Aerodynamics

This article deals with the computation of aerodynamic characteristic of strut-braced wing. Calculations were performed on L-610 airplane with two proposals of wing with the different aspect ratio. Results of these calculations were compared with the original wing of the L-610. Aerodynamic characteristics serve as the basis for the structure analysis and are used for analyses of flight performance.

This article deals with aerodynamic and structural calculations of several wing designs to compare the influence of the shape on the lift distribution. Various shapes of wings for the required lift and bending moment were optimized to minimize drag and thereby reduce fuel consumption. One example was a wing with a bell-shaped lift distribution, which was proposed by Ludwig Prandtl and has been forgotten over the years. The first part of the paper focuses on minimization of the wing drag coefficient by a low fidelity method and the results are compared with the CFD calculation with good agreement. In the structural part of the analysis, the inner layout of the studied wings was designed. The structural design, containing elementary wing components and optimization loop, was carried out to minimize weight with respect to panel buckling. From these calculations the weights of wings were obtained and compared. In the last part of this study, an analysis of flight performance of an airpl...

This article deals with the computation of aerodynamic characteristic of strut-braced wing. Calculations were performed on L-610 airplane with two proposals of wing with the different aspect ratio. Results of these calculations were compared with the original wing of the L-610. Aerodynamic characteristics serve as the basis for the structure analysis and are used for analyses of flight performance.

In this article different wings are computed by low and high-fidelity methods to compare their aerodynamic characteristics. Thanks to the unusual properties of the wing with the bell-shaped lift distribution, several general geometrical variants of the wings were calculated and their results are presented in this work. Three general wings are assumed and their geometry is defined as rectangular, trapezoidal and elliptical. Airspeed, total lift force, shape of airfoil and root chord are defined, and bending moment is assumed as a surrogate model for wing weight. The goal of optimization is minimization of aerodynamic drag.

In this paper a computational methodology of aerodynamic interaction between propeller and wing is described. Presented work is focused on development of quick and accurate tool. Lifting line theory (LLT) with nonlinear airfoil characteristic is used to solve a finite span wing aerodynamic to predict downwash and lift distribution respectively. Blade element momentum theory (BEM) is used as a computational tool for estimating total thrust, torque, axial and tangential velocity distributions. Model of slipstream development is considered. Influence of propeller model to wing is simulated as contribution of higher dynamic pressure and change of angle of attack behind the propeller.

In this paper, an aerodynamic and structural computation framework was produced to develop a more efficient aircraft configuration considering a wing with a distributed electric propulsion and its use in different flight missions. For that reason, a model of a regional airplane was used as a case study. The considered model was a nine-seat light airplane with a cruise speed of 500 km/h at an altitude 9000 m. The design of the distributed system is introduced, then the aerodynamic and structural aspects of the new wing with distributed electric propulsion system are calculated, and finally flight performances are calculated for the purpose of analysis of the DEP effect. The design of the DEP system aimed at meeting the required landing conditions and the masses of its components, such as the electric motors, the control units and the power source of the DEP system were estimated. Aerodynamic calculations included computations of different wing aspect ratios. These calculations take i...

A computational method of fluid-structure coupling is implemented to predict the fatigue response of a high-pressure turbine blade. Two coupling levels, herein referred to as a “fully coupled” and “decoupled” methods are implemented to investigate the influence of multi-physics interaction on the 3 D stress state and fatigue response of a turbine blade. In the fully-coupled approach, the solutions of the fluid-flow and the solid-domain finite element problem are obtained concurrently, while in the decoupled approach, the independently computed aerodynamic forces are unilaterally transferred as boundary conditions in the subsequent finite element solution. In both cases, a three-dimensional unsteady stator-rotor aerodynamic configuration is modelled to depict a forced-vibration loading of high-cycle failure mode. Also analyzed is the low-cycle phenomenon which arises due to the mean stresses of the rotational load of the rotating turbine wheel. The coupling between the fluid and soli...

