Nilay Sezer Uzol

Middle East Technical University | METU · Department of Aerospace Engineering

Wind turbines usually operate in a highly unsteady environment affected by the atmospheric conditions and the wakes of the upstream turbines. Thus, an active flow control strategy may significantly improve the aerodynamic performance of individual turbines and the net energy production of a wind farm. This work investigates the impact of a boundary...

Moleküler dinamik simülasyonları sürekli ortam varsayımının uygun olmadığı akış problemleri için kullanılabilir ve bu tür akış simülasyonlarında türbülans mikro ölçekte incelenebilir. Bu çalışmada, daha önce geliştirilmiş moleküler dinamik simülasyon kodu, grafik işlem birimi üzerinde CUDA ile paralel hale getirilerek çalıştırılmıştır. Bu sayede yü...

Rüzgar türbinlerine eklenen aktif akış kontrol sistemleri elde edilen enerjinin farklı akış koşulları boyunca en yüksek seviyede tutulabilmesi için kullanılabilmektedir. Bu çalışmada kontrol sistemleri içerisinde yer alan sınır tabaka emme sistemi eniyileştirilmiştir. Eniyileştirme deney tasarımı yöntemini baz alarak bir tasarım uzayı ile yapılmışt...

Energy demands are rising in all countries, particularly in emerging nations. Energy sector advances attempt to deliver high energy efficiency in energy systems, lower investment costs, and minimize emissions that are discharged into the environment, which are very detrimental to human health and cause climate change. Even the most advanced fossil...

View Video Presentation: https://doi.org/10.2514/6.2022-3387.vid Recently, with the advances in modern missile industry, faster and more maneuverable missiles became fashionable. Designing fast and agile missiles requires efficient and strong control surfaces and grid fin is a candidate to fulfill this need. Grid fins are unconventional control sur...

In this chapter on CFD simulations for airfoil polars, we focus on studies that are relevant to wind turbine airfoils, which have been investigated at reasonably high Reynolds numbers (i.e., Re>~1×106). We specifically focus on topics such as solution approaches, grid characteristics, effects of turbulence models, near/post-stall behavior predictio...

Fast and parametrical aerodynamic analyses for design of high speed jet aircraft is important especially during the initial design phases. In this study, different wing/body configurations defined with specific geometrical parameters for a jet aircraft are analyzed by using the panel method solver PANAIR. The analysis and design process is automate...

In this paper, the aerodynamic properties of a selected aircraft geometry are calculated in supersonic flow condition using PANAIR. PANAIR is an open-source high-order panel method solver for irrotational and inviscid flows and it is more efficient than higher fidelity CFD analyses for the preliminary design process since it is faster and easier to...

In this paper, wake shapes of wind turbine rotors are investigated by using CFD and analytical wake models. The flow around the NTNU model turbine is simulated using the Reynolds-Averaged Navier-Stokes Equations with Spalart-Allmaras, standard k-epsilon, standard k-omega, and k-omega SST turbulence models, k-kL-omega and Transition SST transition m...

Bu çalışmada, açık kaynak kodlu yüksek mertebeli panel metot akış çözücüsü PANAIR'de kullanılan teori ve yöntemler ve elde edilen çözümlerin doğruluğu ses-üstü akış koşulları için incelenmiştir. Seçilen bir kanat/gövde uçak geometrisi için 2,01 Mach sayısına sahip serbest akış hızı ve farklı hücum açılarında analizler yapılmıştır. Analizlerdeki ön...

In this study, a design space for aircraft aerodynamic design at high speeds is created by keeping certain design variables in desired ranges and the aerodynamic performance coefficients are investigated. In aerodynamic analyses, high-order, 3-dimensional panel method solver PANAIR is used and pre- and post-processing utility codes are developed fo...

Bu çalışmada, uçak konsept tasarım aşamasında, kanat/gövde konfigürasyonlarının ses altı ve ses üstü hızlarda aerodinamik analizi için oluşturulan hesaplamalı aerodinamik analiz ve tasarım altyapısı içerisinde, 3-boyutlu panel kodu kullanılarak seçilen kanat/gövde ikilisinin aerodinamik performansı incelenmiştir. Bu çalışmada yüksek mertebeli, 3-bo...

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...

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 practical swarm navigation algorithm based on potential functions and properties of inviscid incompressible flows. Panel methods are used to solve the flow equations around complex shaped obstacles and to generate the flowlines, which provide collision-free paths to the goal position. Safe swarm navigation is achieved by follo...

Bu çalışmada, Model boyutlarında helikopter döner kanat sistemi test düzeneği kurulmuştur. Rotor yer etkisi durumunda ve yer etkisi dışında deneyler yapılmış ve balans sistemi ile kuvvet ve moment ölçümleri alınmış ve performans hesaplamaları yapılmıştır. Ayrıca, rotor eğimli yüzey üzerinde iken yer etkisi durumları incelenmiş, yüzeydeki akışın dur...

