Influence Of Support Structure Research Articles

Research on Wake Field Characteristics and Support Structure Interference of Horizontal Axis Tidal Stream Turbine

The harnessing and utilization of tidal current energy have emerged as prominent topics in scientific inquiry, due to their vast untapped resource potential, leading to numerous investigations into the efficacy of hydrokinetic turbines under various operational conditions. This paper delineates the wake field characteristics and performance of horizontal axis tidal stream turbines under the influence of support structures, using a comprehensively blade-resolved computational fluid dynamics (CFDs) model that employs Reynolds-averaged Navier–Stokes (RANS) equations in combination with the RNG k-ε turbulence model. To achieve this, the study utilized experimental tank tests and numerical simulations to investigate the distribution characteristics and recuperative principles of the turbine’s wake field. The velocity distribution and energy augmentation coefficient of the wake field showed strong agreement with the experimental results. To further assess the effect of support structures on the flow field downstream of the unit and its performance, the hydrodynamic attributes of the turbine wake field were analyzed with and without support structures. The interference elicited by the support structure modified the velocity distribution of the near-wake flow field, resulting in a 4.41% decrease in the turbine’s power coefficient (Cp), significantly impacting the turbine’s instantaneous performance.

Influence of Support Structure on Catalytic Performance of Supported Liquid-Phase (SLP) Catalysts in Hydroformylation of 1-Butene

Several supported liquid-phase (SLP) catalysts with immobilized Rh-biphephos complexes on monolithic supports were prepared and applied for continuous gas-phase hydroformylation (HyFo) of 1-butene. The support comprised macroporous monolithic silicon carbide (SiC) with deposited silica nanoparticles (NPs) in order to provide mesopores with enhanced capillary forces to retain the liquid-phase. Variable parameters were examined for the monolithic SiC supports, including size and loading of deposited silica NPs and intermediate calcination between silica deposition steps to obtain the most efficient support configuration for the SLP system. The SLP catalysts with larger deposited silica NPs gave higher catalytic activity (i.e. 1-butene conversion and turnover frequency) compared to the supports with smaller sized silica NPs. However, the selectivity towards the preferred linear aldehyde was higher in the SLP catalysts with supports containing less silica with small silica NPs. Importantly, the prepared SLP catalyst systems showed long-term stability in HyFo with negligible formation of high boiling aldol condensation products.

Influence of 3D printed downstream support structures on pressure drop and entrainment of oleophilic and oleophobic oil mist filters

Industrially applied coalescence filters, e.g. oil mist filters, usually consist of several filter layers in combination with a downstream support grid. While in the past the focus of research on coalescence filters has been e.g. on the filter media itself, information on the influence of support structures on pressure drop and entrainment is scarce. Recent studies on the influence of support structures on differential pressure and entrainment showed, that stainless-steel perforated sheets are particularly well suited for this purpose. Based on these findings, innovative 3D printed support structures with novel printed modifications, like conical holes instead of cylindrical holes or additional roofs above each hole, in comparison to the state-of-the-art stainless-steel perforated sheets, were developed and evaluated in this work. Especially for oleophilic filter media, where the oil film in quasi-steady state is build up on the filter rear side and thus, noticeably affected by support structures, the differential pressure was in some cases slightly reduced, whereas entrainment was significantly reduced (up to −75%) by the developed 3D printed support structures. For oleophobic filter media entrainment was mainly affected by the 3D printed support structures and was significantly reduced.

Analysis of orthogonal signal of dual-mass micro-machined gyroscope

The dual-mass Silicon micro-machined gyroscope was processed by micro-fabrication technology. It could lead to quadrature coupling error and influence the output of the silicon micro-gyroscope. We select two commonly used gyroscope structures and analyze their quadrature coupling coefficient. Firstly, the complete dynamic model is proposed for the DMSG and the theoretical models of sensitivity and orthogonal signals are given by the dynamic model. Second, the influence of support structure on sensitivity and orthogonal signals are analyzed. The sensitivity and orthogonal signal of the two types of DMSG are derived and compared. The results show that the theoretical accuracy of the sensitivity and orthogonal signals can be improved about 50% and 30% after considering the support structure. The type-B gyroscope are insensitive to the Coriolis force (≈13% reduction) when compared to Type-A gyroscope. On the other hand the type-B gyroscope are insensitive to coupling stiffness (≈85% reduction) when compared to Type-A gyroscope. At last, the reliability of the theory is verified by simulations and experiments.

