<p class="Abstraktpspvku">This paper presents a basic description of measurements on the experimental air turbine located in the laboratories of the Department of Power System Engineering (KKE). The research on this turbine focuses on the flow in a one-stage air turbine. It monitors the influence of the spatial formation of the blades on the efficiency of the stage. A new geometry with reaction blading is currently being tested. This work has been carried out in cooperation with an industrial partner, Doosan Skoda Power (DSPW).</p>

This article describes a measuring methods and evaluating measured data on a single-stage axial turbine with reaction (~ 50 %). One turbine operating mode was selected, in which the traversing behind the nozzle and bucket with two 5-hole pneumatic probes took place. The results are distributions of flow angles, reactions, or losses distribution/efficiencies along the blades.

The article describes the measurement methods and data evaluation from a single-stage axial turbine with high reaction (50%). Four operating modes of the turbine were selected, in which the wake traversing behind nozzle and bucket with five-hole pneumatic probes took place. The article further focuses on the evaluation of bucket losses for all four measured operating modes, including the analysis of measurement uncertainties.

Long-term efforts have been made to understand loss generation and its reduction in the field of axial turbomachines. The traditional approach to losses for an isolated blade row considers the profile and the secondary losses as a result of viscous flow. The additional kinds of losses in the stage are connected with the shear stress in the mixing process. These losses result from the mixing of the main stream flow with 1) the stator leakage injected through the root axial gap and 2) the return of the tip leakage over the bucket shroud. This article focuses on the first type of mixing losses. The leakage to the main stream flow ratio and the root reaction are the two key parameters investigated in this study. The primary data source for this study is the experiment. An experimental single stage air turbine was modified to set and precisely measure the stator leakage flow. Three configurations of the single-stage test rig with different reaction levels were tested. The second data source for this study is CFD computation. These computations are applied to different geometries and conditions from the experiment; they are derived from real steam turbine stages designed in DSPW. The computations simulate multistage configuration and real steam is considered as the working fluid. CFD computations were performed in the commercial software ANSYS CFX. Each configuration task was computed in three iterative steps. Each step takes the distribution of the flow parameters on the boundary domains from the previous iteration. The final results from this ‘repeating boundary conditions’ approach better correspond with the real expansion in a multistage configuration. The two data sources are not directly comparable. The experiment is used for validation of the trends. The computations provide the possibility of a multi-parametric study. The multi-parametric study is necessary to obtain a more general loss model which can be used during turbine design. The evaluation of the experimental and numerical parts focuses on a comparison of the overall stage performance. Stage efficiency and reaction are presented in relation to the ratio between leakage and main stream flow.

The nuclear power plant also includes a secondary cycle, one of the main components of which is a steam turbine. This device processes the thermal and pressure energy of steam and converts it into mechanical energy. The heat from the reactor is conveied to the secondary cycle in the steam generator. Reliable and safe operation of the steam turbine, and thus of the entire block, is ensured by valves. Flow in a pair of control valves is considered, where the steam flows through the valve chamber past the first valve to the second valve. The experimentally determined flow characteristic of both valves is presented. Data of the distribution of pressures in selected places of these valves are presented. For the typical operating characteristics of a turbine, the course of the coefficient of total pressure distribution losses on the surface of the valves is evaluated. The pressure at the bottom of the cone is compared with the pressure on the wall of the diffuser throat. The energy loss in the valves is compared with the loss in a separate diffuser with varying degrees of expansion. There is also distinguished whether the flow is separated out of the diffuser walls or not.