Hydraulic Tube Research Articles

Technical aspects of intravascular pressure monitoring during donor care

Many biological signals must be measured and interpreted accurately to titrate therapy properly during donor care. Although the technological aspects of intravascular pressure monitoring are usually delegated to bedside nursing colleagues, organ procurement coordinators should be familiar with those devices and methods. The equipment, supplies, and procedures used for arterial and central venous pressure monitoring are reviewed. Transducer leveling and zeroing plus maintenance of the hydraulic tubing system between the transducer and bedside monitor are especially important. These variables may greatly influence the accuracy of the displayed pressures and, therefore, must be considered during donor assessment as treatment is considered.

Intermittent-Chaos-and-Cepstrum-Analysis-Based Early Fault Detection on Shuttle Valve of Hydraulic Tube Tester

To ensure the safety and continuity of production, make a reasonable maintenance plan, and save the cost of maintenance for a hydraulic tube tester, it is needed to quickly identify an assignable cause of a fault. This paper is concerned with early fault detection of shuttle valves, which are the key components in hydraulic tube tester. An intermittent-chaos-and-cepstrum-analysis-based method is proposed to detect this early fault on the hydraulic tube tester. The presented approach is based on the insight that the phase transition of Duffing oscillator is very sensitive to a periodic weak signal having tiny angular frequency difference with the reference signal in this oscillator. Thus, to determine the angular frequency of the reference signal, cepstrum analysis is used to determine the eigenfrequency of the fault signal, and then, the angular frequency of the referential signal is computed according to this eigenfrequency. Finally, a Lyapunov exponent is introduced to realize computer observation of the shuttle valve early fault. The presented method is experimented with data simulated from an AMESim model of hydraulic tube tester. The results indicate that the proposed approach is capable of detecting the signal of shuttle valve early fault in the hydraulic tube tester.

Intermittent chaos and sliding window symbol sequence statistics-based early fault diagnosis for hydraulic pump on hydraulic tube tester

To ensure the safety, continuity of production, make a reasonable maintenance plan, save the cost of maintenance for hydraulic tube tester, it is needed to quickly identify an assignable cause of a fault. This paper is concerned with early fault diagnosis of hydraulic pump which are the heart of hydraulic tube tester. Considering that the signal of the hydraulic pump early fault is a periodic weak signal, an intermittent chaos, sliding window symbol sequence statistics-based method is proposed to detect the early fault of one single piston loose shoes of hydraulic pump on a hydraulic tube tester. The approach presented is based on the insight that the phase transition of chaos oscillator, for example, the Duffing oscillator, is very sensitive to a periodic weak signal having little angular frequency difference with the referential signal of the oscillator. While observing the intermittent chaos phenomenon through figure is not easy for computer, a sliding window symbol sequence statistics is developed to realize real-time computer observation of this phenomenon. Rather more, this paper takes a trick to decreasing the computational complexity of the sliding window symbol sequence statistics method, also analyzes the influences of different window size, depths of the symbol tree on the information entropy. At last, a control limit is introduced to realize automatic early fault alarm. The resultant approach is experimented with data simulated from an AMESim model of hydraulic tube tester. The results indicate that the proposed approach is capable of detecting the signal of hydraulic pump early fault on hydraulic tube tester.

Core competencies for diversifying: case study of a small business

Abstract This paper addresses a significant gap within the present body of work on the resource‐based view of the firm: the lack of empirical research on the resource‐based perspective within the SME sector (Newbert, 2007). This study applies the resource‐based view and core competencies analysis in a very practical situation: a small manufacturing firm in the UK. The study is the result of a two‐year ‘action research’ project where the researcher was embedded within the firm. The manufacturing firm supplies hydraulic tube assemblies to the yellow construction industry and has experienced rapid growth over the past 10 years. Using a causal mapping methodology the findings reveal distinctive capabilities that the firm is able to use as a basis for diversification into the leisure marine industry. The findings contribute to the body of literature on the resource‐based view of the firm by providing a methodological approach which helps to uncover core competencies in practice. Copyright © 2009 John Wiley & Sons, Ltd.

FE evaluation of effect of groove geometry on roller and hydraulically expanded joint strength

The grooves machined in heat exchanger tube holes tend to improve the strength of tube-tubesheet joints and provide additional locking against leakage. The present work investigates the effect of tubesheet groove geometry on the contact stress of roller expanded and hydraulically expanded tube to tubesheet joints. The configuration of the geometry of the tube bores are varied with respect to its position, width, depth and spacing between grooves. The results of the study indicate that the effect of increasing groove width was to increase interfacial residual contact stress in hydraulically expanded joints while it has the effect of decreasing the pressure in roller expanded joints. On the other hand, groove depth, spacing and location have no significant effect for both hydraulic and roller tube expansion methods; though the residual contact stress is higher for roller expansion than for hydraulic expansion.

