Feeding Holes Research Articles

Monster munch: Watching a black hole feed

The dark monster at the centre of the Milky Way has been a gentle giant – but that could change this year as it gets its first meal for centuries

C29 大負荷回転軸用の自成絞り非対称給気静圧ジャーナル軸受の特性(M-OS5-2 フルードパワーの基礎,M-OS5 フルードパワーの基礎と応用,「海を越え,国を越え,世代を超えて!」)

Rotating machineries have problems at bearings to support a rotor such as seismic ACROSS (Accurately Controlled Routinely Operated Signal System) transmitters. The rotor is supported by rolling contact bearings. The bearings in the transmitters, large heat generation occur caused by the high friction loss. In order to solve this problem, externally pressurized gas journal bearings with asymmetrically arranged inherent orifices has been developed for large load rotors. Numerical calculation of this bearing was carried out to obtain the characteristics using Divergence Formulation Method. Three types of bearing models have different placement of feed holes, respectively, i.e., Type A is the conventional symmetric type, which has eight feed holes in the bearing surface with equal distance. Type B is the proposed asymmetrical type, which has six feed holes at loading side of bearing surface and two feed holes at that of counter-loading side. Type C is also the proposed asymmetrical type, which has seven feed holes and one feed hole. The results showed that the proposed asymmetrical bearings have large load capacity and small flow rate compared with the conventional symmetric bearing.

Numerical investigation of cavitation flow in journal bearing geometry

The appearance of cavitation is still a problem in technical and industrial applications. Especially in automotive internal combustion engines, hydrodynamic journal bearings are used due to their favourable wearing quality and operating characteristics. Cavitation flows inside the bearings reduces the load capacity and leads to a risk of material damages. Therefore an understanding of the complex flow phenomena inside the bearing is necessary for the design development of hydrodynamic journal bearings. Experimental investigations in the fluid domain of the journal bearing are difficult to realize founded by the small dimensions of the bearing. In the recent years more and more the advantages of the computational fluid dynamics (CFD) are used to investigate the detail of the cavitation flows. The analysis in the paper is carried out in a two-step approach. At first an experimental investigation of journal bearing including cavitation is selected from the literature. The complex numerical model validated with the experimental measured data. In a second step, typically design parameters, such as a groove and feed hole, which are necessary to distribute the oil supply across the gap were added into the model. The paper reflects on the influence of the used design parameters and the variation of the additional supply flow rate through the feed hole regarding to cavitation effects in the bearing. Detailed pictures of the three-dimensional flow structures and the cavitation regions inside the flow film of the bearing are presented.

C30 傾斜した給気孔を有する慣性気体軸受のCFD解析と実験的検証(M-OS5-2 フルードパワーの基礎,M-OS5 フルードパワーの基礎と応用,「海を越え,国を越え,世代を超えて!」)

C30 傾斜した給気孔を有する慣性気体軸受のCFD解析と実験的検証(M-OS5-2 フルードパワーの基礎,M-OS5 フルードパワーの基礎と応用,「海を越え,国を越え,世代を超えて!」)

In-hole and mainflow velocity measurements of low-momentum jets in crossflow emanating from short holes

Discrete hole film cooling utilizes jet-in-crossflow geometry where the jet is supplied through a short hole which may be pitched relative to the main flow. Typically, the velocity ratio is near one. Under these conditions, the mean flow structure of the jet/mainstream interaction may be strongly affected by the characteristics of the flow within the hole. Magnetic resonance velocimetry (MRV) is used to measure the 3-dimensional mean velocity field for various jets in crossflow with short holes of varied inclination angles and blowing ratios typically of gas turbine applications. Novel measurements of the flow within inclined feed holes are captured using MRV. Secondary flows within the hole are found to be strongly dependent on the inclination of the hole. The traditional counter-rotating vortex pair is observed in the mainstream, as well as high levels of wall-normal vorticity. The 3D vorticity field is used to modify traditional jet-in-crossflow vortex ring theory to apply to low-momentum jets which remain attached to the ejection surface.

Analysis of Material Removal Rate and Surface Roughness on Advanced Ceramics Materials Micro-Hole Drilling

