Dilek Funda Kurtulus

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• Prof. Dr.; LL.M; Executive MBA
• Professor (Full) at Middle East Technical University

Even for the stationary airfoils, due to the boundary and shear layer interactions of upper and lower surface of the airfoils, alternating vortex patterns form and the flow becomes time dependent. In the current study, the unsteady behavior of the flow around a symmetric airfoil is considered as incidence angle increases. The flow patterns are pres...

In the current study, numerical simulations are performed in order to investigate effects of incidence angle and airfoil thickness on alternating vortex pattern of symmetric airfoils at Re = 1000. This alternating vortex pattern is found to be significantly varying in shape as the incidence angle increases. The results are obtained with 1° incremen...

The present paper aims to investigate numerically small amplitude oscillation of NACA 0012 airfoil at Re = 1000. The airfoil is sinusoidally pitching around the quarter chord point with 1° pitch amplitude about a mean angle of attack. The computations are performed for mean angles of attack ranging from 0° to 60° and for pitching frequencies of 1 H...

The low Reynolds number aerodynamics is important to investigate for micro air vehicle applications. The current paper covers numerical simulations to present the downstream development of the wake patterns and detailed analysis of the vortices generated at the downstream of NACA 0012 airfoil around the critical angle of attack where the instantane...

In the domain of unmanned aerial vehicles (UAVs), evaluating electric propulsion systems is pivotal for enhancing performance and efficiency. This study employs a scaled conjugate gradient (SCG) algorithm to train an artificial neural network (ANN) for the propulsion system evaluation, offering a cutting-edge alternative to traditional experimental...

A parametric CFD investigation into SuperElliptical Wing Planforms is presented. By defining a wing planform using a superellipse with exponent slightly greater than two, it was speculated that a more-elliptical lift distribution may be obtained that from an actual elliptical wing, resulting in a reduction in induced drag. CFD analysis by three org...

In this study, parametric optimization is employed to identify optimal output parameters for physical components of HOMER nozzle type fluidic thrust vectoring (FTV) system. Optimization study is conducted on seven output parameters: moment around upper Coanda surface, M A ; performance parameter, PP; thrust vectoring angle, θ T ; total thrust, T; t...

The current study analyzed the piezoelectrically driven mechanism responsible for generating force in both rectangular and hummingbird wings, which mimicked the flapping motion of the micro air vehicles, utilizing a combination of numerical simulation and experimental approaches. Digital image correlation technology was employed within the experime...

This paper aims to explore the feasibility of providing boundary layer propulsion and flow control by means of embedded aerofoils that are oscillating in the pure plunge mode. To this end, Navier-Stokes calculations of the low-speed flow over a flat plate with an oscillating small foil in close vicinity to the plate were performed to determine the...

Fluid dynamics, a foundational area of fluid mechanics, is a vital field with applications across numerous industries. Its principles are utilized in the design and structural integrity of aerodynamic vehicles and in the prediction of natural phenomena such as airflow patterns. An understanding of fluid behavior under varying conditions is essentia...

This paper unveils a numerical simulation of the aerodynamic characteristics of crescent wings across a range of high Reynolds numbers varying from 2×10^7 to 4×10^7. The study also explores the influence of the crescent wing's zero-sweep line on its aerodynamic performance. The wing sections of all models are NACA64A-010 airfoils. The turbulent flo...

In the present study, numerical simulation for a two-dimensional NACA0005 is performed for angles of attack α = 0 • − 15 •. The Reynolds numbers 1000, 2000 and 5000 are considered. Simulations show that the flow fields can be classified due to characteristics of vortex shedding based on Reynolds number and angle of attack. Furthermore, this study r...

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This paper investigates the formation control of multiple heterogeneous quadrotor unmanned aerial vehicles (UAVs). The research focuses on developing a distributed robust formation control strategy to effectively manage the translational and attitude motions of the UAVs utilizing an active virtual leader. The communication of each agent in a connec...

A nonlinear wing model based on a quasi-steady approach and the blade element theory is used to calculate the instantaneous aerodynamic forces for Flapping flight control simulations. Due to its robustness against external disturbances and nonlinear uncertainties, an Active Disturbance Rejection Controller (ADRC) with an Extended State Observer is...

