This study presents the results of measurements in a scaled model turbine test rig operated at Mitsubishi Hitachi Power Systems, Ltd. In order to understand the aerodynamic behavior of a low pressure steam turbine, numerical and experimental results obtained on a four-stage scaled steam turbine module are presented. 
&nbsp;Main performance curves were reported in GT2019-90640 and the verification test results and the corresponding CFD results were compared and evaluated. According to the previous report, the overall performance and exhaust food flow field predicted by CFD were well showing the verification test results. In this paper, the flow pattern obtained by traverse measurements are evaluated and compared with the results of CFD. 
&nbsp;&nbsp;&nbsp; In order to investigate the flow field in the low pressure steam turbine, the tests are carried out using a test turbine (4 stages) of × 0.33 scale. The velocity and pressure fields are evaluated by traverse measurements and the wall pressure is evaluated by wall pressure measurements. The spanwise distributions of pressure and velocity at the last stage exit are measured by radially traversing of a 5-holes pneumatic probe. 
&nbsp;&nbsp;&nbsp; The corresponding CFD are performed by ANSYS CFX. Generally, shroud and stub are used in last stage rotating blades of industrial steam turbine to provide high structural stability by increasing stiffness and damping. Of course, these shroud and stub effect on the overall performance and flow fields in a low pressure steam turbine. In this study, the shroud and stub are modeled in CFD to evaluate the effect on flow pattern. Besides, in order to evaluate the effects of super cooling in blade rows, non-equilibrium condensation are modeled in CFD by ANSYS CFX. The computation model is constructed as accurate reproduction of the scaled model test steam turbine including some steam pipes, supporting sheet metal and the measurement equipment such as traverse pipes and instruments. However, the simple computation model which consists of blade rows with cavities (multi stages) and short diffuser is applied for non-equilibrium condensation calculation due to convergence problems. Additionally, a detailed comparison of three-dimensional CFD results performing an equilibrium condensation model and a non-equilibrium condensation model are evaluated with test data. 
&nbsp;&nbsp;&nbsp; Comparative evaluation of the test results with the corresponding CFD results showed that the flow patterns predicted by CFD are good. In order to capture the flow pattern characteristics by CFD, it is necessary to consider both real shape modeling and non-equilibrium condensation modeling. Therefore, it was found that CFD is useful for understanding the flow pattern of a low-pressure steam turbine. 
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Experimental and Numerical Investigation of the Effects of Real Shape Modeling and Non-Equilibrium Condensation Modeling on the Flow Pattern in Steam Turbine

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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