This study discussed the rotary ultrasonic machining (RUM) parameters and tool geometry parameters of optimized hole wall quality, and obtained better and uniformly distributed surface roughness of deep hole walls. The experimental configuration of this study was planned using Taguchi orthogonal array, where the hole diameter, spindle speed, feed rate and power were taken as the experimental factors. Drilling machining experiment was carried out using the parameter combination configured by the experimental design, and wall surface roughness of the drilled holes was measured. A relation model between the average surface roughness and standard deviation of the hole walls and processing parameters and tool geometry were established, so as to achieve optimized surface roughness of the overall deep hole walls. The optimization process respectively aimed at the minimum surface roughness and maximum metal removal rate. The experimental results proved that application of the optimized parameter combination in rotary ultrasonic machining of hole processing can obtain better and more uniform hole wall surface quality.The effect of control factors on the hole quality was discussed from the respects of the straightness deviation, minimum surface roughness and maximum metal removal rate of related factors on the hole when the Taguchi method was applied to rotary ultrasonic machining of hole drilling. The results showed that the level of straightness factors of produced holes can be fully presented. Keywords-Advanced Ceramics; Rotary Ultrasonic Machining; Surface Roughness; Material Removal Rate; Holes Deviation; Taguchi Method

Analysis of glass flow during extrusion of optical fiber preforms

Billet extrusion is a powerful technique for fabricating soft glass optical fiber preforms. This paper reports progress in the understanding of the relationships between extrusion process parameters and the die geometry. The friction for glass flow within the die is described by a die constant that can be either calculated using die feature dimensions or determined using processing parameters and a glass with known temperature-viscosity behavior. In complex dies in which the glass flows through an array of feed holes the friction can be calculated from the number, length and diameter of the individual channels within the die. The glass flow analysis allows improvement of the extrusion process and guidance of future die design.

Antixenosis in Maize Reduces Feeding by Western Corn Rootworm Larvae (Coleoptera: Chrysomelidae)

SUM2162 is the first known example of a naturally occurring maize, Zea mays L., genotype with antixenosis (nonpreference) resistance to western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), larval feeding. Behavioral responses of neonate western corn rootworm larvae were evaluated in laboratory bioassays with seven maize genotypes selected for native resistance to rootworm feeding damage. Two susceptible maize genotypes and one transgenic (Bacillus thuringiensis) maize genotype were included as controls. In soil bioassays with cut roots, no larvae entered the roots of the resistant variety SUM2162, but at least 75% of the larvae entered the roots of every other maize type. Larvae made significantly fewer feeding holes in the roots of SUM2162 than in all the other maize genotypes, except the isoline control. In feeding bioassays, larval feeding varied significantly among maize genotypes, but there was no significant difference between the resistant varieties and the susceptible controls. There were no significant differences among any of the genotypes in host recognition (search) behavior of larvae after exposure to the roots. Little variation in feeding stimulant blends was observed among maize genotypes, indicating minimal contribution to the observed antixenosis.

Mass Conserving Cavitation Effects in Squeeze-Film Journal Bearings Subjected to Sinusoidal Loads

This article presents a study of cavitation effects associated with the performance of fluid-film journal bearings subjected to fully reversing sinusoidal loading. Employing an established mass-conserving cavitation algorithm, it is observed that periodic time histories of journal eccentricity and maximum film pressure are strongly influenced by the process of cavitation formation and collapse. A new set of design charts for the prediction of cyclic-minimum film thickness is provided over a range of nondimensional loads, bearing geometric parameters, feed hole orientations, and cavitation threshold pressures typically found in practice. Good agreement of numerical and experimental results is obtained over a large range of loads for cavitation threshold pressure values typically associated with vaporous cavitation.

Stability of rigid rotor–aerostatic bearings with double compensations caused by orifice and inherence in series

This study elucidates the coupled effects of pressure compensation that is caused by orifice and inherence in series on static and dynamic characteristics of a rigid rotor that is supported by orifice-restricted aerostatic bearings. The load capacity and stability threshold are analyzed and compared to those obtained with separate orifice and inherence restrictions for various eccentricities, rotor speeds and restriction parameters and numbers of feeding holes. The simulation results have revealed clearly that the effects of orifice and inherence in series on bearing performance cannot be ignored in the design of aerostatic bearings.

Effects of leaf surfaces on first‐instar Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) behaviour

Abstract Helicoverpa armigera is a common pest insect on several economically important crops. While the feeding behaviour of later instars of this and other herbivorous larvae has been studied extensively, less has been done on the behaviour of newly hatched larvae. The behaviour of neonate H. armigera larvae on leaves from a variety of food plants and on two artificial diets was detailed. Recordings of the individual neonate larva's behaviour were taken for 3 h following the initiation of feeding. Analysis of the data suggested that larvae behaved differently in response to plant surfaces. Larvae took more bouts when feeding on the significantly thicker leaves of canola, with longer first meals on waxy canola than on a wax‐less variety. Analysis of feeding holes using a scanning electron microscope suggested that the longer feeding bouts were due to the pre‐processing time required to remove the wax from the leaf surface. Larvae feeding on trichome‐rich plants like tobacco and tomato also had to remove these obstacles before feeding. Increased time spent feeding or moving on the leaf surface could lead to increased exposure to predation, indicating that larval food choice or host choice by the ovipositing adult moth may have important implications in larval survival.

