DOCSLIB.ORG

On the Flow Behaviour of a Vortex-Trapping Cavity NACA0020 Aerofoil at Ultra-Low Reynolds Number

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
On the Flow Behaviour of a Vortex-Trapping Cavity NACA0020 Aerofoil at Ultra-Low Reynolds Number 17th International Symposium on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, 07-10 July, 2014 On the flow behaviour of a vortex-trapping cavity NACA0020 aerofoil at ultra-low Reynolds number 1 2* 1 Shengxian Shi , T.H. New and Yingzheng Liu 1: Gas Turbine Research Institute, School of Mechanical Engineering, Shanghai Jiao Tong University 200240, Shanghai, China 2: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 * correspondent author: [email protected] Abstract An experimental study on a NACA0020 aerofoil with or without a semi-circular cavity on its upper surface has been performed to examine the effect of trapped vortex cell on flow separation behaviour. Particle-streak visualisations and time-resolved particle image velocimetry (TR-PIV) measurements were conducted in a low-speed recirculation water channel at ultra-low Reynolds number of Rec=5000 (based on chord length) with angles-of-attack (AOA) varying between α=0о to 20о. Time-series of instantaneous velocity fields were analysed by Proper Orthogonal Decomposition (POD). Flow structures of the two aerofoils were examined in detail by means of time-averaged velocity fields, dominant flow modes and phase-averaged vortex-shedding pattern. Results revealed that the trapped vortex actually results in earlier flow separation in the present flow conditions, which leads to a consistently larger wake size than the standard NACA0020 aerofoil for the tested AOAs. 1. Introduction The ever increasing demands of aerodynamically more efficient aircraft urge the developments of advanced flow-separation control techniques. Various investigations have been focused on flow control strategies dedicated towards suppressing or delaying aerofoil flow separations. One of such efforts is by trapping a vortex in an aerofoil cavity to mitigate flow separation events. The concept of vortex-trapping cavity was firstly proposed by Ringleb (1961), and Kasper (1977) firstly applied such a concept into real flight tests. He claimed that the BKB-1 tailless glider achieved better manoeuvrability at low speeds (around 20mph) by trapping a tornado like vortex over the upper wing surface. However, subsequent wind tunnel tests on a Kasper wing model did not prove the superiority of this concept over conventional clean aerofoil (Kruppa 1977). Probably due to the contradiction between flight tests and wind tunnel experiments, the research on vortex- trapping cavity aerofoil did not continue until late 1990s. Savitsky (1995) filed a patent on an “EKIP” aircraft design, which declared that the trapped vortices on the aerofoil upper surface can prevent large-scale flow separation. Chernyshenko (1995) theoretically analysed the effect of incoming flow oscillation on the stabilisation of trapped vortex, and Bunyakin et al. (1998) provided a theoretical framework on designing an aerodynamically efficient vortex-trapping cavity aerofoil. This concept regained attention in 2005 when the European Union announced the VortexCell2050 project, which aimed to develop trapped-vortex and active flow control techniques for next- generation thick-wing aircraft. De Gregorio and Fraioli (2008) performed pressure and flow measurements on an aerofoil with a vortex-trapping cavity at chord based Reynolds number of Rec=3.5×105~7.0×105, and demonstrated that flow separation can only be controlled if suction was applied in the cavity region. Similar experimental studies were performed for a modified NACA0024 aerofoil at Rec=6.67×105 and 106 to investigate the effectiveness of vortex-trapping- suction combined flow control method (Lasagna et al. 2011). It was found that the modified - 1 - 17th International Symposium on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, 07-10 July, 2014 aerofoil has distinct low- and high-drag modes across the tested AOA range, which correspond to stable vortex-trapping inside the cavity and large scale vortex shedding from the cavity respectively. The authors