ABSTRACTThis paper provides an assessment of current rotor design comparison practices. First, the employed CFD method is validated for a number of rotor designs and is shown to achieve accurate performance predictions in hover and high-speed forward flight. Based on CFD results, a detailed investigation is performed in terms of comparing different rotor designs. The CFD analysis highlighted the need of high fidelity methods due to the subtle aerodynamics involved in advanced planforms. Nevertheless, the paper suggests that the correct basis for comparison in terms of performance metrics must be used to inform decisions about the suitability of the rotor blades designs for specific applications. In particular, when comparing blades of advanced planforms, direct torque and thrust comparisons are better than the commonly used lift to drag ratio and figure of merit.

Fluid Mechanics 4E by Kundu & Cohen offers a comprehensive introduction to fluid mechanics, covering fundamental principles such as the behavior of fluids in motion and at rest, the properties of solids, liquids, and gases, and crucial concepts like the continuum hypothesis and transport phenomena. The text also delves into applications including fluid statics and thermodynamics, underlining its relevance to both theoretical frameworks and practical scenarios in engineering and physical sciences.

The aircraft is surely one of the most considerable invention that changed the transport-engineering field, since flying was already an ancient dream come true just a few years ago. Now it is really easy to reach many far places even if most people have no clue how flying is possible. However, as factories do, these large and faster and faster machines return a consistent amount of pollution every day. During take-off, engines reach the highest RPMs returning the most noise possible, and during landing, mobile surfaces produce a lot of aerodynamic disturbs releasing energy in the air while landing gears constantly produce drag in both circumstances. The need to be able to predict the sound emission of an acoustic source represents an extremely current engineering challenge: in particular, a numerical code that would let the user to listen noise produced by a flyover, since acoustic reports are just numerical statistics and spectrogram plots. In this paper, a numerical formulation is suggested for the prediction of the acoustic emission in the frequency domain. The main task of the project was to develop a program that makes dynamic analysis of the signal taking into account the source movement. Moreover, the simulations predicted the noise levels, thus explicitly accounting for the scattering acoustic effects of incidence and geometrical obstacles as well. Geometrical reflections and absorptions of certain frequencies depending on the material have been comprised in the model.

The Internal Multi-Ailerons System (IMAS) is an advanced AI-driven aerodynamic control architecture designed to enhance UAV stability, precision, and stealth in extreme flight conditions. The system employs multiple internal ailerons operated autonomously through a hybrid Model Predictive Control (MPC) and Reinforcement Learning (RL) framework, ensuring real-time balance and adaptability during turbulence, low-speed manoeuvres, and missile deployment. IMAS integrates an intelligent sensor fusion network-combining IMU, GNSS/RTK, air data, and pressure feedback-to maintain optimal positioning and responsiveness. Additionally, it incorporates LED camouflage and radar-absorbent materials for low observability and anti-radar protection. This integration of intelligent control, aerodynamic optimization, and stealth technology establishes IMAS as a foundational innovation for the seventh generation of UAV bombardiers, enabling precise mission performance with superior aerodynamic resilience and survivability.

In the last decade the popularity of hydrofoil-assisted monohulled yachts has increased, especially for high performance racing crafts, as the ones used in the Vendée Globe. In the academic environment some research has been done to follow the industry evolution to better understand the behaviour of such vessels, yielding to the need of developing a tool able to predict the performance of such boats. For this reason, the present document aims to propose a simplified model that forecasts the velocity of hydrofoil-assisted monohulled yachts through the development of velocity prediction program (VPP). Due to the complexity of describing the behaviour of a complete sailing yacht, the developed tool uses empirical and analytical equations only, being a useful solution for a preliminary design stage. The aerodynamic model is based in the Offshore Racing Congress (ORC) documentation, the hydrodynamic model uses the Delft Systematic Yacht Hull Series (DSYHS) method, and the foil model is based in the Glauert's biplane theory, corrected and adapted for hydrofoil with towing tank tests. The combination of the three models allowed the development of a VPP that balances forces and moments in three degrees of freedom: surge, sway and roll. The VPP includes three different hydro foils designs: Dali Moustache, developed for the IMOCA 60 class by VPLP and used in the 2016-17 Vendée Globe regatta; Chistera, also developed by VPLP but now for the new Beneteau Figaro 3; Dynamic Stability System, patented by Hugh Burkewood Welbourn and largely used in several different vessels for racing and cruising. Finally, the present thesis: compares the performance of different foils, pointing its advantages and drawbacks; discuss possible optimizations for the foils design and the precautions that should be taken; presents the limitations of the used models, which yields to the VPP limitations and suggests future works that should be done to better predict the performance of such yachts.