Nanosecond pulsed laser micromachining for experimental fatigue life study of Ti–3Al–2.5V tubes

Defects on external surface of in-service hydraulic tubes can reduce total life cycles for operation. Evaluation of fatigue life of the tubes with damage is thus critical for safety reasons. A methodology of generating defects in the Ti–3Al–2.5V tube—a widely used pipeline in hydraulic systems of aircrafts—using nanosecond pulsed laser for experimental fatigue life study is described in this paper. Straight tubes of five different sizes were laser micromachined to generate notches of given length and depths on the outside surface. Approaches were developed to precisely control the notch dimensions. The laser-notched tubes were tested with cyclic internal impulse pressure and fatigue life was measured. The laser notches and fatigue cracks were characterized after the test. It is concluded that laser micromachining generated consistent notches, and the influence of notch depth on fatigue life of the tube is significant. Based on the experimental test results, the relationship between the fatigue life of the Ti–3Al–2.5V tube and the notch depth was revealed. The research demonstrated that laser micromachining is applicable for experimental fatigue life study of titanium tubes. The presented test data are useful for estimating the damage limits of the titanium tubes in service environment and for further theoretical studies.

Low temperature neutron irradiation effects on microstructure and tensile properties of molybdenum

Polycrystalline molybdenum was irradiated in the hydraulic tube facility at the High Flux Isotope Reactor to doses ranging from 7.2 × 10 −5 to 0.28 dpa at ∼80 °C. As-irradiated microstructure was characterized by room-temperature electrical resistivity measurements, transmission electron microscopy (TEM) and positron annihilation spectroscopy (PAS). Tensile tests were carried out between −50 and 100 °C over the strain rate range 1 × 10 −5 to 1 × 10 −2 s −1. Fractography was performed by scanning electron microscopy (SEM), and the deformation microstructure was examined by TEM after tensile testing. Irradiation-induced defects became visible by TEM at ∼0.001 dpa. Both their density and mean size increased with increasing dose. Submicroscopic three-dimensional cavities were detected by PAS even at ∼0.0001 dpa. The cavity density increased with increasing dose, while their mean size and size distribution was relatively insensitive to neutron dose. It is suggested that the formation of visible dislocation loops was predominantly a nucleation and growth process, while in-cascade vacancy clustering may be significant in Mo. Neutron irradiation reduced the temperature and strain rate dependence of the yield stress, leading to radiation softening in Mo at lower doses. Irradiation had practically no influence on the magnitude and the temperature and strain rate dependence of the plastic instability stress.

Multi-stage extreme learning machine for fault diagnosis on hydraulic tube tester

The running status of hydraulic tube tester is reflected by the boosting pressure curve in Hydrostatic testing process. The authors present the extreme learning machine (ELM), a novel good learning scheme much faster than traditional gradient-based learning algorithms, as a mechanism for clustering the pressure curves. However, it caused low accuracy for clustering pressure curves for hydraulic tube tester. In this paper, a multi-stage ELM is proposed to improve the accuracy of clustering. During the process of this new ELM, the input data were divided into several stages, then, every stage was analyzed independently. At last, this method has been used in hydraulic tube tester data. Compared with individual ELM, it has better function for considering the characteristics of input data.

Response surface‐based shape optimization of a Francis draft tube

PurposeThis paper aims to develop an efficient and accurate numerical method that can be used in the design process of the waterways in a hydropower plant.Design/methodology/approachA range of recently published (2002‐2006) works, which aim to form the basis of a shape optimization tool for flow design and to increase the knowledge within the field of computational fluid dynamics (CFD) and surrogate‐based optimization techniques.FindingsProvides information about how crude the optimization method can be regarding, for example, the design variables, the numerical noise and the multi objectives, etc.Research limitations/implicationsIt does not give a detailed interpretation of the flow behaviour due to the lack of validation data.Practical implicationsA very useful flow design methodology that can be used in both academy and industry.Originality/valueShape optimization of hydraulic turbine draft tubes with aid of CFD and numerical optimization techniques has not been performed until recently due to the high CPU requirements on CFD simulations. The paper investigates the possibilities of using the global optimization algorithm response surface methodology in the design process of a full scale hydraulic turbine draft tube.

