turbine.