Swirl flame stabilization is widespread among burners' manufacturers, but the complex flow patterns are not yet fully understood. The interaction of two confined swirling jets leads to the formation of two recirculation zones being the flame located on the shear layer between the both zones. In such conditions, the lean mixtures can be burned producing low emissions. In the present study, flow structure and turbulent mixing of two isothermal coaxial jets are investigated using Large Eddy Simulation (LES). This is a challenging tool to achieve accuracy but it requests demanding spatial resolution and special treatment of results. By contrasting time-averaged radial profiles with experimental data of a classical benchmark, the model is validated. Results show that LES is able to reproduce the basic features of the flow pattern. Besides, the spectra analysis of instantaneous flow fields provides not only the energy decay but also the most energetic flow structures.

В данной работе были исследованы карты распределения ближнего поля InGaAs/GaAs/AlGaAs полосковых инжекционных лазеров при различных токах накачки. Было показано, что в структурах, состоящих из двух резонансно связанных волноводов, наблюдается подавление мод высоких порядков.Near field intensity distributions of InGaAs/GaAs/AlGaAs lasers including broadened waveguides based on coupled large optical cavity (CLOC) structures were investigated. It was demonstrated that scanning near field optical microscopy gives direct proof of suppressing the transverse high-order mode lasing.Работа выполнена при поддержке РНФ (соглашение № 14-42-00006-П

Three-dimensional Direct Simulation Monte Carlo simulations of Columbia Shuttle Orbiter flight STS-107 are presented. The aim of this work is to determine the aerodynamic and heating behavior of the Orbiter during aerobraking maneuvers and to provide piecewise integration of key scenario events to assess the plausibility of the candidate failure scenarios. The flight of the Orbiter is examined at two altitudes: 350 kft and 300 kft. The flow field around the Orbiter and the heat transfer to it are calculated for the undamaged configuration. The flow inside the wing for an assumed damage to the leading edge in the form of a 10-inch hole is studied.

This paper briefly outlines how a combination of various computational methodologies could reduce the enormous computational costs envisioned in using advanced CFD codes in gradient-based optimized multidisciplinary design (MdD) contribution here is observing how they fit together in a mutually beneficial way.

According to aircraft manufacturers and several air transportation players, the main challenge the civil aviation will have to deal with in the future is to provide a sustainable growth strategy, in order to face the growing demand of air traffic all over the world. The sustainability requirements are related to air pollution, noise impact, airport congestion, competitiveness of the air transportation systems in terms of travel time and passengers' comfort. Among the possible ways to allow a sustainable growth of the air transportation systems, disruptive aircraft configurations have been object of study for several years, in order to demonstrate that the improvement of aircraft performance can enable the envisaged growth. This paper presents the study of a possible novel configuration called “PrandtlPlane,” having a box-wing layout derived from Prandtl's “Best Wing System” concept. The paper deals with the definition of top level requirements and faces the conceptual study ...

