A 3D-Navier-Stokes solver was used to analyse the complete flow field of the 15-stage axial compressor of Siemens model V84.3A advanced gas turbine. The paper presents the flow simulation including modelling of rotor tip clearances and bleeds for turbine cooling air supply. All computations were performed for coupled blade rows to account for the time averaged impact of interaction effects arising from adjacent airfoil rows. The evaluation of such two-blade-row calculations allows the update of the inlet boundary conditions for the following downstream two-blade-row combination. Successive computations from inlet guide vanes to exit stator thus yield the flow field of the whole compressor. The main objective is the analysis of the numerical results. Special attention is given to the front stage, stage matching, endwall flow effects, tip leakage and the cooling air extractions. The comparison to experimental data of the full load gas turbine test facility generally shows a good agreement. The results demonstrate the reliability and power of a modern CFD tool to perform advanced design studies, geometry modifications and calibration of fast 2D-Codes more efficiently and less expensively than performing any physical experiments.

Siemens H-Class. Siemens has developed the world-largest H-class Gas Turbine (SGT™) that sets unparalleled standards for high efficiency, low life cycle costs and operating flexibility. With a power output of 340+ MW, the SGT5–8000H gas turbine will be the primary driver of the new Siemens Combined Cycle Power Plant (SCC™) for the 50 Hz market, the SCC5–8000H, with an output of 530+ MW at more than 60% efficiency. After extensive lab and component testing, the prototype has been shipped to the power plant for an 18-month validation phase. In this paper, the compressor technology, which was developed for the Siemens H-class, is presented through its development and validation phases. Reliability and Availability. The compressor has been extensively validated in the Siemens Berlin Test Facility during consecutive engine test programs. All key parameters, such as mass flow, operating range, efficiency and aero mechanical behavior meet or exceed expectations. Six-sigma methodology has been exploited throughout the development to implement the technologies into a robust design. Efficiency. The new compressor technology applies the Siemens advanced aerodynamics design methodology based on the high performance airfoil (HPA) systematic which leads to broader operation range and higher efficiency than a standard controlled diffusion airfoil (CDA) design. Operational Flexibility. The compressor features an IGV and three rows of variable guide vanes for improved turndown capability and improved part load efficiency. Serviceability. The design has been optimized for serviceability and less complexity. Following the Siemens tradition, all compressor rotating blades can be replaced without rotor lift or destacking. Evolutionary Design Innovation. The compressor design incorporates the best features and experience from the operating fleets and technology innovation prepared through detailed research, analysis and lab testing in the past decade. The design tools are based on best practices from former Siemens KWU and Westinghouse with enhancements allowing for routine front-to-back compressor 3D CFD multistage analysis, unsteady blade row interaction, forced response analyses and aero-elastic analysis.

The subject of this paper is a numerical method for the calculation of the transonic flow field of multistage turbines, taking high coolant flow into account. To reduce the processing time, a throughflow method based on the principels of Wu is used for the hub-to-tip calculation. The flow field is obtained by an iterative solution between a three-dimensional inviscid hyperbolic time-dependent algorithm with an implicit finite volume method for the blade-to-blade calculations using C-meshes and a single representative meridional S2m-streamsurface. Along the S2m-plane with respect to nonorthogonal curvilinear coordinates, the stream function equation governing fluid flow is established. The cooling air inflow inside the blade passage forbids the assumption of a constant mass flow along the main stream direction. To consider the change of the aerodynamic and thermodynamic behavior, a cooling air model was developed and implemented in the algorithm, which allows the mixing of radially arbitrarily distributed cooling air in the trailing edge section of each blade row. The viscous effects and the influence of cooling air mixing are considered by the use of selected loss correlations for profile, tip leakage, secondary flow and mixing losses in the S2m-plane in terms of entropy. The method is applied to the four-stage high-temperature gas turbine Siemens KWU V84.3. The numerical results obtained are in good agreement with the experimental data.

During the last few decades extremely powerful Quasi-three-dimensional (3D) codes and fully 3D Navier-Stokes solvers have been developed and successfully utilized in the design process and optimization of multistage axial-flow compressors. However, most of these methods proved to be difficult in handling and extremely time consuming. Due to these disadvantages, the primary stage design and stage matching as well as the off-design analysis is nowadays still based on fast 2D methods incorporating loss-, deviation- and end wall modeling. Only the detailed 3D optimization is normally performed by means of advanced 3D methods. In this paper a fast and efficient 2D calculation method is presented, which already in the initial design phase of multistage axial flow compressors, considers the influence of hub leakage flows, tip clearance effects, and other end wall flow phenomena. The method is generally based on the fundamental approach by Howard and Gallimore (1992). In order to allow a more accurate prediction of skewed and nondeveloped boundary layers in turbomachines, an improved theoretical approach was implemented. Particularly the splitting of the boundary layers into an axial and tangential component proved to be necessary in order to account for the change between rotating and stationary end walls. Additionally, a new approach is used for the prediction of the viscous end wall zones including hub leakage effects and strongly skewed boundary layers. As a result, empirical correlations for secondary flow effects are no longer required. The results of the improved method are compared with conventional 2D results including 3D loss- and deviation-models, with experimental data of a three-stage research compressor of the Institute for Jet Propulsion and Turbomachinery of the Technical University of Aachen and with 3D Navier-Stokes solutions of the V84.3A compressor and of a multistage Siemens research compressor. The results obtained using the new method show a remarkable improvement in comparison with conventional 2D methods. Due to the high quality and the extremely short computation time, the new method allows an overall viscous design of multistage compressors for heavy duty gas turbines and aeroengine applications.