Parallel CFD simulations of an original and redesigned hydraulic turbine draft tube

The design of hydraulic turbine draft tubes has traditionally been based on simplified analytic methods, model and full-scale experiments. In the recent years the use of numerical methods such as computational fluid dynamics (CFD) has increased in the design process, due to the rapid escalation in computer performance. Today with parallel computer architectures, new aspects of flow can be considered. However, several problems have still to be solved before CFD can routinely be applied in product development. This paper aims to investigate the parallel performance of commercial CFD software on homogeneous computer networks, as common solutions encountered in the industry today. In addition, the efficiency improvements obtained in earlier experiments by modifying the shape of the draft tube will be considered, to deduce if the improvements can be captured with aid of CFD. Results from both the steady and the unsteady CFD simulations show that almost full scalability is obtained with the commercial CFD software CFX-5.7.1. Furthermore, no noticeable improvement in the pressure recovery factor or the flow field is noticed in the CFD simulations as compared to experiments. The discrepancy may be to the applied inlet boundary conditions and/or the turbulence model.

Computer simulation of turbulent flow through a hydraulic turbine draft tube

Based on the Navier-Stokes equations and the standardk-e turbulence model, this paper presents the derivation of the governing equations for the turbulent flow field in a draft tube. The mathematical model for the turbulent flow through a draft tube is set up when the boundary conditions, including the inlet boundary conditions, the outlet boundary conditions and the wall boundary conditions, have been implemented. The governing equations are formulated in a discrete form on a staggered grid system by the finite volume method. The second-order central difference approximation and hybrid scheme are used for discretization. The computation and analysis on internal flow through a draft tube have been carried out by using the simplec algorithm and cfx-tasc flow software so as to obtain the simulated flow fields. The calculation results at the design operating condition for the draft tube are presented in this paper. Thereby, an effective method for simulating the internal flow field in a draft tube has been explored.

Post-Expansion Tube Response Under Mechanical and Hydraulic Expansion—A Comparative Study

This paper presents a mathematical model of post-expansion tube response under mechanical expansion. The stress, pressure, and displacement waves propagating through the tube-fluid system and their effect on the tube response are studied. The model takes into account coupling between the solid tube and surrounding fluid at the borehole/expanded tube annulus, as well as the damping effect on tube structural response. The paper also conducts a comparative study aiming at studying the post-expansion tubular fluid response and identifying the different features between hydraulic and mechanical solid tube expansion. The results showed that the mechanical expansion is less harmful to the tube structural integrity. Unlike the hydraulic expansion, which resulted in local stress buildup along the tube, the mechanical expansion was characterized by low equivalent stress throughout its length and a smooth dying out response.

Two-phase frictional pressure gradient of R236ea, R134a and R410A inside multi-port mini-channels

In the present paper the pressure drop characteristics of a 1.4 mm hydraulic diameter multiport minichannel tube during adiabatic two-phase flow of HFC refrigerants are discussed. The tube consists of eleven parallel rectangular cross section channels. Although much experimental research has been devoted to investigate the pressure drop characteristics of R134a inside multiport minichannels in the last years, very little information is available on different refrigerants, such as R236ea (low pressure) and R410A (high pressure), whose behaviour is different from R134a. The experimental runs are carried out at mass velocities ranging from 200 to 1400 kg/(m 2 s), depending on the refrigerant under test, at constant value of vapour quality. The frictional pressure gradient is obtained from the saturation temperature drop measurement. The results presented here cover a wide range of the reduced pressure, from 0.1 up to 0.5. The experimental frictional pressure drop data is compared against models available in the literature for prediction of frictional pressure gradient in channels. The comparison of calculated to experimental values shows that the R134a frictional pressure gradient in the multiport minichannel test tube can be fairly well predicted by available correlations, but not satisfactory agreement is found for R236ea data and even worse in the case of R410A data.

A study of process and die design for ball valve forming from stainless steel tube

In this paper, two process and die design methods for ball valve forming from stainless steel tubes are compared: one is the tube hydroforming method (THFM), and the other is the tube nosing method (TNSM). Simulations on hydraulic expansion, axial feeding, and tube nosing of the ball shell forming with the two methods using the program DEFORM-3D are carried out. The influence of the two methods on workpiece formability and wall thickness distribution of ball valve forming is examined. A tube nosing experiment is carried out with a SUS304 stainless steel tube at room temperature. An accepted product of ball valve satisfying the industrial demand is obtained using TNSM.

Werle´–Legendre Separation in a Hydraulic Machine Draft Tube

The three-dimensional turbulent flow in a compact hydraulic machine elbow draft tube is numerically investigated for several operating conditions, covering an extended range around the best efficiency point. Comparisons with the experimental data are presented as validation. The interest is focused on the experimentally observed pressure recovery drop occurring near the best efficiency point. The flow is first analyzed locally by means of a topological analysis, then globally with an energetic approach. The study provides evidence for the role played by a Werle´–Legendre separation originating in the bend. The separation is due to the contrasting flow angles imposed by the blades, and the angle resulting from the secondary flow.

