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  1. Article: Numerical modeling and CFD simulation of diffuser augmented dual vertical axis hydrokinetic Banki-Michell turbine.

    Mereke, Nebiyu Bogale / Ancha, Venkata Ramayya / Hendrick, Patrick

    Heliyon

    2024  Volume 10, Issue 5, Page(s) e26970

    Abstract: Hydrokinetic Banki turbines present an affordable, technically feasible, environmentally friendly technology. Their construction without requiring more expensive structures like diversion weirs, canals, forebay, and penstock, makes their initial ... ...

    Abstract Hydrokinetic Banki turbines present an affordable, technically feasible, environmentally friendly technology. Their construction without requiring more expensive structures like diversion weirs, canals, forebay, and penstock, makes their initial investment much lower than commonly used horizontal Banki turbine of the same capacity. The possibility to install in the existing canals for Ultra Low Head applications is the additional motivating factor for this research. The system studied includes two Banki runners without internal shafts mounted vertically side by side surrounded by nozzle and diffuser structures. In the first scenario, Nozzle and then the Nozzle-diffuser augmented structures were separately studied to enhance the output of the runner for ultra-low head application, and the effects of each on the speed, pressure, and power output were analyzed. For the case of commonly used Banki, without nozzle and diffuser augmentation the speed for Ultra Low Head was minimum and determined to be 344 rpm, which is far below the recommended value of 800 rpm for safe operation at a flow rate of 1 m^3/s. In view of this, in the present study the enhanced speed on account of improvement was found to be 850 rpm and 1025 rpm for the design without and with diffuser assemblies respectively. Besides, the performance is seen to be improved by 7.6% with the diffuser as compared with the one without diffuser assembly. Detailed simulation results are presented and discussed: 3D ANSYS-FLUENT optimization result provided optimum number of blades for each runner to be 19 and with the optimum throat width in both cases as 202 mm. On account of the lack of any results reported so far for this innovative geometry, validation of the simulated results was carried out with reported results for the dual horizontal axis Banki turbines with good agreement.
    Language English
    Publishing date 2024-02-28
    Publishing country England
    Document type Journal Article
    ZDB-ID 2835763-2
    ISSN 2405-8440
    ISSN 2405-8440
    DOI 10.1016/j.heliyon.2024.e26970
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  2. Article: Particle image velocimetry for velocity measurement of muzzle flow: Detailed experimental study

    Moumen, Abdelhafidh / Stirbu, Bogdan / Grossen, Jurgen / Laboureur, Delphine / Gallant, Johan / Hendrick, Patrick

    Powder technology. 2022 June, v. 405

    2022  

    Abstract: A deep understanding of muzzle flow fields is essential for optimizing muzzle devices and projectile design. This flow characterization has been heretofore limited to local and intrusive measurement techniques such as pressure measurements using pencil ... ...

    Abstract A deep understanding of muzzle flow fields is essential for optimizing muzzle devices and projectile design. This flow characterization has been heretofore limited to local and intrusive measurement techniques such as pressure measurements using pencil probes. Consequently, the quantitative experimental data are limited, so are the number of numerical codes validated in this field. The objective of the present work is to demonstrate the applicability of the Particle Image Velocimetry (PIV) technique to provide accurate velocity measurements in the challenging environment of the propellant flow of a .300 blackout weapon. During this work, we have studied the feasibility of PIV on the muzzle flow using: (i) the naturally existing particles in the combustion gas as tracers, (ii) two different solid tracers; namely TiO₂ and ZrO₂ particles with a nominal size of 100 nm, seeded using two different methods. The first method implies coating the propellant grains with the tracer powder, in the second one the tracer is added directly inside the cartridge case. The experiments aim to demonstrate in particular: (i) the capability of PIV to resolve the main structures of the flow, (ii) the assessment of particle response across the Mach disk, and (iii) the non-alteration of the weapon's ballistics. To achieve this goal, an experimental setup with five different measurements was installed: (i) PIV system, (ii) classical high-speed schlieren visualization, (iii) optical particle counter, (vi) pressure transducer in the combustion chamber, and (v) projectile velocity measurement. The experimental results demonstrated (i) the ability of PIV to accurately resolve the main features of the flow as well as the instantaneous velocity field; (ii) that the combustion products contain sub-micrometric particles which can follow with high fidelity the gas flow; (iii) that solid ZrO₂ particles, when coated on the propellant grains, are suitable as tracers presenting a good flow fidelity and that the seeding of these inert particles is recommended in subsonic conditions (or whenever there is a lack of unburned particles); and (iv) that the TiO₂ particles intended to act as tracers, surprisingly not only melted but also functioned as a combustion accelerator and decreased the number of particles in the propellant gas.
    Keywords combustion ; particle image velocimetry ; technology
    Language English
    Dates of publication 2022-06
    Publishing place Elsevier B.V.
    Document type Article
    ISSN 0032-5910
    DOI 10.1016/j.powtec.2022.117509
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  3. Article: Numerical investigation on the volute cutwater for pumps running in turbine mode

