Further Improvement of the Mathematical Model of Thermo and Gas-Dynamic Processes in a Turbine without Working Blades of Some Stages

The current state of the Ukrainian power system is characterized by significant stress and a shortage of generating capacities. Restoration and implementation of new generating capacities require a huge amount of appropriate resources and a lot of time. The optimal low-cost and relatively fast option for improving the state of the power system may be the temporary use of damaged power equipment after taking appropriate preventive and repair measures. The emergency state of steam turbines of many power plants requires a special tool for assessing their efficiency and power, as well as the possibility and feasibility of their further use after damage. This paper gives consideration to an improved mathematical model of thermo and gas-dynamic processes in a turbine without working blades of some stages. The test calculation data obtained for the flow parts of the cylinders of various steam turbines in the absence of working blades were presented both for individual stages and the groups of stages. Characteristic patterns of the effect of the location of the stage without working blades in the turbine cylinder on the efficiency of the flow part have been established. The greatest decrease in the efficiency and power of the cylinder occurs in the case of the absence of working blades in the stages located closer to the cylinder head. The lowest efficiency and power losses are observed in the absence of working blades of the last stage. In the nozzle cascades of the stages located directly behind the stages without working blades, the levels of energy losses are increased significantly. The use of the developed mathematical model allows us to find solutions to increase the efficiency of turbines with missing working blades in some stages by changing the geometry of the appropriate nozzle cascades.