Turbulent Drag Reduction Using Compliant Coatings
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| Author | : |
| Publisher | : |
| Total Pages | : 18 |
| Release | : 2002 |
| Genre | : |
| ISBN | : |
An experimental study was carried in a water tunnel, where the drag of several compliant coatings in the turbulent boundary layer was measured. An axi-symmetric test model similar to that used by NUWC was designed and built, and identical compliant coatings were tested as a part of collaboration between UK, U.S. and Russia. While experimental results in the UK show small drag reductions by up to 3% in some of the compliant coatings tested, skin-friction drags of compliant coatings measured at MIT are consistently greater than that of rigid surface. The Russian data are not yet available at the time of writing this report. The aging of the compliant coatings are thought to be the reason for these discrepancies. A better coordination will be required for the rest of the program to overcome this problem.
| Author | : Maghin Tamilarasan |
| Publisher | : |
| Total Pages | : |
| Release | : 2000 |
| Genre | : |
| ISBN | : |
| Author | : Edward F. Blick |
| Publisher | : |
| Total Pages | : 29 |
| Release | : 1974 |
| Genre | : |
| ISBN | : |
Research on skin friction reduction by compliant coating conducted at the University of Oklahoma during the past eight years is reviewed. At the University of Oklahoma wind tunnel experiments showed that compliant coatings composed of a thin sheet of polyvinyl chloride covering either a thin layer of liquid or a thin layer of polyurethane foam reduced the turbulent skin friction drag by as much as 40% on flat plates. Hot wire anemometer measurements also indicated corresponding reductions in Reynolds stresses and turbulence intensities in the boundary layer. An NACA 0009 airfoil was found to have as much as 30% less drag when equipped with a 'polyvinyl chloride-polyurethane foam' compliant coating. (Author).
| Author | : F. W. PURYEAR |
| Publisher | : |
| Total Pages | : 14 |
| Release | : 1962 |
| Genre | : |
| ISBN | : |
Tests were conducted on 6 models of identical size to determine whether a reduction in drag could be obtained by the use of compliant coatings (trademarked Lamiflo) to stabilize a laminar boundary layer. Two noncompliant plastic models were manufactured. One was used as a standard for comparing the drag obtained on four models covered with various compliant coatings, and the other was instrumented with pressure taps in order to obtain body pressure measurements. None of the compliant bodies showed a drag reduction. The inability, during fabrication and testing, to maintain a faired transition from the metal nose adapter ring to the coating caused separation to occur at this discontinuity and probably turbulent flow to exist in an area designed to be laminar. Laminar flow on the forward portion of the coating is required if the coating is to stabilize the laminar boundary layer. (Author).
| Author | : K.-S. Choi |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 344 |
| Release | : 2012-12-06 |
| Genre | : Technology & Engineering |
| ISBN | : 9401135266 |
The European Drag Reduction Meeting has been held on 15th and 16th November 1990 in London. This was the fifth of the annual European meetings on drag reduction in engineering flows. The main objective of this meeting was to discuss up-to-date results of drag reduction research carried out in Europe. The organiser has adopted the philosophy of discussing the yesterday's results rather than the last year's results. No written material has therefore been requested for the meeting. It was only after the meeting the submission of papers was requested to the participants, from which 16 papers were selected for this proceedings volume. The meeting has attracted a record number of participants with a total of 52 researchers from seven European countries, U. K. , France, Germany, the Netherlands, Italy, Switzerland and U. S. S. R. as well as from Japan, Canada and Australia. The subjects covered in this proceedings volume include riblets, LEBUs (Large Eddy Break-Up device), surface roughness, compliant surfaces and polymer additives. Riblets seem to be one of the most extensively studied devices in the past years. Reflecting this situation in the European community, there are six papers on riblets covering their practical applications to aircraft and to a model ship, near-wall coherent structure of the boundary layer and effects of flow three-dimensionality. Possibility of heat-transfer enhancement with riblets and potential use in the laminar flow are also investigated. An analytical model is developed for the boundary-layer with a LEBU device.
| Author | : S. C. Dickinson |
| Publisher | : |
| Total Pages | : 48 |
| Release | : 1984 |
| Genre | : |
| ISBN | : |
The drag of three compliant coatings was measured in the DTNSRDC 36-inch water tunnel. Two coatings were of the 'Kramer' type, while the other one was a closed-cell neoprene foam. The drag of the 2.032-m (80-in.) long and 0.737-m (29-in.) wide compliant coatings was compared to the drag of a smooth, solid reference plate.
