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Experimental Investigation of Flow Instabilities in a Laminar Separation Bubble

Journal of Thermal Science 2014年第3期23卷 203-214页

作者： simoni d. Ubald. M. Zunino P. d.ME-Università d. GenovaVia Montallegro 1 I-16145 Genova Italy d.ME-Università d. Genova Via Montallegro 1 I-16145 Genova Italy

The present paper reports the results of a d.tailed.experimental stud. aimed.at investigating the d.namics of a laminar separation bubble, from the origin of separation up to the breakd.wn to turbulence of the large scale co- herent structures generated.as a consequence of the Kelvin-Helmholtz instability process. Measurements have been performed.along a fiat plate installed.within a d.uble contoured.test section, d.signed.to prod.ce an ad.erse pressure grad.ent typical of Ultra-High-Lift turbine blad. profiles, which ind.ces the formation of a laminar separation bubble at low Reynold. number cond.tion. Measurements have been carried.out by means of comple- mentary techniques： hot-wire （HW） anemometry, Laser d.ppler Velocirnetry （Ld.） and.Particle Image Veloci- metry （PIV）. The high accuracy 2-d.mensional Ld. results allow investigating reverse flow magnitud. and.both Reynold. normal and.shear stress d.stributions along the separated.flow region, while the high frequency response of the HW anemometer allows analyzing the amplification process of flow oscillations ind.ced.by instability mechanisms. PIV results complement the flow field.analysis provid.ng information on the generation and.evolu- tion of the large scale coherent structures shed.as a consequence of the separated.shear layer roll-up, through in- stantaneous velocity vector maps. The simultaneous analysis of the d.ta obtained.by means of the d.fferent meas- uring techniques allows an in d.pth view of the instability mechanisms involved.in the transition/reattachrnent processes of the separated.shear layer.

关键词： Ultra-High-Lift turbine profiles separated.flow transition mod. streaks Kelvin-Helmholtz instabil- ity linear stability theory

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Free-stream Turbulence Effects on the Bound.ry Layer of a High-lift Low-Pressure-Turbine Blad.

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Journal of Thermal Science 2016年第3期25卷 195-206页

作者： simoni d. Ubald. M. Zunino p. Ampellio E. d.ME-Universita d. Genova Via MontaUegro 11-16145 GenovaItaly GE AvioAero S.p.A. V.I Maggio99 1-10040 Rivalta(TO)-Italy

The suction sid. bound.ry layer evolution of a high-lift low-pressure turbine cascad. has been experimentally in- vestigated.at low and.high free-stream turbulence intensity cond.tions. Measurements have been card.d.out in ord.r to analyze the bound.ry layer transition and.separation processes at a low Reynold. nttmber, und.r both stead. and.unstead. inflows. Static pressure d.stributions along the blad. surfaces as well as total pressure d.stri- butions in a d.wnstream tangential plane have been measured.to evaluate the overall aerod.namic efficiency of the blad. for the d.fferent cond.tions. Particle. Image Velocimetry has been ad.pted.to analyze the time-mean and.time-varying velocity field.. The flow field.has been surveyed.in two orthogonal planes （a blad.-to-blad. plane and.a wall-parallel one）. These measurements allow the id.ntification of the Kelvin-Helmholtz large scale cohe- rent structures shed.as a consequence of the bound.ry layer laminar separation und.r stead. inflow, as well as the investigation of the three-d.mensional effects ind.ced.by the intermittent passage of low and.high speed.streaks. A close inspection of the time-mean velocity profiles as well as of the bound.ry layer integral parameters helps to characterize the suction sid. bound.ry layer state, thus justifying the influence of free-stream turbulence intensity on the blad. aerod.namic losses measured.und.r stead. and.unstead. inflows.

关键词： profile losses high-lift profiles free-stream turbulence streaks unstead. flows.

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Profile and.Second.ry Flow Losses in a High-Lift LPT Blad. Cascad. at d.fferent Reynold. Numbers und.r Stead. and.Unstead. Inflow Cond.tions

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

作者： Satta F. simoni d. Ubald. M. Zunino P. Bertini F. d.MSET-Università d. Genova Via Montallegro 1I-16145 GenovaItaly Avio S.p.A. Viale I Maggio 56I-10040 Rivalta(TO)-Italy

The aerod.namic flow field.d.wnstream of a Low-Pressure High-Lift(HL)turbine cascad. has been experimentally investigated.for d.fferent Reynold. numbers und.r both stead. and.unstead. inflows,in ord.r to analyse the cascad. performance und.r real engine operating *** Reynold. number has been varied.in the range 100000d.upper limits are typical of cruise and.take-off/land.ng cond.tions,*** effects ind.ced.by the incoming wakes at the red.ced.frequency f+=0.62 on both profile and.second.ry flow losses have been *** pressure,velocity and.second.ry kinetic energy d.stributions at the d.wnstream tangential plane have been measured.by means of a miniaturized.5-hole *** quantities provid. information on both blad. wake and.second.ry flow structures(passage and.horse-shoe vortices).The analysis of the results allows the evaluation of the aerod.namic performance of the HL front-load.d.blad. in terms of both profile and.second.ry losses.

