: An experimental investigation was conducted in a water tunnel to explore the application of Coanda-effect circulation control to low aspect ratio wings. The facility was the Large Cavitation Channel in Memphis, TN. The intended application is to high-lift control surfaces (appendages) on underwater naval vehicles. Test results are interpreted in light of both theory and the extensive experience with circulation control (CC) technology at NSWCCD. The semi-span wing test model with a taper ratio of 0.76 was mounted on a load cell; a reflection plane provided for an effective aspect ratio of 2. Dual upper/lower trailing edge tangential jet slots were incorporated for bi-directional force generation. Findings include: finite-span effects on CC augmented lift are consistent with the effects on conventional lift-due-to-angle-of-attack, and cavitation in the Coanda wall jet region does not result in jet detachment or an abrupt lift stall. Wing lift augmentation ratios are up to 36 and meet expectations. Unexpected virtues of a dual-slotted configuration were found that enhance the value of CC to ship and VSTOL aircraft applications. A small flow from the second slot will significantly extend the lift capability beyond that of single slot operation by preventing what is believed to be the adverse effects of excessive turning of the wall jet at high momentum coefficients. Dual slot flow produces a merger of the two wall jets into a free planar jet that enables static thrust vectoring of the jet momentum flux over the full 0-360 degree range. This steerable-jet provides a jet-flap mode of lift development for use at very low vehicle speeds, as an extension of the high efficiency CC mode.

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA436473&Location=U2&doc=GetTRDoc.pdf

Characteristics of a Dual-Slotted Circulation Control Wing of Low Aspect Ratio Intended for Naval Hydrodynamic Applications

A unified lifting line method for the design and analysis of axial flow propellers and turbines is presented. The method incorporates significant improvements to the classical lifting line methods for propeller design to extend the method to the design of turbines. In addition, lifting line analysis methods are developed to extend the usefulness of the lifting line model to allow generation of performance curves for off-design analysis. The result is a fast computational methodology for the design and analysis of propellers or turbines that can be used in preliminary design and parametric studies. Design and analysis validation cases are presented and compared with experimental data.

Unified Rotor Lifting Line Theory

Efficient and multi-objective cavitating propeller optimization: An application to a high-speed craft

Influence of skew on the added mass and damping characteristics of marine propellers

