Fluid-dynamics of Turbomachinery
Research focus
The Peer review has evaluated this group as Good
The working group has been operating since more than 30 years in the field of theoretical, experimental and computational analysis and optimisation of turbomachines fluid dynamics performance and related phenomena. As well known, most part of the energetic plants is based upon turbomachines and the deeper knowledge of the complex fluid dynamics phenomena occurring in turbomachines is a fundamental tool for the improvement of machine performances and plants. The working fields of the group can be divided into two main activities: 1) Development and application of own developed and commercial CFD codes. The use of these tools allows for important savings of time and investment during the machine design and the performance analysis process. 2D and 3D codes (for viscous and non viscous flows, for uncompressible flows and for transonic regime) have been developed by means of public and private grants. Recently, after a wide validation process based on the available experimental data produced by the laboratory, the use of commercial CFD codes has also been introduced as a standard tool for the computational analysis of complex fluid dynamic environments such as full turbomachinery stages also evidencing unsteady stator-rotor interaction phenomena. The application of CFD combined with the experimental activity allows to go deep insight of the phenomena under analysis. 2.) Experimental analysis of the flow field in real turbomachines, models or components.The experimental analysis is mostly devoted to the comprehension of the basic fluid dynamic phenomena, to the evaluation of fluid dynamic performance, to the validation of CFD codes, that, at the moment, still require particular calibrations especially concerning the turbulence flow models parameters. The most recent activities, are here below briefly summarized: - Detailed definition of the 3D flow downstream of steam and gas blade turbines. The analysis also included the turbulent mixing evolution description by means of the direct measurement of the turbulent stress tensor. - Experimental and computational detailed analysis of the effect produced by the use of 3D design geometry techniques (e.g. lean, bow, compound lean, etc.) on the flow field and fluid dynamics performances of turbine cascades and stages. Development of a standard model for the prevision of the flow distribution downstream of the blades. - Experimental analysis of the internal and external flow field of blowers and radial impellers. - Experimental analysis of the internal and external flow fields of radial pumps, with particular emphasis on the methodology for deriving the performance curve of the pump when used as a turbine (reverse flow) also in presence of two phase flows. Another topics in the field of hydraulic machines concerns the 36 analysis of the unsteady impeller-diffuser interaction on the machine performance by means of phase solved optical measurements (PIV). - Analysis of the downstream flow field of cooled gas turbine blades (linear cascades). In particular a new model for the prevision of the aerodynamic loss has been proposed - Development of miniaturized 2D and 3D pneumatic probes with frequency response up to 80 kHz suitable for unsteady measurements in turbomachinery; application of the fast response probes for the analysis of the unsteady phenomena characterizing the so called stator rotor interaction in turbine stages, with particular emphasis on the effect of loss transport unsteady mechanism on stage performance. - Analysis of the operational and discharge characteristics of safety valves operating with uncompressible and compressible flows especially when operating under back pressure. Effects of scaling small size models to very large sizes (e.g for protecting steam generators, petrochemical plants, chemical reactors, etc.) that can not be tested in laboratories, on the discharge capacity of the safety valve.
Dipartimento di afferenza
Docenti afferenti
Full Professors
Carlo Osnaghi
Associate Professors
Vincenzo Dossena
Assistant Professors
Paolo Gaetani
Arnaldo Boccazzi