Influence of the number of feeding holes on the performances of aerostatic bearings

PurposeThe purpose of this paper is to study the influence of number of feeding holes on the performance of aerostatic bearings with spindle rotation. In traditional design of aerostatic bearings, the selection of hole numbers is dependent only on spindle size. However, when the hole numbers of air feeding are enough, the performance of the aerostatic bearing cannot be enhanced by increasing the hole numbers.Design/methodology/approachThe Reynolds equation is utilized to model the air film within bearing clearance at constant temperature and the state equation of adiabatic process is for air feeding within bearing clearance. The finite difference method with relaxation algorithm is utilized to determine the pressure distributions from discretized and coupled equations of flow continuity. The eccentricity, spindle speed, and the number and arrangement of feeding holes are considered in the analyses to determine the load capacity, attitude angle, and flow rate for the comparisons between various designs of aerostatic bearings.FindingsIt is seen from the simulation results that the aerostatic bearing designed with a small number of feeding holes and without locating at bearing bottom is most suitable for the spindle operating at high speed, while the bearing designed with a large number of feeding holes is suitable for the spindle operating at low speed, and the load capacity is increased with the increasing number of feeding holes for low journal speed.Originality/valueThe paper proposes an extensive database as a critical requirement in the design for number and arrangement of feeding holes of aerostatic bearings for the spindle operating at low or high speed.

Resistance of Landscape-Suitable Elms to Japanese Beetle, Gall Aphids, and Leaf Miners, with Notes on Life History of Orchestes alni and Agromyza aristata in Kentucky

Twenty genotypes of landscape-suitable Dutch elm disease-resistant elms (Ulmus spp.) were evaluated in a replicated field study for resistance to multiple insect pests in Lexington, Kentucky, U.S. The European elm flea weevil (EEFW), Orchestes alni, a recentlyintroduced pest that disfigures elms by leaf-mining and adult feeding, was found as a new state record so its feeding preferences and life history were monitored. U. parvifolia and U. propinqua, originally from Japan, were relatively resistant to Japanese beetles, and U. americana was generally less susceptible than most hybrids. Agromyza aristata, a serpentine leaf-mining fly, favored American elms, whereas Kaliofenusa ulmi a blotch-mining sawfly, and aphid (Tetraneura nigriabdominalis) pouch galls were uncommon on American and Asian elms but abundant on certain hybrids. EEFW infested all elms but at highest densities, (>20 mines per 30 cm shoot and >85 adult feeding holes per leaf), on certain hybrids. American elms, especially ‘Jefferson’, were somewhat less susceptible. EEFW laid eggs in expanding leaves; mines were initiated in late April and completed by mid- to late- May. Newly-emerged adults extensively damaged leaves in late May and June but nearly disappeared from tree canopies by mid-July. Implications for re-introduction of elms into urban landscapes are discussed.

Numerical investigation of static and dynamic characteristics of aerostatic thrust bearings with small feed holes

Recently, laser beam machining and micro drills have made it easier to manufacture small feed holes of less than 0.1 mm diameter. Accordingly, aerostatic bearings with these small feed holes have become commercially available for improving bearing performance. In this work, an aerostatic annular thrust bearing with small feed holes of less than 0.05 mm diameter was treated and the static and the dynamic characteristics of this type of bearing were investigated numerically. In numerical calculations, computational fluid dynamics (CFD) was used to determine discharge coefficients for a small feed hole and the finite difference method (FDM) was used to obtain the bearing characteristics. In addition, the characteristics of this type of bearing were compared with those of aerostatic thrust bearings with typical compound restrictors to show clearly the features of this type of bearing.

1105 超精密加工機用静圧気体スピンドルの振れまわりに関する数値的研究(潤滑剤・機械要素,一般講演)

Recently, in a spindle of precision machine tools, higher rotational speed, larger stiffness and higher accuracy of motion have been strongly required to achieve higher geometrical and dimensional accuracy of machined parts. This kind of spindle is usually supported by aerostatic journal bearings and reducing the run-out of a spindle in rotation becomes important for accuracy. Therefore, in this paper, the run-out of a spindle with roundness error supported by two aerostatic journal bearings with feed holes is numerically investigated. It was found that there were two run-out modes, translatory and conical modes, which were varied by the relative position of feed holes between two bearings.

G1100-1-5 溝付き静圧気体ジャーナル軸受の回転精度([G1100-1]機素潤滑設計部門一般講演(1))

In this paper, the characteristics of rotating accuracy of hydrostatic gas journal bearing are analyzed theoretically with special attention to the relation with the machining errors of the bearing system. The features and magnitudes of loci of the shaft are discussed in relation to lobe numbers of form deviation of the shaft cross section and feeding hole numbers.. The effect of shaft roundness on the bearing characteristics are discussed. Moreover the rotating accuracy of hydrostatic gas journal bearing with circumferential groove is also investigated. The obtained results may establish fundamental concept of precision design of the hydrostatic gas journal bearing with respect to the rotating accuracy of the shaft.

