This paper presents a numerical investigation of the impact of different part-span connector (PSC) configurations on the flow field in a turbine passage. For this purpose a linear cascade based on a profile section of a typical reaction blade used in industrial steam turbines was modeled and 3D simulations with varying size, shape, axial position and yaw incidence angle of the PSC were performed. Air modeled as ideal gas was chosen as the working fluid.
Apart from a sensitivity study of the above mentioned parameters on the losses incurred by PSCs based on the numerical results, a detailed investigation of the flow field was carried out to highlight the interaction with the incoming flow. Moreover, the variation of the flow field behind the cascade was examined to assess the impact on the subsequent blade row. It is shown that depending on the geometry and the position of the PSC, different vortex structures are established in the wakes. These wakes interact with the main flow in the passage, thus influencing both dissipation and the downstream flow field. Major changes of the wake flow character and extent could be observed.
Comparisons of the CFD results against commonly used analytical loss correlations for PSC revealed large differences, especially as certain parameters such as the yaw incidence angle are generally not considered by the latter. As a consequence, the analytical models need to be improved and extended. The results of this study indicate that the possibility of reducing the losses incurred by PSC by careful selection of design parameters within the design space dictated by its mechanical constraints.