The aerodynamic performance of a gas turbine nozzle vane cascade was investigated over a range of Mach and Reynolds numbers.The work is part of a vast research project aimed at the analysis of fluid dynamics and heat ...The aerodynamic performance of a gas turbine nozzle vane cascade was investigated over a range of Mach and Reynolds numbers.The work is part of a vast research project aimed at the analysis of fluid dynamics and heat transfer phenomena in cooled blades.In this paper computed results on the"solid vane"(without cooling devices)are presented and discussed in comparison with experimental data.Detailed measurements were provided by the University of Bergamo where the experimental campaign was carried out by means of a subsonic wind tunnel.The impact of boundary layer transition is investigated by using a novel laminar kinetic energy transport model and the widely used Langtry-Menterγ-Reθ,t model.The comparison between calculations and measurements is presented in terms of blade loading distributions,total pressure loss coefficient contours downstream of the cascade,and velocity/turbulence-intensity profiles within the boundary layer at selected blade surface locations at mid-span.It will be shown how transitional calculations compare favorably with experiments.展开更多
The aerodynamic performance of a high-load low-pressure turbine blade cascade has been analyzed for three different distributed surface roughness levels(Ra) for steady and unsteady inflows. Results from CFD simulation...The aerodynamic performance of a high-load low-pressure turbine blade cascade has been analyzed for three different distributed surface roughness levels(Ra) for steady and unsteady inflows. Results from CFD simulations and experiments are presented for two different Reynolds numbers(300000 and 70000 representative of take-off and cruise conditions, respectively) in order to evaluate the roughness effects for two typical operating conditions. Computational fluid dynamics has been used to support and interpret experimental results, analyzing in detail the flow field on the blade surface and evaluating the non-dimensional local roughness parameters, further contributing to understand how and where roughness have some influence on the aerodynamic performance of the blade. The total pressure distributions in the wake region have been measured by means of a five-hole miniaturized pressure probe for the different flow conditions, allowing the evaluation of profile losses and of their dependence on the surface finish, as well as a direct comparison with the simulations. Results reported in the paper clearly highlight that only at the highest Reynolds number tested(Re=300000) surface roughness have some influence on the blade performance, both for steady and unsteady incoming flows. In this flow condition profile losses grow as the surface roughness increases, while no appreciable variations have been found at the lowest Reynolds number. The boundary layer evolution and the wake structure have shown that this trend is due to a thickening of the suction side boundary layer associated to an anticipation of transition process. On the other side, no effects have been observed on the pressure side boundary layer.展开更多
基金the project INSIDE(Aerothermal Investigation of cooled Stage turb Ine:Design optimization and Experimental analysis)PRIN 2011 n.2010K3B4RLfunded by the Italian Ministry of Instruction,University and Research(MIUR)
文摘The aerodynamic performance of a gas turbine nozzle vane cascade was investigated over a range of Mach and Reynolds numbers.The work is part of a vast research project aimed at the analysis of fluid dynamics and heat transfer phenomena in cooled blades.In this paper computed results on the"solid vane"(without cooling devices)are presented and discussed in comparison with experimental data.Detailed measurements were provided by the University of Bergamo where the experimental campaign was carried out by means of a subsonic wind tunnel.The impact of boundary layer transition is investigated by using a novel laminar kinetic energy transport model and the widely used Langtry-Menterγ-Reθ,t model.The comparison between calculations and measurements is presented in terms of blade loading distributions,total pressure loss coefficient contours downstream of the cascade,and velocity/turbulence-intensity profiles within the boundary layer at selected blade surface locations at mid-span.It will be shown how transitional calculations compare favorably with experiments.
基金part of a joint research project between GE Avio,University of Genova,and University of Florence
文摘The aerodynamic performance of a high-load low-pressure turbine blade cascade has been analyzed for three different distributed surface roughness levels(Ra) for steady and unsteady inflows. Results from CFD simulations and experiments are presented for two different Reynolds numbers(300000 and 70000 representative of take-off and cruise conditions, respectively) in order to evaluate the roughness effects for two typical operating conditions. Computational fluid dynamics has been used to support and interpret experimental results, analyzing in detail the flow field on the blade surface and evaluating the non-dimensional local roughness parameters, further contributing to understand how and where roughness have some influence on the aerodynamic performance of the blade. The total pressure distributions in the wake region have been measured by means of a five-hole miniaturized pressure probe for the different flow conditions, allowing the evaluation of profile losses and of their dependence on the surface finish, as well as a direct comparison with the simulations. Results reported in the paper clearly highlight that only at the highest Reynolds number tested(Re=300000) surface roughness have some influence on the blade performance, both for steady and unsteady incoming flows. In this flow condition profile losses grow as the surface roughness increases, while no appreciable variations have been found at the lowest Reynolds number. The boundary layer evolution and the wake structure have shown that this trend is due to a thickening of the suction side boundary layer associated to an anticipation of transition process. On the other side, no effects have been observed on the pressure side boundary layer.
