Aerodynamics

Written for students of aeronautical engineering and based on a range of detailed aircraft design projects, this wide-ranging book draws together the elements of aircraft design and will support any aircraft design project. Written by experienced U.K. and U.S. based authors this is a unique resource that opens up the initial design process, explores the experience of others on similar projects, and clarifies the processes that are behind the equations and calculations used in aircraft design. Armed with this knowledge, readers will be freer to concentrate on the innovative and analytical aspects of their own project work. Key features include: demonstration of how the basic design process can be successfully applied to a wide range of aircraft; highly illustrated case studies that provide a valuable teaching and learning tool, examining how others have approached particular design challenges; and coverage of commercial, military, and concept aircraft design, plus award winning student projectsthat offer an insight into the conceptual design process from the student perspective.

In the last years UAV (Unmanned Aerial Vehicle)-systems became relevant for applications in precision farming and in
infrastructure maintenance, like road maintenance and dam surveillance. This paper gives an overview about UAV (Unmanned
Aerial Vehicle) systems and their application for photogrammetric recording and documentation of cultural heritage.
First the historical development of
UAV systems and the definition of UAV-helicopters will be given. The advantages of
a
photogrammetric system on-board a model helicopter will be briefly discussed and compared to standard aerial and terrestrial
photogrammetry.
UAVs are mostly low cost systems and flexible and therefore a suitable alternative solution compared to other
mobile mapping systems.
A mini UAV-system was used for photogrammetric image data acquisition near
Palpa in Peru. A settlement from the 13
th
century
AD, which was presumably used as a mine, was flown with a model helicopter. Based on the image data, an accurate 3D-model
will be generated in the future. With an orthophoto and a DEM derived from aerial images in a scale of 1:7 000, a flight planning
was build up. The determined flying positions were implemented in the flight control system. Thus, the helicopter is able to fly to
predefined
pathpoints automatically. Tests in Switzerland and the flights in
Pinchango Alto showed that using the built-in
GPS/INS- and stabilization units of the flight control system, predefined positions could be reached exactly to acquire the images.
The predicted strip crossings and flying height were kept accurately in the autonomous flying mode.

The team conducted the experiment to determine the effects of pressure distribution on lift and pitching moment and the behavior of stall for laminar and turbulent boundary layers in the USNA Closed-Circuit Wing Tunnel (CCWT) with an NACA 65-012 airfoil at a Reynolds number of 1,000,000. The airfoil was tested in a clean configuration at angles of attack of 0, 5, 8, 10, and 12 degrees. Tape added to the leading edge tripped the boundary layer, and pressure distributions were taken at 8, 10, and 12 degrees angle of attack. Experimental results showed a suction peak at less than 1% of chord, providing a beneficial test article for contrast between smooth and laminar boundary layer behavior at the stall condition. The maximum lift coefficient for the clean airfoil was 0.9 at 10 degrees angle of attack, and tripped airfoil reached a maximum lift coefficient of 1.03 at 12 degrees angle of attack, a 14% increase. These data were 10% lower than the empirical airfoil data found in Theory of Wing Sections from Abbott and von Doenhoff.  Pitching moment coefficient about the quarter chord remained near zero below stall as expected for a symmetrical airfoil, but rapidly became negative after stall for experimental and empirical data. The airfoil exhibited a leading edge stall for both laminar and turbulent boundary layers.

This research was funded by, and implemented within, a UK national research organisation, while the author was the KE and Impact Evaluation Manager responsible for assessing impact on a £15m UK government-funded research programme.

This work was also submitted as the authors MBA dissertation which was accepted and awarded in 2009.

ABSTRACT: A methodology and methods ‘toolbox’ is proposed for conducting impact research and assessment from within research programmes. The emphasis is upon how to clarify and assess the wider impacts from the early stages onwards.

The approach explicitly acknowledges, and attempts to address, the known issues and challenges of impact assessment while drawing upon the resources and opportunities available to research managers and researchers within such programmes.

