İki elemanlı bir profil sisteminde yüksek basınç gradyantlı flap üstü akım alanının incelenmesi

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1996Thesis (Ph.D.) -- İstanbul Technical University, Institute of Science and Technology, 1996Sınırlı pist uzunlukları nedeniyle kalkış ve iniş hızlarının küçük olması ve buna bağlı olarak da tutunma kaybı sınırı yakınlarında uçulması zorunluluğu, uçaklar için bu uçuş rejimlerini kritik hale sokmaktadır. Bu hallerde kanatların performanslarını, slat ve flap adı verilen aşın-taşıma düzeneklerini açarak iyileştirmek mümkündür. Ancak aşın taşıma şartlarında kanat etrafındaki akım alam hayli karmaşıktır ve bu konuya yönelik çalışmalar teorik ve deneysel olarak devam ettirilmektedir. Bu tez çalışmasında flaplı bir NLR 7301 profili etrafındaki akım alam teorik ve deneysel olarak incelenmiştir. Teorik incelemelerde profil etrafmdaki gerçek viskoz akımın bir sürtünmesiz akım/viskoz akım birleştirme yöntemiyle hesaplanması amaçlanmıştır. Bu amaçla, tek elemanlı profiller için geliştirilmiş olan bir yöntem bu çalışma kapsamında çok elemanlı profiller için uyarlanmış, ayrıca yöntemin sürtünmesiz akım hesaplamalarıyla ilgili kısmım oluşturan panel yöntem de yine bu çalışma kapsamında kompleks düzlem kullanılarak çok elemanlı profiller için geliştirilmiştir. Genelleştirilen bilgisayar kodu analitik kökenli tek ve çok elemanlı kanat profilleri üzerinde geniş bir şekilde test edilerek başarısı kanıtlanmıştır. Deneysel çalışmalar kapsamında NLR flaplı profilinin modern malzeme ve tekniklerle üretilen bir modeli üzerinde elektronik çoklu-basmç-ölçer kullanılarak basınç ölçmeleri ve sıcak-tel anemometresi kullanılarak hız ölçmeleri gerçekleştirilmiştir. Ayrıca bu çalışmalarda kullanılmak üzere bir çok bilgisayar programı ve donanım geliştirilmiştir. İlk safhada, yüzey basınç dağılımım belirlemek üzere flap açısının 20° değerinde ve değişik hücum açılarında (0°-14°), 726.000 Reynolds sayısmda yapılan deneylerde, küçük hücum açılarında gerek potansiyel akım ve gerekse gerçek akım hesaplamalarının sonuçlarının deneysel sonuçlara hayli yakın olduğu, ancak gerçek akım sonuçlarının viskoz etkilerin de hesaba katılması nedeniyle deneysel sonuçlara daha yakın olduğu tespit edilmiştir. Bu deneyler potansiyel akım çerçevesinde desteklenerek sonuçlar üzerindeki rüzgar tüneli duvar etkileri incelenmiş ve düzeltilmiştir. İkinci grup deneyler olarak model sisteminin flapüstü bölgesinde sıcak- tel anemometresiyle değişik istasyonlarda hız ve türbülans ölçmeleri gerçekleştirilmiştir. Elde edilen sonuçlardan, ana kanat izinin flap üzerindeki gelişimini görmek mümkün olmaktadır. Özellikle türbülans profilleri, ana kanat iziyle flap üzerindeki sınır tabakanın kuvvetli bir karışım göstermediğini ortaya koymaktadır. Flap firar kenarı bölgesine yaklaştıkça karışımın bir miktar arttığı dikkati çekmektedir. Sonuçlar, incelenen akım alam için anlamlı hız ve türbülans haritalarının ortaya konulabileceğini gösterir niteliktedir. One of the most critical maneouvers of an aircraft is always the take off or the landing. Because of the insufficient speed to create the necessary lift of aircraft results in high angles of attack near the stalling conditions. For military aircaft, the requirement to operate from shortened runways, places a greater emphasis on the performance at take-off and landing. For civil aircraft, improving the airfield performance has always been recognized as an important ingradient in achieving the best overall performance. The lifting capability of a wing is impoved by deploying devices such as slats and flaps which increase the camber and chord of the aerofoil. These devices distributes the large pressure rise over the upper surface of the aerofoil associated with the high lift coefficients into several parts, thus a fresh boundary layer is generated to compensate for the pressure gradiant and separation is less likely to occur than for the corresponding pressure drop on a single aerofoil. However the flow about a two- dimensonal high-lift aerofoil contains several complicating features in comparison with a single aerofoil. These include: a) the region of flow is multiply connected, which makes even the calculation of the inviscid flow difficult. b) the wakes from upstream elements interact with the boundary layers on downstream elements. c) initially the wake from upstream elements develop in the strong pressure gradients induced by the downstream elements. d) the viscous flow region over the flap is very thick with the curvature of the flow producing significant pressure gradients across the region. e) the flow curvature has a marked effect upon the development of the turbulent viscous layers. f) the slat and flaps must fit snugly back to form the cruise aerofoil with the result that when the devices are deployed there are coves on the lower surfaces of the slat and the wing and the flow in these regions is separated. Xll g) for a multi-element airfoil, there is a small region of supersonic flow on the upper surface of the slat even at low freestream Mach numbers (say 0.2). h) for large deflections of the flap the flow on the upper surface