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Aerodynamic Loading Distribution Effects on the Overall Performance of Ultra-High-Lift LP Turbine Cascades

Journal of Thermal Science 2014年第1期23卷 1-12页

作者： M.Berrino f.satta D.Simoni M.Ubaldi P.Zunino f.Bertini DIME Università degli Studi di Genova Via Montallegro 1I-16145 GenovaItaly Avio S.p.A. Professors I Maggio 56I-10040 Rivalta (TO) Italy

The present paper reports the results of an experimental investigation aimed at comparing aerodynamic perform- ance of three low-pressure turbine cascades for several Reynolds numbers under steady and unsteady inflows. This study is focused on finding design criteria useful to reduce both profile and secondary losses in the aero-engine LP turbine for the different flight conditions. The baseline blade cascade, characterized by a standard aerodynamic loading （Zw=1.03）, has been compared with two Ultra-High-Lift profiles with the same Zweifel number （Zw=1.3 for both cascades）, but different velocity peak positions, leading to front and mid-loaded blade cascade configurations. The aerodynamic flow fields downstream of the cascades have been experimentally in- vestigated for Reynolds numbers in the range 70000〈Re〈300000, where lower and upper limits are typical of cruise and take-off/landing conditions, respectively. The effects induced by the incoming wakes at the reduced frequency ./＋=0.62 on both profile and secondary flow losses for the three different cascade designs have been studied. Total pressure and velocity distributions have been measured by means of a miniaturized 5-hole probe in a tangential plane downstream of the cascade for both inflow conditions. The analysis of the results allows the evaluation of the aerodynamic performance of the blade cascades in terms of profile and secondary losses and the understanding of the effects of loading distribution and Zweifel number on secondary flows. When operating un- der unsteady inflow, contrarily to the steady case, the mid-loaded cascade has been found to be characterized by the lowest profile and secondary losses, making it the most attractive solution for the design of blades working in real conditions where unsteady inflow effects are present.

关键词： Low-Pressure Turbine Ultra-High-Lift Prof'des Profile Losses Secondary Losses Mid-Loaded Blade Cascades Aft-Loaded Blade Cascades.

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Experimental Investigation of Separation and Transition Processes on a High-Lift Low-Pressure Turbine Profile Under Steady and Unsteady Inflow at Low Reynolds Number

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Journal of Thermal Science 2010年第1期19卷 26-33页

作者： satta f Simoni D Ubaldi M Zunino P Bertini f DIMSET-Università di Genova Via Montallegro 1I-16145 GenovaItaly Avio R&D V.I Maggio99 I-10040 Rivalta(TO)-Italy

The effects induced by the presence of incoming wakes on the boundary layer developing over a high-lift low-pressure turbine profile have been investigated in a linear cascade at *** tested Reynolds number is 70000,typical of the cruise operating *** results of the investigations performed under steady and unsteady inflow conditions are *** unsteady investigations have been performed at the reduced frequency of f+=0.62,representative of the real engine operating *** aerodynamic loadings as well as boundary layer velocity profiles have been measured to survey the separation and transition *** analysis has been also performed to better understand the phenomena associated with the transition process under steady *** the unsteady case,a phase-locked ensemble averaging technique has been employed to reconstruct the time-resolved boundary layer velocity distributions from the hot-wire instantaneous signal *** ensemble-averaging technique allowed a detailed analysis of the effects induced by incoming wakes-boundary layer interaction in separation ***-resolved results are presented in terms of mean velocity and unresolved unsteadiness time-space plots.

关键词： boundary layer separation boundary layer transition wake-boundary layer interaction high-liftprofile low-pressure turbine

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Profile and Secondary flow Losses in a High-Lift LPT Blade Cascade at Different Reynolds Numbers under Steady and Unsteady Inflow Conditions

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Journal of Thermal Science 2012年第6期21卷 483-491页

作者： satta f. Simoni D. Ubaldi M. Zunino P. Bertini f. DIMSET-Università di Genova Via Montallegro 1I-16145 GenovaItaly Avio S.p.A. Viale I Maggio 56I-10040 Rivalta(TO)-Italy

The aerodynamic flow field downstream of a Low-Pressure High-Lift(HL)turbine cascade has been experimentally investigated for different Reynolds numbers under both steady and unsteady inflows,in order to analyse the cascade performance under real engine operating *** Reynolds number has been varied in the range 100000f cruise and take-off/landing conditions,*** effects induced by the incoming wakes at the reduced frequency f+=0.62 on both profile and secondary flow losses have been *** pressure,velocity and secondary kinetic energy distributions at the downstream tangential plane have been measured by means of a miniaturized 5-hole *** quantities provide information on both blade wake and secondary flow structures(passage and horse-shoe vortices).The analysis of the results allows the evaluation of the aerodynamic performance of the HL front-loaded blade in terms of both profile and secondary losses.