concluded that the vortex-trapping-suction is only effective for a very limited AOA range (-2° ≤ α ≤ 8°). Olsman and Colonius (2011) demonstrated numerically, by means of DNS simulations on a vortex-trapping cavity NACA0018 aerofoil at Rec=2.0×104, that the flow within the cavity exhibits two shear layer modes for different AOAs, and it helps to suppress separation or narrow wake structure regardless of the AOA variation. The modified NACA0018 aerofoil was further studied experimentally to explore the coupling between aerofoil elastic vibrations (simulated via acoustic forcings) and cavity flow oscillations at Rec=O(104)~O(105) (Olsman et al. 2011). While the oscillation of cavity shear layer did respond linearly to acoustic forcing at Rec=O(104), the pressure and lift measurements did not show significant deviation between the modified and standard NACA0018 aerofoils across the tested Reynolds numbers. These preceding works mainly focused on force measurements and theoretical/numerical analysis on flow inside vortex-trapping cavity implemented on aerofoils at high Reynolds numbers, with very little attention (e.g. flow visualisation, hot-wire) paid towards experimentally examine the flow structures associated with such aerofoils. In addition, these studies provided inconsistent conclusions on the efficiency of a trapped vortex on flow-separation control, which further intrigued the authors into exploring the differences, from flow structural point-of-view, between vortex-trapping and standard aerofoils, so as to shed some light on mechanism of flow control via trapped vortex. Towards this end, particle-streak flow visualisation and TR-PIV measurements were performed on both standard and modified NACA0020 aerofoils. POD and phase-averaged analysis were employed to allow fuller comparisons on flow structures of the standard and modified aerofoils. 2. Experimental set-up and data reduction methods Experiments were conducted in a recirculating water tunnel at School of Mechanical Engineering, Shanghai Jiao Tong University. Water was driven by a frequency invertor controlled centrifugal pump and conditioned sequentially by honeycombs, three layers of coarse-to-fine screens and a 4:1 ratio contraction section. It then entered a Plexiglas test-section with a dimension of 250 mm (H) × 150 mm (W) × 1050 mm (L). To minimise any undesired free surface effects as well as ease the mounting procedure, the test aerofoil models were enclosed within a Plexiglas frame, which has an internal dimension of 200 mm (H) × 120 mm (W) × 500 mm (L) (Fig. 1). One NACA0020 aerofoil and a modified NACA0020 aerofoil with semi-circular cavity on its upper surface were studied in the current experiments (Fig. 2). The models were machined from aluminium, and both the upper and lower surface were carefully polished and coated with matt black paint for optical measurements. The free stream velocity was maintained at approximately 0.085m/s throughout, with a resultant chord length (c=60mm) based Reynolds number of Rec=5000. The AOA varied о о о between 0 to 20 with increment of 5 . During the tests, the water tunnel was homogenously seeded with 20~30µm hollow glass beads, which scattered light after illumination from a laser sheet formed by a 8W 532nm continuous- wave DPSS laser. Two types of cameras were used for the experiments. Particle-streak images were recorded by a Canon 550D DSLR camera to obtain first-hand observations for the flow structures, while time-series particle images were captured by a 1280 × 1024 px2 Mikrotron EoSens camera at 250 frames-per-second (fps) for TR-PIV analysis. 