In the framework of the PARSIFAL research project, funded by the European Community in the Horizon 2020 program, the PrandtlPlane (PrP) configuration has been proposed as an innovative alternative to the current commercial aircraft of conventional architecture; the PrP configuration development is presented in order to satisfy the future air traffic growing requirements with better performances than conventional one, in terms of fuel efficiency, safety, pollution and noise emissions. In this paper a preliminary aerodynamic investigation of the transonic behaviour of the PrP wing system is presented; this study has been carried out by means of CFD analyses, with the aim to collect relevant information and to detect the proper design and operative space, fundamental for the following aerodynamic design activity of the aircraft. Investigations have been made on macro parameters (like wing loading or cruise Mach number) and also on local critical issues. The results obtained allows to design some initial reference configurations with satisfactory cruise performance in this very initial stage of the design process. c

This paper presents a methodology for the design of the primary flight control surfaces, in terms of size, number and location, for fixed wing aircraft (conventional or unconventional). As test case, the methodology is applied to a 300 passenger variant of the Prandtl Plane. This box wing aircraft is deemed to have low induced drag compared to conventional aircraft. The methodology is completely physics based and includes an aerodynamic analysis, followed by a control allocation algorithm and an analysis of the flight mechanics. The design has to fulfill a set of handling qualities requirements with a minimum total control surface area. An optimization algorithm is used to find the best design. Results indicate that this is possible with ailerons outboard on both wings, elevators inboard on both wings and conventional rudders in the vertical tail. The configuration allows for pure torque control and also direct lift control in the longitudinal axis. These features can potentially enhance airfield performance.

With the development of so-called 'electric' aircraft, the integration of jet pumps to various systems of the engines could offer significant gains (mass, reliability,...) over the technologies currently used. Since jet pumps may directly contribute to ramp noise, an accurate predictive tool is therefore desired to propose adapted noise reduction solutions in an industrial context. A direct computation of the unsteady turbulent flow being too expensive, the main idea is to compute acoustic sources from a stochastic velocity field and to inject it in Euler's equations to model near-field acoustic propagation. A Kirchoff analogy is then used to reduce calculation cost in the far field. In following previous works by Bailly and Juvé (AIAA Paper 99-1872) and Billson et al. (AIAA paper 2003-3282), a combined approach to generate a stochastic velocity field is presented and validated in the present work. This methodology is based on the sweeping hypothesis -or the fact that small scale turbulent structures are advected by energy containing eddies. The validation study is done on aerodynamic quantities of a cold free jet at Mach number M=0.72. The capability of the method to reproduce space-time velocity correlations in the shear layer is shown. The model is then tested on a cold free jet configuration to predict radiated acoustic levels using a volumic Lighthill solver.

A predictive tool for acoustics of confined subsonic jets, developped in the framework of a PhD thesis funded by Liebherr Aerospace (LTS) and hold at Onera, is presented in this paper. An hybrid method, combining turbulence generation by a stochastic model, and acoustic propagation by an Euler solver is there used. A new combined approach based on the sweeping hypothesis to generate isotropic turbulent fields starting from a steady RANS computation is introduced. In addition of allowing the modeling of space-time velocity correlation functions and the preservation of the turbulent kinetic energy spatial distribution, it integrates mean flow effects on the turbulent velocity field (AIAA paper 2011-2888). This stochastic model has been coupled with Onera's Euler solver sAbrinA v0 and the resulting tool has been tested on a subsonic free jet with a nozzle diameter D = 80mm at Mach number 0.72. Numerical spectra in the far-field are compared to experimental data available at Onera.

With the development of so-called 'electric' aircraft, the integration of jet pumps to various systems of the engines could offer significant gains (mass, reliability,...) over the technologies currently used. Since jet pumps may directly contribute to ramp noise, an accurate predictive tool is therefore desired to propose adapted noise reduction solutions in an industrial context. A direct computation of the unsteady turbulent flow being too expensive, the main idea is to compute acoustic sources from a stochastic velocity field and to inject it in Euler's equations to model near-field acoustic propagation. A Kirchoff analogy is then used to reduce calculation cost in the far field. In following previous works by Bailly and Juvé (AIAA Paper 99-1872) and Billson et al. (AIAA paper 2003-3282), a combined approach to generate a stochastic velocity field is presented and validated in the present work. This methodology is based on the sweeping hypothesis -or the fact that small scale turbulent structures are advected by energy containing eddies. The validation study is done on aerodynamic quantities of a cold free jet at Mach number M=0.72. The capability of the method to reproduce space-time velocity correlations in the shear layer is shown. The model is then tested on a cold free jet configuration to predict radiated acoustic levels using a volumic Lighthill solver.

