Babayev A. Influence of the steam distribution on the efficient operation of the high-power turbines

The work is devoted to gas-dynamic processes investigation in the flow path of high-power steam turbines, in particular, stop valves and control valves flow path, and as well to develop the design of device meant to reduce turbine flow path abrasive wear. As the main investigation method of the gas-dynamic processes in the steam distribution flow path was used the numerical method of mathematical modeling of three-dimensional stationary and no stationary flow of viscous superheated steam and air based on the use of Reynolds-Averaged Navier-Stokes equations in combination with the semi-empirical turbulence model κ-ω SST and the numerical method based on the control volume. The credibility of the obtained results is confirmed by verification of numerical method results with the experimental data. To determine the effect of flow pattern formed in the flow path of control valve on the efficiency of subsequent elements of steam turbine flow path, the numerical investigation of gas-dynamic processes in the inlet path of steam turbine K-200-130, consisting of control valve, inlet duct and nozzle apparatus of turbine first stage was carried out. It was determined that the total energy losses of working fluid in the joint operation of these elements exceed the losses in their isolated work. The main influence for the increase in energy losses, which for the nozzle apparatus can reach on 25 %, is the presence of uneven parameters of the input flow formed in the previous valve. In the result of numerical investigation of non-stationary gas-dynamic processes, it is found that with the large lift of valve the design of locking plug of the profiled type (Venturi) is most effective. The design of valve with locking cup of this type has a high throughput and the lower level of fluctuations in steam flow parameters. With the small lift of plug, the valve design with a deep cut-off plug is more stable. In the result of numerical investigation of the influence of the geometric characteristics of input compartment of the flow path of the valve, the range of geometric ratios of the valve input compartment, which provides a low level of energy loss of the working fluid, is established. To reduce the energy loss in the flow path of stop and control valves of the corner type with one-sided lateral supply of the flow to the valve chest, the design of valve guide glass with a screen having an impenetrable sector facing to the inlet pipe has been developed. In the result of numerical investigation it is determined that its incorporation leads to an increase of the gas dynamic efficiency of the valve. The coefficient of total energy loss in the diffuser section of valve and the necessary pressure drop was reduced by 50 %. Based on the numerical investigations were further developed method of stop valves and control valves design, which includes the effect of geometric correlations of valve input compartment of flow path for their performance and reliability. To maintain the efficiency of steam turbine during the period of operation, the original design of device for the elements of flow path protection from abrasive wear is proposed. The development is patent protected. Work principle of the proposed device is to separate the solid particles of erodent from the steam flow by using the inertial forces acting on the particle in the flow with the changes in flow direction.