10,000 instantaneous images were - 2 - 17th International Symposium on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, 07-10 July, 2014 captured for each AOA and subjected to two-pass multi-grid cross-correlation process. Using a final interrogation window size of 32 × 32 px2 with 75% overlap, a 157 × 125 velocity matrix was obtained for every image pairs (i.e. frames 1 and 2, frames 2 and 3), which provided a spatial resolution of approximately 0.95mm/vector. The raw velocity vectors were post-processed by local median filter, and any spurious vectors which were determined less than 2%, were replaced by a 3 × 3 interpolation scheme. For each tested AOA, a total of 9999 instantaneous velocity fields were produced for further POD analysis, which decomposed the flow field into different modes with associated energy coefficient, and allowed the differentiation of dominant flow structures from small scale ones (Lumley 1967, Kim and Rockwell 2005). The POD analysis also provided phase information about the flow fields, and phase-averaged wake structures were calculated by о о averaging instantaneous velocity vectors at 90 intervals at a phase bin size of 5 . Fig. 1 Mounting frame used in the current experiments (a) Standard NACA0020 aerofoil (b) Vortex-trapping NACA0020 aerofoil Fig. 2 Aerofoil geometries 3. Results and discussions Figure 3 presents flow visualisation results for the standard and vortex-trapping NACA0020 aerofoils. A direct qualitative observation from the figure is that the vortex-trapping aerofoil produces consistently larger flow separation bubble than the standard aerofoil for AOAs varying from 5о to 20о. Another interesting difference between flow structures of the two aerofoils is that the particle-streak images for the standard aerofoil tend to be much clearer than that of the vortex- trapping aerofoil, although exactly same camera parameters were used
Load more

Recommended publications
  • Defense Industry Restructuring in Russia
    S t a n f o r d U n i v e r s i t y C I S A C Center for International Security and Arms Control The Center for International Security and Arms Control, part of Stanford University’s Institute for International Studies, is a multidisciplinary community dedicated to research and train- ing in the field of international security. The Center brings together scholars, policymakers, scientists, area specialists, members of the business community, and other experts to examine a wide range of international security issues. CISAC publishes its own series of working papers and reports on its work and also sponsors a series, Studies in International Se- curity and Arms Control, through Stanford University Press. Center for International Security and Arms Control Stanford University 320 Galvez Street Stanford, California 94305-6165 (415) 723-9625 http://www-leland.stanford.edu/group/CISAC/ Contents Acknowledgments iv Executive Summary v I Introduction 1 Section One: Case Studies II The Central Aerohydrodynamic Research Institute (TsAGI) 9 III ELVIS+ and The Moscow Center for SPARC Technology (MCST) 28 IV Impuls 45 V The Mashinostroenie Enterprise 59 VI The Saratov Aviation Plant 79 Section Two: Analysis VII Privatization at Four Enterprises 111 VIII Organizational Restructuring 137 IX Principal Differences in Accounting Systems in Russia 163 and the United States X Reallocation of the Social Services 183 XI Conclusion 207 Glossary 216 1 Acknowledgments Many people have contributed to this report, and still more have contributed to the research leading up to it. In writing this report, we have not attempted to reach consensus among the authors on the interpretations to be drawn from the data.
    [Show full text]
  • Requirements and Selection of Design Concepts to Be Investigated
    GF_WP1_TN_Requirements GF_WP1_TN_Requirements Department of Automotive and Aeronautical Engineering Hamburg University of Applied Sciences (HAW) Berliner Tor 9 D - 20099 Hamburg Green Freighter – Requirements and Selection of Design Concepts to be Investigated Kolja Seeckt Dieter Scholz 2007-11-29 Technical Note 1 GF_WP1_TN_Requirements Dokumentationsblatt 1. Berichts-Nr. 2. Auftragstitel 3. ISSN / ISBN GF_WP1_TN_Requirements Grüner Frachter (Entwurfsuntersuchungen zu --- umweltfreundlichen und kosteneffektiven Fracht- flugzeugen mit unkonventioneller Konfiguration) 4. Sachtitel und Untertitel 5. Abschlussdatum Green Freighter – Requirements and Selection of Design Concepts to 29.11.2007 be Investigated 6. Ber. Nr. Auftragnehmer GF_WP1_TN_Requirements 7. Autor(en) (Vorname, Name) 8. Vertragskennzeichen Kolja Seeckt ([email protected]) 1710X06 Dieter Scholz ([email protected]) 9. Projektnummer FBMBF06-004 10. Durchführende Institution (Name, Anschrift) 11. Berichtsart Hochschule für Angewandte Wissenschaften Hamburg (HAW) Technische Niederschrift Fakultät Technik und Informatik 12. Berichtszeitraum Department Fahrzeugtechnik und Flugzeugbau Forschungsgruppe Flugzeugentwurf und Systeme (Aero) 06.12.2006 - 20.09.2007 Berliner Tor 9 13. Seitenzahl D - 20099 Hamburg 96 14. Fördernde Institution / Projektträger (Name, Anschrift) 15. Literaturangaben Bundesministerium für Bildung und Forschung (BMBF) 70 Heinemannstraße 2, 53175 Bonn - Bad Godesberg 16. Tabellen Arbeitsgemeinschaft industrieller Forschungsvereinigungen 10 „Otto