The study has two triangulating foundations. Firstly, it examines the academic literature to help identify and design the pilot methodology and methods. Secondly it trials these in a real programme to both test and improve them.

The study was conducted over one year within one leading UK research organisation, where two research programmes (and around 60 research projects of £15m total value) were being assessed for their impacts. The study draws upon actual impact management experience and reflection, prospective (ex ante) and retrospective (ex post) assessments, participatory contributions from leading researchers undergoing assessment, and consultation with external users. The findings of this study outline the pilot and its first iteration. Recommendations are made for improvement to the methodology and methods.

A subsequent follow-on bid to UK government incorporating the impacts identified from implementing this methodology, successfully led to a further £15m of government funding.

It is expected the pilot methodology and methods will be applicable to other organisations, conducting and funding such research programmes, required to research and assess the wider research impacts.

Although primary focus of implemetation trials was upon research in physical sciences, technology, high-tech engineering, computing/IT, and environment, the wider literature study, the methodology design and justification, the methods proposed and used, and the resulting general recommendations and lessons are expected to apply more broadly to many other research areas, where the impact is to be found more widely in the society, economy, government or public sector or within organizations, policies, professions or the public.

Interest in this work is expected from research programme managers, impact managers and assessors, management consultants advising in this area, and government funding managers, all seeking to embed a developing approach to understand, capture, and enhance wider impact.

The report is the description of a project of designing and producing a bellmouth intake for the test run of Alison 250 C-10 D. The first phase of any design is the preliminary phase in which the data from manufacturer and other similar type project along with their result is evaluated to choose any particular design. Then comes the detailed design in which the design is optimised to meet the demands and every particular bit is looked at in this phase. Then the design is analysed very cautiously before passing it to the manufacturing phase. The method of manufacturing and the selection of material are carefully studied in this phase and then finally the design is manufactured.

The bellmouth intake is now, manufactured and is ready to assist the engine for the test run. This project report deals with all the required steps which were used to design and manufacture the intake. The performance of the design is well analysed all the above mentioned procedures are explained in full details in this project.

Abstract
Thresher machine is one of the agricultural machines that are used to separate the harvested grain from its stalk by hitting the stalk with rotary drum that have blade on it. The machine has a number of different components such as vertical stand frame (bars), horizontal bars, and gear driving pinion gear inside the gear box that is used to drive the whole system to operate, attached to pulleys, shafts, drum and spring. These components are faced to different type of loads and forces like shear force, compressive and tensile loads. The dimensions of and materials of the vertical and horizontal frames or bars were determining by assumption of an operator medium height. And the dimensions of the main parts like rack gear and spur gear and also the spring is determined by analyzing it to maximum bending, deflection and shear stress and loads produced on each of them. The pinion driving gear’s material and profile had been determined by designing due to the generated torque from the operator applied force.
The material for most of the components of this machine except for the pulleys, shafts and gears was supposed to be an iron for its availability.
The vertical and bars and some horizontal bars are made of angle iron (L shape) with dimension of standard from manufacturing at the length of 1000 mm and the horizontal bar has length of 600 mm, the gear has pitch diameter of 68 mm, module of 7, pressure angle of  full depth and 10 and 40 number of teeth.