Model Test Study on the Influence of Supporting Structure on the Long-Term Stability of Tunnel Surrounding Rock

Objective: To explore the influence of different supporting structures on the long-term stability of tunnel surrounding rock. Methods: establish the mechanical model of tunnel surrounding rock, and explore its influence on the model shape by changing the support structure parameters. Results: different supporting structures will affect the shape of tunnel surrounding rock model, indicating that it has a certain impact on the long-term stability of tunnel surrounding rock. Conclusion: when carrying out tunnel surrounding rock support, four reasonable support parameter design schemes, such as 0.5m structural plane spacing and 75 ° ~90 ° inclination angle, can be selected to ensure the safety and stability of tunnel surrounding rock to the greatest extent.

Influence of Support Structures on the Microstructure and Mechanical Properties of Case Hardening Steel in Laser Powder Bed Fusion

Additive manufacturing, especially laser powder bed fusion (LPBF), enables the manufacturing of complex and lightweight parts. LPBF is a technology with high geometric degrees of freedom, but there are production restrictions, e.g., with regard to overhangs. One strategy to produce these components despite the restrictions is the use of support structures. After the LPBF process the support structures are removed by hand or through machining before general post-processing, e.g., manufacturing of functional surfaces or heat-treatments are concluded. However, support structures change the local process conditions during LPBF depending on the parts geometry (no support structures vs. use of support structures). The influence is mainly caused by the changed heat dissipation of the support structures compared to dense part material. In this contribution, the influence of support structures on the resulting microstructure and the mechanical properties are determined for the case hardening steel 16MnCr5. Case hardening steels are used for gearings and pinions for wide applications in the aerospace industry, e.g., engine gear boxes for helicopters or UAVs (unmanned aerial vehicles). It can be seen that the height of the applied support structures has great influence on the microstructure. Mechanical properties are determined through notched bar impact testing showing an increase in toughness in the as-built state with increasing support structure height. The findings correspond with the increasing content of ferrite seen in the microstructure. The effect of subsequent heat treatments (stress relief annealing and case hardening) on the mechanical properties is also investigated. Furthermore, generalized operating principles for the influence of support structures and the occurring insitu heat treatment in LPBF are presented and described based on the results shown.

Influence of support structures on tidal turbine power output

A fully blade resolved CFD model with a RANS formulation using the k−ω SST turbulence model was used to study the tidal turbine performance in the presence of two support structures with cylindrical and elliptical cross-sections. The integrated rotor force coefficients were higher in the presence of the cylindrical support structure than the elliptical support due to the higher opposing thrust from the cylinder in the channel increasing the local flow velocity near the top half of the rotor. The angle of attack on the blade decreases as it approaches the support structure due to the reduction in stream-wise flow velocity just ahead of the support structure. This drop is higher for cylindrical support than the elliptical support due to its larger opposing thrust to the flow causing a larger drop in stream-wise velocity. The drop in the angle of attack due to the presence of support structures causes a significant drop in the blade sectional forces as it approaches the support structure. The presence of rotor also causes a drop in the forces on the support structure. The mean stream-wise force coefficients of the cylindrical and elliptical support structures are 0.21 and 0.12 respectively, which are much lower than if they were in open water without a rotor. In case of both the support structures, the stream-wise sectional forces behind the rotor swept area are lower than that in open-water whereas the mean cross-stream forces are higher. The thrust from the rotor and the support structure has a direct influence on the wake velocity. The velocity deficit just in-front of the support structure is 20% higher for the cylindrical support than the elliptical support due to its higher opposing thrust to the flow, and further downstream, the case with cylindrical support has higher velocity deficit followed by elliptical support and then the case with no support structure.

Influence of Support Structure on the Ultraviolet Photoluminescence Enhancement from Graphene/ZnO Hybrid Structures

Novel application of graphene combined with light emitting materials has been proposed recently due to the plasmonic effects of graphene. Here, we report our investigations on the structural and optical properties of two graphene/ZnO hybrid structures that fabricated based on different ZnO supports. Plasmon-enhanced ultraviolet photoluminescence has been observed from both samples. The combined Raman and photoluminescence studies suggest a strong interaction between ZnO and graphene, which is affected by the surface structures of ZnO. Our results develop insights about the influence of ZnO supports on the PL enhancement and interfacial coupling in graphene/ZnO hybrid structures, which provides a reference for the design and fabrication of optoelectronic devices with high efficiency.