    [Show full text]
  • Vortexcell2050
    Sixth EU Framework Programme for Research and Technological Development (FP6) Contract No AST4-CT-2005-012139. 2005-2009 VortexCell2050 Specific Targeted Research Project “Fundamentals of actively controlled flows with trapped vortices ” Publishable executive summary VortexCell2050 aimed at delivering a new technological platform combining two cutting-edge technologies, the trapped-vortex and the active flow control. Trapping vortices is a technology for preventing vortex shedding and reducing drag in flows past bluff bodies. Active flow control is a form of control which requires energy input. The project outcomes will serve the designers of the next-generation thick-wing aircraft, and will also be applied in other areas where reduction in drag in a flow past a bluff body is desirable. VortexCell2050 developed a tool for vortex cell design, collected a substantial amount of data on three-dimensional and actively controlled flows in vortex cells, and demonstrated the advantage of a thick airfoil with a properly designed vortex cell with active control over a thick airfoil without a vortex cell, thus opening a possibility of trying this technology in specific applications. VortexCell2050 also highlighted several promising avenues for further improvement of the vortex cell performance. The results of VortexCell2050 ensure European Aeronautical Sector a leadership in a small but critical area, the importance of which will grow in the future with an increase in aircraft size. This summary outlines the project context, major activities, and outcomes . Partners University of Southampton, UK Politecnico di Torino, Italy Centro Italiano Ricerche Aerospaziali ScpA, Italy Piaggio Aero Industries, Italy Technical University of Munich, Germany University of Bordeaux 1, France Battery Company RIGEL, Russian Federation Glasgow University, UK Technische Universiteit Eindhoven, Netherlands Institute of Mechanics of the Moscow State University, Russian Federation Contacts Prof.
    [Show full text]
  • Los Angeles World Airports
    Los Angeles World Airports April 29, 2013 Los Angeles City Council City of Los Angeles Room 395, City Hall Los Angeles, CA 90012 LAX RE: REVIEW OF COMMENTS RECENTLY RECEIVED ON THE LAX SPECIFIC PLAN AMENDMENT STUDY (COUNCIL FILE NO. 13-0285 and COUNCIL LA/Ontario FILE NO. 13-0285-S1) Van Nuys City of Los Angeles Honorable City Council: Antonio R. Villaraigosa Mayor Over the past several months, the City of Los Angeles has received a number of letters, Board of Airport e-mails, other written materials, and oral testimony pertaining to the LAX Specific Plan Commissioners Amendment Study (SPAS). The aforementioned materials and testimony are in Michael A. Lawson addition to the written comments and public meeting testimony received during the 75- President day public review period for the SPAS Draft Environmental Impact Report (EIR), all of Valeria C. Velasco Vice President which have been addressed in the written responses to comments contained within the SPAS Final EIR that was distributed on January 25, 2013. Joseph A. Aredas Robert D. Beyer Ann M. HOllister Fernando M, rcrres-en Los Angeles World Airports (LAWA) has carefully reviewed the written materials and the oral testimony received after the close of the Draft EIR review period. These materials Gina Marie Lindsey EXecutive Director and testimony do not contain any new issues or significant new information. They primarily reiterate, either verbatim or in essence, many of the same comments received during the SPAS Draft EIR review period. Nevertheless, LAWA staff would like to clarify and amplify certain points in response to these new comments.