Obtaining pressure force for freely swimming microorganisms is a challenging yet important problem. Here, we report the swimming kinematics and dynamics of the zooplankton Acartia tonsa nauplius investigated using Micro Particle Image Velocimetry (μPIV). Using rigid object tracking, we obtain sub-pixel accurate localization of freely swimming A. to...

In this paper, a brief review is given of the physics of oscillating foil propulsion. It is then shown that the jet flow generated by an oscillating foil can be used as a flow control device. Experimental and computational fluid dynamic investigations are presented that show that the separated flow downstream of a rounded foil trailing edge can be...

We address the lack of research regarding aerodynamic events behind respiratory distress at COVID-19. The use of chest CT enables quantification of pneumonia extent; however, there is a paucity of data regarding the impact of airflow changes. We reviewed 31 COVID-19 patients who were admitted in March 2020 with varying severity of pulmonary disease...

The current paper aims to analyze the design and the efficiency of a small scale solar powered UAV. The selection of solar cells is performed in view of the current solar cell technologies. The aerodynamic analysis and the initial design of a small scaled UAV wing that uses flexible solar cells are performed. Solar-array area on the upper surface o...

A nonlinear wing model based on a quasi-steady approach and the blade element theory is used to calculate the instantaneous aerodynamic forces for flapping flight control simulations. Due to its robustness against external disturbances and non-linear uncertainties, an Active Disturbance Rejection Controller (ADRC) with an Extended State Observer is...

The impact of taper ratio, dihedral angle and wing tip shape on the aerodynamics of a Very Light Aircraft's wing has been investigated by performing URANS simulations at Reynolds number of 5×10 6 for pre-and post-stall conditions. SD 7062 airfoil is selected for the cross-section of the wing geometries investigated. The mean aerodynamic coefficient...

This study aims to create an interdisciplinary, multi-level design approach for fixed wing aircrafts. A case study is performed using Cessna 172N aircraft characteristics that is based on a mathematical model having six degrees of freedom (DOF). A Model Based Aircraft Design Software (MAD) is developed using a mathematical dynamic model in Python e...

Reynolds number (Re) has a dominant effect on the aerodynamic characteristics of airfoils specifically at low Reynolds numbers. In particular, low Reynolds number flows (Re<100000) where viscous forces are dominant compared to the inertial forces, results in a laminar boundary layer that is more prone to separation and transition to turbulence. To...

A NACA0012 airfoil undergoing sinusoidally plunging motion at Re=1000 is simulated by both analysing as laminar and also using the transitional shear-stress transport (SST) γ-Re_θ turbulence model. Depending on the key parameters of reduced frequency, plunge amplitude, plunge frequency and non-dimensional plunge velocity, complex flow fields might...

The current study aims to examine the flow field around a Monarch butterfly wing at different angles of attack. A fully opened forewing configuration for the Monarch butterfly wing has been selected for analysis at a maximum chord length. To mimic the membrane of the real Monarch butterfly wing, the thickness of the wings has been taken as 0.15 mm....

The two-dimensional numerical simulations using unsteady Reynolds-averaged Navier-Stokes are performed to investigate the aerodynamic performance of SD7062 airfoil with a 0.30 single-slotted flap at cruise, takeoff, and landing conditions for various angles of attack corresponding to pre-and post-stall regimes. The time-averaged aerodynamic charact...

In the realm of aviation, jet propulsion systems serve to provide enhanced maneuverability and to make sure that the aircraft thrust is accurately and precisely regulated during takeoff and landing operations. The movement of aerodynamic control surfaces (flaps, slats, elevators, ailerons, spoilers, wing attachments) determines the mobility of prac...

A reinforcement learning (RL) vibration control comparative study is carried out for a mass-spring-damper system. A comparative study on the implementation of two RL algorithms, proximal policy optimization (PPO) and deep-Q network (DQN) for the vibration control of the system with a discrete action space is first carried out. Thereafter, an invest...

The discrete control problem of vertical take-off and landing unmanned aerial vehicle (VTOL UAV) in the presence of time-varying uncertain disturbances is developed in this paper. The complexity of control problem is managed by dividing the dynamical model into two subsystems i.e. translational dynamics and rotational dynamics, where each subsystem...

This study aims to create an interdisciplinary, multi-level design approach that is based on six degrees of freedom mathematical model. The model provides all disciplines to communicate with each other simultaneously, thanks to an automated process chain system. The main advantage of automatization of analyses for the design process is observing in...