of the flap is usually separated throughout the incidence range. All the features of this flow may be captured by a solution of the 'Reynolds-averaged' Navier-Stokes equations with a suitable turbulence model. Although solutions of the Navier-Stokes equations can now be produced on supercomputers in under one hour for a wing, the turbulence models are not sufficient to represent all the features of the flow for a high-lift aerofoil such as the changes in the turbulence structure induced by the flow curvature. For the aircraft designer the adoption of a Navier-Stokes solution would require access to a supercomputer; the development of a suitable turbulence model; an algorithm for which the numerical method does not introduce a high level of artificial diffusion and a fast algorithm to meet the tight schedules of aircraft design. With these problems in mind, the computation of the flow about high-lift aerofoils has relied upon viscous-inviscid interaction methods. Improved schemes describe accurately more of the features of the flow. While notable progress is being made in the development of methods of computing flows around single airfoils, including flow separations at subcritical speeds, methods that compute the flow around high-lift systems of multi-element airfoils, including realistic representations of complex shear flows, do not widely exist, and development efforts are currently being made. The complex geometric configurations and the resulting complexity of the physics of the flow mechanisms of such systems make the task very difficult if details of the shear flows are to be modeled. At present, due to the scarcity of experimental data that contain sufficient details of the flowfield, it is not even clear what features need to be modeled and to what level of sophistication. Among the published data on multielement airfoil flows, few of them appears to be extensive and detailed, revealing a number of features that draw the attention of computational modelers. They give limited information about small- and large-scale separations, complex interacting shear layers, highly curved boundary layers, and near wakes, although in most high-lift cases, the viscous-inviscid interaction appears to be strong. It is clear that experimental data are needed that contain the detailed information including turbulence characteristics of shear flows about realistic multielement airfoils under realistic flight conditions. The theoretical and experimental works in this thesis summarized below contain primarily: - a viscous / inviscid coupling method to calculate the real flow around multi-element airfoils, xm - detailed investigations of the flowfield around a flapped NLR 7301 airfoil model at low Reynolds number. Theoretical methods The theoretical work has been focused mainly on the calculation of the real flow around multi-element airfoils by a viscous / inviscid coupling technique. However, a two-dimensional panel method developed in complex plane was used to support the experimental works, particularly in order to investigate the wind tunnel wall effects and to correct them. The coupling method originally developed for single element airfoils by B.R. Williams has been adopted for multi-element airfoils in the frame work of this thesis. The potential flow part of the method also reconsidered in the complex plane to obtain a formulation for multi-element airfoils. Experimental Arrangement Wind Tunnel In this thesis, the experiments have been realized in the low speed closed circuit wind tunnel of ITU Aeronautical and Astronautical Faculty (Gümüşsüyü), having a test section of 80x1 10x160 cm. The flow quality in the test section was improved before the experimental works, by introducing some vortex producing devices on the walls at the entreance of the diffuser to remove the flow separations on its side walls. The vortex generators diminish the flow Auctions in the test section from 4% to 1.5%. The turbulence level in the test section is about % 0.6. Multielement Airfoil Model The two-element airfoil used in the experiments is an NLR 7301 flapped airfoil originally developed in NLR. The coordinates of main element of this flapped airfoil is the same of the original NLR 7301 airfoil up to 94,36% on the upper surface and up to 60% on the lower surface. The rest of the main element is modified to obtain a good flow characteristics with no separation under the effect of the flap. Aerodynamic characteristics of the flapped airfoil have been invested in various researches. The results of these investigations indicate how carefully the airfoil coordinates have been selected, giving a very big advantage for experimental investigations on complicated problems. Models have been produced in slices by a kind of hard plastic material KESTAMID used videly in the industry to produce some machine parts. The slices have been manufactured in a CNC machine. Slices have than been connected with centralized pins and long bolts. There are fifty pressure holes on the middle slices of the models (34 on the main element and 14 on the flap). It has been a great advantage of using a plastic material