    [Show full text]
  • Chinese Telecom Equipment Industry a Thesis Submitted
    STATE-LED CATCH-UP: CHINESE TELECOM EQUIPMENT INDUSTRY A THESIS SUBMITTED TO THE GRADUATE SCHOOL OF SOCIAL SCIENCES OF MIDDLE EAST TECHNICAL UNIVERSITY BY A. ULAŞ EMİROĞLU IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE DEPARTMENT OF SCIENCE AND TECHNOLOGY POLICY STUDIES FEBRUARY 2014 Approval of the Graduate School of Social Sciences Prof. Dr. Meliha Altunışık Director I certify that this thesis satisfies all the requirements as a thesis for the degree of Doctor of Philosophy. Prof. Dr. Erkan Erdil Head of Department This is to certify that we have read this thesis and that in our opinion it is fully adequate, in scope and quality, as a thesis for the degree of Doctor of Philosophy. Prof. Dr. Haluk Geray Prof. Dr. Erkan Erdil Co-Supervisor Supervisor Examining Committee Members Assoc. Prof. Dr. Teoman Pamukçu (METU,STPS) Prof. Dr. Erkan Erdil (METU, STPS) Assoc. Prof. Dr. Funda Başaran Özdemir (AU, ILEF) Assist. Prof. Dr. Semih Akçomak (METU, STPS) Assist. Prof. Dr. Erdal Akdeve (YBU, IIBF) I hereby declare that all information in this document has been obtained and presented in accordance with academic rules and ethical conduct. I also declare that, as required by these rules and conduct, I have fully cited and referenced all material and results that are not original to this work. Name, Last name : A. Ulaş Emiroğlu Signature : iii ABSTRACT STATE-LED CATCH-UP: CHINESE TELECOM EQUIPMENT INDUSTRY Emiroğlu, A. Ulaş Ph.D., Department of Science and Technology Policy Studies Supervisor: Prof. Dr. Erkan Erdil Co-Supervisor: Prof. Dr.
    [Show full text]
  • Fen Bilimleri Enstitüsü
    FEN BİLİMLERİ ENSTİTÜSÜ 20.07.1982 tarihinde yürürlüğe giren Yükseköğretim Kurumları Teşkilatı hakkındaki 41 Sayılı Kanun Hükmünde Kararnameyle kurulmuş olan Anadolu Üniversitesi Fen Bilimleri Enstitüsü, 18.08.1993 tarihinde yürürlüğe giren 496 sayılı Kanun Hükmünde Kararnameyle yeni kurulan Osmangazi Üniversitesine devredilmiştir. Aynı Kanun Hükmünde Kararname ile Anadolu Üniversitesi bünyesinde Fen Bilimleri Enstitüsünün yeniden kurulması öngörülmüş ve Anadolu Üniversitesi Fen Bilimleri Enstitüsü, 1993-1994 Öğretim yılı Bahar Yarıyılında eğitim-öğretime başlamıştır. Müdür : Prof. Dr. Hasan Ferdi GERÇEL Müdür Yardımcısı : Doç. Dr. Yunus ÖZDEMİR Müdür Yardımcısı : Yard. Doç. Dr. Erhan AYAS Enstitü Sekreteri : Demet BAYRAKTAR ÖĞRETİM ELEMANLARI Araştırma Görevlileri: Fesih KESKİN, Ahmet Murat TÜRK BİLGİSAYAR MÜHENDİSLİĞİ ANABİLİM DALI Anabilim Dalı Başkanı : Doç. Dr. Hüseyin POLAT DOKTORA DERS PROGRAMI I. YARIYIL II. YARIYIL Seçmeli Dersler (4) - 30,0 Seçmeli Dersler (3) - 22,5 30,0 22,5 III. YARIYIL IV. YARIYIL BİM 890 Tez 0+1 30,0 BİM 890 Tez 0+1 30,0 30,0 30,0 SEÇMELİ DERSLER BİL 616 Örüntü Tanıma Uygulamaları 3+0 7,5 BİL 604 Bilişim Teknolojileri Yönetimi 3+0 7,5 BİL 617 Kriptoloji 3+0 7,5 BİL 605 Dağıtık Hesaplama Yöntemleri 