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Your search keyword '"Barigozzi, G."' showing total 118 results
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118 results on '"Barigozzi, G."'

1. High sensitivity measurements of thermal properties of textile fabrics

Author

Romeli, D., Barigozzi, G., Esposito, S., Rosace, G., and Salesi, G.

Subjects
Physics - Instrumentation and Detectors, Condensed Matter - Materials Science
Abstract

A new testing apparatus is proposed to measure the thermal properties of fabrics made from polymeric materials. The calibration of the apparatus and the data acquisition procedure are considered in detail in order to measure thermal conductivity, resistance, absorption and diffusivity constants of the tested fabric samples. Differences between dry and wet fabrics have been carefully detected and analyzed. We have developed a new measurement protocol, the "ThermoTex" protocol, which agrees with the UNI EN 31092 standard and entails an accurate quantification of the experimental errors according to a standard statistical analysis, thus allowing a rigorous investigation of the physical behavior of the phenomena involved. As a consequence, our machinery exhibits great potentialities for optimizing the thermal comfort of fabrics, according to the market demand, thanks to the possible development of a predictive phenomenological theory of the effects involved., Comment: RevTeX4 source file; 9 pages, 9 figures

Published
2013
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20. An experimental investigation of stator induced unsteadiness on centrifugal impeller outflow

Author

Ubaldi, M., Zunino, P., Barigozzi, G., and Cattanei, A.

Subjects
Compressors -- Blades, Centrifugal pumps -- Research, Flow meters -- Analysis, Fluid dynamics -- Research, Science and technology
Abstract

Detailed flow measurements were taken in a centrifugal turbomachine model to investigate the aerodynamic influence of the vaned diffuser on the impeller flow. The model consists of an unshrouded centrifugal impeller with backswept blades and a rotatable vaned diffuser, which enables a continuous variation of the vaned diffuser location with respect to the measuring points. Phase-locked ensemble-averaged velocity components have been measured with hot-wire probes at the impeller outlet for 30 different relative positions of the probe with respect to the diffuser vanes. The data also include the distribution of the ensemble-averaged static pressure at the impeller front end, taken by means of miniature fast response pressure transducers flush-mounted at the impeller stationary casing. By circumferentially averaging the results obtained for the different circumferential probe locations, the periodically perturbed impeller flow has been split into a relative steady flow and a stator-generated unsteadiness. The results for the different probe positions have also been correlated in time to obtain instantaneous flow field images in the relative frame, which provide information on the various aspects of the diffuser vane upstream influence on the relative flow leaving the impeller.

Published
1996

21. Pressure Sensitive Paint and Large Eddy Simulation Investigation on the Impact of Trench Depth on Flat Plate Film Cooling Through Shaped Holes

Author

Abdeh, H., Barigozzi, G., Zamiri, A., and Chung, J. T.

Abstract

To increase film cooling effectiveness levels downstream of film cooling holes, trenches manufactured in the thermal barrier coating can be adopted. The performance of this solution depends on the trench geometrical characteristics, namely its depth and width. A large eddy simulation (LES)-based numerical study has been performed at Korea University to investigate the effects of trench configuration on thermal protection, resulting in a 22% increase in cooling performance compared to the reference case without a trench. The present paper reports the results of an experimental investigation carried out at Bergamo University on a Plexiglass flat plate model with a set of three fan-shaped holes incorporated into an existing wind tunnel, replicating the numerical setup. Pressure-sensitive paint (PSP) technique was used to measure the adiabatic film cooling effectiveness. Besides the standard shaped hole case, the best and worst trench configurations coming from a DoE approach have been examined at various coolant to mainstream blowing ratios M in the range between 0.5 and 3. Cases at M = 1.5 were used to cross-check the prediction capability of the LES numerical simulation for the selected trenched cases. PSP and LES results are in good agreement, also with the literature data. The high depth/low width trench was shown to give an improved performance for M larger than 1.