In this paper, an Insulated Gate Bipolar Transistor (IGBT) module designed for aeronautic applications is investigated using structural reliability methods coupled with Finite Elements (FE) modeling. The lifetime of the module with respect to its solder joints failure, is evaluated using its thermomechanical response, in association with a low cycle fatigue model. The simulation of an aeronautic typical Accelerated Thermal Cycling (ATC) test configuration allows checking in a first step, the relevancy of the numerical procedure by assessing the experimental lifetime of the connections, and comparing them to experimental results. Then, the structural reliability of the module is evaluated over the target aircraft predicted useful lifetime, comparing the First Order Reliability Method (FORM) and Monte-Carlo Simulation (M-CS). The appropriate temperature mission profile and flight time are therefore considered with their scatters, in addition to those of the parameters of the fatigue model. Regarding these latter parameters, a simulation based approach is proposed and applied for the determination of their probability density function (pdf). For reasonable reliability analysis time, the thermomechanical response of the module was surrogated using Kriging metamodels. The paper ends with the exploitation of the reliability importance factors for identifying and proposing improvements, with the demonstration of considerable reliability increase.

In this paper, an Insulated Gate Bipolar Transistor (IGBT) module designed for aeronautic applications is investigated using structural reliability methods coupled with Finite Elements (FE) modeling. The lifetime of the module with respect to its solder joints failure, is evaluated using its thermomechanical response, in association with a low cycle fatigue model. The simulation of an aeronautic typical Accelerated Thermal Cycling (ATC) test configuration allows checking in a first step, the relevancy of the numerical procedure by assessing the experimental lifetime of the connections, and comparing them to experimental results. Then, the structural reliability of the module is evaluated over the target aircraft predicted useful lifetime, comparing the First Order Reliability Method (FORM) and Monte-Carlo Simulation (M-CS). The appropriate temperature mission profile and flight time are therefore considered with their scatters, in addition to those of the parameters of the fatigue m...

Hybrid cloud environments often face challenges in balancing workloads, managing resources, and ensuring resilience, which can lead to performance bottlenecks and higher costs. To address this, the Hyper Responsive Artificial Intelligent based Hybrid Cloud Load Balancer (HRAIHCLB) is proposed as an AI-driven system that integrates three key modules: the AI Driven Load Prediction Distributor (ADLPD) for forecasting workloads and distributing traffic dynamically, the Cloud Orchestration and Resource Optimizer Module (COROM) for seamless public–private cloud integration, energy-efficient scaling, and cost optimization, and the Resilience and Monitoring Module (RMM) for security enforcement, compliance, and adaptive learning. Evaluated on metrics such as load balancing efficiency, resource utilization, response time, migration cost, and throughput, HRAIHCLB demonstrated significant improvements in adaptability, cost reduction, and resilience, making it a promising solution for enterprise hybrid cloud management with potential future applications in multi-cloud and edge computing ecosystems.

The article presents reasons of an helicopter’s ising as well as an aircraft’s ising. The maion attention is addressed a conteraction of an ising. Autors divide the problem an two groups: an ising of an airframe – mostly lifting surfaces, an ising of engines. According to authors reasons, an extension (first of all) consequences of airframe’s ising considerably differ from seemingly similar events in an engine. The considerable attention is concentrated on a connteraction of consequences of an ising during the flight. The most complicated ising referes to helicopters, considering their particular aerodynamics characteristics. The autors dedicated is greather attention. Results reached during investigations of heating rotor blades in ITWL are presented.