3+0 7,5 BİL 619 İleri Ayrık Matematik 3+0 7,5 BİL 606 Doğal Dil İşleme 3+0 7,5 BİL 620 Çok Erkinli Sistemler 3+0 7,5 BİL 607 İleri Bilgi Erişim Sistemleri 3+0 7,5 BİL 621 Metin Analitiği 3+0 7,5 BİL 612 Veri ve Metin Madenciliği 3+0 7,5 UBM 901 Uzmanlık Alan Dersi 5+0 7,5 BİL 613 Makine Öğrenimi 3+0 7,5 UBM 902 Uzmanlık Alan Dersi 5+0 7,5 BİL 615 Bilişim Teknolojilerinde Özel Konular 3+0 7,5 1 TEZLİ YÜKSEK LİSANS 1999-2000 Öğretim Yılı Güz Yarıyılından itibaren Bilişim Yüksek Lisans Programında Tezli ve Tezsiz; 2000-2001 Öğretim Yılı Bahar Yarıyılından itibaren Bilgisayar Mühendisliği Anabilim Dalında Tezli Yüksek Lisans Eğitim ve Öğretimi sürdürülmektedir Bölümümüzün amacı Bilgisayar mühendisliği ve Yazılım Mühendisliği alanlarında gerekli olan nitelikli personeli ve akademik kariyer yapmayı düşünen öğrencileri yetiştirmektir.
    [Show full text]
  • Understanding the Change in Intelligence Organizations
    UNDERSTANDING THE CHANGE IN INTELLIGENCE ORGANIZATIONS: AN INSTITUTIONAL FRAMEWORK by Ahmet Ates A dissertation submitted to the Faculty of the University of Delaware in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Political Science and International Relations Summer 2020 © 2020 Ahmet Ates All Rights Reserved UNDERSTANDING THE CHANGE IN INTELLIGENCE ORGANIZATIONS: AN INSTITUTIONAL FRAMEWORK by Ahmet Ates Approved: __________________________________________________________ David Redlawsk, Ph.D. Chair of the Department of Political Science and International Relations Approved: __________________________________________________________ John A. Pelesko, Ph.D. Dean of the College of Arts and Sciences Approved: __________________________________________________________ Douglas J. Doren, Ph.D. Interim Vice Provost for Graduate and Professional Education and Dean of the Graduate College ii I certify that I have read this dissertation and that in my opinion it meets the academic and professional standard required by the University as a dissertation for the degree of Doctor of Philosophy. Signed: __________________________________________________________ M.A. Muqtedar Khan, Ph.D. Professor in charge of dissertation I certify that I have read this dissertation and that in my opinion it meets the academic and professional standard required by the University as a dissertation for the degree of Doctor of Philosophy. Signed: Daniel M. Green, Ph.D. Member of dissertation committee I certify that I have read this dissertation and that in my opinion it meets the academic and professional standard required by the University as a dissertation for the degree of Doctor of Philosophy. Signed: __________________________________________________________ Kassra A. R. Oskooii, Ph.D. Member of dissertation committee I certify that I have read this dissertation and that in my opinion it meets the academic and professional standard required by the University as a dissertation for the degree of Doctor of Philosophy.
