Study of Wet Steam Flow in Model Steam Turbines

A complex for studying the structure of the wet-steam flow for a stand with a model turbine of the NPO TsKTI is presented. On the stand, the flow parts of steam turbines have been tested for more than 20 years. The experimental turbine is a model of the flow part of a low-pressure cylinder at a scale of 1 : 3. It is equipped with an extensive measuring system for the study of the vibration reliability of the elements of the flow part and the structural and kinematic characteristics of the flow. One of the most important parts of the measuring system is a complex for studying the dispersed structure of the wet-steam flow, which allows measurements to be carried out simultaneously in three control sections of the flow part and in two sampling pipes. It includes optical probes, secondary hardware units, a traversion system, and software. Measurements made using the optical spectral transparency method allow one to set the size and volume concentration of droplets in the wet-steam stream. A new method for determining droplet size distribution based on optical measurements is described. The droplet size distributions obtained by this method in two control sections are presented. It is shown that the calculation of the degree of humidity according to optical measurements is possible with the involvement of the results of independent measurements of both the vapor pressure and its temperature recorded by the optical probe. A comparison of the calculations of the degree of humidity based on pressure and temperature measurements for model and full-scale turbines was made. The result of the complex is the distribution of the degree of humidity, the size of the droplets, and the temperature of the flow along the height of the blade. The distribution of moisture parameters by the height of the blade in three control sections is given.