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32 results on '"Arcangeli, Lorenzo"'

14. Correlative analysis of effusion cooling systems

Author

Arcangeli, Lorenzo, Facchini, Bruno, Surace, Marco, and Tarchi, Lorenzo

Subjects
Turbomachines -- Research, Science and technology
Abstract

Gas turbine cooling has steadily acquired major importance whenever engine performances have to be improved. Among various cooling techniques, film cooling is probably one of the most diffused systems for protecting metal surfaces against hot gases in turbine stages and combustor liners. Most recent developments in hole manufacturing allow us to perform a wide array of microholes, currently referred to as effusion cooling. Though some drawbacks of such a concept still need to be solved (manufacturing costs, holes blockage, and then system reliability), its potential is now worth investigating. This paper presents the validation of a simplified numerical two-dimensional conjugate approach through a comparison with the experimental results of effectiveness for an effusion plate. A preliminary test is performed with the steady-state technique, using thermochromic liquid crystal wide-band formulations. Results are obtained in terms of local distributions of adiabatic effectiveness. Average values are compared with calculations to validate the numerical code. Then, the design of experiment approach is used to perform several conjugate numerical tests (about 180), so as to derive the behavior of different effusion plates in terms of overall effectiveness and mass flow rate. Data are analyzed in detail, and a correlative approach for the overall effectiveness is proposed. [DOI: 10.1115/1.2749298]

Published
2008

32. The Influence of Roughness on a High-Pressure Steam Turbine Stage: An Experimental and Numerical Study.

Author

Bellucci, Juri, Rubechini, Filippo, Marconcini, Michele, Arnone, Andrea, Arcangeli, Lorenzo, Maceli, Nicola, and Dossena, Vincenzo

Subjects
*STEAM-turbines, *SURFACE roughness, *REYNOLDS number, *AERODYNAMICS research, *COMPUTATIONAL fluid dynamics, *EQUIPMENT & supplies
Abstract

This work deals with the influence of roughness on high-pressure steam turbine stages. It is divided in three parts. In the first one, an experimental campaign on a linear cascade is described, in which blade losses are measured for different values of surface roughness and in a range of Reynolds numbers of practical interest. The second part is devoted to the basic aspects of the numerical approach and consists of a detailed discussion of the roughness models used for computations. The fidelity of such models is then tested against measurements, thus allowing their fine-tuning and proving their reliability. Finally, comprehensive computational fluid dynamics (CFD) analysis is carried out on a high-pressure stage, in order to investigate the influence of roughness on the losses over the entire stage operating envelope. Unsteady effects that may affect the influence of the roughness, such as the upcoming wakes on the rotor blade, are taken into account, and the impact of transition-related aspects on the losses is discussed. [ABSTRACT FROM AUTHOR]

Published
2015
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