The increasing performance of modern aeroengines led the research towards the optimization of machine components not deeply analyzed in the past.In this context,the mechanisms driving the interaction process between t...The increasing performance of modern aeroengines led the research towards the optimization of machine components not deeply analyzed in the past.In this context,the mechanisms driving the interaction process between the secondary flows evolving at the hub of low-pressure turbines with the rotor-stator cavity systems have been poorly investigated in the literature.In this work,an experimental and numerical analysis of the interaction between the endwall near wall flow and the leakage flow of a real cavity system is presented.The experimental results were carried out in the annular low-pressure axial flow turbine of the University of Genova.Experimental blade loading and pressure distributions into the cavity,as well as the measured total pressure loss coefficient,have been used for a proper validation of CFD results.Both steady and unsteady calculations were carried out through the commercial solver Numeca.Particularly,several numerical approaches have been tested into this work:RANS,Non Linear Harmonic(NLH),and URANS.The most promising CFD techniques have been firstly identified by comparison with experimental results and then systematically employed to extend the analysis of secondary flow-cavity flow interaction to positions and quantities not available from the experiments.Losses characterizing the mean flow-cavity flow interaction process will be shown to cover a great amount of the overall stage losses and should be properly accounted for the design of future optimized cavity configurations.展开更多
The present work is part of an extensive experimental activity carried out by the authors in recent years aimed at investigating the boundary layer transition phenomenon in turbine blades. The large scale of the casca...The present work is part of an extensive experimental activity carried out by the authors in recent years aimed at investigating the boundary layer transition phenomenon in turbine blades. The large scale of the cascade and the use of advanced LDV instrumentation and precision probe traversing mechanism resulted in high degree of spatial resolution and high accuracy of measurements. The main dissipation mechanism determining the profile losses in turbomachinery blades is the work of deformation of the mean motion within the boundary layer operated by both viscous and turbulent shear stresses. In the present paper, the local viscous and turbulent deformation works have been directly evaluated from the detailed measurements of boundary layer mean velocity and Reynolds shear stress. The results show the distributions and the relative importance of the viscous and turbulent contributions to the loss production, in relation with the boundary layer states occurring along the turbine profile.展开更多
基金funding from the European Union Seventh Framework Program FP7/2007-2013 under grant agreement No.ACP2-GA-2012-314366-E-BREAK.
文摘The increasing performance of modern aeroengines led the research towards the optimization of machine components not deeply analyzed in the past.In this context,the mechanisms driving the interaction process between the secondary flows evolving at the hub of low-pressure turbines with the rotor-stator cavity systems have been poorly investigated in the literature.In this work,an experimental and numerical analysis of the interaction between the endwall near wall flow and the leakage flow of a real cavity system is presented.The experimental results were carried out in the annular low-pressure axial flow turbine of the University of Genova.Experimental blade loading and pressure distributions into the cavity,as well as the measured total pressure loss coefficient,have been used for a proper validation of CFD results.Both steady and unsteady calculations were carried out through the commercial solver Numeca.Particularly,several numerical approaches have been tested into this work:RANS,Non Linear Harmonic(NLH),and URANS.The most promising CFD techniques have been firstly identified by comparison with experimental results and then systematically employed to extend the analysis of secondary flow-cavity flow interaction to positions and quantities not available from the experiments.Losses characterizing the mean flow-cavity flow interaction process will be shown to cover a great amount of the overall stage losses and should be properly accounted for the design of future optimized cavity configurations.
文摘The present work is part of an extensive experimental activity carried out by the authors in recent years aimed at investigating the boundary layer transition phenomenon in turbine blades. The large scale of the cascade and the use of advanced LDV instrumentation and precision probe traversing mechanism resulted in high degree of spatial resolution and high accuracy of measurements. The main dissipation mechanism determining the profile losses in turbomachinery blades is the work of deformation of the mean motion within the boundary layer operated by both viscous and turbulent shear stresses. In the present paper, the local viscous and turbulent deformation works have been directly evaluated from the detailed measurements of boundary layer mean velocity and Reynolds shear stress. The results show the distributions and the relative importance of the viscous and turbulent contributions to the loss production, in relation with the boundary layer states occurring along the turbine profile.
