Necrotizing sialometaplasia. A disease simulating malignancy.

Here, we reviewed published aerodynamic efficiencies of gliding birds and similar sized unmanned aerial vehicles (UAVs) motivated by a fundamental question: are gliding birds more efficient than comparable UAVs? Despite a multitude of studies that have quantified the aerodynamic efficiency of gliding birds, there is no comprehensive summary of these results. This lack of consolidated information inhibits a true comparison between birds and UAVs. Such a comparison is complicated by variable uncertainty levels between the different techniques used to predict avian efficiency. To support our comparative approach, we began by surveying theoretical and experimental estimates of avian aerodynamic efficiency and investigating the uncertainty associated with each estimation method. We found that the methodology used by a study affects the estimated efficiency and can lead to incongruent conclusions on gliding bird aerodynamic efficiency. Our survey showed that studies on live birds gliding in wind tunnels provide a reliable minimum estimate of a birds' aerodynamic efficiency while simultaneously quantifying the wing configurations used in flight. Next, we surveyed the aeronautical literature to collect the published aerodynamic efficiencies of similar-sized, non-copter UAVs. The compiled information allowed a direct comparison of UAVs and gliding birds. Contrary to our expectation, we found that there is no definitive evidence that any gliding bird species is either more or less efficient than a comparable UAV. This non-result highlights a critical need for new technology and analytical advances that can reduce the uncertainty associated with estimating a gliding bird's aerodynamic efficiency. Nevertheless, our survey indicated that species flying within subcritical Reynolds number regimes may inspire UAV designs that can extend their operational range to efficiently operate in subcritical regimes. The survey results provided here point the way forward for research into avian gliding flight and enable informed UAV designs.

Aerodynamic efficiency of gliding birds vs comparable UAVs: a review

Kanat tasarimi, tum hava araclari icin oldugu gibi, planorler icin de aerodinamik performans acisindan kritik oneme sahiptir. Aerodinamik olarak verimli bir planor kanadi tasariminin en onemli asamalarindan biri de uygun kanat kesit geometrisi (kanat profili) secimidir. Bir kanat tasariminin kanat kesit geometrisi secimi, oncelikle belirlenen gerekliliklere dayanarak karsilastirmak uzere, farkli kanat kesit geometrilerinin aerodinamik performans analizlerini gerektirir. Bu calismada, dokuz farkli kanat kesit geometrisi planor aerodinamik performansi acisindan karsilastirmak uzere genel kamu lisansli XFLR5 programi kullanilarak numerik olarak incelenmistir. Oncelikle karsilastirilacak geometriler Eppler, Goettingen, NACA ve Wortmann kanat kesit geometrisi ailelerinden secilmistir. Karsilastirma icin programin deneysel verilerle iki boyutlu dogrulamasi yapilmis ve secilen kanat kesit geometrileri ayni kosullar altinda analiz edilmistir. Analizler 2x10 5 Reynolds sayisinda ve -5 ile 20 derece arasindaki hucum acilarinda gerceklestirilmistir. Analizlerden elde edilen sonuclara gore kanat kesit geometrileri belirlenen gereklilikler olan kalinlik, maksimum kaldirma katsayisi ve hucum acisi, maksimum kaldirma durumundaki suruklenme katsayisi, maksimum suzulme orani, sifir kaldirma durumundaki yunuslama momenti ve guc faktorune gore karsilastirilmistir.

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Numerical Investigation of Different Airfoils at Low Reynolds Number in terms of Aerodynamic Performance of Sailplanes by using XFLR5

Slotted aerofoils have been suggested by numerous researchers as an effective means of controlling boundary layer flow separation, and improving aerodynamic performance. Numerous slot designs have been studied at high Reynolds number, but there is scarcity of study of such slots effect on aerofoil performance in low Reynolds number scenarios. In the present work, wind tunnel and numerical investigation of the effect of a unique slot configuration and its geometric parameters on the aerodynamic performance of a NACA0018 aerofoil at low Reynolds number was executed. The aim of this work is to ascertain if the unique slot configuration on the NACA0018 can improve the aerodynamic performance compared to a plain NACA0018, and if the slotted NACA0018 could be applied as rotors on a Darrieus-style vertical axis micro wind turbine for small scale energy conversion at low wind speeds. Four aerofoils were initially fabricated for the wind tunnel tests, each conforming to the NACA0018 profile; a plain aerofoil and three other slotted aerofoils, each with a span–length slot positioned at X=15%, X=45% and X=70% from the leading edge. The, chord length (c), span, slot slope (ψ) and slot width of the slotted aerofoils were 0.25m, 0.3m, 55° and 0.02c respectively. A 2D wind tunnel set up was used in testing the four aerofoils at Reynolds numbers of 92x103 138x103, 184x103 and 230x103, within 0° to 20° range of incidence. Comparing the slotted and plain aerofoils, the aerodynamic force data shows that the presence of the slots was detrimental to aerodynamic performance especially when the slot location is closer to the leading edge. Therefore, a 2D numerical parametric study of slot width and slope was carried out using ANSYS FLUENT 16.0 with the intention of improving the lift–to–drag (L/D) ratio of the span–length slotted aerofoils. Furthermore, a final slot configuration consisting of segmented slot pattern which incorporated the results of the parametric study was fabricated and tested in a wind tunnel. The aerodynamic force analysis shows a 50% increase in L/D ratio of the slotted aerofoil with slot position at X=70%, but its aerodynamic performance was still less than the Plain NACA0018. Thus this work proves that the suggested slot layout did not improve the aerodynamic performance of the NACA0018 aerofoil and as a result, it cannot be recommended to be used as a vertical axis wind turbine rotor. Finally, in order to improve the NACA0018 aerofoil performance, it was suggested that a new slot layout with slot slope on the pressure side inclined towards the leading edge should be designed and studied.