The influence of support structures on cell immobilization and acetone–butanol–ethanol (ABE) fermentation performance

Cell immobilization is an efficient technique for achieving high-cell density; it has been shown to benefit acetone–butanol–ethanol (ABE) fermentation. In this study, the biodegradable material, poly(3-hydroxybutyrate) (PHB), was fabricated into plate-like structures by solvent casting (SC) and into fibrous structures by wet jet (WJ) and electrospinning (ES). The BET data showed that the specific surface areas of PHBSC, PHBWJ, and PHBES were 0.17, 18.30, and 22.45m2/g, respectively. Butanol yields of 0.25±0.04, 0.28±0.01, and 0.20±0.01g-butanol/g-glucose were obtained for PHBSC, PHBWJ, and PHBES during batch ABE fermentation. OD600 of fermentation broths that contain PHBSC, PHBWJ, and PHBES can be used to evaluate the immobilization ability. It was found that while OD600 of fermentation broths without an immobilization material was 12.0±1.6, OD600 of fermentation broths containing PHBWJ was 4.3±0.3, which was the best for the three PHB materials tested. In summary, a high specific surface area with a pore size up to several hundred microns is recommended. The robustness and stability of PHB as an immobilization material for ABE fermentation was clearly confirmed.

Influence of support structure on the permeation behavior of polyetherimide-derived carbon molecular sieve composite membrane

Abstract Polyetherimide (PEI) was used as polymeric precursor to prepare selective carbon molecular sieve (CMS) layer supported by a porous Al2O3 ceramic disk. The effects of the porous structure and surface roughness of the ceramic support on the interfacial adhesion and texture of the PEI/Al2O3-derived composite CMS membrane were investigated by modulating the sintering temperature and holding time. When the surface roughness of the ceramic support increased, the pore size and its distribution of the selective CMS layer were found to have shifted to the larger one and its roughness increased from the top to the bottom surface. This structure resulted in high permeability and low selectivity. Our results indicate that the porous structure of the ceramic support also played an important role in dominating the pore size and its distribution of the selective CMS layer, which influences the gas separation performance.

Influence of membrane support structure on the efficiency of an iron-modified silica nanofiltration membrane

Inorganic membranes are generally created by depositing a thin film separation (membrane) layer atop a supporting structure in order to provide for the physical durability of the membrane. The separation layer thickness and morphology are normally evaluated to determine their contribution to fluid flow resistance across the membrane. The supporting structure is often ignored, yet can affect the quality of the membrane formed and significantly influence the global efficiency of the membrane module. In this paper, three different support structures are compared and evaluated with respect to the efficiency (rejection and flux) of an iron-modified silica separation layer. The main difference in the supports was the nominal pore size of the surface responsible for facilitating the membrane layer. The pore sizes of the supports investigated were 5, 10, and 20 nm in diameter. It was hypothesized that the largest pore size support would produce a higher water flux. However, this support did not provide an adequate surface for the deposition of a high quality membrane layer. The formation of an intact membrane layer was successfully achieved using the other two support structures. From the results obtained from salt rejection and flux data of these two functional membrane modules, the influence of the support structure on the overall efficiency of the membrane module was assessed. The 10 nm support structure produced a water flux that was 1.6 times greater than that of the 5 nm pore size support, without sacrificing the rejection of the electrolytes studied.

Influence of Planetary Needle Bearings on the Performance of Single and Double Pinion Planetary Systems

Abstract Planetary gears are widely used in automotive and aerospace applications. Due to demands for greater power density, these gearsets often operate at extremely high stress levels. This has caused system level influences once considered secondary to become critical to the success of planetary gears. One such system level effect that has been largely overlooked is the influence of support structures like planetary needle bearings. There are interactions between the gear distributed loads and the resulting bearing loads and deflections that have implications for both gear and bearing designs. Also, double pinion planetary arrangements are increasingly becoming common. There are still greater interactions between the gear and bearing components in double pinion planetary arrangements. In this paper, we will examine the influence of the bearing deflections (tilt) on the gear load distribution and contact pattern. We will also show the influence of distributed gear loads on the bearing loads (moments) and deflections (tilts). Both, single and double pinion planetary arrangements will be considered. It will be shown that the tilting stiffnesses of the needle bearings have a major influence on gear contact pattern and consequently on contact and bending stresses. It will also be shown that the double pinion planetary arrangement is more likely to result in off-centered loading. Parametric studies will be performed to show the influence of a few design parameters. Theoretical derivations will be validated by numerical simulations. A system level gear analysis model will be used to illustrate the issues involved and quantify the results.

Influence of support structure on microdisk resonator performance

Cylindrical dielectric and semiconducting microdisks are becoming attractive for use as electromagnetic resonators for optical and terahertz-frequency devices. The effects of the substrate and the support pedestal on microdisk performance, however, are not well understood due to limitations of conventional analytical techniques. We present a study of the influence of the support structure, namely, the substrate and pedestal, on microdisk resonator performance using the finite-difference time-domain method. The field distributions, resonant frequencies, and Q factors of the microdisk are computed at various distances from the substrate and for different pedestal sizes. Results show that the supporting structure can significantly distort the field distribution in the disk, and therefore have significant effects on both resonant frequency and Q factor, which are major parameters in microdisk design.

