Active and Passive Separation Control for Drag Reduction of a Maneuvering Hull Form - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Active and Passive Separation Control for Drag Reduction of a Maneuvering Hull Form write by James Crandall Schulmeister. This book was released on 2017. Active and Passive Separation Control for Drag Reduction of a Maneuvering Hull Form available in PDF, EPUB and Kindle. Boundary layer separation is a source of large fluid dynamic forces on many engineered vehicles and structures, limiting the speed and efficiency at which we transport people and goods. The maneuvering of ocean and air vehicles in particular is limited by resistance due to cross-flow separation. Hull forms with lower hydrodynamic resistance in maneuvers are able to follow trajectories with tighter turns and at higher speeds. Despite the progress that has been made in the control of two dimensional flow separation, little has been done to apply flow control to complex three-dimensional separation from maneuvering hull forms. This thesis studies and develops mechanisms for mitigating three-dimensional cross-flow separation to reduce the drag of hull forms in maneuvers. A new strategy is proposed for designing flow control mechanisms for the three dimensional flow past maneuvering hull forms based on the unsteady cross-flow analogy. The unsteady cross-flow analogy relates the steady flow past a three-dimensional body to an analogous unsteady two-dimensional flow past a cylinder that changes size and shape in time. This provides a framework for adapting two-dimensional drag reduction techniques to the three-dimensional flow. In addition, the unsteady cross-flow analogy is computationally inexpensive and so is suitable for iterative use in preliminary design. The new strategy is considered by first implementing the unsteady cross-flow analogy in numerical simulations. Next, passive and active flow control mechanisms are studied experimentally for drag reduction of a circular cylinder and then adapted through the analogy for drag reduction of a slender body at an angle of attack. Passive control is exerted through modifications to the shape of the body and active control is exerted with rotating control cylinders. Both passive and active methods are experimentally demonstrated to reduce the drag. The experimental results also confirm key predictions of the unsteady cross-flow analogy, demonstrating that it is a promising tool for developing three-dimensional separation control techniques.
Mitigation Of Hydrodynamic Resistance: Methods To Reduce Hydrodynamic Drag
Mitigation Of Hydrodynamic Resistance: Methods To Reduce Hydrodynamic Drag - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Mitigation Of Hydrodynamic Resistance: Methods To Reduce Hydrodynamic Drag write by Marc Perlin. This book was released on 2014-11-18. Mitigation Of Hydrodynamic Resistance: Methods To Reduce Hydrodynamic Drag available in PDF, EPUB and Kindle. This text presents the state of the art in friction drag/resistance reduction technologies for BODIES and crafts operating in liquids at and beneath the free surface. It is useful for professionals with backgrounds in advanced fluid dynamics as well as by academics teaching introductory graduate courses in this area. Active control of resistance will include a discussion of friction reduction, for example through the injection of gas that can form air layers and polymers that initially reside adjacent to the hull, including the use of partial and super cavities. The book discusses passive resistance control achieved through changes in the overall hull shape and appendages, including the application of lifting bodies, bulbous bows, and stern flaps. It also addresses passive reduction of skin friction through the application of hull coatings and other elements of hull husbandry.
Turbulence Control by Passive Means
Turbulence Control by Passive Means - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Turbulence Control by Passive Means write by E. Coustols. This book was released on 2012-12-06. Turbulence Control by Passive Means available in PDF, EPUB and Kindle. Proceedings of the 4th European Drag Reduction Meeting
Aerodynamic Design of Active Flow Control Systems Aimed Towards Drag Reduction in Heavy Vehicles
Aerodynamic Design of Active Flow Control Systems Aimed Towards Drag Reduction in Heavy Vehicles - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Aerodynamic Design of Active Flow Control Systems Aimed Towards Drag Reduction in Heavy Vehicles write by David E. Manosalvas-Kjono. This book was released on 2018. Aerodynamic Design of Active Flow Control Systems Aimed Towards Drag Reduction in Heavy Vehicles available in PDF, EPUB and Kindle. The trucking industry is an irreplaceable sector of our economy. Over 80% of the world population relies on it for the transportation of commercial and consumer goods. In the US alone, this industry is responsible for over 38% of fuel consumption as it distributes over 70% of our freight tonnage. In the design of these vehicles, particular emphasis has been placed on equipping them with a strong engine, a relatively comfortable cabin, a spacious trailer, and a flat back to improve loading efficiency. The geometrical design of these vehicles makes them prone to flow separation and at highway speeds overcoming aerodynamic drag accounts for over 65% of their energy consumption. The flat back on the trailer causes flow to separate, which generates a turbulent wake. This region is responsible for a significant portion of the aerodynamic drag and currently the most popular solution is the introduction of flat plates attached to the back of the trailer to push the wake downstream. These passive devices improve the aerodynamic performance of the vehicle, but leave opportunities for significant improvement that can only be achieved with active systems. The current procedure to analyze the flow past heavy vehicles and design add-on drag reduction devices focuses on the use of wind tunnels and full-scale tests. This approach is very time consuming and incredibly expensive, as it requires the manufacturing of multiple models and the use of highly specialized facilities. This Dissertation presents a computational approach to designing Active Flow Control (AFC) systems to reduce drag and energy consumption for the trucking industry. First, the numerical tools were selected by studying the capabilities of various numerical schemes and turbulence model combinations using canonical bluff bodies. After various numerical studies and comparisons with experimental results, the Jameson-Schmidt-Turkel (JST) scheme in combination with the Shear-Stress-Transport (SST) turbulence model were chosen. This combination of tools was used to study the effect of AFC in the Ground Transportation System (GTS) model, which is a simplified representation of a tractor-trailer introduced by the US Department of Energy to study the separation behind this type of vehicle and the drag it induces. Using the top-view of the GTS model as a two-dimensional representation of a heavy vehicle, the effect that the Coanda jet-based AFC system has on the wake and integrated forces have been studied. These two-dimensional studies drove the development of the design methodology presented, and produced the starting condition for the three-dimensional Coanda surface geometry and the jet velocity profile. In addition, the influence in wake stability that this system demonstrated when operating near its optimum drag configuration, allowed for the decoupling of time from the three-dimensional design process. A design methodology that minimizes the number of required function evaluations was developed by leveraging insights obtained from previous studies; using the physical changes in the flow induced by the AFC system to eliminate the need for time integration during the design process; and leveraging surrogate model optimization techniques . This approach significantly reduces the computational cost during the design of AFC drag reduction systems and has led to the design of a system that reduces drag by over 19% and power by over 16%. In the US trucking fleet alone, these energy savings constitute 8.6 billion gallons of fuel that will not be burned and over 75 million tons of CO2 that will not be released into the atmosphere each year.
Automotive Drag Reduction by Flow Separation Control
Automotive Drag Reduction by Flow Separation Control - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Automotive Drag Reduction by Flow Separation Control write by Brent Van Stuyvendaele. This book was released on 2014. Automotive Drag Reduction by Flow Separation Control available in PDF, EPUB and Kindle.
