In this work, the effects of Turbine Center Frame (TCF) wakes on the aeromechanical behavior of the downstream Low Pressure Turbine (LPT) blades are numerically investigated and compared with experimental data. A small industrial gas turbine has been selected as a test case, composed of a TCF followed by the two low pressure stages and a Turbine Rear Frame (TRF) before the exhaust plenum. Full annulus unsteady computations of the whole low-pressure module have been performed. Two operating conditions, full (100%) and partial (50%) load, have been investigated with the aim of highlighting the impact of TCF wakes convection and diffusion through the downstream rows. Attention was paid to the harmonic content of rotors’ blades. From an aerodynamic point of view, the results show a slower decay of the wakes through the downstream rows in off-design conditions as compared to the design point. The wakes generated by the struts at partial load persist throughout the domain outlet, while they are chopped and circumferentially transported by the rotors motion. This is due to the strong incidence variation at which the TCF works, which induces the growth of wide regions of separated flow on the rear part of the struts. Nevertheless, the analysis of the rotors’ frequency spectrum reveals that moving from design to off-design conditions, the effect of the TCF does not change significantly, thanks to the filtering action of the first LPT stage movable Nozzle Guide Vane (NGV). From unsteady calculations the harmonic contribution of all turbine components has been extracted, highlighting the effect of statoric parts on the last LPT blade. Anyhow the TCF harmonic content remains the most relevant from an aeromechanic point of view as per experimental evidence, and it is considered for a Forced Response Analysis (FRA) on the last LPT blade itself. Finally, aerodynamic and aeromechanic predictions have been compared with the experimental data to validate the numerical approach. In the last part of this paper some general design solutions, that can help mitigation of the TCF wakes impact, are discussed.

In this work, the effects of turbine center frame (TCF) wakes on the aeromechanical behavior of the downstream low-pressure turbine (LPT) blades are numerically investigated and compared with the experimental data. A small industrial gas turbine has been selected as a test case, composed of a TCF followed by the two low-pressure stages and a turbine rear frame (TRF) before the exhaust plenum. Full annulus unsteady computations of the whole low-pressure module have been performed. Two operating conditions, full (100%) and partial (50%) load, have been investigated with the aim of highlighting the impact of TCF wakes convection and diffusion through the downstream rows. Attention was paid to the harmonic content of rotors’ blades. The results show a slower decay of the wakes through the downstream rows in off-design conditions compared with the design point. The analysis of the rotors’ frequency spectrum reveals that moving from design to off-design conditions, the effect of the TCF does not change significantly. The harmonic contribution of all turbine components has been extracted, highlighting the effect of statoric parts on the last LPT blade. The TCF harmonic content remains the most relevant from an aeromechanic point of view as per experimental evidence, and it is considered for an forced response analysis (FRA) on the last LPT blade itself. Finally, aerodynamic and aeromechanic predictions have been compared with the experimental data to validate the numerical approach. Some general design solutions aimed at mitigating the TCF wakes impact are discussed.

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This work measures the total economic impact, with a special focus on the agri-food sector of the Summer Jamboree, the largest international music festival of its kind taking place in a small town in central Italy mainly known for its beaches and seaside activities. The aim was to understand how and to what extent a large-scale event can bring benefits to the territory and the rural development of an area with a great, though only partially exploited, tourism potential. To this end, we used an Input-Output model fed by a sample survey carried out among the visitors and by the balance sheet data of the festival organizers. In order to obtain accurate and not overinflated estimated expenditures, we asked visitors to self-report their motivation for attending the area (seaside tourism vs festival), and then used their motivation as a weight to revise expenditures, thus providing a novel approach in impact assessment studies. The results show that the total economic impact reaches €28.8 million, triggered by a direct impact that, in the agro-industrial sector alone, amounts to €9 million. In addition, for 1€ public money invested in this event, 6.3€ is generated in the primary sector and in the food sector alone. Additionally, the estimated value of the sale of typical products amounts to €1.3 million. Hence, under certain conditions, major cultural events can bring significant benefits to the development of the territory, enhancing the whole agri-food value chain and favouring a more even distribution of the capital generated. This study is an important contribution to the literature, as it encourages the development of studies focusing on the specific spillovers of tourism, not necessarily rural, on the agricultural, rural and food sectors, that should interact more frequently with the economic system in general and with the touristic sector as well.