Influence of plastic mulch on damage and yield of yam tuber by yam beetles (<i>Heteroligus</i> spp.) in Delta State, Nigeria

The effects of plastic mulch on damage and yield of yam tuber by yam beetles were investigated at two locations in 2005 and 2006 cropping seasons in Delta State. Trials were laid out in Randomized Complete BlockDesign with three treatments: black plastic mulch, white plastic mulch and as unprotected control plot which were replicated three times. Data collected were, the number, depth and diameter of feeding holes on yam tuber (Dioscorea rotundata cv adaka), tuber yield and percentage yield increase over control as well as percentage tuber attacked and damage scores. The plastic mulch protected plots had positive impact on tuber yields as indicated by the relatively high percentage yield increase over control which ranged from 23%-66%. It was generally observed that plastic mulch protected plots were significantly different (P< 0.05) from the control in all the locations and year of cropping. Investigation revealed that white and black plastic mulches were not very effective against the beetle devastation but offered some protection.

Heterapoderopsis bicallosicollis(Coleoptera: Attelabidae): A Potential Biological Control Agent forTriadica sebifera

Native to China, Chinese tallow, Triadica sebifera L. Small (Euphorbiaceae), is an invasive plant in the southeastern United States. The leaf-rolling weevil, Heterapoderopsis bicallosicollis Voss, is a common herbivore attacking this plant in China. To evaluate its potential as a biological control agent of T. sebifera, biology and host specificity of this weevil were studied in China. H. bicallosicollis occurs over a wide, native, geographic range and its immatures successfully develop at 15-35 degrees C, indicating its physiological potential to establish and persist throughout the range of climatic conditions where the target plant grows in the United States. Adults make feeding holes on leaves. Before oviposition, the female makes a sealed leaf roll called a nidus and then lays one to two eggs inside. Eggs, larvae, and pupae develop within nidi, and larvae survive only when they develop inside the nidi. This requirement makes the weevil highly host specific to T. sebifera. In laboratory no-choice tests of 54 species from eight families, adults fed on only 3 plant species, T. sebifera, Sapium chihsinianum S. K. Lee, and Phyllanthus urinaria L. and only oviposited on T. sebifera. These results were confirmed where, in multiple-choice tests, adults only oviposited on T. sebifera. Given that T. sebifera is the only species in the genus Triadica in the United States, the results of this study suggest that H. bicallosicollis is a potential biological control agent of T. sebifera and should be considered to be imported into quarantine in the United States for further tests on native North American species.

Damage evaluation of Rhynchites cribripennis (Col., Attelabidae) in olive fruits

Abstract Rhynchites cribripennis is a pest of olives widely distributed in the Mediterranean region. The adults drill holes in the flesh of olives, resulting in fruit drop. Although earlier studies reported high damage levels, its damage potential has not been specifically investigated. In the current study, the damage potential of this weevil was evaluated with regard to its density. Olive shoots were enclosed in muslin cages, along with two or four adult weevils, during the initial phase of the olive fruit development. In each cage, the shoots bore 357 fruits, on average. The percentage of fruits dropped and the damage level on the fruits were recorded at about 1‐month intervals. At harvest, the fruits that remained on the shoots were individually weighed to evaluate the damage as regards fruit weight. The results showed that R. cribripennis can cause a significant damage because of fruit drop (54 ± 6%, 38 ± 4% and 16 ± 2% in the cages with 4, 2 and 0 adults, respectively). The damage was more severe in fruits within the first month after their formation. A single feeding hole was shown to cause the drop of small fruits. The high percentage of dropped fruits caused a significant decrease in the weight of the olives at harvest among treatments. These results show that R. cribripennis can cause serious damage to olive production and offer useful information for quantifying its damage potential and developing a more rationale control strategy for this pest.

A novel capillary-effect-based solder pump structure and its potential application for through-wafer interconnection

Through-wafer electrical interconnection is a critical technology for advanced packaging. In this paper, a novel capillary-effect-based solder pump has been proposed and analyzed, which could produce interconnects through and between silicon dies. The principle of this pump is to use the surface tension of a molten solder, introduced in the form of balls, to drive sufficient material into a deep reactive-ion etched hole to form a through-wafer conductive path. The solder pump structure uses unwettable through-wafer holes of different diameters together with wettable metallization on two dies to provide the pressure differential and flow path. Using multiple feed holes and a single via hole complete through-wafer interconnects are demonstrated.