Recent improvements in accuracy and efficiency of numerical simulation techniques in the field of engineering have led to an increasing interest in applying high-fidelity models for wind turbine design. Computational Fluid Dynamics (CFD) based on Reynolds-Averaged Navier-Stokes (RANS) equations in a co-rotating reference frame has shown promising results for performing design analysis. However, using high-fidelity techniques for wind turbine blade design optimization is not yet fully understood. Especially, high-fidelity aerodynamic shape optimization for wind turbine blades has not yet been employed in the industry due to its computational inefficiency when large number
of design variables are used with traditional techniques such as finite difference derivatives and gradient-free optimization methods.
This dissertation presents an efficient and robust high-fidelity aerodynamic shape optimization methodology for rotating flow problems. The high-fidelity optimization method consists of a multi-block, structured RANS-based CFD simulation tool, a discrete adjoint method, a shape parametrization method, a mesh perturbation technique and a gradient-based optimizer. Steady-state solutions are obtained by the RANS-based CFD analysis method based on a co-rotating reference frame. The turbulence model is a segregated one-equation SA model. Total derivatives of the flow solution and
constraint(s) are computed by a discrete adjoint method. For reducing the computational cost of computing partial derivatives that are required in the discrete adjoint method, forward automatic differentiation is used. Once the total derivatives and flow solution are computed, the gradient-based optimizer based on sequential quadratic programming computes a better design by using an augmented Lagrangian formulation with quasi-Newton approximations for the Hessian. The change in design variables obtained by the optimizer is parametrized with a Free Form Deformation (FFD) volume approach. After performing surface perturbations, the mesh is deformed using a hybrid mesh
deformation scheme, that combines an algebraic and linear elasticity method. The linear elasticity method based on finite elements is used for large perturbations, while the algebraic method attenuates small perturbations. When the optimality condition is satisfied, the iterative procedure ends with the optimal design.
Verification and validation of the developed codes are performed using the NREL VI wind turbine. The RANS-based CFD solver is validated by comparing numerical results with NREL VI sequence S experimental data. The solver resolves attached flow conditions accurately, while separated flow conditions lead to inaccurate flow solutions due to insufficient transition and turbulence modelling. DES can resolve the inaccuracy associated with separated flow conditions. Total derivatives of the adjoint method are verified by comparing derivatives of the complex and finite difference method. The quality of (perturbed) meshes are verified by using mesh quality metrics. Correct shape
parametrization is assured after careful examining the direction and magnitude of the deformations.
Since the NREL VI wind turbine blade rotates at a constant angular velocity, the power generation is considered to be only dependent on torque. Therefore, the objective of the optimization is maximizing the torque coefficient with shape, twist, and pitch design variables. Thickness constraints between 15% and 50% are added for representing a wing box. The thickness constraints impose thicknesses of the blade to increase only up to 300% of the original thickness. No reduction in thickness with respect to the baseline design at that region of the blade is possible in order to fit the original wing box. For future research, the objective and constraint function(s) can be easily adapted to more realistic and modern rotating flow problems.
From the aerodynamic shape optimization of the NREL VI blade, an increase of at least 22.4% in torque is achieved. The airfoil shapes tends to become more cambered and less thick. The nose of the airfoil is more aligned to the inflow. At root section of the wind turbine blade, the trailing edge of the airfoil acts as a flap in order to obtain higher loads at low relative velocity. Three different mesh refinements are employed for optimization. The first mesh is a coarse mesh that is used for verification purposes of the optimization procedure. The second mesh is employed for obtaining accurate aerodynamic shape optimization results. The final design variable values of the medium refined mesh are projected on the most refined mesh, because computational costs would be too
high for performing optimization. An increase of 29.1% in torque is achieved, indicating that the increase in optimized torque for more refined meshes will be higher when using coarser meshes. Since wind turbines are operating in a range of wind speeds, multipoint optimization from cut-in to rated wind speed is performed. Similar results as in single-point optimization are achieved. An increase of 22.2% in Annual Energy Production AEP is obtained. The adjoint method and high-fidelity aerodynamic shape optimization methodology allow designers to examine accurately the trade-off between various design variables at the early stage of the design process. For future research purposes, aerostructural and aeroelasticity optimization can be employed with the same framework.

