Wind Tunnel Model Design Research Articles

Low Observable Uncrewed Aerial Vehicle Wind Tunnel Model Design, Manufacturing, and Aerodynamic Characterization

Developing wind tunnel models is time consuming, labor intensive, and expensive. Rapid prototyping for wind tunnel tests is an effective, faster, and cheaper method to obtain aerodynamic performance results while considerably reducing acquisition time and cost for the models. Generally, the rapid prototyping models suffer from insufficient stiffness or strength to withstand the loads generated during a wind tunnel test. In the present study, a rapid prototype model reinforced with metallic inserts was produced to experimentally investigate the aerodynamic characteristics of an uncrewed aerial vehicle with various wingtip deflections. The fused deposition modeling process was used to make the outer mold, whereas the metallic parts were produced using laser cutting and the computer numerical control machining process. Then, the model was evaluated both experimentally and numerically. The test campaign presented in this work was conducted in the de Havilland low-speed wind tunnel facility at the University of Glasgow. For better characterization of flow patterns dominated by leading edge vortices, numerical simulations were run using OpenFOAM 8.0 and validated with experimental data. The experimental data obtained from the hybrid rapid-prototyped model agreed well with the numerical results. This demonstrates the efficacy of hybrid rapid-prototyped models in providing reliable results for initial baseline aerodynamic database development within a short period and at a reduced cost for wind tunnel tests.

Aeroservoelastic Wind Tunnel Evaluation of Preview and Gust Load Alleviation

Studies of preview gust load alleviation and controllers via synthesis, simulation, wind tunnel tests, and test/simulation correlation are presented in this paper. University of Washington active aeroservoelastic wind tunnel model design, construction, and testing capabilities are used. The test article is a flexible half wing–body–tail model with active control surfaces of two ailerons and an elevator. The model moves in a combination of rigid-body and elastic motions. The commands of gust vanes are used both to generate gusts and to provide real-time preview gust encounter information. A discrete-time linear-time-invariant output feedback system is augmented with various preview lengths of information. The experimental results show that gust loads are reduced with gust preview information compared to feedback-only control and are halved with the fullest gust preview information compared to the open-loop case. The wind tunnel results validated the simulations and added insights to the performance of preview and control implementation. The closed-loop analysis quantified the margins and robustness of the systems and correlated with the time history of both simulations and experiments. This paper presents preview gust load alleviation robust control test results, not available so far, in a realistic experimental setting.

Wind Tunnel Model Design and Aeroelastic Measurements of the RIBES Wing

AbstractSeveral experimental databases of aeroelastic measurements performed on aircraft wing models are available for the validation of fluid–structure interaction (FSI) numerical methodologies. M...

Different fidelity computational models in aeroelastic design of aircraft and WT models

Abstract Using of different fidelity computational models and relations between them in the multidisciplinary design system is considered. A structural design procedure and optimization methods for aeroelastic design of aircraft and wind tunnel models are discussed. An application of the topology-based optimization together with the two-level structural sizing method is considered. Main stages of the approach to synthesis of structural layouts of aircraft components are described. Some numerical examples of analysis and aero-structural optimization of aircraft wings are considered to demonstrate the proposed methods and algorithms. The accuracy, reliability and efficiency of using of the considered structural models at design studies are discussed.

Design and construction of aeroelastic wind tunnel models

AbstractThe design and building of accurately scaled aeroelastic wind-tunnel models is difficult, time consuming and very costly. With the increasing usefulness of computational methods for predicting aeroelastic phenomena, few complex models have been built in recent years. New fighter aircraft projects are also becoming more and more scarce, and transport aircraft have essentially the same configuration since half a decade. This also significantly reduces the need for aeroelastic wind-tunnel models. However, there still is an interest in the results from aeroelastic testing. In some cases new and radical configurations may warrant wind-tunnel testing and in other cases complex phenomena arising in fight testing may need carefully performed experiments to resolve problems. However, there is definitely a trend towards building models and performing testing in the support of the development of computational methods.The developments in computer technology do not only improve the computational methods for aeroelasticity. Modern Computer Aided Design and Manufacturing techniques can significantly improve the quality and efficiency of the design and build process for aeroelastic models. There have also been some recent improvements in measurement techniques which have proven very useful for testing of aeroelastic wind-tunnel models. The paper will present some new design and build techniques developed for the manufacturing of a large scale wind-tunnel model of a canard delta wing fighter aircraft configuration. In the build process fiber-reinforced composites will be used, hence, challenges and possible solutions concerning the ability to produce a model with well defined material properties and fiber angles will be discussed. Further challenges arise when both measurement equipment and adjustable control surfaces should be attached inside the model using techniques that are possible to describe with computational methods. In addition, equipment, such as pressure taps, and control surface mechanics need to fit and function in a flexible structure. As a result, the above requirements will lead to necessary compromises in the design, hence, the paper will present the choices taken during the build process and for which reasons. The use of an optical positioning measurement system will also be discussed for both the validation of model properties and non-contact measurement of model deformations during wind-tunnel testing.

