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Category: Aerodynamic shape optimization

Aerodynamic shape optimization

The graphical user interface GUI provides a toolbox for pre- and post-processing. In preliminary design, the designer typically needs to modify the aircraft shape many times to explore the design space. Therefore, the aircraft model in Aeolus ASP is fully parametric and provides direct access to geometry parameters, making it very simple to apply changes and re-run analysis within seconds.

Post-processing features particularly include 3D surface pressure plots, surface flow vectors, flight mechanics properties, tabulated forces and performance indicators as well as plots of all major aerodynamic coefficients. A built-in optimization feature has been developed for Aeolus ASP taking advantage of the computational efficiency and the parametric design.

With only a few clicks you can set-up your optimization problem and automatically search the design space for the best solution.

Mode ling. Aerodynamic Analysis and Optimization. Aeolus ASP. Free Download. What is Aeolus ASP? Built-in Shape Optimization. Key Features. Blend radius feature for winglets and non-planar wings Nacelle feature Symmetric and asymmetric wings Propellers compressor or turbine mode, single- or multi blade. Parameter Studies and Optimization Understanding the impact of model parameters using the Parameter Study Feature Optimization of arbitrary model parameters, including wing shape, flight condition, and discretization.

Optimize for different objectives, including lift-to-drag, longitudinal stability, centre of gravity, aerodynamic center, and many more. Learn More.

aerodynamic shape optimization

This website uses cookies. Cookies improve the user experience and help make this website better. By continuing to use the site, you agree to our cookie policy: More details here: Cookie Policy Ok.Aerodynamic shape optimization driven by high-fidelity computational fluid dynamics CFD simulations is still challenging, especially for complex aircraft configurations.

The main difficulty is not only associated with the extremely large computational cost, but also related to the complicated design space with many local optima and a large number of design variables. Therefore, development of efficient global optimization algorithms is still of great interest. This study focuses on demonstrating surrogate-based optimization SBO for a wing-body configuration representative of a modern civil transport aircraft parameterized with as many as 80 design variables, while most previous SBO studies were limited to rather simple configurations with fewer parameters.

The freeform deformation FFD method is used to control the shape of the wing. Kriging is used to build a surrogate model for the drag coefficient, which is to be minimized, based on the initial samples. The surrogate model is iteratively refined based on different sample infill strategies.

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For 80 design variables, the SBO-type optimizer is shown to converge to an optimal shape with lower drag based on about samples. Several studies are conducted on the influence of the resolution of the computational grid, the number and randomness of the initial samples, and the number of design variables on the final result.

This research work was sponsored by the German national aeronautics research project AeroStruct. Skip to main content. Advertisement Hide.

aerodynamic shape optimization

Symposium on AeroStructures. Conference paper First Online: 31 January This is a preview of subscription content, log in to check access. Acknowledgements This research work was sponsored by the German national aeronautics research project AeroStruct.

Hicks, E. Munnan, G. Hicks, P. Henne, Wing design by numerical optimization. Jameson, Aerodynamic design via control theory. Reuther, A.The development of high strength concrete, higher grade steel, new construction techniques and advanced computational technique has resulted in the emergence of a new generation oftall structures that are flexible, low in damping, slender and light in weight.

These tall structures are sensitive to dynamic wind loads. Due to high slenderness, low natural frequencies, low inherent damping levels and high wind speeds at upper level, super-tall buildings are susceptible to wind excitations, particularly to vortex-induced oscillations.

It is well known that the behavior of wind response is largely determined by building shapes. Considerations regarding aerodynamic optimization of building shapes in early architectural design stage is proved to be the most efficient way to achieve in windresistant design. Wind-resistant design and aerodynamic optimization are the modern topics in building design community.

However, its practice and successful example can be traced back a long time ago. In ancient China, tall buildings appear to be those of traditional pagodas. Some of them even meet the modern definition of slenderness for super-talls Fig.

The tallest one is The two identical shorter pagodas have a height of After the completion of these pagodas, a monastery was built. Over the long period of extreme climates and natural disasters, the original monastery was completely destroyed by natural forces but the pagodas have miraculously survived. In addition to extremely strong earthquakes in and the pagodas also experienced strong winds in history.