in order to dril holes for pressure ports and to connect these ports to the manometer situated and out of the wind tunnel. XIV Circular lids of runnel test section are used in model mounting. Models have been fitted to these lids and angle of attack of the models could be changed under control by turning the lids. Measurement Systems The measuring devices used in the experiments are an electronic pressure scanning system of S CANI VALVE, a constant temperature hot-wire anemometer of DISA, an electronic micromanometer of FURNESS CONTROL, a three dimensional traversing mechanism and a data acquisition system of PCL 818 connected to a PC 386. Electronic pressure scanning system has 32 pressure sensors, with a 2x32 channels capability and a high sampling rate. For the efficient use of the system; a data acquisition system having digital output functions and some pneumatic flow control elements with high pressure air supply is needed to select operational modes. For the boundary layer measurements a DISA 55M CTA hot-wire anemometer system have been used. During this investigation the possibility of producing an anemometer by the researcher himself also was searched, a pilot work was started and a prototype was produced. Unfortunately, there was no time during the thesis to test this anemometer. The data acquisition methods has been effectively used in the hot-wire anemometry. The traversing mechanism was produced locally within the frame work of this thesis, by the support of NATO/ AG ARD Fluid Dynamics Panel through the Support Project T-76. The mechanism have three axis, one of them controlled by a step motor while two other are controlled manually. The necessary software to control the traversing mechanism also have been developed locally during this thesis. A FURNESS CONTROL 's electronic micromanometer was used to measure the free stream dynamic pressure in the test section. Thus the little effect on the measurements of the flow fluctuations in the test section also removed by non- dimensionalizing all the measured data with this real time measured dynamic pressure. A PC-Lab 's PCL-818 interface board having a 12 bit resolution on 16 channel with analog/digital and digital/analog conversion capability, digital input/output and counter/timer functions was used for all data acquisition requirements during the experiments. The necessary software have been developed locally in the frame of this thesis in QBASIC 4.0 language. The programs allow the users to see the results of measurements with the graphics plotted on the computer screen during the experiments. Thus all the evaluations during the experiments can be judged. Measurements Although around the main aim of the experimental work in this thesis is to analyse the flow field the NLR 7301 airfoil 's flap under large pressure gradient, pressure measurements on the airfoil surface are also realized to understand the overall XV characteristics of the airfoil system. Before the experiments in flapped case some initial measurements are made on the main element to test the model, measurement system, softwares etc. and to compare the results with potential flow calculations and real flow calculations. The wind tunnel wall effects was investigated before producing the models as to decide on the chord length and a length of 400 mm was found convenient. However some corrections are needed on the experimental results. The flow around the flapped airfoil was visualized by tufts to check the effects of test section side walls on the two dimensionality of the flow. A system to suck the boundary layer around the model side wall connection regions is developed. However there was no need generally to use this system, since the experiments were not covering the separated flow cases. The free stream velocity was about 26-29 m/s and the based on the chord length Reynolds number was about 0.7-0.75 million during the pressure and hot-wire measurements. The flap angle was choosen as 20° to give high pressure gradient on the flap with no separation. Angle of attack was changed between 0° to 14° by 2° of steps for single element case. 14° angle of attack excluded for flapped case, since the airfoil was stalled. Results The experimental results both for isolated and for flapped cases deviate from the potential flow calculations and indicate the importance of viscous effects at the current Reynolds number. The real flow calculations in isolated case coincide well with the experimental results indicating the success of the theoretical approach. The mean velocity and the turbulence profiles obtained from the hot-wire measurements in the wake of the main element on the upper surface of the flap are given on graphs to ve an insight about the flow field. The development of the wake of the main element on the upper surface of the flap can easily be seen from the results obtained. Especially the turbulence profiles show that the wake of the main element and the boundary layer on the upper surface of the flap do not mix considerably. Results can be used to obtain the maps of meaningful velocity and turbulence in the flowfield examined.DoktoraPh.D