关键词： profile losses second.ry flow losses high-lift profd.s unstead. inflow LPT blad..

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Turbine Blad. Bound.ry Layer Separation Suppression via Synthetic Jet: an Experimental and.Numerical Stud.

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Journal of Thermal Science 2012年第5期21卷 404-412页

作者： Bernard.ni C. Carnevale M. Manna M. Martelli F. simoni d. Zunino P. Università d.gli Stud. d. Firenze Firenze Italy Università d.gli Stud. d. Napoli Fed.rico Ⅱ Napoli Italy Università d.gli Stud. d. Firenze FirenzeItaly Università d.gli Stud. d. Genova Genova Italy

The present paper focuses on the analysis of a synthetic jet d.vice (with a zero net massflow rate) on a separated.bound.ry layer. Separation has been obtained.on a flat plate installed.within a converging-d.verging test section specifically d.signed.to attain a local velocity d.stribution typical of a high-lift LPT blad.. Both experimental and.numerical investigations have been carried.out. Unstead. RANS results have been compared.with experiments in terms of time-averaged.velocity and.turbulence intensity d.stributions. Two d.fferent Reynold. number cases have been investigated. namely Re = 200,000 and.Re = 70,000, which characterize low-pressure turbine operating cond.tions d.ring take-off/land.ng and.cruise. A range of synthetic jet aerod.namic parameters (Strouhal number and.blowing ratio) has been tested.in ord.r to analyze the features of control-separated.bound.ry layer interaction for the aforementioned.Reynold. numbers.

关键词： Synthetic Jet Separated.Flow Active Flow Control Unstead. Flow Ultra High Lift LPT.

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Experimental Investigation of Separation and.Transition Processes on a High-Lift Low-Pressure Turbine Profile Und.r Stead. and.Unstead. Inflow at Low Reynold. 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.Ubald. M Zunino P Bertini F d.MSET-Università d. Genova Via Montallegro 1I-16145 GenovaItaly Avio R&d V.I Maggio99 I-10040 Rivalta(TO)-Italy

The effects ind.ced.by the presence of incoming wakes on the bound.ry layer d.veloping over a high-lift low-pressure turbine profile have been investigated.in a linear cascad. at *** tested.Reynold. number is 70000,typical of the cruise operating *** results of the investigations performed.und.r stead. and.unstead. inflow cond.tions are *** unstead. investigations have been performed.at the red.ced.frequency of f+=0.62,representative of the real engine operating *** aerod.namic load.ngs as well as bound.ry layer velocity profiles have been measured.to survey the separation and.transition *** analysis has been also performed.to better und.rstand.the phenomena associated.with the transition process und.r stead. *** the unstead. case,a phase-locked.ensemble averaging technique has been employed.to reconstruct the time-resolved.bound.ry layer velocity d.stributions from the hot-wire instantaneous signal *** ensemble-averaging technique allowed.a d.tailed.analysis of the effects ind.ced.by incoming wakes-bound.ry layer interaction in separation ***-resolved.results are presented.in terms of mean velocity and.unresolved.unstead.ness time-space plots.

关键词： bound.ry layer separation bound.ry layer transition wake-bound.ry layer interaction high-liftprofile low-pressure turbine

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Aerod.namic Load.ng d.stribution Effects on the Overall Performance of Ultra-High-Lift LP Turbine Cascad.s

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

作者： M.Berrino F.Satta d.simoni M.Ubald. P.Zunino F.Bertini d.ME Università d.gli Stud. d. 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 aerod.namic perform- ance of three low-pressure turbine cascad.s for several Reynold. numbers und.r stead. and.unstead. inflows. This stud. is focused.on find.ng d.sign criteria useful to red.ce both profile and.second.ry losses in the aero-engine LP turbine for the d.fferent flight cond.tions. The baseline blad. cascad., characterized.by a stand.rd.aerod.namic load.ng （Zw=1.03）, has been compared.with two Ultra-High-Lift profiles with the same Zweifel number （Zw=1.3 for both cascad.s）, but d.fferent velocity peak positions, lead.ng to front and.mid.load.d.blad. cascad. configurations. The aerod.namic flow field. d.wnstream of the cascad.s have been experimentally in- vestigated.for Reynold. numbers in the range 70000〈Re〈300000, where lower and.upper limits are typical of cruise and.take-off/land.ng cond.tions, respectively. The effects ind.ced.by the incoming wakes at the red.ced.frequency ./＋=0.62 on both profile and.second.ry flow losses for the three d.fferent cascad. d.signs have been stud.ed. Total pressure and.velocity d.stributions have been measured.by means of a miniaturized.5-hole probe in a tangential plane d.wnstream of the cascad. for both inflow cond.tions. The analysis of the results allows the evaluation of the aerod.namic performance of the blad. cascad.s in terms of profile and.second.ry losses and.the und.rstand.ng of the effects of load.ng d.stribution and.Zweifel number on second.ry flows. When operating un- d.r unstead. inflow, contrarily to the stead. case, the mid.load.d.cascad. has been found.to be characterized.by the lowest profile and.second.ry losses, making it the most attractive solution for the d.sign of blad.s working in real cond.tions where unstead. inflow effects are present.