关键词： profile losses secondary flow losses high-lift profdes unsteady inflow LPT blade.

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Unsteady Inflow Effects on the Wake Shed from a High-Lift LPT Blade Subjected to Boundary Layer Laminar Separation

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Journal of Thermal Science 2012年第2期21卷 97-108页

作者： francesca satta Marina Ubaldi Pietro Zunino Università degli Studi di Genova

An experimental investigation on the near and far wake of a cascade of high-lift low-pressure turbine blades subjected to boundary layer separation over the suction side surface has been carried out, under steady and unsteady inflows. Two Reynolds number conditions, representative of take-off/landing and cruise operating conditions of the real engine, have been tested. The effect of upstream wake-boundary layer interaction on the wake shed from the profile has been investigated in a three-blade large-scale linear turbine cascade. The comparison between the wakes shed under steady and unsteady inflows has been performed through the analysis of mean velocity and Reynolds stress components measured at midspan of the central blade by means of a two-component crossed miniature hot-wire probe. The wake development has been analyzed in the region between 2% and 100% of the blade chord from the central blade trailing edge, aligned with the blade exit direction. Wake integral parameters, half-width and maximum velocity defects have been evaluated from the mean velocity distributions to quantify the modifications induced on the vane wake by the upstream wake. Moreover the thicknesses of the two wake shear layers have been considered separately in order to identify the effects of Reynolds number and incoming flow on the wake shape. The self-preserving state of the wake has been looked at, taking into account the different thicknesses of the two shear layers. The evaluation of the power density spectra of the velocity fluctuations allowed the study of the wake unsteady behavior, and the detection of the effects induced by the different operating conditions on the trailing edge vortex shedding.

关键词： Wake-wake unsteady interaction high-lift blade profiles low-pressure turbine blade wake.

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An Experimental Investigation of the Dissipation Mechanisms in the Suction Side Boundary Layer of a Turbine Blade

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Journal of Thermal Science 2008年第4期17卷 289-297页

作者： francesca satta Daniele Simoni Marina Ubaldi Pietro Zunino Dipartimento di Macchine Sistemi Energetici e Trasporti-Università di Genova

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.

关键词： Axial flow turbines Profile boundary layer Energy dissipation mechanism Boundary layer transition Laser Doppler measurements.

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Experimental Analysis of the Aerodynamic Performance of an Innovative Low Pressure Turbine Rotor

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Journal of Thermal Science 2016年第1期25卷 22-31页

作者： Infantino Daniele satta francesca Simoni Daniele Ubaldi Marina Zunino Pietro Bertini francesco DIME-Universita degli Studi di Genova Via MontaUegro 11-16145 GenovaItaly Avio Aero Viale I Maggio 56I-10040 Rivalta(TO)-Italy

In the present work the aerodynamic performances of an innovative rotor blade row have been experimentally investigated. Measurements have been carried out in a large scale low speed single stage cold flow facility at a Reynolds number typical of aeroengine cruise, under nominal and off-design conditions. The time-mean blade aerodynamic loadings have been measured at three radial positions along the blade height through a pressure transducer installed inside the hollow shaft, by delivering the signal to the stationary frame with a slip ring. The time mean aerodynamic flow fields upstream and downstream of the rotor have been measured by means of a five-hole probe to investigate the losses associated with the rotor. The investigations in the single stage research turbine allow the reproduction of both wake-boundary layer interaction as well as vortex-vortex interaction. The detail of the present results clearly highlights the strong dissipative effects induced by the blade tip vortex and by the momentum defect as well as the turbulence production, which is generated during the migration of the stator wake in the rotor passage. Phase-locked hot-wire investigations have been also performed to analyze the time-varying flow during the wake passing period. In particular the interaction between stator and rotor structures has been investigated also under off-design conditions to further explain the mechanisms contributing to the loss generation for the different conditions.