Bu çalı¸smada, potansiyel akı¸s hesaplamaları robot sürülerine çarpı¸smasız seyrüsefer algoritması geli¸stirmek için kullanılmı¸stır. Akı¸skanlar mekani˘ginde iyi bilinen, sıkı¸stırılmayan viskos olmayan potansiyel akı¸s genel denklemlerini akı¸sın yüzeyine paralel olma ko¸sulunu sa˘glayarak çözen panel metodu kullanılarak, sürü erkinleri için hede...

Computational fluid dynamics simulations for initially hydro-dynamically fully developed laminar flow with nanofluids in a circular duct under constant wall temperature condition are performed with two-phase mixture model by using Fluent software. Thermal behaviors of the system are investigated for constant wall temperature condition for Al2O3/wat...

The main purpose of this paper is to study the aerodynamic effects of blade tip tilting on power production of horizontal-axis wind turbines by using Computational Fluid Dynamics (CFD). For validation and as a baseline rotor, the NREL Phase VI wind turbine rotor blade is used. The Reynolds-Averaged Navier–Stokes Equations are solved and different t...

In this study, the thermal and hydrodynamic performance analyses of sa elected gasketed-plate heat exchanger with different number of plates are performed experimentally. A gasketed-plate heat exchanger (GPHE) test set-up is designed and constructed to perform experimental measurements for thermal and hydrodynamic performance analyses of plate heat...

Unsteady free-wake solutions of wind turbine flow fields involve computationally intensive interaction calculations, which generally limit the total amount of simulation time or the number of turbines that can be simulated by the method. This problem, however, can be addressed easily using high-level of parallelization. Especially when exploited wi...

In this study flow over two axially non-aligned wind turbines is investigated via 3-D CFD analysis by solving Navier-Stokes equations. This setting is the test case geometry for the NTNU's "Blind-Test" Workshop 3 (BT3) and it aims to predict the performance of the wind turbines and their wake development under asymmetrical flow conditions. The perf...

In this study CFD investigation of flow over the NREL S826 airfoil is performed. NREL S826 airfoil was designed for HAWTs of 10-15 meter diameters. However, it is used in the NTNU wind turbine rotor model and low Reynolds number flow characteristics become important in the validations with the test cases of this rotor model. The airfoil CFD simulat...

The main objectives of this study were to aerodynamically design and optimize a winglet for a wind turbine blade by using computational fluid dynamics (CFD) and to investigate its effect on the power production. For validation and as a baseline rotor, the National Renewable Energy Laboratory Phase VI wind turbine rotor blade is used. The Reynolds-a...

In this study, an experimental set-up for testing chevron type gasketed plate heat exchangers is utilized to investigate the thermal and hydraulic characteristics of different plate geometries. The experiments can be performed using various number of plates and wide range of plate sizes. The experiments are carried out for different temperatures, f...

In this study, forced convection heat transfer characteristics of nanofluids are investigated by numerical analysis of incompressible transient laminar flow in a circular duct under step change in wall temperature and wall heat flux. The thermal responses of the system are obtained by solving energy equation under both transient and steady-state co...

Günümüzde askeri ve sivil havacılık başta olmak üzere birçok alanda kullanılmakta olan helikopterlerin gürültü karakteristikleri oldukça karmaşık olup, birçok fiziksel sebeplerden kaynaklanabilmektedir. Bu bildiride, bir lisans bitirme projesi olarak yapılmakta olan " Sessiz Helikopter Tasarım ve Analizi Projesi " kapsamında yapılan literatür araşt...

The main purpose of this paper is to optimize winglet geometry by using CFD with Genetic Algorithm and study its effects on power production. For validation and as a baseline rotor, the NREL Phase VI wind turbine rotor blade is used. The Reynolds-Averaged Navier-Stokes equations are solved and different turbulence models including the Spalart-Allma...

In this study, a computer program is developed to design and compare gasketed plate heat exchangers with double pipe heat exchangers. The computer program is coded in MATLAB. The user interface of the program is prepared in MATLAB Guide. The program uses hot and cold fluid properties as input data and calculates the characteristics of gasketed plat...

In this paper, potential flow calculations for incompressible inviscid flows are used to develop a collision free navigation algorithm for a robot swarm. Robots are equiped with laser scanners which are used to detect the obstacles in the environment. Then, a real-time panel method is used to calculate the streamlines of the potential flow around t...

This paper presents an investigation of the aerodynamic interactions between two UH-1H helicopter rotors in forward flight. The wake flow structure and performance characteristics of the rotors are investigated when the rear rotor is operating within the wake of the front rotor. A 3-D unsteady vortex-panel method potential flow solver based on a fr...