These surviving ancient structures at least reveal two important facts which are helpful even for modern design practice.

Aerodynamic Shape Optimization of a Vertical-Axis Wind Turbine Using Differential Evolution

A structure which is immersed in a given flow field is subjected to aerodynamic forces. For typical tall buildings, aerodynamic forces includes are drag along-wind forces, lift across-wind forces and torsional moments. The alongwind forces act in the direction of the mean flow.

The alongwind motion primarily result from pressure fluctuations on windward and leeward faces and generally follows fluctuations in the approaching flow. The crosswind forces act perpendicular to the direction of mean wind flow. The torsional motion is developed due to imbalance in the instantaneous pressure distribution on each face of the building.

In other words, if the distance between elastic center of the structure and aerodynamic center is large, the structure is subjected to torsional moments that may significantly affect the structural design.

It has been recognized that for many high-rise buildings, the crosswind and torsional responses may exceed the along wind response in terms of both limit state and serviceability designs. For wind-resistant design of buildings, it is important to identify the type of wind response that governs the design.

The plot indicates that for along-winds i. For across-wind directions i. The main reason that the across-wind loads can dominate the design of super-tall buildings is explained in Fig. Compared with alongwind response, across-wind response is more sensitive to wind speed. At lower wind speeds, the along-wind loads normally dominate but with increase of wind speed the acrosswind loads take over. Due to relatively lower natural frequencies of super-tall buildings or longer natural periods ,in addition to higher wind speeds at upper levels of the boundary layer, the reduced frequency of a super-tall building at design wind speed can be very close to the reduced frequency where the peak of the across-wind force spectrum occurs.

The approaches of aerodynamic optimization would be different when dealing with along-wind or across-wind responses.Aerospace collectively represents one of the most sophisticated technological endeavors and largest markets in the world. Coming with substantial costs, nearly every aspect of the industry, from aircraft design to material selection to operation, has been optimized in at least one way.

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A critical design consideration in any aircraft is its three-dimensional wing shape; this will be explored as an example of optimization's role and importance in industry. In designing the wing of an airplane, several fluid dynamic concepts come into play. The two most prominent ones are lift and drag, which correspond to a wing's ability to fly the airplane against gravity without wasting energy by moving forward.

The behavior of an airfoil, or cross-section, of wings in air is thoroughly studied to make efficient airplanes. Secondly, the overall shape of the wing can be optimized as well. Considerations generally include lift and drag, as with the airfoil, but also noise and stability. Some of the earliest wing optimization attempts can be traced back to the late s. Newton applied variational calculus to drag minimization problems. The next leap in the field, however, didn't come until the s when numerical solutions became available with advances in hardware.

The 70s saw the application of gradient-based models for aerodynamic shapes, solving for up to 11 different variables in a three-dimensional design space. Later methods used the Stokes flow equations with Euluer's incompressible medium equations to solve for sing airfoils or cross-sections. When iterative computational fluid dynamics CFD became feasible for small-mesh models, the solutions became even more robust [1].

Because of the limited types of aircraft missions military and commercialtwo main wing platforms dominate the design space. Most commercial and military aircraft adopt this wing style, where wings are separate from and extend out of the fuselage. This wing orientation, unlike the blended wing body, typically allows for faster speeds which improve lift at the expense of smaller wings which typically hinder lift. The blended wing body configuration is highly fuel efficient as it maximizes the lift of the entire airplane while also improving cabin size.

Therefore, the commercial implications of this design are drastic. The military has already begun using this platform in the iconic B-2 bombers, along with several smaller drones. A popular enhancement on traditional wing design is the 'winglet. Since extending the length of the wing allows for significantly more area and improves stability, this constraint is almost always active.

To continue getting more wing "length" while allowing planes to fit in the airport gates, winglets were quickly introduced. Even when meeting the numerous technical requirements to make an operable wing, there are several ways of gauging performance.

The lift coefficient,corresponds to the wings' ability to keep a given weight,at a horizontal cruising speed, called the stall speed.

For commercial flights, higher lift coefficients of rouhgly 3. Military aircraft, by contrast, are willing to sacrifice their lift coefficients, going as low as 1. Unlike commercial airplanes, military pilots usually have an eject seat so losing power is non-fatal making maximum speed more valuable than reliable flight.