This paper investigates by an energetic approach possible new configurations of aircrafts, which can rival in low speed operations against helicopters. It starts from an effective energy balance of helicopters during fundamental operations: takeoff, horizontal flight, hovering, and landing. The energy state of a helicopter can be written as: E = ½ mV 2 + mgh + ½ I ω 2 (1) where m is mass of helicopter, I is total rotor inertia, ω is rotor rotational speed. By taking the partial derivative with respect to time of equation 1, the power is expressed as dE/dt = ΔP = mV dV/dt + mg dh/dt (2) By optimizing the energy balance of the helicopter a new aircraft configuration has been obtained that allow a very high lift even at very low speed, but drastically reducing the energy consumption during horizontal flight. The total power required is obtained by rotor power and overall efficiency factor (η) and HP req total = η HP req rotor By equations (1) and (2) it has been produced a preliminary optimization in different operative conditions considering a speed range from 0.5 (hovering conditions) to 50 m/s. By an accurate balance of the results, it has been identified that the most disadvantageous situation for a helicopter is forward flight. A new powered wing architecture has been specifically studied for replicating the behaviour of helicopters. Preliminary it has been defined by starting from the energy equations the main characteristics of the propelled wing. From those numerical results it has been defined a new configuration of propelled wing and the new aircraft configuration which allow adequate performance against helicopter. Those wings take a large advantage of two not common features: symmetry with respect to a vertical axis and possibility of optimizing the shape for specific missions. It has been designed and optimized in different configurations by CFD. In particular, an accurate analysis of fluiddynamic of the system allows quantifying the different effects that allows realizing an extraordinary ratio between lift and thrust producing an effective vehicle that can rival against helicopter also at very low speeds with a morphing configuration that will be presented in the final paper because of patenting reasons. Results show that the proposed innovative aircraft configuration allows hovering and very low speed flight. In particular, the conditions and the design for this kind of operation are presented even if still in initial design stage. The presented aircraft architecture can also allow inverting the direction of motion just by inverting the direction of the thrust. In this case, it will allow overcoming completely the performances of helicopters. The energetic balance of flight has been evaluated and the advantages with respect to helicopters have been finally expressed with surprising results.

A Didactical Handbook on Math Methods for Physical Sciences. PhD Shawn D. Ryan is the only author; never me.
Redistributable under Creative Commons Alike Licence, for non profitable purposes.
Copyright  2015-2016 Dr. Shawn D. Ryan
PUBLISHED ONLINE
See the License for the specific language governing permissions and limitations under the License.
First published online, February 2016

Suspension bridges are longest span structures, however, the major problem of those structures are its stability under wind loads. The stability of those bridges depends majorly on aerodynamic forces and structural supporting system; this study worked on those two major axes.
Aerodynamic axis was to minimize aerodynamic forces by optimizing deck shape. Computational fluid dynamic (CFD) is an effective numerical tool for simulating flow around bridge deck, which was verified in the literature. six deck cross sections were studied – three elliptical deck shapes and three closed trusses-; their generated aerodynamic forces were compared with forces acting on Sutong Bridge and the best one was modelled as unsteady- state model for calculating flutter derivatives. The elliptical deck shape is found to generate the least static pressure and aerodynamic forces relative to the box and closed truss shapes; that proves, as deck shape get smoother aerodynamic forces generated by the deck reduces
Structural axis was to improve the stability of cable supporting system. A combination of three-dimensional suspension cable and cable-stay systems studied. Catenary theory was improved for determining three-dimensional suspension cable profile. Three models suspension bridge and eight models cable-stayed suspension cable were studied. The use of three-dimensional suspension cable improved critical wind speed..

This experiment analyzed the coefficients of lift, drag and moment about the quarter chord for the NACA 0024 airfoil for Reynolds Numbers of [4.1 x 105] and [5.1 x 105] corresponding to angles of attack ranging from -4 degrees to 14.5 degrees, at the L.A. Comp Wind Tunnel (University of Oklahoma, Norman). The data was compared to the data for the NACA 0012 airfoil as well as the data acquired from the thin airfoil theory to show correlation. The airflow was also analyzed using tufts of yarn attached to the model.

