A high-pressure vane (HPV) equipped with a realistic film-cooling configuration has been studied. The vane is characterized by the presence of multiple rows of fan-shaped holes along pressure and suction side, while the leading edge (LE) is protected by a showerhead system of cylindrical holes. Steady three-dimensional Reynolds-averaged Navier–Stokes simulations have been performed. A preliminary grid sensitivity analysis with uniform inlet flow has been used to quantify the effect of spatial discretization. Turbulence model has been assessed in comparison with available experimental data. The effects of the relative alignment between combustion chamber and HPVs are then investigated, considering realistic inflow conditions in terms of hot spot and swirl. The inlet profiles used are derived from the EU-funded project TATEF2. Two different clocking positions are considered: the first in which hot spot and swirl core are aligned with passage; and the second in which they are aligned with the LE. Comparisons between metal temperature distributions obtained from conjugate heat transfer (CHT) simulations are performed, evidencing the role of swirl in determining both the hot streak trajectory within the passage and the coolant redistribution. The LE aligned configuration is determined to be the most problematic in terms of thermal load, leading to increased average and local vane temperature peaks on both suction side and pressure side with respect to the passage-aligned case. A strong sensitivity to both injected coolant mass flow and heat removed by heat sink effect has also been highlighted for the showerhead cooling system.

A new high-speed linear cascade has been developed for low-pressure turbine (LPT) studies at The Ohio State University. A compressible LPT profile is tested in the facility and its baseline performance at different operating conditions is assessed by means of isentropic Mach number distribution and wake total pressure losses. Active flow control is implemented through a spanwise row of vortex-generator jets (VGJs) located at 60% chord on the suction surface. The purpose of the study is to document the effectiveness of VGJ flow control in high-speed compressible flow. The effect on shock-induced separation is assessed by Mach number distribution, wake loss surveys and shadowgraph. Pressure sensitive paint (PSP) is applied to understand the three dimensional flow and shock pattern developing from the interaction of the skewed jets and the main flow. Data show that with increasing blowing ratio, the losses are first decreased due to separation reduction, but losses connected to compressibility effects become stronger due to increased passage shock strength and jet orifice choking; therefore, the optimum blowing ratio is a tradeoff between these counteracting effects. The effect of added surface roughness on the uncontrolled flow and on flow control behavior is also investigated. At lower Mach number, turbulent separation develops on the rough surface and a different flow control performance is observed. Steady VGJs appear to have control authority even on a turbulent separation but higher blowing ratios are required compared to incompressible flow experiments reported elsewhere. Overall, the results show a high sensitivity of steady VGJs control performance and optimum blowing ratio to compressibility and surface roughness.

Unsteady component interaction represents a crucial topic in turbomachinery design and analysis. Combustor/turbine interaction is one of the most widely studied topics both using experimental and numerical methods due to the risk of failure of high-pressure turbine blades by unexpected deviation of hot flow trajectory and local heat transfer characteristics. Compressor/combustor interaction is also of interest since it has been demonstrated that, under certain conditions, a non-uniform flow field feeds the primary zone of the combustor where the high-pressure compressor blade passing frequency can be clearly individuated. At the integral scale, the relative motion between vanes and blades in compressor and turbine stages governs the aerothermal performance of the gas turbine, especially in the presence of shocks. At the inertial scale, high turbulence levels generated in the combustion chamber govern wall heat transfer in the high-pressure turbine stage, and wakes generated by low-pressure turbine vanes interact with separation bubbles at low-Reynolds conditions by suppressing them. The necessity to correctly analyze these phenomena obliges the scientific community, the industry, and public funding bodies to cooperate and continuously build new test rigs equipped with highly accurate instrumentation to account for real machine effects. In computational fluid dynamics, researchers developed fast and reliable methods to analyze unsteady blade-row interaction in the case of uneven blade count conditions as well as component interaction by using different closures for turbulence in each domain using high-performance computing. This research effort results in countless publications that contribute to unveiling the actual behavior of turbomachinery flow. However, the great number of publications also results in fragmented information that risks being useless in a practical situation. Therefore, it is useful to collect the most relevant outcomes and derive general conclusions that may help the design of next-gen turbomachines. In fact, the necessity to meet the emission limits defined by the Paris agreement in 2015 obliges the turbomachinery community to consider revolutionary cycles in which component interaction plays a crucial role. In the present paper, the authors try to summarize almost 40 years of experimental and numerical research in the component interaction field, aiming at both providing a comprehensive overview and defining the most relevant conclusions obtained in this demanding research field.

CFD prediction of the unsteady aero-thermal interaction in the HP turbine stage, with inlet temperature non-uniformity, requires appropriate unsteady modelling and a low diffusive numerical scheme coupled with suitable turbulence models. This maybe referred to as high fidelity CFD. A numerical study has been conducted by the University of Florence in collaboration with ONERA to compare capabilities and limitations of their CFD codes for such flows. The test vehicle used for the investigation is a turbine stage of three-dimensional design from the QinetiQ turbine facility known as MT1. This stage is a high pressure (HP) transonic stage that has an un-shrouded rotor, configured un-cooled with 32 stators and 60 rotor blades. Two different CFD solvers are compared that use different unsteady treatment of the interaction. A reduced count ratio technique has been used by the University of Florence with its code HybFlow, while a phase lag model has been used by ONERA in their code, elsA. Four different inlet conditions have been simulated and compared with a focus on the experimental values provided by QinetiQ in the frame of TATEF and TATEF2 EU 6th Framework projects. The differences in terms of performance parameters and hot fluid redistribution, as well as the time- and pitch-averaged radial distributions on a plane downstream of the rotor blade, have been underlined. Special attention was given to the predictions of rotor blade unsteady pressure and heat transfer rates.