| Author | : |
| Publisher | : AIAA |
| Total Pages | : 542 |
| Release | : 1990 |
| Genre | : Boundary layer |
| ISBN | : 9781600863783 |
| Author | : Feng-Chen Li |
| Publisher | : John Wiley & Sons |
| Total Pages | : 233 |
| Release | : 2012-01-10 |
| Genre | : Science |
| ISBN | : 1118181115 |
Turbulent drag reduction by additives has long been a hot research topic. This phenomenon is inherently associated with multifold expertise. Solutions of drag-reducing additives are usually viscoelastic fluids having complicated rheological properties. Exploring the characteristics of drag-reduced turbulent flows calls for uniquely designed experimental and numerical simulation techniques and elaborate theoretical considerations. Pertinently understanding the turbulent drag reduction mechanism necessities mastering the fundamentals of turbulence and establishing a proper relationship between turbulence and the rheological properties induced by additives. Promoting the applications of the drag reduction phenomenon requires the knowledge from different fields such as chemical engineering, mechanical engineering, municipal engineering, and so on. This book gives a thorough elucidation of the turbulence characteristics and rheological behaviors, theories, special techniques and application issues for drag-reducing flows by surfactant additives based on the state-of-the-art of scientific research results through the latest experimental studies, numerical simulations and theoretical analyses. Covers turbulent drag reduction, heat transfer reduction, complex rheology and the real-world applications of drag reduction Introduces advanced testing techniques, such as PIV, LDA, and their applications in current experiments, illustrated with multiple diagrams and equations Real-world examples of the topic’s increasingly important industrial applications enable readers to implement cost- and energy-saving measures Explains the tools before presenting the research results, to give readers coverage of the subject from both theoretical and experimental viewpoints Consolidates interdisciplinary information on turbulent drag reduction by additives Turbulent Drag Reduction by Surfactant Additives is geared for researchers, graduate students, and engineers in the fields of Fluid Mechanics, Mechanical Engineering, Turbulence, Chemical Engineering, Municipal Engineering. Researchers and practitioners involved in the fields of Flow Control, Chemistry, Computational Fluid Dynamics, Experimental Fluid Dynamics, and Rheology will also find this book to be a much-needed reference on the topic.
| Author | : Alfredo Soldati |
| Publisher | : Springer |
| Total Pages | : 319 |
| Release | : 2014-05-04 |
| Genre | : Technology & Engineering |
| ISBN | : 370912574X |
Controlling turbulence is an important issue for a number of technological applications. Several methods to modulate turbulence are currently being investigated. This book describes various aspects of turbulence structure and modulation, and explains and discusses the most promising techniques in detail.
| Author | : Viktor V. Babenko |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2013 |
| Genre | : Boundary layer control |
| ISBN | : |
While other methods of drag reduction are well-known in marine R & D and ship design environments worldwide, compliant coating drag reduction remains less well-known and poorly understood. This important book presents cutting-edge techniques and findings from research sources not generally accessible by Western researchers and engineers, aiding the application and further development of this potentially important technology. Beginning with an introduction to drag reduction that places the authors' work on elastic surfaces and combined techniques in context, the book moves on to provide a comprehensive study of drag reduction through elastic coating with both flow and material properties considered. Coverage includes: Experimental findings around coherent vortical structures (CVS) in turbulent boundary layers and methods of controlling them Static and dynamic mechanical characteristics of elastic composite coatings, as well as new techniques and devices developed for their measurement Combined methods of flow control and drag reduction, including the effect of injection of polymer solutions, elastic coatings and generated longitudinal vortical structures on hydrodynamic resistance Intended as a reference for senior engineers and researchers concerned with the drag reduction and the dynamics of turbulent boundary layer flows, Boundary Layer Flow over Elastic Surfaces provides a unique source of information on compliant surface drag reduction and the experimental techniques around it that have shown measurable and repeatable improvements over recent years. This compilation of research findings and new techniques developed for measurement will aid R & D engineers, naval architects and senior designers in their quest to achieve drag reductions that will deliver significant efficiency savings. Unique source of information on compliant surface drag reduction-an important area of technology with practical application to ships-from otherwise inaccessible research studiesUpdates the knowledge-base on boundary layer flow and surface friction reduction, critical topics in the global quest for increased ship efficiency and fuel economyReveals new techniques and devices developed for measurement and provides a comprehensive study of drag reduction through elastic coating with both flow and material properties covered.