Small-scale vertical-axis wind turbines can be used as a source of electricity in rural and urban environments. According to the authors' knowledge, there are no validated simplified aerodynamic models of these wind turbines, therefore the use of more advanced techniques, such as for example the computational methods for fluid dynamics is justified. The paper contains performance analysis of the small-scale vertical-axis wind turbine with a large solidity. The averaged velocity field and the averaged static pressure distribution around the rotor have been also analyzed. All numerical results presented in this paper are obtained using the SST k-ω turbulence model. Computed power coefficients are in good agreement with the experimental results. A small change in the tip speed ratio significantly affects the velocity field. Obtained velocity fields can be further used as a base for simplified aerodynamic methods.

—The main objective of aircraft aerodynamics is to enhance the aerodynamic characteristics and maneuverability of the aircraft. This enhancement includes the reduction in drag and stall phenomenon. The airfoil which contains dimples will have comparatively less drag than the plain airfoil. Introducing dimples on the aircraft wing will create turbulence by creating vortices which delays the boundary layer separation resulting in decrease of pressure drag and also increase in the angle of stall. In addition, wake reduction leads to reduction in acoustic emission. The overall objective of this paper is to improve the aircraft maneuverability by delaying the flow separation point at stall and thereby reducing the drag by applying the dimple effect over the aircraft wing. This project includes both computational and experimental analysis of dimple effect on aircraft wing, using NACA 0018 airfoil. Dimple shapes of Semi-sphere, hexagon, cylinder, square are selected for the analysis; airfoil is tested under the inlet velocity of 30m/s and 60m/s at different angle of attack (5˚, 10˚, 15˚, 20˚, and 25˚). This analysis favors the dimple effect by increasing L/D ratio and thereby providing the maximum aerodynamic efficiency, which provides the enhanced performance for the aircraft.

Air Superiority Fighter is considered to be an effective dogfighter which is stealthy, highly maneuverable to surprise enemy along with improve survivability against the missile fire. This new generation fighter aircraft requires fantastic aerodynamics design, low wing loading (W/S), high thrust to weight ratio (T/W) with super cruise ability. Conceptual design is the first step to design an aircraft. In this paper conceptual design of an Air Superiority Fighter Aircraft is proposed to carry 1 crew member (pilot) that can fly at maximum Mach No of 2.3 covering a range of 1500 km with maximum ceiling of 61,000 ft. Payload capacity of this proposed aircraft is 6000 lb. that covers two advanced missiles & one advanced gun. The Air Superiority Fighter Aircraft was designed to undertake all the following missions like: combat air petrol, air to air combat, maritime attack, close air support, suppression, destruction of enemy air defense and reconnaissance.

CFD predictions of transitional flows and distributed roughness over a wind turbine airfoil to account for variable life cycle operational regimes are presented. The panel method code Xfoil 6.96 and the CFD commercial code Fluent 12.0.3 Beta are valuated for the prediction of 2D wind turbine airfoil aerodynamic performance. The aim of the work is to asses the accuracy of the various methods in the determination of integrated loads (i.e. Cl, Cd, L/D and Cm) for airfoils with both clean and rough surfaces that simulate contamination arising from wind turbine operational life.

Numerical data are compared to experimental results for the NREL S814 wind turbine airfoil. Xfoil and Fluent are used to predict the three states present in a wind turbine blade life cycle. The aerodynamic characteristics are calculated with transition and no roughness (also called clean configuration), with fully turbulent flow and no roughness and finally applying roughness under fully turbulent flow conditions. Validation cases are presented where computations are compared to experimental data for cases with locally distributed roughness at the leading edge of the airfoil. Roughness of this type simulates airfoil contamination by bugs, dirt or debris.

Results for smooth clean surfaces and fully turbulent flows (e.g. tripped boundary layer) are very similar for the two codes for attached or mildly separated flows. The transitional model (k-omega-gama-Re_theta) of Fluent gives reasonable results when compared to transition free experimental data and Xfoil computed with free transition. To account for roughness effects, the SST k-omega model modified to take into account surface roughness has been used in its Fluent version. CFD calculations, where roughness is modelled, are in good agreement with experimental data. It is shown that roughness originated from contamination has a more damaging effect on the aerodynamic performance than a boundary layer tripping. It is concluded that CFD can simulate all the variety of flows that an operational wind turbine airfoil can encounter throughout its life cycle.