High-speed propulsor blades often experience moderate to substantial amounts of unsteady cavitation, and up to now have been designed via design methods for noncavitating blades combined with methods for the analysis of cavitating flows in a trial-and-error manner. In this thesis a numerical non-linear optimization algorithm is developed for the automated, systematic design of cavitating blades. The objective and constraint functions in the optimization process are expressed in terms of the design variables via linear approximations of the results from an existing lifting-surface analysis method, in the first stage of the algorithm, and quadratic approximations in the final stage. In this way the number of required geometries to be analyzed and the associated computational effort are minimized. The developed methodology is implemented in a modular manner so that future improvements in the modeling of cavitating flows can be readily incorporated. The proposed algorithm is validated with several known non-linear optimization test problems. The method is first applied to the design of efficient two-dimensional partially and supercavitating hydrofoil sections and the results are compared to those from a previously developed optimization procedure. Then, the method is applied to the design of propeller blades in uniform flow. The blade mean camber surface is defined via a cubic B-spline polygon net in order to facilitate the handling of the geometry, and to reduce the number of the design parameters. Non-cavitating blade geometries designed by the present method are directly compared to those designed via an existing lifting-line/lifting-surface design approach. Finally, the optimization algorithm is applied to the design of cavitating blades in non-uniform flow. The objective of the design is to obtain maximum propeller efficiency for given conditions by allowing controlled amounts of sheet cavitation. Several constraints on the unsteady cavity characteristics, such as the area of cavity planform and the amplitudes of the cavity volume velocity harmonics, are incorporated in the optimization technique. The effect of the constraints on the efficiency of the propeller design is demonstrated with various test cases. Thesis Supervisor: Spyros A. Kinnas Title: Assistant Professor Department of Civil Engineering, The University of Texas at Austin Acknowledgments There are a lot of contributions from many people to this thesis work. I first would like to express my greatest possible gratitude to my thesis supervisor, Professor Spyros Kinnas, at the University of Texas at Austin. He has always been encouraging me and giving me invaluable advices in every situation, even on weekends. I got several pieces of email every week from him and I knew he cared about my work. This pushed me to keep working hard. His contribution is so large that I almost feel as if he were a co-author of this thesis. I would also like to thank my "step" supervisor at MIT, Professor Jake Kerwin, for his insightful and friendly advices on both good (rarely) and bad (mostly) results. He made comments always in a humorous way. I sometimes didn't realize the funny point until Todd Taylor explained it for me. Professor Dimitris Bertsimas of the Sloan School of Management accepted to become a member of my thesis committee as an expert in optimization. He attended all the committee meetings and gave many useful comments from an optimization point of view, which I would have missed without him. Dr. Ki-Han Kim of DTMB traveled all the way from Washington D.C. sometimes via Minneapolis to MIT and provided many practical suggestions, which I believe made this thesis more valuable. I was really lucky to get to know smart Propnut members: Dr. Dave Keenan, Dr. Charlie Mazel, Dr. Ching-Yeh Hsin, Dr. Neal Fine, Dr. Mike Hughes, Dr. Tatsuro Kudo, Ms. Beth Lurie, Mr. Todd Taylor, Mr. Scott Black, Mr. Bill Milewski, Mr. Cedric Savineau, Mr. Wes Brewer, Dr. Bill Ramsey, Mr. Rich Kimball, Mr. Gerard Mchugh, Ms. Dianne Egnor, and Ms. Barbara Smith. Weekly group meetings were very helpful to get useful hints in my own research and to know other researches that were going on. Bill Milewski took time to review my thesis draft and gave me good suggestions on it. Dr. Takashi Maekawa has been a good friend and I enjoyed talking with him over lunch. Mr. Tatsuo Mori and Mr. Hideki Shimizu deserve credit for their friendship with me. I would like to thank my former supervisors at the University of Tokyo, Professors Koichiro Yoshida, Hiroharu Kato, and Hideyuki Suzuki for their encouragements. Professor Toshikazu Murakami of Tokai University is the person who made me consider studying at MIT, without whom I wouldn't even have started hydrodynamics research. Special thanks go to my host family, Dr. and Mrs. Seigo Matsuda, who made my stay in Boston always much easier and more enjoyable. Finally I would like to thank my wife, Naomi, for everything. I owe too much to her. Much of the computation was performed remotely on "cavity", a DEC Alpha 600(5/266) computer of the Ocean Engineering Group in the Department of Civil Engineering at the University of Texas at Austin. This research was supported by an international consortium of the following companies and research centers: Daewoo Heavy Industries Ltd., David Taylor Model Basin, El Pardo Model Basin, Hamburg Ship Model Basin, Hyundai Heavy Industries Co., Ltd., Ishikawajima-Harima Heavy Industries Co., Ltd., KaMeWa AB, Mercury Marine, Michigan Wheel Corporation, Outboard Marine Corporation, Rolla SP Propellers SA, Sulzer-Escher Wyss GmbH, Ulstein Propeller AS, Volvo-Penta of the Americas, and Widrtsili Propulsion Financial support for my stay at MIT was provided by the Technical Research & Development Institute, Japan Defense Agency.

Design of cavitating propeller blades in non-uniform flow by numerical optimization

: Correction factors for camber, ideal angle due to loading, and ideal angle due to thickness, which are based on propeller lifting surface theory, are presented for a series of propellers. This series consists of optimum free- running propellers with chordwise loadings the same as an NACA a = 0.8 mean line and with NACA-66 chordwise thickness distributions. The results of the calculations show that the three-dimensional camber and ideal angle are generally greater than the two-dimensional camber and ideal angle at the same lift coefficient. The correction factors increase with increasing expanded area ratio, and those for camber and ideal angle due to loading decrease with increasing number of blades. Thickness, in general, induces a positive angle to the flow, which necessitates a correction to the blade pitch. This ideal angle is largest near the blade root and decreases to negligible values toward the blade tip and increases with increasing number of blades. Skew induces an inflow angle, necessitating a pitch change which is positive toward the blade root and negative toward the blade tip.

/pdf/propeller-lifting-surface-corrections-1t4o9z3c81.pdf

Vladimir Silovic

Papers

Propeller lifting-surface corrections