1,309 research outputs found
Prognostic factors in mild dystrophinopathies.
No full textAngelini C, Fanin M, Freda MP, Martinello F, Miorin M, Melacini P, Siciliano G, Pegoraro E, Rosa M, Danieli G
Utilizzo del codice MULTALL nel progetto preliminare di turbine radiali con cassa a spirale priva di palette distributrici
No full textPreliminary design of radial turbomachines is supported by “single-channel” CFD models, ideal for design concepts comparison. Unfortunately, these models do not suit non-periodic domain calculations like those of turbines with vaneless spiral casings. A new approach that makes such domains periodic was implemented in the open-source code MULTALL and validated against non-periodic-domain results of state-of-the-art commercial codes
EFFECTS OF BLADE SOLIDITY AND ASPECT RATIO ON A 0.5 HUB-TO-TIP RATIO TUBE-AXIAL FAN
No full textBlade solidity and aspect ratio are the two geometrical parameters that bridge the preliminary sizing of the fan with the aerodynamic design of the blade. In a previous work, the present authors started investigating the topic with a comprehensive experimental campaign focused on 16 Propeller fan design variants with 0.2 hub-to-tip ratio, all designed for best efficiency operation at approximately 0.075 flow rate coefficient and 0.008 pressure coefficient. As further step of the research, this paper investigates by experiments the influence of blade solidity and aspect ratio on the global aerodynamic performance of 0.5 hub-to-tip ratio tube-axial fan rotors designed for best efficiency operation at approximately the same flow rate coefficient as the 0.2 hub-to-tip ratio fans studied in the previous research.
Aim of the work is twofold: first, to extend the experimental data set of aerodynamic performance of comparable axial-flow industrial fan designs characterised by different blade solidity and aspect ratio; second to investigate the role of the hub-to-tip ratio on the effects of the two design parameters. To this end, 18 additional fan design variants were designed and tested in accordance with the ISO-5801 standard and the collected data were compared to the data set made available by testing the original 16 design variants. The results confirm that the global aerodynamic performance of a fan design at best efficiency operation is primarily set by the hub-to-tip ratio. Solidity plays a role comparable to the hub-to-tip ratio only within the minimum to low solidity range, whereas the aspect ratio contributes to the definition of the fan efficiency, in designs with high hub-to-tip ratio only, and the flow rate coefficient at best efficiency operation, in designs with low hub-to-tip ratio only
PRELIMINARY HYDRAULIC PERFORMANCE MODEL FOR THE OPEN REV EVO PUMP
No full textThis brief technical note deals with a preliminary empirical model aimed at describing the hydraulic performance of a partial emission pump operating in the around of its own best efficiency point. In particular, the high-speed pump design internally named as OpenREV EVO is considered. Such design is the more recent evolution of the partial emission pump prototypes conceived to pressurise the fuel and oxidiser of a rocket engine to be installed in a European lunar lander, being developing by NAMMO UK under ESA funding. The aim of the technical note is to report the equations suggested as base for a mathematical model of the pump hydraulic performance.
To this purpose, the experimental data acquired by T4i were made dimensionless and approximated by polynomial curve fitting. The polynomials describing the dimensionless performance were finally rearranged to obtain dimensional equations of the pump pressure rise and hydraulic efficiency as a function of the pump mass flow rate, impeller rotational speed, and mass density of the working fluid. The results show the dimensional maps of the 45mm diameter OpenREV EVO prototype in the operation with the fuel and the oxidiser, as obtained using the presented equations, superimposed to the 50%, 100% and 117% nominal operation point requirements
Selection of the pump type for the propellants of the high-performance engine of a European lunar lander
No full textHYDRAULIC PERFORMANCE MODEL FOR THE OPEN REV EVO PUMP
No full textThis technical note presents the empirical model describing the hydraulic performance of the high-speed pump design internally named as OpenREV EVO. The latter is the more recent evolution of the partial emission pump prototypes conceived to pressurise the fuel and oxidiser of a rocket engine to be installed in a European lunar lander, being developing by NAMMO UK under ESA funding. The aim of the technical note is to update and extend to the entire pump operation range the equations suggested in a previous note as base for a mathematical model of the pump hydraulic performance in operation around its best efficiency point.
