Effects Of Convoluted Divergent Flap Contouring On The Performance Of A Fixed Geometry Nonaxisymmetric Exhaust Nozzle
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Effects of Convoluted Divergent Flap Contouring on the Performance of a Fixed-Geometry Nonaxisymmetric Exhaust Nozzle
Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 76 |
Release | : 2018-05-30 |
Genre | : |
ISBN | : 9781720483830 |
An investigation was conducted in the model preparation area of the Langley 16-Foot Transonic Tunnel to determine the effects of convoluted divergent-flap contouring on the internal performance of a fixed-geometry, nonaxisymmetric, convergent-divergent exhaust nozzle. Testing was conducted at static conditions using a sub-scale nozzle model with one baseline and four convoluted configurations. All tests were conducted with no external flow at nozzle pressure ratios from 1.25 to approximately 9.50. Results indicate that baseline nozzle performance was dominated by unstable, shock-induced, boundary-layer separation at overexpanded conditions. Convoluted configurations were found to significantly reduce, and in some cases totally alleviate separation at overexpanded conditions. This result was attributed to the ability of convoluted contouring to energize and improve the condition of the nozzle boundary layer. Separation alleviation offers potential for installed nozzle aeropropulsive (thrust-minus-drag) performance benefits by reducing drag at forward flight speeds, even though this may reduce nozzle thrust ratio as much as 6.4% at off-design conditions. At on-design conditions, nozzle thrust ratio for the convoluted configurations ranged from 1% to 2.9% below the baseline configuration; this was a result of increased skin friction and oblique shock losses inside the nozzle.Asbury, Scott C. and Hunter, Craig A.Langley Research CenterCONVERGENT-DIVERGENT NOZZLES; BOUNDARY LAYER SEPARATION; WIND TUNNEL NOZZLES; WIND TUNNEL TESTS; NOZZLE FLOW; OBLIQUE SHOCK WAVES; FLOW VISUALIZATION; NOZZLE GEOMETRY; AERODYNAMIC DRAG; SKIN FRICTION; PRESSURE RATIO; FLAPS (CONTROL SURFACES)
Unsteady Computational Fluid Dynamics in Aeronautics
Author | : P.G. Tucker |
Publisher | : Springer Science & Business Media |
Total Pages | : 432 |
Release | : 2013-08-30 |
Genre | : Technology & Engineering |
ISBN | : 9400770499 |
The field of Large Eddy Simulation (LES) and hybrids is a vibrant research area. This book runs through all the potential unsteady modelling fidelity ranges, from low-order to LES. The latter is probably the highest fidelity for practical aerospace systems modelling. Cutting edge new frontiers are defined. One example of a pressing environmental concern is noise. For the accurate prediction of this, unsteady modelling is needed. Hence computational aeroacoustics is explored. It is also emerging that there is a critical need for coupled simulations. Hence, this area is also considered and the tensions of utilizing such simulations with the already expensive LES. This work has relevance to the general field of CFD and LES and to a wide variety of non-aerospace aerodynamic systems (e.g. cars, submarines, ships, electronics, buildings). Topics treated include unsteady flow techniques; LES and hybrids; general numerical methods; computational aeroacoustics; computational aeroelasticity; coupled simulations and turbulence and its modelling (LES, RANS, transition, VLES, URANS). The volume concludes by pointing forward to future horizons and in particular the industrial use of LES. The writing style is accessible and useful to both academics and industrial practitioners. From the reviews: "Tucker's volume provides a very welcome, concise discussion of current capabilities for simulating and modellng unsteady aerodynamic flows. It covers the various pos sible numerical techniques in good, clear detail and presents a very wide range of practical applications; beautifully illustrated in many cases. This book thus provides a valuable text for practicing engineers, a rich source of background information for students and those new to this area of Research & Development, and an excellent state-of-the-art review for others. A great achievement." Mark Savill FHEA, FRAeS, C.Eng, Professor of Computational Aerodynamics Design & Head of Power & Propulsion Sciences, Department of Power & Propulsion, School of Engineering, Cranfield University, Bedfordshire, U.K. "This is a very useful book with a wide coverage of many aspects in unsteady aerodynamics method development and applications for internal and external flows." L. He, Rolls-Royce/RAEng Chair of Computational Aerothermal Engineering, Oxford University, U.K. "This comprehensive book ranges from classical concepts in both numerical methods and turbulence modelling approaches for the beginner to latest state-of-the-art for the advanced practitioner and constitutes an extremely valuable contribution to the specific Computational Fluid Dynamics literature in Aeronautics. Student and expert alike will benefit greatly by reading it from cover to cover." Sébastien Deck, Onera, Meudon, France
