Влияние температуры вдуваемого пара на характеристики жидкой фазы за изолированной сопловой решеткой

Abstract

Erosion damage of the steam turbine flow path surfaces operating in the wet-steam region is presently a topical issue. Steam injection in locations containing the highest liquid film concentrations is considered to be one of promising ways to combat the adverse effect of erosion-hazardous coarse moisture droplets. The article presents the results from experimental studies aimed at determining the effect the steam injection temperature has on the characteristics of wet-steam flow liquid phase downstream of an isolated turbine blade cascade. A flat cascade of hollow nozzle vanes with a slit for steam injection located on the vane pressure surface near its trailing edge was used as the studied subject. The experiments were carried out on the experimental steam dynamics facility installed at the laboratory of the Moscow Power Engineering Institute National Research University's (MPEI) Department for Steam and Gas Turbines. Steam from extraction of the steam turbine installed at the MPEI's combined heat and power plant was used as the working fluid for the experimental facility. The experimental data were obtained for two initial moisture content values. The injected steam temperature was varied while keeping constant steam pressure in the injection chamber. The PIV method implemented in the POLIS laser diagnostic system was used for determining the effect of steam injection on the liquid phase characteristics. The average diameters of droplets downstream of the vane cascade were measured using the contactless technique developed at the MPEI Department for Steam and Gas Turbines. Angular misalignment between the phases was also analyzed, and the diameters of coarse droplets downstream of the vane trailing edge were estimated. An analysis of the obtained data has shown that steam injection affects the coarse droplet existence area downstream of the vane cascade. The coarse droplet slip coefficient is almost independent on the injected steam temperature, and the efficiency of the proposed technique is almost independent on the steam temperature upstream of the injection chamber.