To this purpose, additional experimental data acquired by T4i for pump operation up to the maximum flow rate were included in the data set used to define an appropriate polynomial curves fitting model of the dimensionless pump performance parameters. The revised model incorporates corrections accounting for the effects of the Reynolds number in order to obtain as output reliable values of the pump pressure rise and hydraulic efficiency as a function of the pump mass flow rate, impeller rotational speed, and molecular properties of the working fluid. The model was used to build the dimensional maps of the 45mm diameter OpenREV EVO prototype in operation with the fuel and the oxidiser. To further exploit the capabilities of the model, the performance maps expected by the OpenRev EVO prototype if manufactured with a 40mm diameter impeller are presented as well
ADAPTION OF THE SINGLE-CHANNEL APPROACH TO USE THE CFD CODE MULTALL AS AN EFFECTIVE TOOL IN THE PRELIMINARY DESIGN OF RADIAL INFLOW TURBINES WITH VANELESS SPIRAL CASING
No full textThe preliminary design of radial-inflow turbines is commonly supported by CFD tools which require computation time and resources dependent on the model complexity. Single-channel CFD models allow for rapid and generally sufficiently accurate computations. However, they cannot be applied in non-periodic domains such the ones of turbines with vaneless spiral casing. To overcome this limitation, the present authors suggested in a previous publication a modelling approach which reduces the non-periodic domain of a spiral volute to a periodic one. Also, it was verified that such approach fits the capabilities of the open-source CFD code MULTALL. This code was chosen for its widely validated capabilities and basic physics modelling, which permit fast computations suited to support the preliminary design phase where the rapid check of a large set of designs is most important. In the present paper, the aerodynamic performance of a small-scale turbine with vaneless spiral casing as predicted by single-channel calculations performed with MULTALL, is compared with the prediction obtained using the state-of-the-art CFD code Star CCM+. The single-channel CFD solved with Star CCM+ was calculated on a non-periodic domain made of a turbine slice including only one runner passage, being the boundary conditions extracted from preliminary simulations of the full turbine domain. The results show that the turbine’s global performance as predicted in accordance with the periodic-domain approach implemented in MULTALL very well agrees with that obtained from the computations on the non-periodic single-channel domain using a state-of-the-art CFD code. These findings confirm the validity of the proposed modelling approach and demonstrate that MULTALL can be successfully used in the preliminary design of radial inflow turbines with vaneless spiral casing
ASSESSMENT OF A NEW 0.2 HUB-TO-TIP RATIO PROPELLER FAN DESIGN WITH RIGID-BODY BLADE LOADING
No full textThis paper presents the numerical assessment of a new 0.2 hub-to-tip ratio propeller with specific speed equal to 8.2, by means of an original low-order CFD modelling approach. The new fan implements the rigid body blade loading distribution and it was designed by the authors using the classical “Kahane-Wallis” method. First aim of the work is to give a preliminary feedback on the possibility that the new fan improves the aerodynamic performance of a high efficiency fan designed by the authors in a previous work, which implements the constant-swirl blade loading distribution. Second aim of the work is to verify the effectiveness of the “Kahane-Wallis” method for the design of very low hub-to-tip ratio fan rotors with rigid-body blade loading distribution. The third aim is to present the new low-order CFD modelling approach that the authors conceived for a low-computational-cost preliminary estimate of the aerodynamic performance expected from ISO 5801 Type-A performance tests.
The results demonstrated that the “Kahane-Wallis” method allows for rigid-body designs with very low hub-to-tip ratio and pressure coefficients remarkably high. Such designs unlikely exceed the efficiency achieved by constant-swirl designs at the expense of lower pressure coefficients. Moreover, the successful application of the method is doubtful for designs with flow separation at the blade root or immediately downstream of the rotor. Finally, it is found that the new low-order CFD approach offers potentialities as a tool for the support of the preliminary fan design and deserves future investigations
Technetium-99m Sestamibi imaging in the detection of axillary lymph node involvement in patients with breast cancer.
No full textAnticancer Res. 1997 May-Jun;17(3B):1607-10.
Technetium-99m sestamibi imaging in the detection of axillary lymph node involvement in patients with breast cancer.
Schillaci O, Scopinaro F, Danieli R, Tavolaro R, Cannas P, Picardi V, Colella AC.
SourceDepartment of Experimental Medicine and Pathology, University La Sapienza, Rome, Italy.
Abstract
BACKGROUND: The status of the axillary lymph nodes is the most important prognostic factor in breast cancer, and the findings of axillary node dissection remain the gold standard for the patients staging and prognosis. The aim of this study was to evaluate the usefulness of Tc-99m sestamibi scintigraphy in the detection of axillary node involvement.
MATERIALS AND METHODS: Forty-nine patients (age range: 32-72 years) with breast cancer were studied. Dynamic images (1-20 minutes post-injection of the radiopharmaceutical) followed by multiple planar views and tomographic images were performed. Final diagnosis was achieved by histology after surgery.
RESULTS: Metastatic axillary lymph node involvement was present in 21 patients: sensitivity was 81% (17/21) for tomographic and 61.9% (13/21) for planar images; specificity was 92.9% (26/28) and 96.4% (27/28), respectively.
CONCLUSIONS: Tc-99m sestamibi imaging is a promising noninvasive method to detect axillary node metastases in patients with breast cancer, tomography appears more sensitive than planar views.
PMID:9179202[PubMed - indexed for MEDLINE
Prefazione
No full textIl volume, curato da Michele Danieli, è dedicato alle Memorie dell'Accademia degli Indomiti e si occupa in particolar modo di arte bolognese, soprattutto del Seicento. La prefazione dell'autore traccia un fil rouge critico e storiografico attraverso i contributi dei numerosi autori spesso caratterizzati da prospettive e orizzonti molto diversi
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