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Hydraulic Design (hydraulic + design)

Distribution by Scientific Domains

Engineering	33%

Selected Abstracts

Ontogenetically stable hydraulic design in woody plants

FUNCTIONAL ECOLOGY, Issue 2 2006
J. S. WEITZ
Summary 1An important component of plant water transport is the design of the vascular network, including the size and shape of water-conducting elements or xylem conduits. 2For over 100 years, foresters and plant physiologists have recognized that these conduits are consistently smaller near branch tips compared with major branches and the main stem. Empirical data, however, have rarely been assembled to assess the whole-plant hydraulic architecture of woody plants as they age and grow. 3In this paper, we analyse vessels of Fraxinus americana (White Ash) within a single tree. Vessels are measured from cross-sections that span 12 m in height and 18 years' growth. 4We show that vessel radii are determined by distance from the top of the tree, as well as by stem size, independently of tree height or age. 5The qualitative form for the scaling of vessel radii agrees remarkably well with simple power laws, suggesting the existence of an ontogenetically stable hydraulic design that scales in the same manner as a tree grows in height and diameter. 6We discuss the implications of the present findings for optimal theories of hydraulic design. [source]

A Screening Model for Injection-Extraction Treatment Well Recirculation System Design

GROUND WATER MONITORING & REMEDIATION, Issue 4 2008
Monica Y. Wu
Implementation of injection-extraction treatment well pairs for in situ, in-well, or on-site remediation may be facilitated by development and application of modeling tools to aid in hydraulic design and remediation technology selection. In this study, complex potential theory was employed to derive a simple one-step design equation and related type curves that permit the calculation of the extraction well capture zone and the hydraulic recirculation between an injection and extraction well pair oriented perpendicular to regional flow. This equation may be used to aid in the design of traditional fully screened injection-extraction wells as well as innovative tandem recirculating wells when an adequate geologic barrier to vertical ground water flow exists. Simplified models describing in situ bioremediation, in-well vapor stripping, and in-well metal reactor treatment efficiency were adapted from the literature and coupled with the hydraulic design equation presented here. Equations and type curves that combine the remediation treatment efficiency with the hydraulic design equation are presented to simulate overall system treatment efficiency under various conditions. The combined model is applied to predict performance of in situ bioremediation and in-well palladium reactor designs that were previously described in the literature. This model is expected to aid practitioners in treatment system screening and evaluation. [source]

An assessment of hydraulic design of trickle laterals considering effect of minor losses,

IRRIGATION AND DRAINAGE, Issue 4 2007
Gürol Y
canalisations d'eau; canalisations tertiaires; conception hydraulique; analyse; perte de charge Abstract The accurate design of trickle irrigation laterals needs to determine the total energy losses that includes the pipe friction losses along the lateral line and the local pressure losses, sometimes called minor losses, due to the protrusion of emitter barbs into the flow. Evaluation of energy losses is usually carried out by assuming the hypothesis that minor losses can be neglected, even if previous experimental studies indicated that minor losses can become a significant percentage of total energy losses as a consequence of the high number of emitters installed along the lateral line. In this study, a simple analytical procedure is presented to evaluate the effect of minor losses which is characterized by a coefficient ,i, expressing the amount of minor head losses as a fraction of the kinetic head, on trickle lateral design. According to both the design cases of without and including minor losses, the dimensionless design curves were developed for both the various lateral diameters and lengths. The results of two practical examples for designing either the diameter or the length indicated that, in some design cases, neglecting minor losses may lead to erroneous designs of the lateral diameter and length. This method is simple and easily adaptable to solve lateral hydraulic problems but sufficiently precise in comparison with the alternative procedures. The proposed equations are useful when applied for design and evaluation purposes and offer a practical field solution for laterals used in irrigation systems. Copyright © 2007 John Wiley & Sons, Ltd. La conception précise des canalisations tertiaires dans un système d'irrigation au goutte à goutte doit déterminer le total des pertes de charge qui viennent du frottement dans la canalisation elle-même mais aussi des pertes locales, parfois appelées pertes mineures, dues à la protubérance de barbes au niveau des goutteurs. Cette évaluation est normalement réalisée en considérant comme négligeables les pertes mineures, même si des études expérimentales ont montré que ces pertes mineures pouvaient constituer un pourcentage significatif de la perte de charge totale du fait du grand nombre de goutteurs installés le long de la canalisation tertiaire. Dans cette étude, une procédure analytique simple est proposée pour évaluer l'effet des pertes mineures sur la conception des canalisations tertiaires grâce à un coefficient ,i, exprimant le montant de ces pertes en une fraction de la charge cinétique. En fonction des diverses options de conception prenant ou non en compte les pertes mineures, des courbes de conception non dimensionnelles ont été tracées pour les diamètres et les longueurs des canalisations. Les résultats de deux exemples concrets montrent que, dans certains cas de conception, le fait de négliger les pertes mineures peut conduire à des conceptions de diamètre et de longueur erronées. Cette méthode est simple et facilement adaptable à la résolution de problèmes hydrauliques au niveau des tertiaires mais suffisamment précise par rapport des méthodes alternatives. Les équations proposées sont utiles pour la conception et l'évaluation et offrent une solution de terrain concrète pour les canalisations tertiaires utilisées dans des systèmes d'irrigation (au goutte à goutte). Copyright © 2007 John Wiley & Sons, Ltd. [source]

Unstable Operation in an Acetaldehyde Purification Tower

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2004
F. Abdolahi
Abstract There are many reasons, such as an inappropriate control system, improper hydraulic design, and operational faults, which can make a tower unstable. In this case, with the aid of simulation and checks on the control system, it has been confirmed using the foaming test that instability is due to foaming in the system. The method described in this article can be used for any separation system with instability problems. [source]