    Morabito, Alessandro / Vagnoni, Elena / Di Matteo, Mariano / Hendrick, Patrick

    Renewable energy. 2021 Sept., v. 175

    2021  

    Abstract: The hydropower sector has recently raised the interest in pump as turbine (PaT) that can be a valid trade-off between capital cost and performance in micro-scale installations. Nevertheless, the modest efficiency of PaTs often restricts their ... ...

    Abstract The hydropower sector has recently raised the interest in pump as turbine (PaT) that can be a valid trade-off between capital cost and performance in micro-scale installations. Nevertheless, the modest efficiency of PaTs often restricts their exploitation. In this paper, available experimental data are used to tune a numerical model which aims to investigate the effect of the pump cutwater design on the PaT performance to improve the hydraulic efficiency. Because of its finite thickness, the cutwater interferes with the flow at the runner inlet, and generates local flaws in the velocity field such as swirl and deviations of the streamlines which limit the machine performance. To identify the geometrical characteristics of the cutwater impacting on the PaT performances, different values of stretching and thickness of the cutwater are studied at variable inclination by computational fluid dynamics (CFD) simulations. A multivariate regression method is applied on the CFD results to build a surrogate model of the PaT hydraulic characteristics as a function of the geometrical parameters of the machine cutwater. Based on this model, an optimization problem is solved to identify the most advantageous geometrical asset of the PaT cutwater to maximize the efficiency. The results highlight that the length and the cutwater angle are the most affecting variables in favouring a tangential component at the entrance of the runner. The hydraulic efficiency peak of the optimized geometry results to be 86.3%, while the baseline configuration records an efficiency of 82.4%, and the Ψ−ϕ characteristic moves the best efficiency point towards higher head (+7.5%) and lower discharge (−13.0%). The proposed methodology allows identifying the best geometrical characteristics of the PaT cutwater to maximize the performances while significantly reducing the computational time.
    Keywords assets ; capital costs ; fluid mechanics ; geometry ; mathematical models ; regression analysis ; system optimization ; water power
    Language English
    Dates of publication 2021-09
    Size p. 807-824.
    Publishing place Elsevier Ltd
    Document type Article
    Note NAL-AP-2-clean
    ZDB-ID 2001449-1
    ISSN 1879-0682 ; 0960-1481
    ISSN (online) 1879-0682
    ISSN 0960-1481
    DOI 10.1016/j.renene.2021.04.112
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  4. Article ; Online: Stochastic simulation of the FDA centrifugal blood pump benchmark.

    Karimi, Mohamad Sadeq / Razzaghi, Pooya / Raisee, Mehrdad / Hendrick, Patrick / Nourbakhsh, Ahmad

    Biomechanics and modeling in mechanobiology

    2021  Volume 20, Issue 5, Page(s) 1871–1887

    Abstract: In the present study, the effect of physical and operational uncertainties on the hydrodynamic and hemocompatibility characteristics of a centrifugal blood pump designed by the U.S. food and drug administration is investigated. Physical uncertainties ... ...

    Abstract In the present study, the effect of physical and operational uncertainties on the hydrodynamic and hemocompatibility characteristics of a centrifugal blood pump designed by the U.S. food and drug administration is investigated. Physical uncertainties include the randomness in the blood density and viscosity, while the operational uncertainties are composed of the pump rotational speed, mass flow rate, and turbulence intensity. The non-intrusive polynomial chaos expansion has been employed to conduct the uncertainty quantification analysis. Additionally, to assess each stochastic parameter's influence on the quantities of interest, the sensitivity analysis is utilized through the Sobol' indices. For numerical simulation of the pump's blood flow, the SST [Formula: see text] turbulence model and a power-law model of hemolysis were employed. The pump's velocity field is profoundly affected by the rotational speed in the bladed regions and the mass flow rate in other zones. Furthermore, the hemolysis index is dominantly sensitive to blood viscosity. According to the results, pump hydraulic characteristics (i.e., head and efficiency) show a more robust behavior than the hemocompatibility characteristics (i.e., hemolysis index) regarding the operational and physical uncertainties. Finally, it was found that the probability distribution function of the hemolysis index covers the experimental measurements.
    MeSH term(s) Benchmarking ; Blood Viscosity ; Cardiovascular Diseases/therapy ; Computer Simulation ; Equipment Design ; Heart-Assist Devices ; Hemodynamics ; Hemolysis ; Humans ; Hydrodynamics ; Models, Cardiovascular ; Models, Theoretical ; Nonlinear Dynamics ; Probability ; Stochastic Processes ; United States ; United States Food and Drug Administration ; Viscosity
    Language English
    Publishing date 2021-06-30
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2093052-5
    ISSN 1617-7940 ; 1617-7959
    ISSN (online) 1617-7940
    ISSN 1617-7959
    DOI 10.1007/s10237-021-01482-0
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    In stock of ZB MED Cologne/Königswinter