Havayolu Sektörüne Yönelik “EASA” Düzenlemelerine Genel Bakış

Türkiye'de sivil havacılık faaliyetleri ve havacılık eğitimlerinde son dönemde önemli gelişmeler görülmesine rağmen sivil havacılığa yönelik yayınların bu hıza erişememesi nedeniyle yeni kaynaklara ihtiyaç bulunmaktadır. Şüphesiz bu alanda Sivil Havacılık Genel Müdürlüğünün mevzuat kaynakları tüm sivil havacılık düzenlemelerini barındırmaktadır. Ancak bu dokümanlardaki formal yapı ve anlatım, herhangi bir sivil havacılık düzenlemesine ilk kez hâkim olmaya çalışan havayolu personeline veya havacılık eğitimleri alan adaylara başlangıçta zorlayıcı gelebilmektedir. Kolaylaştırıcı kaynak niteliği amacıyla hazırlanan bu kitapta, sivil havacılığın en önemli ayağı olan "sivil havacılık düzenlemeleri” Avrupa Birliği Havacılık Emniyeti Ajansı (EASA) perspektifinde ele alınmış, özellikle havayolu sektörüne yönelik "EASA" düzenlemeleri topluca ve kolay anlaşılabilir şekilde tanıtılmıştır. Geçmiş süreçlerden bahisler, resimler, semboller ve alt açıklamalar kullanılarak sivil havacılık mevzuatının kolay anlaşılabilmesi için farklı bir yöntem denenmiştir.Tüm havayolu sektörü personeline ve eğitim sürecinde olan adaylara faydalı olması temennisiyle Havacılık Serisi dâhilinde yayımladığımız bu kitabın geliştirdiği yaklaşımın olumlu/olumsuz geri beslemelerinin değerlendirilmesi ve sivil havacılık mevzuatındaki revizyonlarla bu kitabın yeni baskılarının ve benzer başka kitapların çıkmasına vesile olmasını umarız

Effectiveness of Preemptive Analgesia Using a Frequency Rhythmic Electrical Modulation System in Patients Having Instrumented Fusion for Lumbar Stenosis

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial Licens

The value of echocardiography versus cardiac troponin i levels in the early detection of anthracycline cardiotoxicity in childhood acute leukemia: Prospective evaluation of a 7-year-long clinical follow-up

The present study was designed to evaluate the significance of echocardiography versus cardiac troponin I levels in early detection of anthracycline dependent cardiotoxicity in acute lymphoblastic leukemia (ALL) patients. A total of 276 pediatric ALL patients were included in the study prospectively along 3 phases of data collection lasted from 2002 to 2009; including phase I (March 2002 to February 2003; n = 25; 53.3% females), phase II (September 2003 to April 2004; n = 35; 57.1% females), and phase III (January 2005 to June 2009; n = 216; 52.7% females) with respect to cumulative anthracycline doses applied. Anthracyclinewas administered in accordance with berlin-Franfurt-Munich (BFM)-2000 protocol in doses of 30 to 350 mg/m(2) (in the first phase) and 30 to 240 mg/m(2) (in the following phases). Evaluation of cardiotoxicity was performed via echocardiography and measurement of cardiac troponin I levels. Patients in each phase were homogenous in terms of gender and age. Diastolic dysfunction determined via reduction E/A ratio below the cutoff value was demonstrated to deteriorate earlier than systolic functions and alteration in cardiac enzymes. Being similar between dose groups, cTnI levels were shown to rise in the presence of congestive heart failure. In conclusion, anthracycline cardiotoxicity appears to be detected in an earlier stage by using diastolic parameters compared to systolic parameters and cardiac enzymes