Another performance consideration is stability.The purpose of this study is to introduce and demonstrate a fully automated process for optimizing the airfoil cross-section of a vertical-axis wind turbine VAWT. The objective is to maximize the torque while enforcing typical wind turbine design constraints such as tip speed ratio, solidity, and blade profile.

By fixing the tip speed ratio of the wind turbine, there exists an airfoil cross-section and solidity for which the torque can be maximized, requiring the development of an iterative design system.

The design system required to maximize torque incorporates rapid geometry generation and automated hybrid mesh generation tools with viscous, unsteady computational fluid dynamics CFD simulation software.

The flexibility and automation of the modular design and simulation system allows for it to easily be coupled with a parallel differential evolution algorithm used to obtain an optimized blade design that maximizes the efficiency of the wind turbine. As the world continues to use up nonrenewable energy resources, wind energy will continue to gain popularity.

A new market in wind energy technology has emerged that has the means of efficiently transforming the energy available in the wind to a usable form of energy, such as electricity.

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The cornerstone of this new technology is the wind turbine. A wind turbine is a type of turbomachine that transfers fluid energy to mechanical energy through the use of blades and a shaft and converts that form of energy to electricity through the use of a generator.

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Depending on whether the flow is parallel to the axis of rotation axial flow or perpendicular radial flow determines the classification of the wind turbine. Two major types of wind turbines exist based on their blade configuration and operation.

The first type is the horizontal-axis wind turbine HAWT. This type of wind turbine is the most common and can often be seen littered across the landscape in areas of relatively level terrain with predictable year round wind conditions.

HAWTs sit atop a large tower and have a set of blades that rotate about an axis parallel to the flow direction. These wind turbines have been the main subject of wind turbine research for decades, mainly because they share common operation and dynamics with rotary aircraft.

The second major type of wind turbine is the vertical axis wind turbine VAWT. This type of wind turbine rotates about an axis that is perpendicular to the oncoming flow, hence, it can take wind from any direction.

The Darrieus wind turbine is a VAWT that rotates around a central axis due to the lift produced by the rotating airfoils, whereas a Savonius rotor rotates due to the drag created by its blades. There is also a new type of VAWT emerging in the wind power industry which is a mixture between the Darrieus and Savonius designs.

Recently, VAWTs have been gaining popularity due to interest in personal green energy solutions. Small companies all over the world have been marketing these new devices such as Helix Wind, Urban Green Energy, and Windspire. VAWTs target individual homes, farms, or small residential areas as a way of providing local and personal wind energy.

aerodynamic shape optimization

This reduces the target individual's dependence on external energy resources and opens up a whole new market in alternative energy technology. Because VAWTs are small, quiet, easy to install, can take wind from any direction, and operate efficiently in turbulent wind conditions, a new area in wind turbine research has opened up to meet the demands of individuals willing to take control and invest in small wind energy technology.

The device itself is relatively simple. With the major moving component being the rotor, the more complex parts like the gearbox and generator are located at the base of the wind turbine. This makes installing a VAWT a painless undertaking and can be accomplished quickly.

aerodynamic shape optimization

Because of the VAWTs simple manufacturing process and installation, they are perfectly suited for residential applications. The VAWT rotor, comprised of a number of constant cross-section blades, is designed to achieve good aerodynamic qualities at various angles of attack.

Unlike the HAWT where the blades exert a constant torque about the shaft as they rotate, a VAWT rotates perpendicular to the flow, causing the blades to produce an oscillation in the torque about the axis of rotation.

This is due to the fact that the local angle of attack for each blade is a function of its azimuthal location. Because each blade has a different angle of attack at any point in time, the average torque is typically sought as the objective function.

Even though the HAWT blades must be designed with varying cross-sections and twist, they only have to operate at a single angle of attack throughout an entire rotation. However, VAWT blades are designed such that they exhibit good aerodynamic performance throughout an entire rotation at the various angles of attack they experience leading to high time averaged torque. The majority of wind turbine research is focused on accurately predicting efficiency.