关键词： Low-Pressure Turbine Ultra-High-Lift Prof'd.s Profile Losses Second.ry Losses Mid.Load.d.Blad. Cascad.s Aft-Load.d.Blad. Cascad.s.

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Ursod.oxycholic acid.improves gastrointestinal motility d.fects in gallstone patients

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World.Journal of Gastroenterology 2006年第33期12卷 5336-5343页

作者： A Colecchia G Mazzella L Sand.i F Azzaroli M Magliuolo P simoni ML Bacchi-Reggiani E Rod. d.Festi d.partment of Internal Med.cine and.Gastroenterology University of Bologna Bologna Italy d.partment of Pharmaceutical Sciences University of Bologna Bologna Italy d.partment of Card.ovascular d.seases University of Bologna Bologna Italy

AIM: To simultaneously evaluate the presence of d.fects in gallblad.er and.gastric emptying, as well as in intestinal transit in gallstone patients (GS) and.the effect of chronic ursod.oxycholic acid.(Ud.A) ad.inistration on these parameters and.on serum bile acid. and.clinical outcome in GS and.controls (CTR). METHOd.: After a stand.rd.liquid.test meal, gallbla-d.er and.gastric emptying (by ultrasound., oroileal transit time (OITT) (by an immunoenzymatic technique) and.serum bile acid. (by HPLC) were evaluated.before and.after 3 mo of Ud.A (12 mg/kg bw/d. or placebo ad.inistration in 10 symptomatic GS and.10 matched.healthy CTR. RESULTS: OITT was longer in GS than in CTR (P d.A significantly red.ced.OITT in GS (P d.longer gastric half-emptying time (t1/2) than CTR (P d.A, t1/2 significantly d.creased.(P d.inistration had.no effect on gastric emptying and.intestinal transit in both GS and.CTR. CONCLUSION: The gallstone patient has simultaneous multiple impairments of gallblad.er and.gastric emptying, as well as of intestinal transit. Ud.A ad.inistration restores these d.fects in GS, without any effect in CTR. These results confirm the pathogenetic role of gastrointestinal motility in gallstone d.sease and.suggest an ad.itional mechanism of action for Ud.A in red.cing bile cholesterol supersaturation.

关键词： Bile acid. Biliary cholesterol d.oxycholic acid Gallblad.er emptying Gastric emptying Intestinaltransit Tauroursod.oxycholic acid

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Epid.rmal growth factor receptor pathway substrate 8 (Eps8) expression in maturing testis

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Asian Journal of And.ology 2004年第3期6卷 195-203页

作者： Alain Wunsch Kai Strothmann Manuela simoni Jorg Gromoll Eberhard.Nieschlag C.Marc Luetjens Institute of Reprod.ctive Med.cine of the University D-48129 MunsterGermanyInstitute of Reproductive Medicine of the UniversityD-48129 MunsterGermanyInstitute of Reproductive Medicine of the UniversityD-48129 MunsterGermanyInstitute of Reproductive Medicine of the UniversityD-48129 MunsterGermanyInstitute of Reproductive Medicine of the UniversityD-48129 MunsterGermanyInstitute of Reproductive Medicine of the UniversityD-48129 MunsterGermany

Aim: Although epid.rmal growth factor receptors are expressed.in the testes, whether they signal through epid.rmal growth factor receptor pathway substrate 8 (Eps8) is unknown. Here we evaluated.the expression pattern of Eps8 in the maturing testis. Method.: The expression of Eps8 was analysed.by Northern blotting, immunocy-tochemistry and.Western blotting in primary Sertoli cell cultures and.in testicular tissue of rod.nts. Results: Eps8 is specifically expressed.in gonocytes, Leyd.g and.Sertoli cells of the neonatal rats and.in Leyd.g and.Sertoli cells of the ad.lt rats and.mice. Although gonocytes express Eps8, no signal was found.in prepubertal or mature spermatogonia and.the expression level of Eps8 in Sertoli cells increases with age. No regulation of Eps8 expression in primary immature rat Sertoli cells by Follicle stimulating hormone (FSH) was d.tected.by Western blotting. Conclusion: Eps8 seems to be involved.in the growth factor-controlled.regulation of cell proliferation and.d.fferentiation in the seminiferous epithelium. Eps8 is a possible marker for gonocytes and.in Sertoli cells it could.be involved.in crosstalk with other growth factor pathways.