The rise in the average global surface temperature has caused wildfire seasons to expand leading to more incidents with severe intensities causing a significant increase in suppression expenditures, losses, and casualties. In addition, the larger number of wildfire incidents gives rise to higher carbon release that stays in the atmosphere, therefor...

Electric and hybrid-electric propulsion systems are key technologies for sustainable aviation. Electric propulsion systems introduce many design possibilities, which must be considered in the conceptual design stage to take full advantage of electrification. This makes for a challenging conceptual design problem. Architecture optimization can be ap...

The unsteady vortex evolution of NACA 0012 airfoil is numerically investigated at low angles of attack ranging from 0deg to 10deg where the separation is performed from the trailing edge. The Reynolds number ranges between 1000 and 4000. The laminar separation bubble at the trailing edge is observed and the main flow features are presented. It is f...

The aerodynamic design and analysis of an Unmanned Air Vehicle, capable of vertical takeoff and landing by employing fixed four rotors on the tilt-wing and two rotors on the tilt-tail, will be presented in this study. Both main wing and the horizontal tail can be tilted 90°. During VTOL, transition and forward flight, aerodynamic and thrust forces...

Numerical simulations of cambered airfoils (NACA 1412, NACA 2412, NACA 3412) at Re = 1000 are investigated in the current study to understand the camber effect on unsteady aerodynamic behavior at low Reynolds number. The numerical simulations are performed at angles of attack ranging from 0° to 10°. The aerodynamic coefficients and flow fields are...

In order to design a fixed wing aircraft, certain phases are needed to perform. From these phases, trim analysis and simulation are very crucial for design process. Trim and simulation analysis enable to calculate performance and stability characteristics of the aircraft. After aerodynamic, weight and engine database creation, the next step is trim...

Main aim of this study is to accurately model the wing of a hawkmoth (Manduca sexta) in order to implement it in a flapping wing mechanism for a micro aerial vehicle (MAV). The wing is first modeled in ANSYS/SpaceClaim then the model is verified by performing modal analysis on the finite element model (FEM) of the wing in ANSYS/Mechanical. Grid ref...

An aerodynamic model in order to simulate and control the flapping-wing micro air vehicle based on the quasi-steady approach and blade element theory is developed to calculate the instantaneous aerodynamic forces and moments. The system dynamics of a 2-D flapping-wing MAV in hover mode are modeled. Control simulations are done for hover, takeoff ,...

Aerodynamics and structural dynamics of the insect wings are widely considered in flapping wing micro air vehicle (FWMAV) applications. In this paper, the aerodynamic characteristics of the three-dimensional flapping wing models mimicked from the bumblebee and hawkmoth wings are numerically investigated under steady flow conditions. This study aims...

The development and use of personalized medicine have an increasing importance in patient care. Numerical simulations of various biological phenomena have and continue to enable doctors and medical specialists to diagnose patients and understand how practical and effective treatment can be. The paths to patient-specific diagnosis and preoperative p...

In this study, a 3D model of the bio-inspired blowfly wing Callphere Erytrocephala is created and aeroelastic analysis is performed to calculate its aerodynamical characteristics by use of numerical methods. To perform the flapping motion, a sinusoidal input function is created. The scope of this study is to perform aeroelastic analysis by synchron...

In this study, 3D model of the bio-inspired blow fly wing Callphere Erytrocephala is created and aeroelastic analysis is performed to calculate its aerodynamical characateristic by use of numerical methods. In order to perform the flapping motion, a sinusoidal input function is created. The scope of this study is to perform aeroelastic analysis by...

In this study, we propose a method to reconstruct pressure fields from planar particle image velocimetry measurements for laminar flows by employing semi-implicit method for pressure-linked equations algorithm to solve governing equations where measured velocities are inherently used as boundary conditions. The method starts with interpolating the...

In this work, the ground effect phenomena for a rotary wing is investigated both numerically and experimentally. For this purpose, a test setup with scaled model helicopter rotor is established. The experimental setup give the opportunity to investigate the rotor aerodynamics both with inclined ground and without any inclination. The thrust and tor...

This paper discusses the conceptual design of a hybrid thin haul air taxi. It presents a design methodology for a distributed propulsive hybrid aircraft highlighting the differences in design procedures between conventional design and hybrid distributed propulsion design. In addition, it demonstrates the impact of both hybridization and distributed...