    Zs.A 5966: Show issues Location:
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    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (2.OG)
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  5. Article ; Online: Acute exposure to diesel exhaust impairs nitric oxide-mediated endothelial vasomotor function by increasing endothelial oxidative stress.

    Wauters, Aurélien / Dreyfuss, Céline / Pochet, Stéphanie / Hendrick, Patrick / Berkenboom, Guy / van de Borne, Philippe / Argacha, Jean-François

    Hypertension (Dallas, Tex. : 1979)

    2013  Volume 62, Issue 2, Page(s) 352–358

    Abstract: Exposure to diesel exhaust was recently identified as an important cardiovascular risk factor, but whether it impairs nitric oxide (NO)-mediated endothelial function and increases production of reactive oxygen species (ROS) in endothelial cells is not ... ...

    Abstract Exposure to diesel exhaust was recently identified as an important cardiovascular risk factor, but whether it impairs nitric oxide (NO)-mediated endothelial function and increases production of reactive oxygen species (ROS) in endothelial cells is not known. We tested these hypotheses in a randomized, controlled, crossover study in healthy male volunteers exposed to ambient and polluted air (n=12). The effects of skin microvascular hyperemic provocative tests, including local heating and iontophoresis of acetylcholine and sodium nitroprusside, were assessed using a laser Doppler imager. Before local heating, skin was pretreated by iontophoresis of either a specific NO-synthase inhibitor (L-N-arginine-methyl-ester) or a saline solution (Control). ROS production was measured by chemiluminescence using the lucigenin technique in human umbilical vein endothelial cells preincubated with serum from 5 of the subjects. Exposure to diesel exhaust reduced acetylcholine-induced vasodilation (P<0.01) but did not affect vasodilation with sodium nitroprusside. Moreover, the acetylcholine/sodium nitroprusside vasodilation ratio decreased from 1.51 ± 0.1 to 1.06 ± 0.07 (P<0.01) and was correlated to inhaled particulate matter 2.5 (r=-0.55; P<0.01). NO-mediated skin thermal vasodilatation decreased from 466 ± 264% to 29 ± 123% (P<0.05). ROS production was increased after polluted air exposure (P<0.01) and was correlated with the total amount of inhaled particulate matter <2.5 μm (PM2.5). In healthy subjects, acute experimental exposure to diesel exhaust impaired NO-mediated endothelial vasomotor function and promoted ROS generation in endothelial cells. Increased PM2.5 inhalation enhances microvascular dysfunction and ROS production.
    MeSH term(s) Adult ; Air Pollution/adverse effects ; Cross-Over Studies ; Endothelium, Vascular/physiology ; Hemodynamics/drug effects ; Humans ; Male ; Microcirculation/drug effects ; Nitric Oxide/physiology ; Oxidative Stress ; Reactive Oxygen Species/metabolism ; Respiration/drug effects ; Superoxides/metabolism ; Vasodilation/drug effects ; Vehicle Emissions/toxicity
    Chemical Substances Reactive Oxygen Species ; Vehicle Emissions ; Superoxides (11062-77-4) ; Nitric Oxide (31C4KY9ESH)
    Language English
    Publishing date 2013-08
    Publishing country United States
    Document type Journal Article ; Randomized Controlled Trial ; Research Support, Non-U.S. Gov't
    ZDB-ID 423736-5
    ISSN 1524-4563 ; 0194-911X ; 0362-4323
    ISSN (online) 1524-4563
    ISSN 0194-911X ; 0362-4323
    DOI 10.1161/HYPERTENSIONAHA.111.00991
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    Zs.A 1488: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
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