Effect of steps and gaps on aerothermodynamics for the IXV hypersonic vehicle

The general aerothermodynamics environment of hypersonic vehicles is usually performed considering a smooth simplified geometry. However, in the case of the intermediate experimental vehicle (IXV), the thermal protection system includes a mono-block ceramic matrix composite nose and an assembly of shingles between which steps and gaps are generated. From an aerothermodynamic point of view, such a distributed roughness layout cannot be ignored in terms of modification of the interaction between the flow and the body and possible induced transition along the windward side. To assess these effects, dedicated wind tunnel tests and numerical simulations have been performed. This paper presents the general logic of the work, with emphasis on the wind tunnel model design, tests involving infrared thermal measurements as well as the computational fluid dynamics (CFD) rebuilding of the flow in the wind tunnel and the extrapolation from ground to flight.

Rapid Technique for Wind-Tunnel Model Manufacture

Introduction I N wind-tunnel-based experimental aerodynamic projects a substantial proportion of project resources in terms of both time and cost is consumed by the design and manufacture of wind-tunnel models. This can limit the scope of experiments and cause long lead times. Thus, methods that can expedite the model-building process are highly beneficial. The manufacture of wind-tunnel models has traditionally been a highly skilled and time-consuming process.1 By their nature aerodynamic bodies can have complex three-dimensional curvature and often the experiment requires internal details such as the provision for surface-pressure tappings. Thus, wind-tunnel models are often constructed from a number of parts, which require accurate fitting and hand finishing to obtain the necessary high surface finish. Ideally, the wind-tunnel experiment is an integral part of the design process, which may call for a prescribed range of model configurations to be tested, or alternatively for the iterative optimization of a particular feature of the model. In the former case the range of configurations that can be tested is limited by the cost of each model and in the latter case by the speed at which a model feature can be changed. A number of studies2−5 have demonstrated the advantages of rapid prototyping techniques for building wind-tunnel models in speed and cost relative to traditional techniques. Dimensional tolerances and surface finish may be inferior, which in turn increases experimental uncertainty, but nevertheless the method is quite adequate for preliminary studies. In this Note we outline the use of rapid prototyping for producing wind-tunnel models with internal features. A most advantageous aspect of the rapid-prototyping method is the ability to produce internal forms, that would be difficult to design and manufacture by traditional techniques. Rapid-prototyping technology is reviewed briefly in context and two case studies from the work of the authors are presented.

Aeroelastic model design using parameter identification

Wind-tunnel model design can be very involved, so an approach has been developed that uses optimization methods to automate it. The model design process has been divided into separate stiffness design and mass design stages. Then, a sample structure was manufactured and subjected to static and modal testing using laser holographic techniques. The predicted flutter response of the model matches the predicted flutter response of the full-scale wing very closely. Nomenclature c = element of calculated flexibility matrix F = objective function g = constraint K = stiffness matrix k = proportionality constant M = mass matrix m = total mass x = element of eigenvector matrix 8 = element of target flexibility matrix a) = natural frequency

Errata: Minimum Induced Drag for Wings with Spanwise Camber

French, R. M., An Application of Structural Optimization in Wind Tunnel Model Design, 1990 SDM Conf., AIAA Paper 900956-CP, Long Beach, CA, April 1990. French, R. M., and Kolonay, R. M., An Application of Compound Scaling to Wind Tunnel Model Design, Third Air Force/ NASA Symposium on Recent Advances in Multidisciplinary Analysis and San Francisco, CA, Sept. 1990. Neill, D. J., Johnson, E. H., and Canfield, R. A., ASTROS— Multidisciplinary Automated Structural Design Tool, AIAA Paper 87-0713, Monterey, CA, April 1987. Rogers, W. A., Braymen, W. W., Murphy, A. C., Graham, D. H., and Love, M. H., Validation of Aeroelastic Tailoring by Static Aeroelastic and Flutter Tests, Air Force Wright Aeronautical Lab. TR-81-3160, Wright-Patterson AFB, OH, Sept. 1981. Vanderplaats, G. N., An Efficient Feasible Directions Algorithm for Design Synthesis, AIAA Journal, Vol. 22, No. 11, 1984, pp. 1633-1640. Venkayya, V. B., and Tischler, V. A., A Compound Scaling Algorithm for Mathematical Optimization, Wright Research and Development Center TR-89-3040, Wright-Patterson AFB, OH, Feb. 1990. Venkayya, V. B., Tischler, V. A., Kolonay, R. M., Canfield, R. A., A Generalized Optimality Criteria for Mathematical Optimization, AIAA Paper 90-1192, Long Beach, CA, April 1990.

Demonstration of structural optimization applied to wind-tunnel model design

Demonstration of structural optimization applied to wind-tunnel model design