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This paper describes the design concept and construction of a continuous operating cold flow transonic test turbine facility, which is a unique combination of a 2 MW axial test turbine and a direct coupled brake compressor. To cover the losses additional air is provided through a separate electrically driven compressor station and fed into the turbine inlet casing via special mixer inserts which are also fed by the hot compressed air from the brake compressor. The main test rig dimensions and its capabilities are outlined. A brief description of the design process with step by step advanced technology design methods is presented from the first ideas up to the latest plant expansion for special testing conditions where two industrial transonic turbine stages will be tested. The aerodynamic and structural design of our transonic single turbine stage (TTM-Stage) is described in detail and the results of the respective flow simulations are presented.

In recent years an increased interest in pump-turbines has been recognized in the market. The rapid availability of pumped storage schemes and the benefits to the power system by peak lopping, providing reserve and rapid response for frequency control are becoming of growing advantage. In that context it is requested to develop pump-turbines that reliably stand dynamic operation modes, fast changes of the discharge rate by adjusting the variable diffuser vanes as well as fast changes from pump to turbine operation. Within the present study various flow patterns linked to the operation of a pump-turbine system are discussed. In that context pump and turbine mode are presented separately and different load cases at both operation modes are shown. In order to achieve modern, competitive pump-turbine designs it is further explained which design challenges should be considered during the geometry definition of a pump-turbine impeller. Within the present study a runner-blade profile for a low head pump-turbine has been developed. For the initial hydraulic runner-blade design, an inverse design method has been applied. Within this design procedure, a first blade geometry is generated by imposing the pressure loading-distribution and by means of an inverse 3D potential-flow-solution. The hydraulic behavior of both, pump-mode and turbine-mode is then evaluated by solving the full 3D Navier-Stokes equations in combination with a robust turbulence model. Based on this initial design the blade profile has been further optimized and redesigned considering various hydraulic pump-turbine requirements. Finally, the progress in hydraulic design is demonstrated by model test results which show a significant improvement in hydraulic performance compared to an existing reference design.

External heat transfer predictions are performed for two-dimensional turbine blade cascades. The Reynolds-averaged Navier-Stokes equations with algebraic (Arnone and Pacciani, 1996), one-equation (Spalart and Allmaras, 1994) and two-equation (low-Re k-ε, Biswas and Fukuyama, 1994) turbulence closures are solved with a fully-implicit time-marching finite volume method. Comparisons with measurements (Arts et al., 1990, 1994) for a highly-loaded transonic turbine nozzle guide vane cascade show good agreement in some cases, but also reveal problems with transition prediction and turbulence modeling. Special attention has been focused on the low-Re k-ε model concerning the influence of the inlet boundary condition for the ε-equation and problems in the stagnation point region.

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