Film cooling design is essential for modern HPT vanes. In this paper, a semi-inverse design optimization (SIDO) method for the film cooling arrangement of HPT vanes is introduced, which is based on a combinatorial optimization algorithm, a 1D heat conduction model and CFD methods. The SIDO method can optimize the total coolant amount of the film cooling structure while ensuring an acceptable metal temperature distribution. The optimization methodology was tested on a 2D vane derived from the 1st stage nozzle of a heavy–duty gas turbine, and the optimization result was validated by the conjugate heat transfer (CHT) CFD simulations. In further study, the SIDO method is applied to predict the optimal (necessary) coolant amount of the vane at various design conditions with different inlet temperature, maximal metal temperature allowed, heat conductivity of TBC, and intensity of internal/film cooling structures. The quantitive results suggested that the inlet temperature and the maximal metal temperature allowed are arbitrary to the necessary coolant amount. Improving film cooling performance is more effective to save coolant compared with internal cooling, especially at higher inlet temperature level.

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A numerical model is developed to characterize erosion caused by water droplets impinging against rotor blades at the first stage of an axial flow compressor. Analyses assume a gas turbine operating with an inlet fogging system. The change in the water droplet size attributable to break-up and evaporation during flight is considered. Numerical calculations are executed using a commercial code in a two-dimensional computational domain including an inlet guide vane, rotor, and stator. The calculated erosion depth shows good agreement with that obtained from empirical correlation in the case without a break-up model. Results show that the break-up occurs over a certain rotor speed, leading to marked reduction of the erosion depth. The choice of the droplet critical Weber number determines the rotor velocity which maximizes the erosion depth. Secondary droplets discharged from the trailing edge of IGV (Inlet Guide Vane) affect erosion more than primary droplets, although their mass flow is smaller.

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This paper presents the verification and application of the flutter analysis framework using fluid-structure interaction simulation (FSI). This approach is verified by consulting semi-analytical reference solutions from LINSUB. Aeroelastic eigenmodes and mode shapes obtained by FSI are compared; the proposed approach is found to be capable of accurately obtaining flutter characteristics, even under the presence of aerodynamic coupling between structural modes. This verified approach is applied for predicting the flutter boundary of part-speed transonic stall flutter, which is experienced during the rig test. The flutter boundary obtained by FSI simulations agrees well in a qualitative sense for the high speed lines. However, the simulations cannot reproduce the end of the flutter boundary for the low speed lines. The reason for the mismatch in the flutter boundary is discussed, and it is concluded that highly complex and sensitive near-wall flow phenomena are related to the shock position and flutter characteristics.

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In previous studies, the pressure recovery of highly-loaded annular diffusers was identified to correlate with the Reynolds shear stresses at rotor outlet in the blade tip region. The origin and propagation of the Reynolds shear stresses, however, have not been experimentally clarified yet due to measurement probe constraints. Hence in the present work, the origin of these stresses, as well as the transport throughout the flow channel is analyzed by simulating the rotor with the scale adaptive turbulence model SAS-SST is used. Using the SAS approach, the Reynolds shear stress characteristics of the simulation are validated by the experimental results, whereas common RANS approaches are shown not to be appropriate. The tip leakage vortex is found to be the source of the Reynolds shear stress production. The interaction between vortex and mean flow leads to turbulent momentum transport. The Reynolds shear stresses propagate into the rotor far-field connected to the blade tip vortices which mix about four chord lengths downstream of the rotor trailing edge.

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Several optimization approaches are presented in the paper, and the results of each task depending on the optimization setup are compared and discussed in terms of physical behavior and convergence. The optimization problem is set up and solved for several 2D compressor airfoils with different inlet parameters. The airfoils were generated and their characteristics were built for optimized solutions from different optimization approaches. The novel topology for 2D compressor airfoil is proposed an and successfully utilized. The approach was tested for particular cases and showed a gain in efficiency and flow turning up to 15% (relative) compared with NACA-65 airfoils taken as the initial design.

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