Investigation of the performance of a slotted aerofoil at low Reynolds numbers

This paper concentrates on the design, analysis, and development of fixed-wing hand launch unmanned aerial vehicle (UAV). This flight can able to carry the payloads of 0.8. The design process involves the conceptual, preliminary, and detailed design. This paper involves the investigation of the aerodynamic characteristics over the wing to enhance the aerodynamic design of the UAV. This analysis includes estimating the best gliding ratio to increase the flight mission and attain the maximum altitude. This simulation will be performed for subsonic flow with Mach number 0.04202(14.3m/s). The manufacturing of the UAV is done using composite materials like glass fiber of both (1mm and 2 mm) thickness, carbon fiber of 2mm, and carbon rod is used for connecting the empennage to the fuselage. The detailed design has been done in CATIA V5 and the analysis of the wing has been done using XFLR, ANSYS (fluent). Keywords— Fixed-wing hand launch UAV, Design process, Aerodynamic characteristics, Gliding ratio, Manufacturing, Composite materials, Glass fiber, Carbon fiber, CATIA V5, XFLR, ANSYS (fluent).

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Design, performance analysis of wing, and manufacturing of fixed wing hand launch unmanned aerial vehicle

This paper attempts to bring out the challenges associated with the design of a high altitude mini UAV especially from the aerodynamics perspective. The mini UAV under consideration is a 2 kg class conventional, high wing and T-Tail configuration. A comparative study of various high lift airfoils has been done to illustrate that the selection of a suitable airfoil for high altitude applications is indeed an important part of the design activity and it shows that the wing loading of a UAV designed for high altitudes does not depend on the changes in air density alone. The chosen high lift low Reynolds number airfoil is found to have a minor effect on the aerodynamic parameters (Cl and Cd) with changes in Reynolds number. This paper also addresses the performance variation due to operation at off design condition such as at sea level.

https://nal-ir.nal.res.in/12109/1/cp135.pdf

Design of a High Altitude Fixed Wing Mini UAV - Aerodynamic Challenges

To provide better longitudinal stability at cruise for one of the MAV configurations developed at CSIR-NAL, a modified
version of Eppler-61 airfoil designated as SM-4308 was used. The airfoil geometry was obtained using inverse design method of
XFLR5 and aerodynamic characteristics of the modified airfoil were computed using XFLR5 at cruise Reynolds number of
160,000. To get aerodynamic characteristics at off design Reynolds number, an airfoil of chord 150mm was fabricated and tested
in a 0.55m wind tunnel in the incidence range of -4 to 15 degree at low Reynolds numbers of 46,000, 67,000, 87,000 and
120,000. Surface pressures on the airfoil and total pressures in the wake were measured. From these, the aerodynamic
characteristics in terms of lift, drag and pitching moment coefficients were computed and compared with those obtained on
Eppler-61 airfoil earlier. Comparison shows lower pitching moment with the newer airfoil, associated with lower lift and drag
coefficient. Variation of lift coefficient with incidence was observed to have lower lift curve slope with the stall occurring at
lower angle. Also during positive angle of incidence no sudden change in lift was seen at lower Reynolds number of 47,000 and
67000 as observed on Eppler-61 airfoil. Flow on the airfoil was investigated in a 0.2m tunnel using smoke flow technique at
lower Reynolds number of 67,000 and 87,000. Analysis of these photographs together with surface pressure variation on the
upper surface shows the presence of bubble like structure on the SM-4308 compared to flow separation on Eppler airfoil. The
early stall seen with SM-4308 airfoil was observed to be due to the bursting of bubble. Comparison of surface pressures
computed using XFLR5 with free transition mode on SM-4308 airfoil showed nearly good agreement with experimental data.

Experimental Studies on SM4308 Airfoil at Low Reynolds Numbers

Necrotizing sialometaplasia is an uncommon benign, self limiting, inflammatory lesion of salivary gland which can be both clinically and histologically mistaken for mucoepidermoid carcinoma or squamous cell carcinoma. Here we report the three cases of Necrotizing Sialometaplasia which represented with different symptoms and locations. The purpose of this paper is to report three cases of necrotizing sialometaplasia to highlight the potential diagnostic pitfall.

Histopathology and Its Role in Diagnosing Necrotizing Sialometaplasia: A Report of Three Cases

A Comparative Study of Functional Outcome of Clavicular Fractures Treated By Operative and Non Operative MethodsA Comparative Study of Functional Outcome of Clavicular Fractures Treated By Operative and Non Operative Methods

G. Ramesh

Papers

Design of a High Altitude Fixed Wing Mini UAV - Aerodynamic Challenges

Experimental Studies on SM4308 Airfoil at Low Reynolds Numbers

Histopathology and Its Role in Diagnosing Necrotizing Sialometaplasia: A Report of Three Cases

A Comparative Study of Functional Outcome of Clavicular Fractures Treated By Operative and Non Operative MethodsA Comparative Study of Functional Outcome of Clavicular Fractures Treated By Operative and Non Operative Methods