In this paper an implementation of a collision free navigation algorithm for robot swarm based on the panel method is discussed. The well known panel method is used to solve the governing equations for inviscid incompressible potential flow around rigid objects with tangency boundary conditions, providing the robots with safe trajectories to the ta...

This paper presents an application of the potential field panel method commonly used in aerodynamics analysis to obtain streamlinelike trajectories and use them for path planning and collaborative target tracking for swarming micro air vehicles in an urban environment filled with complex shaped buildings and other architectural structures. In addit...

In this study, a computer program is developed to calculate characteristics of a Chevron type gasketed plate heat exchanger (CTGPHEX) such as: the number of plates, the effective surface area and total pressure drops. The main reason to prefer the use of CTGPHEXs to other various types of heat exchangers is that the heat transfer efficiency is much...

This paper presents the results of three-dimensional and time-accurate, parallel Computational Fluid Dynamics (CFD) simulations of the flow field around a Horizontal Axis Wind Turbine (HAWT) rotor. Large Eddy Simulation (LES) methodology with an instantaneous loglaw wall model is used for the viscous computations. The 3-D, unsteady, parallel, finit...

This paper presents an investigation of the effect of steady and transient free-stream wind shear on the wake structure and performance characteristics of a horizontal axis wind turbine rotor. A new three-dimensional unsteady vortex-panel method potential flow solver based on a free-vortex wake methodology, AeroSIM+, is used for this purpose. The c...

This paper presents the use of Potential Field and Panel Methods to generate trajectories for swarming Micro Air Vehicles (MAVs) to track a moving target. The method provides obstacle and collision avoidance. Each vehicle is represented by a point source singularity in the potential field and the direction to the target is used in the calculations...

This paper presents the results of three-dimensional and time-accurate Computational Fluid Dynamics (CFD) simulations of the flow field around the National Renewable Energy Laboratory (NREL) Phase VI horizontal axis wind turbine rotor. The 3-D, unsteady, parallel, finite volume flow solver, PUMA2, is used for the simulations. The solutions are obta...

In this research, the computational analysis of three-dimensional, unsteady, separated, vortical flows around complex geometries is studied by using stationary or moving unstructured grids. Two main engineering problems are investigated. The first problem is the unsteady simulation of a ship airwake, where helicopter operations become even more cha...

Computational fluid dynamics (CFD) simulations of ship airwakes are discussed in this article. CFD is used to simulate the airwakes of landing helicopter assault (LHA) and landing platform dock-17 (LPD-17) classes of ships. The focus is on capturing the massively separated flow from sharp edges of blunt bodies, while ignoring the viscous effects. A...

The development, integration, and testing of a general-purpose "computational steering" software library with a three-dimensional Navier-Stokes flow solver is described. For this purpose, the portable object-oriented scientific steering environment (called POSSE) library was used. This library can be coupled to any C/C++ simulation code. The paper...

A simulation of the helicopter/ship dynamic interface has been developed and applied to simulate a UH-60A operating from a landing helicopter assault (LHA) class ship. Steady and time-accurate inviscid computational-fluid-dynamics (CFD) simulations are performed over a full-scale LHA class ship using the parallel flow solver PUMA2 to predict the un...

A computational study of unsteady, separated, low and high Reynolds number flows is made using a second-order accurate, cell-centered finite volume method on unstructured grids. The simulations include large-eddy simulation turbulence modeling based on a classical Smagorinsky subgrid-scale model. For the high Reynolds number simulations, wall shear...

While a tremendous amount of work has gone into developing Computational Fluid Dynamics (CFD) software, little has been done to develop computational steering and visualization tools that can be easily integrated with this software. Computational steering can be used to visualize CFD solutions while they are being computed and change simulation par...

A simulation of the helicopter/ship dynamic interface has been developed and applied to simulate a UH-60A operating from an LHA class ship. Time accurate CFD solutions of the LHA airwake are interfaced with a flight dynamics simulation based on the GENHEL model. The flight dynamics model was updated to include improved inflow modeling and gust pene...

The visualization of computational simulations of complex physical problems using virtual reality technology is demonstrated in this study. A general-purpose computational steering system (POSSE) which can be coupled to any C/C++ simulation code, has been developed and tested with a 3-D parallel Navier-Stokes flow solver (PUMA2) [1]. In addition, t...

A general-purpose computational steering system (POSSE) which can be coupled to any C/C++ simulation code, has been developed and tested with a 3-D Navier-Stokes flow solver (PUMA2). This paper illustrates how to use "computational steering" with PUMA2 to visualize CFD solutions while they are being computed, and even change the input data while it...

A general-purpose computational steering system (POSSE) which can be coupled to any C/C++ simulation code, has been developed and tested with a 3-D Navier-Stokes flow solver (PUMA2). This paper illustrates how to use "computational steering" with PUMA2 to visualize CFD solutions while they are being computed, and even change the input data while it...