Glycopeptide Resistant Enterococcus faecium Isolated from Blood Culture

Glycopeptide resistant Enterococcus faecium strain was isolated from the blood cultures of a patient of the Haemotology Department of Gülhane Military Medical Academy, who was diagnosed acute myelocytic leukaemia. The strain was identified by the conventional and commercial automatic systems as E. faecium. Susceptibility pattern showed multiply resistance to all antibiotics except ciprofloxacin and levofloxacin. Using the E-test method, the MIC levels for vancomycin, teicoplanin, ciprofloxacin and levofloxacin were determined as 256 µg/mL, 64 µg/mL, 0.75 µg/mL and 1.5 µg/mL, respectively. VanA-1 and VanA-2 type resistance genes were detected by PCR. This strain is the first glycopeptide resistant E. faecium isolated from our hospital and Ankara and the second from Turkey. In the epidemiologic point of view, taking preventive measures against the wide spread of this dangereous bacteria is crucial

Retrospective analysis of demographic and clinical data in SARS-CoV-2 IgG reactive individuals applied to Cerrahpasa Medical Faculty Hospital: 1 year evaluation

Giriş: SARS-CoV-2 IgG testleri bireyin önceden COVID-19 hastalığını geçirip geçirmediğini, aşı uygulaması sonucu oluşan antikor düzeyini ve toplumdaki COVID-19 seroprevalansını saptamak amacıyla kullanılmaktadır. Çalışmamızda Seroloji/ELISA laboratuvarına infeksiyon şüphesi, infeksiyon geçmişi veya aşı sonrası SARS-CoV-2 IgG düzeyinin saptanması amacıyla başvuran olguların, SARS-CoV-2 IgG düzeylerinin, demografik ve klinik verilerle birlikte retrospektif olarak değerlendirilmesi amaçlanmıştır. Materyal ve Metod: Çalışmaya 4 Ocak 2021-31 Aralık 2021 tarihleri arasında birimimize SARS-CoV-2 IgG test istemiyle başvuran ve antikor testi reaktif saptanan olgular alınmıştır. Olguların demografik ve klinik verileri, geriye dönük sorgulanarak elde edilmiştir. Antikor tespiti için ELISA ve CMIA prensipli test kitleri kullanılmıştır. Bulgular: Çalışmaya SARS-CoV-2 IgG testi reaktif saptanan 549 kişi alınmıştır. Bunların 308’i (%56.10) kadın, 241’i (%43.90) erkek olup yaş ortalamaları 42.31 olarak saptanmıştır. 549 olgunun 159’u (%28.96) ELISA, 390’ı (%71.04) ise CMIA test kitiyle analiz edil- miştir. ELISA yöntemi ile antikor düzeyi belirlenen dönemde infeksiyonu geçiren kişilerde antikor değerleri, aşı sonrası belirlenen antikor değerlerine göre yüksek saptanırken (p 0.05). Sonuç: COVID-19 infeksiyon sonrasında hem humoral hem hücresel immün yanıt geliştiğinden ötürü çalışmamızda ELISA yöntemiy- le çalışılan dönemde infeksiyonu geçiren kişilerin antikor titreleri aşı sonrasına göre yüksek saptanmıştır. Bu sonucun bu dönemde CoronaVac inaktif aşısının uygulanması ve bu aşının daha fazla humoral immün yanıt oluşumuna neden olmasıyla ilişkili olabileceği, ayrıca 61 yaş ve üstü bireylerin antikor düzeylerinin diğer yaş gruplarına göre yüksek saptanmasının aşılanma sürecinde bu yaş aralığı- nın öncelikli olmasından kaynaklandığını düşünmekteyiz. Farklı dönemlerde uygulanan aşı türlerine karşı oluşan antikor titreleri arasında anlamlı farklılık saptanmasa da hatırlatma doz uygulaması sonrasında antikor titrelerinin daha yüksek olduğu belirlenmiştir. Genel popülasyonun hem seroprevalans hem de bağışık yanıtının belirlenmesi için standardizasyona uygun, kantitatif sonuç veren kitlerle geniş ölçekli çalışmaların yapılması gerektiği kanaatindeyiz.Introduction: SARS-CoV-2 IgG tests are used to determine whether an individual has had COVID-19 disease before, the antibody level resulting from vaccination, and the seroprevalence of COVID-19 in the community. Aim of this study was to evaluate the SARS-CoV-2 IgG levels, together with demographic and clinical data retrospectively from the cases who applied to the Serology/ELISA laboratory for suspected infection, history of the disease, or after vaccination. Materials and Methods: Cases that applied to our unit with a SARS-CoV-2 IgG test request between January 4, 2021 and December 31, 2021 and whose antibody test was found to be reactive were included in the study. Demographic and clinical data of the cases were obtained by retrospective examination. ELISA and CMIA based test kits were used for antibody detection. Results: The test was included 549 subjects with reactive SARS-CoV-2 IgG in the study. 308 (56.10%) were female, and 241 (43.90%) were male, with a mean age of 42.31 years. 159 (28.96%) of 549 cases were analyzed with ELISA and 390 (71.04%) with CMIA based test kit. In the period determined by the ELISA method, the antibody titer of the people who had the infection were higher than the antibody titer determined after the vaccination (p 0.05). Conclusion: With the development of humoral and cellular immune response after COVID-19 infection, the antibody titers of people who had the infection during the study period with the ELISA method were found to be higher than after vaccination. Although there was no significant difference between the antibody titers against the vaccine types administered in different periods, it was determined that the antibody titers were higher after the reminder dose administration. We think that the application of the CoronaVac inactivated vaccine in this period and the vaccine causing a more humoral immune response may be related to the fact that the antibody levels of individuals aged 61 and over are higher than other age groups due to the priority of this age range in the vaccination process. We believe that large-scale studies should be conducted with kits suitable for standardization and give quantitative results to determine both seroprevalence and the immune response of the general population