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This paper deals with the research methods of wing-in-ground effect vehicle (WIG vehicle) longitudinal static stability. The methods are focused on the use of the algorithm of preliminary WIG aerodynamics and control system design. The algorithm is based on the iteration process of stability criteria calculations, the subsequent factor analysis of these criteria with respect to their value-determining parameters and variations of WIG vehicle configuration parameters. The methods include preliminary determination of WIG vehicle aerodynamic characteristics. The best results can be obtained when different methods of determining these aerodynamic characteristics (experimental and by means of computational aerodynamics) are combined. In this paper the calculation of aerodynamic characteristics is performed by applying ANSYS software packet. To assess the reliability of the aerodynamic characteristics obtained with the ANSYS program, experimental studies in a wind tunnel and a vertical hydrodynamic pipe were carried out. Certain aerodynamic characteristics are determined by means of originally made computer programs using the method of discrete vortices. A special database is formed of the obtained aerodynamic characteristics. The database essentially is a mathematical model of a WIG vehicle which supplies the characteristics (aerodynamic coefficients and their derivatives) with an estimated degree of reliability within a given range of determining parameters. On the basis of the widely used criterial approach to static stability assessment of various WIG vehicle modifications, a mathematical algorithm for parameter calculation and a computer program were developed. They permit the calculation-based analysis of the factors determining stability or non-stability of a WIG vehicle. The mathematical model of WIG vehicle stability analysis is implemented in the form of a software packet based on MatLab. The results worked out by the program are in the form of data suitable for operational analysis. Using these data, one can assess the WIG vehicle static stability and determine the stability range for the given structural and configurational factors. The results of the analysis make a foundation for subsequent modifications of WIG vehicle's aerodynamic configuration or for working out requirements for automatic control and stabilizing systems' upgrade. The methods demonstrating the analysis of original load-carrying systems design are also presented. For the example analysis, an original WIG-tandem loadcarrying system was chosen. The methods are applicable for the analysis of various aircraft modes' stability, for all vehicles built on aerodynamic principles of flight maintenance.

Аннотация. На основе вычислительного эксперимента проведен ряд исследований по оценке влияния параметров компоновки на аэродинамические характеристики экраноплана схемы «Тандем». Используется программный пакет CFD-моделирования ANSYS. Процесс разбит на этапы, каждый из которых предполагает внесение определенных изменений в компоновку и оценку их влияния на аэродинамические характеристики экраноплана. Каждый последующий этап учитывает результаты предыдущего. На первом этапе исследуются аэродинамические характеристики при различных положениях несущих поверхностей компоновки. Второй этап предполагает оценку эффективности применения в компоновке концевых шайб и винглетов. На третьем этапе ставится задача оценки влияния углов установки несущих поверхностей. На четвертом этапе оценивается влияние фюзеляжа и вертикального оперения. Ключевые слова: экраноплан, аэродинамические характеристики экраноплана, параметры компоновки экраноплана, GEV (ground-effect vehicle), WIG (wing-in-ground-effect) Для цитирования: Кривель С.М., Галушко Е.А. Влияние параметров компоновки экраноплана схемы «Тандем» на его аэродинамические характеристики // Вестник Инженерной школы Дальневосточного федерального университета. 2022. № 2(51). С. 3-16.

This paper deals with the research methods of wing-in-ground effect vehicle (WIG vehicle) longitudinal static stability. The methods are focused on the use of the algorithm of preliminary WIG aerodynamics and control system design. The algorithm is based on the iteration process of stability criteria calculations, the subsequent factor analysis of these criteria with respect to their value-determining parameters and variations of WIG vehicle configuration parameters. The methods include preliminary determination of WIG vehicle aerodynamic characteristics. The best results can be obtained when different methods of determining these aerodynamic characteristics (experimental and by means of computational aerodynamics) are combined. In this paper the calculation of aerodynamic characteristics is performed by applying ANSYS software packet. To assess the reliability of the aerodynamic characteristics obtained with the ANSYS program, experimental studies in a wind tunnel and a vertical hydrodynamic pipe were carried out. Certain aerodynamic characteristics are determined by means of originally made computer programs using the method of discrete vortices. A special database is formed of the obtained aerodynamic characteristics. The database essentially is a mathematical model of a WIG vehicle which supplies the characteristics (aerodynamic coefficients and their derivatives) with an estimated degree of reliability within a given range of determining parameters. On the basis of the widely used criterial approach to static stability assessment of various WIG vehicle modifications, a mathematical algorithm for parameter calculation and a computer program were developed. They permit the calculation-based analysis of the factors determining stability or non-stability of a WIG vehicle. The mathematical model of WIG vehicle stability analysis is implemented in the form of a software packet based on MatLab. The results worked out by the program are in the form of data suitable for operational analysis. Using these data, one can assess the WIG vehicle static stability and determine the stability range for the given structural and configurational factors. The results of the analysis make a foundation for subsequent modifications of WIG vehicle's aerodynamic configuration or for working out requirements for automatic control and stabilizing systems' upgrade. The methods demonstrating the analysis of original load-carrying systems design are also presented. For the example analysis, an original WIG-tandem loadcarrying system was chosen. The methods are applicable for the analysis of various aircraft modes' stability, for all vehicles built on aerodynamic principles of flight maintenance.