Firstly the paper relates the scientific realization of psychrometric tables with wide ranges of temperatures and atmospheric pressures. Afterwards it offers the most important data according with the actual situation of investigation, and resolves the obtainment of original formulations of thermodynamic properties of moist air. The temperatures range selectioned is: From -50°C till 350°C. The altitudes range is: From -2400 m till 5000 m above sea level. The thermodynamic properties of moist air offered are: Humidity ratio, Enthalpy, Entropy, Exergy, Volume, Mixture density, Vapor pressure, Wet bulb temperature. The concordance with ASHRAE, HYLAND & WEXLER has been checked within the possible ranges. (For this work we have taken the HAAR, GALLAGHER & KELL data values for steam.)

In spite of the attractiveness of CFD methods and advanced measurement methods, there is still no full analysis of aerodynamic blade loads for vertical axis Darrieus-type wind turbines. Due to an inherently unsteady flow around the rotor blades, blade-wake-blade interaction and the occurrence of dynamic stall, the aerodynamics of this type of wind turbine is very complex. A two-bladed rotor have been investigated numerically for the tip speed ratio of 5.0. This paper compares results for aerodynamic blade loads obtained applying such turbulence models as: the standard k-ε; the RNG k-ε; the Realizable k-ε and the SST k-ω. As a result, quantitative instantaneous blade forces as well as instantaneous wake profiles behind the rotor have been obtained. Aerodynamic wake behind the rotor is also visualized by using streak lines. All CFD results are compared with experimental data taken from literature. Good agreement between the numerical results and the experiment is shown for the aerodynamic blade loads as well as for aerodynamic wake behind the rotor.

A new exergy-based formulation is derived for the  assessment of the aerothermopropulsive performance of civil aircraft. The choice of exergy is motivated by its ability to provide a well-established and consistent framework for the design of aerospace vehicles. The output of the  derivation process is an exergy balance between the exergy supplied by a propulsion system or by heat transfer, the mechanical equilibrium of the aircraft, and the exergy outflow and destruction within the control volume. The theoretical formulation is subsequently numerically implemented in a Fortran code named ffx for the post-processing of CFD-RANS flow solutions.
Unpowered airframe configurations are examined with grid refinement studies and a turbulence model sensitivity analysis is performed. A numerical correction is introduced and calibrated to obtain an accuracy similar to the near-field drag method. The code is thereby validated against well-tried methods of drag prediction and wind-tunnel tests, when available.
The investigation of powered configurations demonstrates the ability of the approach for assessing the performance of configurations with aerothermopropulsive interactions. First, the formulation is validated for the simple case of a turbojet engine for which consistent figures of merit are exhibited. The method is also proved robust for assessing the overall performance of a boundary layer ingesting propulsion system placed on the upper surface of a simplified blended wing-body architecture. Moreover, this configuration enables the investigation of thermopropulsive interactions by the transfer of heat upstream of the propulsion system.
Subsequently, the integration of a heat exchanger on a commercial aircraft is examined for which the exergy point of view provides guidelines for an efficient design. The ability of the formulation to consistently assess all these types of subsystems is a clear benefit of this method.

This work is on the aerodynamics design of the body and frame of a motor tricycle using SolidWorks 2011 modeling system. Its Computational Fluid Dynamics (CFD) feature was used to run simulation tests at a target speed of 150 km/h to evaluate the aerodynamic performance of the tricycle. Simulation results presented shows that lift and drag forces are diminished considerably and that 170 km/h is the maximum speed to be traveled by the tricycle for a smooth and stable ride. Also, the design reduced drastically the effects of lift and drag forces, increased the tricycle’s stability, traction and performance as well as minimized the weight of the tricycle as a result of the use of high performance to mass ratio materials such as carbon fiber for the body and alloy steel for the frame and rims.