Investigation of obesity-related HAdV-36 in NAFLD patients: A case-control study

Background: HAdV-36 leads to adipocyte proliferation of adipose tissue through E4orf1 gene, leading to the development of obesity and related diseases. We aimed to investigate the presence and any association of HAdV-36 in non-alcoholic fatty liver disease (NAFLD) patients Methods: The patient group was composed of 116 patients; 30 obese patients with NAFLD (BMI > 30 kg/m2), 30 patients with Diabetes Mellitus (DM)+NAFLD (BMI > 30 kg/m2), 16 patients with NAFLD (BMI 30 kg/m2). The control group comprised 81 non-obese healthy adults. Liver adipose tissue samples were obtained in 30 operated NAFLD patients. HAdV-36-DNA, HAdV-36 neutralizing antibodies, serum lipid, and adipokine levels were analyzed. Results: HAdV-36 neutralizing antibodies (HAdV-36 Ab-positive) were detected in 10/116 and 2/81 participants in the study and control groups, respectively; the difference was statistically significant (p < 0.005). LDL, total cholesterol but not adipokine levels were found to be significantly higher in HadV-36 Ab-positive patients (p < 0.05). While HAdV-36 was identified as a risk factor with OR = 4.11 in univariate analyses, there was no significant difference in binary logistic regression analysis. HAdV-36-DNA was detected in the adipose tissue samples of two patients. Conclusions: We suggest that the presence of HAdV-36 may lead to the development of obesity with the increase in adipose tissue, and diseases such as hyperlipidemia, NAFLD, DM, and metabolic syndrome may develop on the basis of chronic inflammation caused by obesity. Thus, HAdV-36 may be a plausible risk factor for the development of NAFLD.Istanbul University-Cerrahpaşa Scientific Research Projects Uni