This thesis presents an investigation of the flow physics governing aerodynamic interaction mechanisms relevant to Formula One racing cars, in particular the influence of the front wing on the car chassis flat underbody and diffuser. Wing 150 8.1 Introduction CONTENTS ix 8.2 Influence of Low Energy Turbulent Wake 8.3 Influence of Full-Span Horizontal Wing 8.4 Influence of Partial-Span Horizontal Wing 8.5 Key Findings 9 Closing Remarks, Conclusions and Suggestions for Further Work 166 9.1 Closing Remarks 9.1.1 Applicability of Results 9.1.2 Relevance to Formula One 9.2 Conclusions 167 9.3 Suggestions for Further Work 171 Appendices 173 A Model Drawings 174 B Aerofoil Co-ordinates B.l Tandem wing model 182 B.2 NASA Langley GA(W)-2 LS(1)-0416 183

This thesis presents an investigation of the flow physics governing aerodynamic interaction mechanisms relevant to Formula One racing cars, in particular the influence of the front wing on the car chassis flat underbody and diffuser. Wing 150 8.1 Introduction CONTENTS ix 8.2 Influence of Low Energy Turbulent Wake 8.3 Influence of Full-Span Horizontal Wing 8.4 Influence of Partial-Span Horizontal Wing 8.5 Key Findings 9 Closing Remarks, Conclusions and Suggestions for Further Work 166 9.1 Closing Remarks 9.1.1 Applicability of Results 9.1.2 Relevance to Formula One 9.2 Conclusions 167 9.3 Suggestions for Further Work 171 Appendices 173 A Model Drawings 174 B Aerofoil Co-ordinates B.l Tandem wing model 182 B.2 NASA Langley GA(W)-2 LS(1)-0416 183

The method of modeling and designing of the car body using modern software tools, in order to obtain as much as possible realistic models is presented in this paper. Also, in this research, model verification with numerical calculations was conducted. Elements of aerodynamics, vehicle dynamics and external influences on it are basic in this paper. After analyzing obtained results with CFD, it was concluded that the model of the car with geometric simplifications meets the criteria of accuracy and this leads to the further course of analysis. The procedures for obtaining results from a combination of more modern tools (CCM+) are presented in this paper.

Drag reduction of a streamlined body at incidence using rotating cylinders JAMES SCHULMEISTER, MICHAEL TRIANTAFYLLOU, MIT -The flow past a streamlined body at incidence is characterized by cross-flow separation that induces large forces and moments. We investigate the use of counterrotating control cylinders to delay separation and reduce the drag on a streamlined body at incidence in water tunnel experiments. A streamlined body model with rotating control cylinders was fixed at angles of incidence up to 30 degrees in a water tunnel while the forces and moments were monitored. The control cylinders have diameters equal to 10% of the maximum diameter of the streamlined body and are embedded in the model such that part of the circumference is exposed to the flow. The control cylinders are counter-rotated so that the moving surface imparts momentum to the flow, encouraging the delay of cross-flow separation and the reduction of drag.