Delayed critical ORNL unreflected uranium (93.20) metal sphere and the pure unreflected uranium (93.80) sphere critical mass

A spherical critical assembly of unreflected and unmoderated uranium (93.20 wt.% 235U) metal was assembled at the Oak Ridge Critical Experiments Facility in 1971. All the characteristics of this assembly are very accurately known; dimensions to ± 0.0001 in, masses to ± 0.01 g, isotopics, impurities, etc. Two spheres were assembled. The first was above delayed criticality and the second, after machining of the first, was slightly below delayed criticality. A variety of reactivity effects such as the influence of support structure, imperfections in the sphere, etc. were evaluated experimentally, where practical. The very accurate description of this sphere, as assembled, establishes it as an ideal benchmark for calculational methods and cross-section data files. In this regard, the accurate specification of one of these spheres for a Monte Carlo code input is included as an Appendix. In order to provide data for verification of one-dimensional, transport-theory calculations, these two spherical uranium metal assemblies were corrected to idealized spherical geometries. Either all imperfections in the sphere were evaluated experimentally or corrections were made based on previous measurements with GODIVA I at Los Alamos National Laboratory. The experimental configurations first were corrected to idealized spheres of pure uranium metal of the density and enrichment of these measurements. In order to compare the results of these experiments to the earlier idealized delayed critical sphere obtained from the GODIVA I experiments, these spheres were also corrected to an enrichment of 93.80 wt.% 235U and density of 18.750 g U/cm 3 with no impurities. The estimates of the purely spherical critical masses of 93.20-wt.%-enriched uranium were 52,911±66 g ( ρ=18.765 g U/cm 3) from the slightly supercritical configuration, and 52,956±64 g ( ρ=18.754 g U/cm 3) from the slightly subcritical configuration. Correction to a pure uranium sphere of enrichment of 93.80 wt.% 235U and density of 18.750 g U/cm 3 with no impurities yielded a critical mass of 52.42±0.07 kg which is in agreement with the value from the GODIVA I experiments, which is 52.30 ± 0.16 kg. The uncertainty in the pure uranium sphere mass from the Oak Ridge experiments is considerably less than that from the GODIVA I experiments because the Oak Ridge spheres were more spherical with less structural material in close proximity to the sphere.

The interaction of carbon monoxide with Rh/Al 2O 3 model catalysts: influence of the support structure

Thermal desorption spectroscopy (TDS) has been used to investigate the interaction of CO with rhodium particles evaporated by electron bombardment onto differently oriented single-crystal alumina supports. Rhodium particle populations of similar particle size and density were deposited onto the (0001), (1-102) and (11-20) α-alumina substrates. The CO TDS results depend on the crystallographic orientation of the support. The CO desorption peak shapes and activation energies, as well as the CO 2 production which accompanies CO desorption, are compared. The data set obtained enables a discussion of the influence of the alumina support structure on the adsorptive and catalytic activity of the rhodium particles.

Chiral HPLC with carbohydrate carbamates: Influence of support structure on enantioselectivity

AbstractThe effect of particle size and pore size of the aminopropylated silica support for cellulose tris(phenylcarbamate) and tris(3,5‐dimethylphenylcarbamate) chiral HPLC phases was investigated. It was necessary to reduce phase loading below 20% w/w as pore size and particle size were reduced, but high efficiency columns could be prepared at a 15% w/w loading on 5 and 2.5 μm supports with 120‐Å‐diameter pores. The 2.5 μm phase permits the use of relatively high flow rates and very efficient enantioselective separations of a range of chiral compounds could be achieved in less than 3 min. © 1994 Wiley‐Liss, Inc.

Influence of Support Structure on Vertical Rotor Stability Problem

回転軸と支持構造物を連成した系の複素固有値を伝達マトリックス法とTraubの逐次計算法で解析した. この解析手法で真円すべり軸受で支えられた立て形電動機の安定性に及ぼす支持構造物の影響について検討し, 構造物の危険速度を越して運転される立て形回転軸系では構造物の振動特性に起因した軸受油膜の不安定が発生し, この発生速度は回転軸に起因したモードの不安定発生速度よりも低いことを明らかにした.

Influence of support structure on preparation and utilization of polymeric reagents

Polymer bound reagents have become established components of the repertoire of synthetic organic chemists. Recent advances in this field are reviewed with particular attention focused upon the nature of the polymer support. The application of condensation polymers as supports are highlighted. Techniques for chlormethylating polymers containing oxyphenylene repeat units with 1,4-bis [chloromethoxy] butane are presented and the properties of the new supports polymers are described. Aspects of site-site interaction of crosslinked polymer matrices are discussed. The review includes a summary of applications for polymer-bound transition metal catalysts, phase transfer catalysts and organic reagents. Finally, the future of polymeric reagents is examined.