Multi-objective optimization of supercooled vapor suction for decreasing the nano-water droplets in the steam turbine blade

Abstract

Nowadays, decreasing the losses in industrial equipment as well as increasing their lifetime are of special importance. A steam turbine is one of the essential equipment in power plants. Due to the high prices of steam turbines, the issues of loss decrease and maintenance are crucial. One of the remarkable problems in the last stage of the steam turbine is the two-phase flow which leads to efficiency reduction and mechanical damage to the turbine blades. One of the techniques for decreasing the liquid phase in the steam turbines is the drainage groove. The innovation of the present paper is utilizing the drainage groove for supercooled vapor suction. Then, through optimization of the drainage groove, attempts are made to decrease the condensation losses, erosion rate, and the entropy generated in the steam turbine blade. To do this, the multi-objective optimization method of TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) is used. The optimization is done on the variables of the drainage groove (location, angle, width, and the pressure of drainage grooves). Based on the results, the optimized status is as follows: location 3, angle 90, width 0.06, and drainage pressure 80 kPa. In this status, condensation loss and erosion rate decreased by 5% and 62%, respectively, the entropy generated increases up to 1.03%, and the liquid drainage ratio and total drainage ratio are 3.22% and 3.8%.