Aerodynamic Shape Optimization of Natural-Laminar-Flow Wing Using Surrogate-Based Approach

Various computational models exist, each with their own strengths and weaknesses that attempt to accurately predict the performance of a wind turbine. Descriptions of the general set of equations that the methods solve can be found in Section 2. Being able to numerically predict wind turbine performance offers a tremendous benefit over classic experimental techniques, the major benefit being that computational studies are more economical than costly experiments.

A survey of aerodynamic models used for the prediction of VAWT performance was conducted by [ 12 ].Simulation engineers from the aerospace, automotive or turbomachinery sector are interested in finding optimal designs with superior performance but also with a high robustness in terms of operating points.

Thanks to the affordable hardware resources, engineers can now scale their design process with a few clicks to explore hundreds or even thousands of design variants.

This article now focuses on giving you a rather quick and practical guide to shape optimization with CFD Computational Fluid Dynamics and other simulation tools. In many organizations, the existing CAD models of their products e.

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However, when it comes to variable geometry that needs to be robust and ready for an optimization loop, many of the traditional CAD systems fail at some stage. The regeneration of geometry sometimes unexpectedly breaks or returns an error. The reason could be as an example a failing intersection or filleting process. This is only one bottleneck. If you have to automatically create a mesh for new design candidates, all face IDs e.

So, the first thing you need is a parametric model of your product that is ready for automation. If you have to pick a CAD software or geometry modeler, you should ideally consider the following issues:. Make sure you use flexible parametric technologies and tools that are geared towards automation. Note that some of the CAD tools on the market were initially not made for this task or do not target such a design process at all.

As an aerodynamic engineer, you should be able to quickly build innovative new ideas into your geometry model e. This is important especially for the long-term competitiveness of your product. Your CAD tool should give you smart techniques for parameter reduction, to minimize the overall simulation time in the optimization. This can be either smart parametric modeling techniques or integrated methodologies such as PCA Principal Component Analysisetc.

The face IDs and names are preserved for all generated designs to automate the meshing and simulation. This is required e. The geometry constraints are automatically satisfied for each design. This includes cross-section areas, thicknesses, and minimum distances packagingetc. For these tasks, your CAD tool needs to offer integrated optimization methods that can be used for defining geometry.

Finally, a few CAE tools expect good-quality STL geometry so you need some controls for the exported surface mesh quality.

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Assign color and triangulation settings for each individual surface patch. Once you have the geometry ready for automation, you need to decide on your meshing and simulation strategy.Search for more papers by this author. Aerodynamic shape optimization of a swept natural-laminar-flow wing in the transonic regime is still challenging. The difficulty is associated with reliable prediction of laminar—turbulence transition and reasonable compromise of viscous and wave drags. This paper proposes to use efficient global optimization based on surrogate models to address this problem.

The Reynolds-averaged Navier—Stokes flow solver features automatic transition prediction via a full e N method, in which dual N factors are used for Tollmien—Schlichting and crossflow instabilities, respectively. The optimizer is based on the kriging surrogate model and parallel infill-sampling method.

The baseline natural-laminar-flow wing for short- and medium-range transport aircraft is designed at a cruise Mach number 0. Then, drag minimization with up to 42 design variables is carried out, and significant drag reduction 8. A close examination of the optimal wing shows that the drag reduction mainly comes from shock-wave weakening on the upper surface and laminar flow extending via suppression of crossflow instability on the lower surface.

Robustness of the optimal wing is investigated, and multipoint optimization is further exercised to improve the robustness to the Mach number variation. It is demonstrated that surrogate-based optimization is feasible and effective for aerodynamic shape optimization of transonic natural-laminar-flow wings.

Mach number. Reynolds number based on airfoil chord or mean aerodynamic chord of wing. Table 4 Results of multipoint optimization for transonic NLF wing. All rights reserved. All requests for copying and permission to reprint should be submitted to CCC at www. Special thanks goes to Jun Liu, who has contributed a lot to the optimization code during his Ph.

The authors are grateful for the thoughtful comments and valuable suggestions given by the anonymous reviewers. Skip to main content. Volume 56, Issue 7. Open Access Regular Article. Box. Member AIAA. Tools Add to favorites Download citation Track citations. Abstract Aerodynamic shape optimization of a swept natural-laminar-flow wing in the transonic regime is still challenging.

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