Body Contouring
Author | : Michele A. Shermak |
Publisher | : McGraw Hill Professional |
Total Pages | : 286 |
Release | : 2010-09-21 |
Genre | : Medical |
ISBN | : 0071604685 |
The definitive full-color illustrated atlas of breast and body contouring surgical procedures Includes DVD with video clips Part of the McGraw-Hill Plastic Surgery Atlas series, Body Contouring is a full-color, step-by-step guide to learning how to perform both traditional and contemporary plastic surgery procedures relative to breast and body contouring. Two hundred medical illustrations and more than two hundred photographs – all in full color – offer unmatched coverage of the required surgical steps and actual results. A companion DVD features skill-building surgical video clips. For each procedure, you’ll find a complete review of key topics, including: Introduction to the surgical approach Relevant anatomy Indications Markings Details of the procedure (incision and exposure) Postoperative care Pitfalls Tips Part I of Body Contouring addresses important clinical concerns such as the safety of surgical techniques, intraoperative positioning, psychological issues, and issues pertaining to massive weight loss and surgical wound care. Part II then reviews specific body contouring surgical procedures by body region, beginning with the upper extremity, and proceeding to the female breast, male chest (gynecomastia), abdomen, back, and lower extremity. Learn all aspects of body contouring surgery, step by step: Breast surgery: Reduction; Mastopexy; Augmentation; Lifting; Gynecomastia; Arm and thigh contouring with liposuction and excisional techniques; Abdominoplasty, upper and lower, with hernia repair techniques; Back contouring
Discharge in Long Air Gaps
Author | : Abderrahmane Beroual |
Publisher | : IOP Publishing Limited |
Total Pages | : 0 |
Release | : 2016 |
Genre | : Science |
ISBN | : 9780750312370 |
'Discharge in Long Air Gaps' presents self-consistent predictive dynamic models of positive and negative discharges in long air gaps. Equivalent models are also derived to predict lightning parameters based on the similarities between long air gap discharges and lightning flashes. Comparisons between computed and experimental results for various test configurations are presented and discussed.
Static Performance of a Fixed-Geometry Exhaust Nozzle Incorporating Porous Cavities for Shock-Boundary Layer Interaction Control
Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 140 |
Release | : 2018-08-20 |
Genre | : |
ISBN | : 9781721081639 |
An investigation was conducted in the model preparation area of the Langley 16-Foot Transonic Tunnel to determine the internal performance of a fixed-geometry exhaust nozzle incorporating porous cavities for shock-boundary layer interaction control. Testing was conducted at static conditions using a sub-scale nozzle model with one baseline and 27 porous configurations. For the porous configurations, the effects of percent open porosity, hole diameter, and cavity depth were determined. All tests were conducted with no external flow at nozzle pressure ratios from 1.25 to approximately 9.50. Results indicate that baseline nozzle performance was dominated by unstable, shock-induced, boundary-layer separation at over-expanded conditions. Porous configurations were capable of controlling off-design separation in the nozzle by either alleviating separation or encouraging stable separation of the exhaust flow. The ability of the porous nozzle concept to alternately alleviate separation or encourage stable separation of exhaust flow through shock-boundary layer interaction control offers tremendous off-design performance benefits for fixed-geometry nozzle installations. In addition, the ability to encourage separation on one divergent flap while alleviating it on the other makes it possible to generate thrust vectoring using a fixed-geometry nozzle. Asbury, Scott C. and Hunter, Craig A. Langley Research Center RTOP 538-14-12-01