Published
2024
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22. An Experimental Study of Flat Plate Film Cooling with Cylindrical Holes by Using PIV, HWA and PSP Techniques.

Author

Rouina, S., Ravelli, S., and Barigozzi, G.

Subjects
PARTICLE image velocimetry, PRESSURE-sensitive paint, SURFACE plates, WIND tunnels, FLOW measurement, FUSION reactor divertors
Abstract

An experimental study was conducted to investigate both the aerodynamic and the thermal behavior of film cooling jets exiting from three cylindrical holes on a flat plate. Measurements have been carried out in a low-speed wind tunnel, at low inlet turbulence intensity level, with blowing ratio (BR) varied in the range between 0.5 and 1.5. A high-resolution Particle Image Velocimetry (PIV) system was used to conduct detailed flow field measurements in the streamwise plane, while the Hot Wire Anemometry (HWA) technique provided measurements of velocity components in the vertical-lateral planes at two locations downstream of the holes. Concerning the thermal measurements, the binary pressure-sensitive paint (PSP) technique has been employed to map the adiabatic film cooling effectiveness (η) on the surface of interest, at density ratio of DR = 1 and 1.5, by using N2 and CO2 as coolant stream, respectively. 2-D flow field measurements in the streamwise plane have shown that the cooling jet stays attached to the flat plate surface at BR < 1. Conversely, jets lift-off at BR > 1. Thermal measurements at DR = 1 confirmed this behavior: at BR = 0.5, the highest levels of film cooling effectiveness are achieved immediately downstream of the hole whereas BR values of 1 and 1.5 have a detrimental impact on the thermal coverage. With a focus on the case at BR = 1, another set of experiments was conducted with CO2 as coolant to investigate the influence of DR on cooling efficiency, either at matched BR or momentum flux ratio (I). The latter was found to be the more appropriate parameter to scale cooling effectiveness results when comparing low and high DR cases. [ABSTRACT FROM AUTHOR]

Published
2019
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40. Solar hybrid combined cycle performance prediction: influence of GT model and spoor arrangement

Author

Barigozzi, G., Franchini, G., Perdichizzi, A., and Ravelli, S.

Subjects
Temperature -- Analysis, Gas-turbines -- Innovations, Power systems (Machinery) -- Analysis -- Thermal properties, Business, Engineering and manufacturing industries
Abstract

Power generation by Concentrated Solar Power systems is a way to reduce dependency on fossil fuels and at the same time to accomplish the international commitment of CO2 reduction. First [...]

Published
2012

41. Aerothermal Performance of a Nozzle Vane Cascade With a Generic Nonuniform Inlet Flow Condition--Part I: Influence of Nonuniformity Location.

Author

Perdichizzi, A., Abdeh, H., Barigozzi, G., Henze, M., and Krueckels, J.

Subjects
AERODYNAMICS, MACH number, STAGNATION point
Abstract

In this paper, the modifications induced by the presence of an inlet flow nonuniformity on the aerodynamic performance of a nozzle vane cascade are experimentally assessed. Tests were carried out in a six vane linear cascade whose profile is typical of a first stage nozzle guide vane of a modern heavy-duty gas turbine. An obstruction was located in the wind tunnel inlet section to produce a nonuniform flow upstream of the leading edge plane. The cascade was tested in an atmospheric wind tunnel at an inlet Mach number Ma1 = 0.12, with a high turbulence intensity (Tu1 = 9%) and variable obstruction tangential and axial positions, as well as tangential extension. The presented results show that an inlet flow nonuniformity influences the stagnation point position when it faces the vane leading edge from the suction side. A relevant increase of both 2D and secondary losses is observed when the nonuniformity is aligned to the vane leading edge. When it is instead located in between the passage, it does not affect the stagnation point location, in the meanwhile allowing a reduction in the secondary loss. [ABSTRACT FROM AUTHOR]

Published
2017
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