A Hydraulic Elastic Feed Drive for Fine Grinding of Non-Circular Element

The hydraulic elastic feed drive utilizes a hydraulic bellows tube as the actuator. While pressure oil is etin, the bellows tube will axially expand and exert a pushing force on the vertical arm of the grinding frame. This pushing force will cause the deformation of the elastic arm and thus the displacement of the grinding head. Within the extent of elasticity, the displacement of the deformation is linearly proportional to the value of pressure. Thus, by controlling the pressure wave form, the desired trajectory of the grinding head can be obtained. A pressure valve is used to create the pressure waves. In this paper, the dynamic characteristics which significantly affect the position accuracy of the grinding head and thus the surface finish quality of the non-circular element are theoretically analyzed. A special experiment has been designed to test the performance of the hydraulic elastic feed drive, in which a constant force is applied to simulate the grinding force while the grinding head is keeping track of the contour of non-circular element. The experimental results demonstrate that the stiffness of the feed drive is large enough to maintain the position accuracy.

Hydraulic Versus Swage Autofrettage and Implications of the Bauschinger Effect

A hybrid method is presented which permits calculation of residual stresses in a swage autofrettaged tube including Bauschinger effect. The results are generally supported by three types of available experimental evidence by comparing “equivalent” swage and hydraulic autofrettage tubes having the same level of overstrain. Radial slitting of the swaged tube is predicted to show a greater opening angle than its hydraulic equivalent. Fatigue lifetime of the swaged tube is predicted to be significantly higher than the hydraulic case. Re-pressurization of the equivalent tubes is predicted to produce initial re-yielding at the same pressure in both cases. Analysis of results shows that permanent strains in the swaged tube are expected to appear at a pressure level below that for the hydraulic tube.

Measurement of the Thermal Neutron Capture Cross Section and the Resonance Integral of the 90Sr(n, γ)91Sr Reaction

The thermal neutron capture cross section (σ0) and the resonance integral (I 0) of the 90Sr(n,γ)91Sr reaction were measured with an activation method to provide fundamental data for research on nuclear transmutation methods of radioactive wastes. Strontium chloride containing 3.7x102 kBq of90Sr was irradiated for 10 h in the hydraulic transfer tube facility of Kyoto University Reactor. Flux monitor wires, Co/Al and Au/Al alloy wires, were irradiated together with the targets to determine the neutron flux and the fraction of epithermal component (Westcott's index) at the target position. A high purity Ge detector was used to measure the γ rays from the irradiated targets and monitor wires. The σ0 was obtained as 10.1 ±1.3 mb, and I0 as 104±16 mb.

Scale effect on porosity and permeability: Kinetics, model, and correlation

AbstractVariation of porosity and permeability by scale dissolution and precipitation in porous media is described based on fractal attributes of the pores, realization of flow channels as a bundle of uniformly distributed mean‐size cylindrical and tortuous hydraulic flow tubes, a permeability‐porosity relationship conforming to Civan's power law flow units equation, and the pore surface scale precipitation and dissolution kinetics. Practical analytical solutions, considering the conditions of typical laboratory core tests and relating the lumped and phenomenological parameters, were derived and verified by experimental data. Deviations of the empirically determined exponents of the pore‐to‐matrix volume ratio compared to the Kozeny‐Carman equation were due to the relative fractal dimensions of pore attributes of random porous media. The formulations provide useful insights into the mechanism of porosity and permeability variation by surface processes and accurate representation of the effect of scale on porosity and permeability by simpler lumped‐parameter models.

Measurement and Network Modeling of Liquid Permeation into Compacted Mineral Blocks

A microbalance has been used to measure the rate of uptake of a wetting fluid, 1,3-propandiol, into a cube of compacted calcium carbonate. The cube had sides 12 mm long, with a wax band applied to the outer perpendicular edges of one basal plane to prevent external surface uptake, and the liquid was applied in a highly controlled manner at this single face only. The percolation characteristics of an identical sample were measured by mercury porosimetry. A three-dimensional void structure was generated with the same percolation characteristics using a software package called “Pore-Cor.” The wetting of 1,3-propandiol into this model structure was then calculated using an extended Lucas-Washburn equation, developed by Bosanquet, which includes viscous, inertial, and capillary force effects. Neither the experimental nor the simulated wetting can be explained in terms of an “hydraulic stream tube” or “effective hydraulic radius” model. A mathematical function is presented which compensates for the differences in the boundary conditions between the simulation and the experiment. The wetting is found to be initially slowed by inertial flow, then speeded up to a t0.8 dependence by the connectivity of the three-dimensional void network. The effect of the inertial flow is most pronounced for larger pores.