In this study, the design and analysis of hovering controller of an UAV which is capable of doing vertical takeoff and landing using the fixed six rotors placed on the tilt-wing and tilt-tail will be explained. The aircraft will have four rotors on the wing and two rotors on the tail. The main wing and horizontal tail will be capable of 90° tilting...

The aerodynamic phenomena of the flapping motion in hover mode is widely considered in micro air vehicle (MAV) applications. In this study, the aerodynamics of a three-dimensional rigid wing mimicked from the hawkmoth Manduca sexta is numerically investigated under pure plunge motion. The sinusoidal motion is provided with a user-defined function (...

This paper presents a method to calculate aerodynamic forces and moment of a hawkmoth Manduca sexta wing and to control a flapping wing Micro Air Vehicle (MAV) for navigation. The dynamical model of the MAV is inspired from hawkmoth Manduca sexta and is derived using 6 states. The control inputs are the stroke plane angle and wingbeat frequency. An...

In this paper, it is introduced to find net aerodynamic lift capacity of proposed flapping-wing micro air vehicle (FWMAV) by performing dynamical calculation and FSI (Fluid Structure Interaction) analysis of a flapping wing test system. In the flapping system, a single degree of freedom type four-bar mechanism which was used as a piezo-driven flapp...

Sustainable water resources development and management is recognized worldwide as an ultimate goal of national water strategies. However there is extreme variability in the distribution of water resources. Spatial and temporal availability of surface water largely depend on precipitation pattern and regional morphology. Due to buffering and storage...

Numerous karst springs in Akyaka (Ula, Muğla, SW Turkey) create Azmak River of 2 km long which discharges to Gökova Bay, Aegean Sea. There is also wetland besides the river near to the sea. The whole area including the bay, the river and the wetland is under environmental protection as national park. Water flow and temperature modelling of the kars...

https://yetkin.com.tr/dilek-funda-kurtulus Son dönemlerde özel şirketler tarafından uzaya seyahatler düzenlenmeye başlanmıştır. Bu durum uzay turizmi ile uzay turisti, uzay katılımcısı veya uzay yolcusu gibi kavramların doğmasına sebep olmuştur. Bir uzay aracı ile seyahat eden uzay yolcusunun uğradığı zarardan doğan sorumluluğun tazmini konusu öğr...

Since the beginning of the aviation industry, fossil fuel is being used as the only source of fuel to power airplanes. Each year the popularity of aviation industry among the passengers is increasing dramatically because of its short journey time. Therefore, the demand of fossil fuel is also increasing to support the additional need. However, the s...

Başkent Üniversitesi Hava ve Uzay Hukuku Yüksek Lisans Tez Sunumu

Bu çalı¸sma, Apprentice E-flite sabit kanatlı bir hava aracında yapısal deği¸siklikler yapılarak elde edilecek hibrit insansız hava aracının modellenmesi ve yükseklik-yönelim dinamiklerinin çoklu doğrusal aktif bozucu denetimci yapısı ile denetimini içermektedir. Sabit kanatlı hava aracında yapılacak yapısal deği¸sikliklerin ardından elde edilecek...

Introduction In the current study, two rectangular flapping wing models are used to investigate unsteady aerodynamic forces in a low speed wind tunnel. The wings are generated from aluminum and plexiglass materials to observe the effects of the wing flexibility on instantaneous aerodynamic forces. A Lead Zirconate Titanate (PZT) piezoelectric actua...

Today, drones are getting more common in every part of human life. Their potential in usage for scientific purposes is encouraging scientists. The data environmental scientists need are often gathered at the field. Colossal study area may cause trouble by means of time and effort. With intent to speed up and facilitate the field work, drones get in...

The low Reynolds number aerodynamics at high angle of attack is crucial for the design of unmanned aerial vehicles and wind turbine blades. The current study aims to enhance the insight on the near wake of airfoils normal to free stream. The near wake structure on a NACA 0012 airfoil normal to free-stream is measured with particle image velocimetry...

The aerodynamics of insects flying at low Reynolds numbers is considered for Micro Air Vehicles (MAV) designs. The aim of this study is to analyze different flapping wing models and to predict generated forces and vortices around the wings. The analyses are significant for understanding properties of flying animals like birds, insects and for impro...

