No abstract

Computational fluid dynamics (CFD) has been widely applied as an effective tool for optimizing products and reducing production cycles in many industrial fields; consequently, engineers are constantly pursuing higher accuracy in the performance predictions of CFD methods. In this paper, an analysis for the flow field of a hydrodynamic torque converter (TC) is conducted to evaluate CFD applications in detail. In the past, Reynolds-averaged Navier-Stokes (RANS) simulations have always played a dominant role in the numerical modeling of TCs because of their efficient calculation speed. However, most RANS models are unable to capture the complicated transient flows whose performance estimation errors are generally greater than 10%. Therefore, large eddy simulation (LES) with various sub-grid scale (SGS) models are applied in order to explore feasible methods for improving numerical accuracy and capturing the detailed transient flow phenomena. The effectiveness of the LES method is verified by comparing the numerical results with experimental data. Although the grid resolution is not fine enough due to the limitations of the high-performance computer (HPC) used, LES with dynamic kinetic energy transport (KET) models were still able to obtain an excellent description of both the near-wall flow and the main-stream flow via quantitative and qualitative analyses. The maximum error in the capacity factor (CF) is remarkably reduced to 4.4%. It is therefore beyond doubt that applying LES methods using coarser grid resolutions can still guarantee higher prediction accuracy through the reasonable selection of SGS models, which can effectively reduce the computing capacity requirements and contribute to the design process of TCs.

No abstract

Following the design, fabrication and test of a series of trial leads, designs of the three types of current leads required for ITER have been developed, and targeted trials of specific features are in progress on the way to fabrication and testing of prototype units. These leads are of the hybrid type with a cold section based on the use of high temperature superconductor (HTS) and a resistive section cooled by forced flow of helium gas, optimized for operation at 68 kA, 55 kA and 10 kA. The leads incorporate relevant features of the large series of current leads developed and constructed for the CERN-LHC, relevant features of the trial leads built for ITER, and additional features required to fully satisfy the exigent constraints of ITER with regard to cooling, insulation, and interfaces to feeder and powering systems. In this report a description of the design of the leads is presented, together with plans for the preparation of prototype manufacture and testing at ASIPP.

ABSTRACT:New coordination polyurethanes based on novel diols bis [N-[[2-hydroxyphenyl]methylene]hydroxylethyleneamino]-copper (II), cobalt (II), and nickel (II) were synthesized successfully. The products are elastomeric materials or powders. Similar to other polyurethane elastomers, the block copolymers synthesized in this paper exhibit two-phase microstructure and thermoplastic properties. Some samples show a Schlieren pattern under the polarizing optical microscope. The geometric structure of the ionic domains, which plays an important role in the properties of these materials, was determined by the nature of the metal ions.KEY WORDS Polyurethane I Metal Ions I Synthesis I Coordination I Macromolecule metal complexes have been studied extensively for several decades. This kind of material, which has many special chemical and physical properties, has attracted scientific and commercial attention. 1 • 2 Polyurethane ionomers are well-known examples of ion-containing materials. 3 Both carboxylated and sulfonated polyurethanes containing pendent ionic groups on the side of polyurethane backbone have been synthesized and studied at our laboratory. 4 • 5 However, polyurethanes contain pendent groups and metal ions in the main chain were not studied to any great extent. Only a few reports of these polymers are known. 6 Recent studies show that some metal complexes offer potentially mesogenic molecular structures. Some coordination polymers having liquid crystalline properties 7 • 8 have been achieved. In this paper, a new kind of polyurethane which is metal coordinated low molecular weight compounds, was synthesized and characterized. EXPERIMENTAL Synthesis of Metallic Dials and PolyurethanesThe synthesis of metallic diols and polyurethanes are summarized in Scheme I.In Scheme !(Ia) stoichiometric ethanolamine was added to a solution of salicylaldehyde in 200 ml of boiling absolute ethanol. Then stoichiometric sodium acetate in 20 ml water was added to the above reaction system. Finally I 00 ml boiling ethanol solution containing a stoichiometric amount of metal acetate were added. The reaction mixture was kept boiling for 15 min. The crystal precipitates from the solution after cooling and a second crystallization occurred from ethanol solution. The product was dried under an infra-red lamp for 24 hours.The coordination polyurethanes were synthesized in N,N'-dimethylformamide (DMF) under nitrogen atmosphere, using 0.5% by weight of stannous octoate catalyst. The poly(tetramethylene oxide) (PTMO Mn = 980) was first reacted with 4,4' -bis(isocyanatophenyl)ether (ODI) or 4,4'-bis(diisocyanatophenyl)methane (MDI) for 30 min at 70oC. The coordination chain extender in DMF solution was then added to the reaction along with 0.5 wt% stannous octoate catalyst. To ensure compJete reaction, the mixture was maintained at 70oC for 4 hours. The product was recovered by precipitation in hot water and further washed with ethanol to remove any residual small molecule products. The films were cast from DMF in Teflon-casting dishes...