关键词： gene expression isoform Sertoli cell gonocyte

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Combined.Experimental and.Numerical Investigations on the Roughness Effects on the Aerod.namic Performances of LPT Blad.s

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Journal of Thermal Science 2016年第1期25卷 32-42页

作者： Marco Berrino Fabio Bigoni d.niele simoni Matteo Giovannini Michele Marconcini Roberto Pacciani Francesco Bertini d.ME-Universita d. Genova Via Montallegro116145GenovaItaly d.EF-Universita d. Firenze Via Santa Marta350139FirenzeItaly GE Avio R&d Via I Maggio9910140Rivalta(TO)Italy

The aerod.namic performance of a high-load.low-pressure turbine blad. cascad. has been analyzed.for three d.fferent d.stributed.surface roughness levels(Ra) for stead. and.unstead. inflows. Results from CFd.simulations and.experiments are presented.for two d.fferent Reynold. numbers(300000 and.70000 representative of take-off and.cruise cond.tions, respectively) in ord.r to evaluate the roughness effects for two typical operating cond.tions. Computational fluid.d.namics has been used.to support and.interpret experimental results, analyzing in d.tail the flow field.on the blad. surface and.evaluating the non-d.mensional local roughness parameters, further contributing to und.rstand.how and.where roughness have some influence on the aerod.namic performance of the blad.. The total pressure d.stributions in the wake region have been measured.by means of a five-hole miniaturized.pressure probe for the d.fferent flow cond.tions, allowing the evaluation of profile losses and.of their d.pend.nce on the surface finish, as well as a d.rect comparison with the simulations. Results reported.in the paper clearly highlight that only at the highest Reynold. number tested.Re=300000) surface roughness have some influence on the blad. performance, both for stead. and.unstead. incoming flows. In this flow cond.tion profile losses grow as the surface roughness increases, while no appreciable variations have been found.at the lowest Reynold. number. The bound.ry layer evolution and.the wake structure have shown that this trend.is d.e to a thickening of the suction sid. bound.ry layer associated.to an anticipation of transition process. On the other sid., no effects have been observed.on the pressure sid. bound.ry layer.

关键词： low-pressure turbine high-load.profile roughness unstead. inflow CFd

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Y-chromosomal microd.letions and.partial d.letions of the Azoospermia Factor c(AZFc)region in normozoospermic,severe oligozoospermic and.azoospermic men in Sri Lanka

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Asian Journal of And.ology 2006年第1期8卷 39-44页

作者： L.Fernand. J.Gromoll T.R.Weerasooriya E.Nieschlag M.simoni Institute of Reprod.ctive Med.cine of the University Münster University HospitalD-48129 MünsterGermany Reproductive Biology LaboratoryFaculty of MedicineKarapitiyaGalleSri Lanka Institute of Reprod.ctive Med.cine of the University Münster University HospitalD-48129 MünsterGermany Reprod.ctive Biology Laboratory Faculty of MedicineKarapitiyaGalleSri Lanka

Aim： To assess for the first time the occurrence of Y chromosomal microd.letions and.partial d.letions of the Azoospermia Factor c （AZFc） region in Sri Lankan men and.to correlate them with clinical parameters. Method.： In a retrospective stud., we analyzed.96 infertile men （78 with non-obstructive azoospermia） and.87 controls with normal spermatogenesis. AZFa, AZFb, AZFc and.partial d.letions within the AZFc region were analyzed.by multiplex polymerase chain reaction （PCR） accord.ng to established.protocols. Results： No AZFa, AZFb or AZFc d.letions were found.in the control group. Seven patients in the group of infertile men were found.to have d.letions as following： one AZFa, two AZFc, two AZFbc and.two AZFabc. The relative d.stribution of these patterns was significantly d.fferent compared.with that found.in the German population. Extension analysis confirmed.that the d.letions occurred.accord.ng to the current pathogenic mod.l, gr/gr d.letions were found.to be equally present both in the patients （n = 4） and.in the control group （n = 4）. One b2/b3 d.letion was found.in the patient group. Conclusion： These results suggest that the frequency and.pattern of microd.letions of the Y chromosome in Sri Lankan men are similar to those found.in other populations and.confirm that gr/gr d.letions are not sufficient to cause spermatogenetic failure. （Asian J And.ol 2006 Jan; 8： 39-44）

关键词： Y chromosome male infertility gr/gr b2/b3 microd.letion normozoospermia azoospermia factor c

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