    [Show full text]
  • Nişantaşi Üniversitesi Meslek Yüksekokulu Uçak
    NİŞANTAŞI ÜNİVERSİTESİ MESLEK YÜKSEKOKULU UÇAK TEKNOLOJİSİ PROGRAMI A.Amaçlar Teorik bilgilerin yanında uygulamaya yönelik öğretim sistemini esas alarak, Uçak Teknolojisi alanında nitelikli insan gücünü yetiştirmek ve mezunlarımızın, sektördeki ulusal ve uluslararası tüm firmalarda görev yapacak donanımda olmalarını sağlamak. Rekabetin yoğunlaştığı havacılık sektöründe çabuk karar verebilen, kavramsal düşünebilen ve aynı zamanda operasyonel düzeydeki faaliyetlere hakim, çok yönlü ara elemanların yetiştirilmesi temel amacımızı oluşturmaktadır. B.Hedefler Son teknik ve bilimsel gelişmeleri yakından takip etmesi gereken uçak teknolojisi teknikerlerini uluslararası standartlarda bilimsel veriler ışığında çalışan ve düşünen, bu alandaki nitelikli insan gücünün boşluğunun doldurulması başlıca hedefimizdir. Mezunlar havacılık sektöründe imalat yapan firmalarda veya büyük çaplı bakım onarım yapan Firmalar da teknik personel olarak çalışabilmektedirler. C. Program Öğrenme Çıktıları 1 Uçaklarda kullanılan her türlü (mekanik,elektrik,elektornik,hidrolik vb.) komponent ve sistemlerin temel çalışma prensiplerini ve fonksiyonlarına ilişkin bilgiye sahiptir. Uçaklarda kullanılan parçaların malzemelerini tanır. 2 Uçakların mekanik ve elektrik sistem /parça çalışma prensiplerini tanır. 3 Atmosfer özelliklerini ve atmosferdeki değişimin uçaklar üzerindeki etkisini bilir. Uçaklarda kaldırma kuvvetinin oluşması ve uçuş teorisini bilir. 4 Pistonlu motorlu uçaklarda bulunan pervaneler hakkında bilgi sahibi olur. 5 Uçak bakım ve onarım yönünden insan faktörlerini
    [Show full text]
  • Flows with Trapped Vortices
    For contact details see http://www3.imperial.ac.uk/people/s.chernyshenko Department of Aeronautics Area of expertise Flows with trapped vortices Wings of the modern aircraft are thin and streamlined Photo from S.Chernyshenko’s archive, the author is not known, but many thus ensuring maximum aerodynamic efficiency. From similar materials are available at http://www.ekip-aviation-concern.com structural viewpoint a thick wing would be more efficient in carrying the load. The tendency of increasing aircraft size shifts the weight of the design balance towards structural considerations. As a result, improving aerodynamics of thick wings is essential for further progress in aviation. Fig.3 In Ekip large-scale separation was prevented by trapped vortices. Ekip, built in 1980th in Russia, became known Fig.1 Fig.2 as a flying saucer in the West. How Trapping vortices is a technology for preventing vortex flying saucers could be observed before ☺ shedding and reducing drag in flows past bluff bodies. 1980th remains a mystery ☺☺. Large vortices forming in high-speed flows past bluff bodies tend to be shed downstream, with new vortices VortexCell2050 outcomes: forming in their stead (Fig. 1). This leads to an increase • A software tool for designing a flow in drag and unsteady loads on the body, and produces past a thick airfoil with a trapped vortex an unsteady wake. If the vortex is kept near the body at assuming that this flow is stable, apart Fig.4. Stabilising the trapped-vortex flow all times it is called trapped. Vortices can be trapped in from small-scale turbulence, was is a challenge.