关键词： Low Pressure Turbine Single Stage Research Turbine Rotor Aerodynamic Loading Hot-wire Anemometry

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Gastroparesis:New insights into an old disease

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World Journal of Gastroenterology 2020年第19期26卷 2333-2348页

作者： Paolo Usai-satta Massimo Bellini Olivia Morelli francesca Geri Mariantonia Lai Gabrio Bassotti Department of Internal Medicine Division of GastroenterologyBrotzu HospitalCagliari 09124Italy Gastrointestinal Unit Department of Translational Research and New Technologies in Medicine and SurgeryUniversity of PisaPisa 56122Italy Gastroenterology and Hepatology Section Department of MedicineUniversity of Perugia Medical SchoolPerugia 06123Italy Gastroenterology Unit University of CagliariMonserrato 09042Italy

Gastroparesis(Gp)is a chronic disease characterized by a delayed gastric emptying in the absence of mechanical *** this condition has been reported in the literature since the mid-1900s,only recently has there been renewed clinical and scientific interest in this disease,which has a potentially great impact on the quality of *** aim of this review is to explore the pathophysiological,diagnostic and therapeutical aspects of Gp according to the most recent evidence.A comprehensive online search for Gp was carried out using MEDLINE and *** is the result of neuromuscular abnormalities of the gastric motor *** is evidence that patients with idiopathic and diabetic Gp may display a reduction in nitrergic inhibitory neurons and in interstitial cells of Cajal and/or *** regards diagnostic approach,99-Technetium scintigraphy is currently considered to be the gold standard for *** limits are a lack of standardization and a mild risk of radiation *** C13 breath testing is a valid and safe alternative method.13C acid octanoic and the 13C Spirulina platensis recently approved by the food and Drug Administration are the most commonly used diagnostic *** wireless motility capsule is a promising technique,but its use is limited by costs and scarce availability in many ***,therapeutic strategies are related to the clinical severity of *** mild and moderate Gp,dietary modification and prokinetic agents are generally *** is the only drug approved by the food and Drug Administration for ***,other older and new prokinetics and antiemetics can be *** a second-line therapy,tricyclic antidepressants and cannabinoids have been *** severe cases the normal nutritional approach can be compromised and artificial nutrition may be *** drug-unresponsive Gp patients some alternative strategies(endoscopic,electric stimulation or surgery)are available.

关键词： Gastroparesis Delayed gastric emptying Gastric Scintigraphy 13C breath testing Wireless motility capsule Prokinetics Antiemetic drugs Gastric-per-oral endoscopic myotomy Gastric electrical stimulation

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Resin foraging dynamics in Varroa destructor-infested hives: a case of medication of kin?

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Insect Science 2019年第2期26卷 297-310页

作者： Michelina Pusceddu Giannella Piluzza Panagiotis Theodorou franco Buffa Luca Ruiu Simonetta Bullitta Ignazio floris Alberto satta Dipartimento di Agraria sezione di Patologia vegetate ed Entomologia Universita di Sassari Sassari Italy lstituto per il Sistema Produzione Animate in Ambiente Mediterraneo (ISPAAM uos Sassari) Consiglio Nazionale delle Ricerche (CNR) Baldinca-Li Punti Sassari Italy General Zoology Institute for Biology Martin Luther University Halle-Wittenberg Halle (Saale) Germany German Centre for integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Leipzig Germany

t Social insects have evolved colony behavioral, physiological, and organiza. tional adaptations (social immunity) to reduce the risks of parasitization and/or disease transmission. The collection of resin from various plants and its use in the hive as propolis is a clear example of behavioral defense. for Apis mellifera, an increased propolis content in the hive may correspond to variations in the microbial load of the colony and to a downregulation of an individual bee's immune response. However, many aspects of such antimicrobial mechanism still need to be clarified. Assuming that bacterial and fungal infection mechanisms differ from the action of a parasite, we studied the resin collection dynamics in Varroa destructor-infested honeybee colonies. Comparative experiments involving hives with different mite infestation levels were conducted in order to assess the amount of resin collected and propolis quality within the hive, over a 2-year period (2014 and 2015). Our study demonstrates that when A. mellifera colonies are under stress because of Varroa infestation, an increase in the number of resin foragers is recorded, even if a general intensification of the foraging activity is not observed. A reduction in the total polyphenolic content in propolis produced in infested versus uninfested hives was also noticed. Considering that different propolis types show varying levels of inhibition against a variety of honey bee pathogens in vitro, it would be very important to study the effects against Varroa of two diverse types of propolis: from Varroa-free and from Varroa-infested hives.