Supplementary Figures for Kurtulus DF, Aerodynamic Loads of Small-Amplitude Pitching NACA 0012 Airfoil at Reynolds Number of 1000, AIAA Journal, 2018, DOI10.2514/1.J056879

Serpentine inlets (S-ducts) are used to supply air to the engine when it is buried in the aircraft. An intake is expected to transport the air mass flow required by the engine with minimum total pressure losses to the aerodynamic interface plane. Separation occurs inside the S-duct and generates distortion leading to instabilities. The flow structu...

The performance of the modern aeroengines is highly dependent on the turbine inlet gas temperature. However, the turbine inlet temperatures of the today’s engines are already beyond the material structural limits. Hence, the turbine section must be cooled down to acceptable levels. Various types of cooling methods like internal cooling, film coolin...

A numerical investigation of the flow field in a short, diffusing S-duct inlet was conducted. The study was carried out in the turbulent flow where Reynolds number is 777,000, and the inlet duct had a length-to-hydraulic diameter ratio of 5.8. The primary discussion herein focuses on flow analysis and development of secondary flow in the S-duct dif...

The study presents the newly developed fast three-dimensional grain burnback tool. The computational method that has been developed is based on minimum distance calculation technique. Structured grid for computational domain modeling has been used, and grid based-surface propagation method has been utilized for grain burnback simulation by using ST...

Potential of unmanned aerial vehicle (UAV) remote sensing in karst springs: Muğla, Turkey

In the last years, there has been lots of investigation on the aerodynamics of flapping wing micro air vehicles. By analysing the flapping mechanics of natural flyers like birds and insects, human made robotical unmanned aircrafts are manufactured. In general, the works which investigates the flows at low Reynolds numbers covers both the biological...

In this study, a numerical investigation of ground effect of a helicopter rotor is investigated with Computational Fluid Dynamics method. For this purpose, a model scale 2 bladed helicopter rotor is chosen. An experimental study is referred for comparison and validity of CFD method.

This paper presents a novel foldable flapping wing micro air vehicle (MAV). This design of the proposed MAV is inspired from origami bird with flapping wings. The proposed method has two major advantages: 1) it eliminates the need for the utilization of heavy materials during manufacturing; 2) the bio-inspired flapping-wing mechanism replaces ornit...

Aerodynamic performance of wings is directly related to the flow characteristics and the wing geometry. The change in the wing geometry by external loads such as the temperature gradient formed by aerodynamic heating and the pressure distribution on wing surfaces affect the flow characteristics around the wing. In addition, the change in the flow c...

One of the most important factors affecting the aerodynamic performance of the aircraft is lift-induced drag caused by wingtip vortices. This study describes the winglet design and analysis for solar-powered unmanned air vehicle (UAV). The motivation of this study is designing elliptical winglet to explore efficient shapes using multiple winglet pa...

Taşınır rehninin ana tipi teslimi zorunlu rehindir. Diğer rehin türleri teslimi zorunlu rehnin birer istisnası olarak ortaya çıkar. Teslim ile meydana gelen bazı sakıncaları gidermek için teslimsiz taşınır rehinleri de oluşturulmuştur. Bunların arasında hayvan rehni, maden rehni, ticari işlemlerde taşınır rehni, gemi rehni ve hava aracı rehni bulun...

UAV Applications in Hydrology: A Case Study in Gökova Basin, Muğla, Turkey

Bu çalışma, hibrit insansız hava aracının (HİHA) tasarımı, matematiksel olarak modellenmesi, denetimci tasarımını ve döngüde donanım testlerinden oluşmaktadır. Sabit kanatlı hava aracı olarak uzaktan kumandalı E-Flite Apprentice marka model uçak seçilmiş ve şaside yapılan değişikler ile dikey iniş kalkış özelliği kazandırılmıştır. Bu tarz hibrit bi...

This paper presents the design and technical features of a robotic flapping wing mechanism and the experimental analysis of 3-D sweeping wings. The wing has three rotational degrees of freedom, which allows the adjustment of different flapping trajectories separately. Three computer-controlled brushless motors drive the three rotational axis of the...

Süpersonik rejimde uçan kanatlar çeşitli yüklemelere maruz kalırlar. Bu yükleme tiplerinden biri olan termal yüklemeler, kanatların tasarımı üzerinde oldukça etkilidir, bu nedenle büyük öneme sahiptir. Termal yükleme kaynaklı oluşan termal gradyan kanatlar üzerinde yapısal bozulmalara yol açabilir. Bu çalışmanın amacı aerodinamik ısınma gibi termal...