The growing number of Floating Offshore Wind Turbine (FOWT) concepts that utilize a single point mooring and therefore rely on the self-alignment capabilities of the wind turbine (e.g. SCD nezzy or SelfAligner by CRUSE Offshore) demands an extension of the simulation methods used for their development. A crucial issue for these concepts is the accurate prediction of forces and moments, which contribute to the self-alignment. In contrast to the well-studied behaviour of torque and thrust, yaw moment and lateral forces on a rotor under yawed conditions have not been in focus of previous experimental tests for the validation of aerodynamic simulation tools. In the present work, a model turbine equipped with a 6-axis force/moment sensor to capture the complete load on the rotor is presented. A detailed study of the two-bladed model turbine’s aerodynamic behaviour under yawed conditions was carried out within a range of yaw angles between -55 to + 55° with steps of 1 – 2.5°.

Three-dimensional aeroelastic phenomena are numerically simulated for the development of a balloon-based operation vehicle (BOV) proposed by the Japan Aerospace Exploration Agency. The structures of the all-moving tail wing composed of several materials are modeled in detail using a finite element method. The vibration modes obtained from the eigenvalue analysis of the three-dimensional solid model are mapped to two-dimensional iso-parametric shell elements for efficient fluid-structure coupled analysis using unstructured computational fluid dynamics. The methods are validated by the fluttering of the National Aerospace Laboratory wing, which has a similar planform to the BOV tail and is referred to as a standard problem. The shape of the flutter boundary is explained by the characteristic shift of the aerodynamic center. The simulation results show the BOV tail has a sufficient safety margin for flutter along the freefall flight path.

In this study, the effect of steady spanwise blowing on the aerodynamic coefficients of a maneuverable aircraft wing model has been simulated three dimensionally applying the fluent software. The simulations have been performed at the Mach number of 0.4 and different angles of attack, using unstructured grid and the (k-ω SST) turbulence model. Numerical simulation results showed that the spanwise blowing along the wing leading edge caused a flow along the axis of leading edge vortex and delayed the vortex breakdown until the high angles of attack. As a result, the lift coefficient increases at higher angles of attack, which is directly related to the jet momentum coefficient. By apply blowing, due to the vortex breakdown on the wing surface, drag coefficient is greater in comparison to the no blowing condition until the angle of attack 24 degrees and after this angle, the drag coefficient decreases. Also, drag coefficient decrease is lower at greater jet momentum coefficients. By injecting the flow over the wing, the vortex increases in different longitudinal sections and causes a greater pressure drop on the upper surface of the wing. Also, the greatest amount of pressure in the inner span of the wing and near the edge of the wing attack is observed.

A numerical study of the aeroacoustic properties of a pair of orifices placed in a duct is presented. Two configurations with two different distances in between the orifices have been analysed to consider conditions with or without tonal noise sources. Large Eddy Simulations have been performed and validated with respect to experimental measurements for both aerodynamic and acoustic predictions. Data series from an acoustically excited LES have been post-processed through System Identification techniques to concurrently model noise sources and acoustic scattering. The model of the noise obtained has been used as to confirm the good prediction of the acoustic scattering.

A building-integrated wind turbine (BIWT) is an alternative way to assess renewable energy. BIWTs produces their own energy without relying on fossil fuels. However, only a few researchers have studied BIWTs. Greater wind velocity (V) results in greater potential energy (P). The aerodynamic design has an important role to play in increasing wind velocity and reducing turbulence intensity. CFD simulations taken from previous research have revealed that round-shaped buildings increase velocity up to 30%. This study focuses on the wind response of square and toprounded-shaped building models, and their optimization based on variations in wind velocity. Wind tunnel studies were conducted to study wind flow around the building, followed by a computer simulation to verify the results. In a wind tunnel, three BIWT models (1:150 in scale) located in Seoul, South Korea (terrain B), were evaluated. The results of the study show that the streamline should be followed when installing wind turbines on rectangular rooves with flat surfaces. This method allows wind speed to be elevated significantly, when compared to a turbine at a higher height. In addition, round corners can produce wind velocity that is up to 34% greater than sharp corners beside a building. In summary, this paper presents a five-step analysis framework that can be used by researchers who wish to analyze BIWTs through wind tunnel experiments and CFD.