关键词： Apis mellifera host-parasite interaction polyphenols propolis selfmedication social immunity

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Irritable bowel syndrome: a disease still searching for pathogenesis, diagnosis and therapy

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World Journal of Gastroenterology 2014年第27期20卷 8807-8820页

作者： Massimo Bellini Dario Gambaccini Cristina Stasi Maria Teresa Urbano Santino Marchi Paolo Usai-satta Gastrointestinal Unit Department of Gastroenterology University of Pisa 56124 Pisa Italy Department of Experimental and Clinical Medicine University of florence 50134 Florence Italy Epidemiological Observatory Health Agency of Tuscany 50141 Florence Italy Gastrointestinal Unit P. Brotzu Hospital09124 Cagliari Italy

Irritable bowel syndrome (IBS) is the most frequently diagnosed functional gastrointestinal disorder in primary and secondary care. It is characterised by abdominal discomfort, pain and changes in bowel habits that can have a serious impact on the patient’s quality of life. The pathophysiology of IBS is not yet completely clear. Genetic, immune, environmental, inflammatory, neurological and psychological factors, in addition to visceral hypersensitivity, can all play an important role, one that most likely involves the complex interactions between the gut and the brain (gut-brain axis). The diagnosis of IBS can only be made on the basis of the symptoms of the Rome III criteria. Because the probability of organic disease in patients fulfilling the IBS criteria is very low, a careful medical history is critical and should pay particular attention to the possible comorbidities. Nevertheless, the severity of the patient’s symptoms or concerns sometimes compels the physician to perform useless and/or expensive diagnostic tests, transforming IBS into a diagnosis of exclusion. The presence of alarming symptoms (fever, weight loss, rectal bleeding, significant changes in blood chemistry), the presence of palpable abdominal masses, any recent onset of symptoms in patient aged over 50 years, the presence of symptoms at night, and a familial history of celiac disease, colorectal cancer and/or inflammatory bowel diseases all warrant investigation. Treatment strategies are based on the nature and severity of the symptoms, the degree of functional impairment of the bowel habits, and the presence of psychosocial disorders. This review examines and discusses the pathophysiological aspects and the diagnostic and therapeutic approaches available for patients with symptoms possibly related to IBS, pointing out controversial issues and the strengths and weaknesses of the current knowledge.

关键词： Irritable bowel syndrome Pathogenesis Diagnosis Therapy

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Raman spectra and vibrational analysis of CsPbI3:A fast and reliable technique to identify lead halide perovskite polymorphs

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Journal of Materiomics 2021年第1期7卷 127-135页

作者： Jessica satta Claudio Melis Carlo Maria Carbonaro Andrea Pinna Manuel Salado Daniel Salazar Pier Carlo Ricci Department of Physics University of CagliariS.p.No.8 Km 0.70009042MonserratoCAItaly Department of Mechanical Chemical and Materials EngineeringCINSAINSTMUniversity of CagliariVia Marengo 2CagliariI-09123Italy BCMaterials Basque Center for MaterialsApplications and NanostructuresUPV/EHU Science Park48940LeioaSpain

A major issue in the development of Lead halide perovskites is the assessment of the crystal structure of the samples,due to their typically limited time-stability,and the understanding of the role of external factors that can induce a crystal phase transformation(such as humidity,intense light flux,temperature,etc.).In this perspective,it is of utmost importance to have at disposal a fast and reliable experimental tool able to give an immediate indication of the polymorph of the sample with the possibility to integrate in-situ measurements for constant *** this paper we propose Raman spectroscopy as the ideal technique to solve this *** vibrational analysis of CsPbI3 in the a-phase and 5-phase and of the Cs4PbI6 secondary phase is reported and all the vibrational modes are assigned by comparing experimental spectra of the phases to Raman modes calculated within the DfT ***,the mechanism of laser induced phase degradation was studied using in-situ Raman measurements providing new insights on the secondary phase generated during the process.

关键词： Raman spectroscopy CsPb13 Inorganic lead halide perovskites Phase transformation

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