UBALDI M.

The bursting phenomenon consists in the switch of a laminar separation bubble from a short to a long configuration. In the former case, reduced effects on profile pressure distribution are typically observed with respect to the attached condition. On the contrary, long bubbles provoke significant variations in the loading coefficient upstream...

The bursting phenomenon consists in the switch of a laminar separation bubble from a short to a long configuration. In the former case, reduced effects on the profile pressure distribution are typically observed with respect to the attached condition. On the contrary, long bubbles provoke significant variations of the loading coefficient...

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ABSTRACT The present paper discusses the results of a large experimental data set describing transitional boundary layers. Time resolved Particle Image Velocimetry (PIV) measurements have been adopted to survey the boundary layer developing over a flat plate under prescribed adverse pressure gradients typical of turbomachinery components. The...

This work reports the application of an extended proper orthogonal decomposition (E-POD) procedure to multi-plane particle image velocimetry (PIV) measurements describing the evolution of laminar separation bubbles (LSBs). Measurements were performed over a flat plate installed between adjustable end-walls providing a prescribed adverse...

In this work, streamwise oriented riblets were installed on a flat plate exposed to an adverse pressure gradient simulating the diffusing part of a low-pressure turbine (LPT) blade and, successively, on the suction side of an LPT cascade operating under unsteady inflow condition. Different riblets heights, spacings and positions have been...

In this work, streamwise oriented riblets were installed on a flat plate exposed to an adverse pressure gradient typical of low-pressure turbine (LPT) blade and, successively, on the suction side of an LPT cascade operating under unsteady flow. Different riblet dimensions and positions have been tested to quantify their effects on the boundary...

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In the present paper, an optimized design procedure capable of providing the geometry of a high efficiency compact hydraulic propeller turbine for low head is proposed and developed. The turbine preliminary design is based on fundamental turbomachinery mean-line equations and on the employment of statistical correlations, which relate the main...

In this paper, a design procedure for a compact hydraulic propeller turbine for low heads is proposed and developed. The design is based upon classical criteria and on the employment of statistical correlations, which relates the main geometrical parameters to the fundamental design parameters of turbomachinery. The procedure for obtaining the...

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In the present work, Large Eddy Simulations (LES) of a low pressure turbine cascade have been carried out to understand the different sensitivity to incidence angle variation observed under steady and unsteady inflow conditions. Indeed, experimental evidence shows poor sensitivity to incidence angle variation for the steady case in a range of...

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