    [Show full text]
  • REC 5 4800 FP6 Symposiumprempart.Indd
    � � � � � � � � ���������� ������������������ Aeronautics Research in the Sixth framework Programme (2003 - 2006) KI-72-05-427-EN-C This project synopsis represents Aeronautics Research projects from the Sixth European Research Framework Programme from the fi rst and second Aeronautics Research Aeronautics calls for proposals. Grouped by sector and technological areas, projects and other research Research actions are detailed according to their objectives, methodologies and results. Administrative information is also provided and a comprehensive partner index lists all project participants. 2003 - 2006 projects Research Projects from 2003 - 2006 projects Project synopses the fi rst and second calls the fi – volume 1 Project synopses – volume 1 Research Projects from ISBN 92-79-00643-6 the fi rst and second calls PROJECT SYNOPSES 9 789279 006432 Interested in European research? SALES AND SUBSCRIPTIONS RTD info is our quarterly magazine keeping you in touch with main developments (results, programmes, events, etc.). It is available in English, French and German. A free sample copy or Publications for sale produced by the Office for Official Publications of the European free subscription can be obtained from: Communities are available from our sales agents throughout the world. European Commission You can find the list of sales agents on the Publications Office website Directorate-General for Research (http://publications.eu.int) or you can apply for it by fax (352) 29 29-42758. Information and Communication Unit B-1049 Brussels Contact the sales
    [Show full text]
  • Green Freighter Green Freighter Development of an Eco-Friendly Freighter at HAW Hamburg DIPL.-ING
    panorama Green Freighter Green Freighter development of an eco-friendly freighter at HAW Hamburg DIPL.-ING. KOLJA SEECKT; PROF. DR.-ING. DIETER SCHOLZ, MSME Department of Automotive and Aeronautical Engineering, Hamburg University of Applied Sciences » ”Elegant“, ”quiet“, or ”green“ are not normally of the project is to research unconventional cargo catchwords associated with cargo aircraft. In fact, aircraft confi gurations and to compare these to discarded passenger aircraft that have been con- conventional ones. verted for a second life as a freighter are the fi rst thought to cross one‘s mind: robust workhorses, Unconventional Confi gurations: Practically often the last of their kind at European airports. all of today‘s transport aircraft have the con- But for these aircraft, the air is getting thinner. ventional confi guration, or tail-aft as it is also Prof. Dr.-Ing. Nighttime and noise restrictions, rising fuel pri- called. It is defi ned by three main features: a Dieter Scholz ces and the coming emission-related taxes are fuselage which accommodates the payload, a graduated in increasing the pressure on logistics companies to wing attached to the fuselage that produces the mechanical operate more modern aircraft. Today, brand new lift, and an empennage, also called a tailplane engineering at cargo aircraft are already available and in opera- or just a tail, at the aft end of the fuselage for Purdue Univer- sity Lafayette tion. Others, like the Boeing B747-8F or the Air- stability and control. and at Univer- bus A380-800F, are about to follow to meet the Any aircraft confi guration that differs from sity Hannover.
    [Show full text]
  • Flow Control on Wing by Means of Trapped Vortex Cell
    European Drag Reduction and Flow Control Meeting – EDRFCM 2010 September 2–4, 2010, Kyiv, Ukraine FLOW CONTROL ON WING BY MEANS OF TRAPPED VORTEX CELL D. Lasagna, G. Iuso Dipartimento di Ingegneria Aeronautica e Spaziale, Politecnico di Torino, Corso Duca degli Abruzzi, 10129 Torino, Italy [email protected] INTRODUCTION A flow control strategy which has not received a great attention is the so called ”trapped vortex cav- ity”, (TVC). The proposed technique consists in a cavity accommodated on the upper surface of the airfoil, with a shape optimized for trapping a vortex. Under appropriate conditions, a steady, large vor- tical structure forms in the cavity creating a ”moving interface”. The vortex cell causes the boundary layer flowing past it to remain more filled, moving the separation point dowstream. The goal is to in- crease the aerodynamic performances of the wing, both at low and high angles of attack. Most of the work on this subject, see [1], has been done in the framework of the VortexCell2050 project, even if pre- vious implementation of this technique are known, such as the EKIP aircraft [2] and the Kasper wing [3]. Both numerical and experimental investigations have shown that the success of this flow control technique tightly depends on the stabilization of the vortex. In fact theoretical investigations [4] have shown that a trapped vortex can have a limited stability region, i.e. it is unstable and cannot be kept trapped if some control in the cavity region is not exerted. Several authors have demonstrated experimentally [5] and numerically [6] the positive effects of suction for controlling the stability of the vortex in the cavity.
    [Show full text]