Session 3: Low-speed wind tunnel testing

**Chair: Huub Timmermans, Netherlands Aerospace Centre**Analysis and Testing of the Pazy Benchmark WingThe Pazy wing is an aeroelastic benchmark wing design to explore nonlinear aeroelastic phenomena due to large deformations and gather data for model validation. The Pazy wing was tested in the low-speed wind tunnel at the Technion at static loading conditions that led to deformations in the order of the wing's semispan. The wing underwent limit cycle oscillations at some airspeed and angle of attack combinations. The talk will review the Pazy wing's design, the analyses conducted using the Modal Rotation Method, the test results, and insight into the wing's nonlinear aeroelastic behavior. Active Aeroelastic Wind Tunnel ExperimentsAeroelastic research has become very multidisciplinary involving various disciplines such as flight dynamics, control theory, morphing, novel aircraft, wing and movable concepts, just to mention a few. As a result aeroelastic tests have also grown in scope and complexity to provide validation data for the modelling and design methodologies. This talk will present some of the recent active aeroelastic tests conducted in TU Delft including the test design, hardware and software development and the main outcomes. In the end also the lessons learnt and the outlook will be elaborated.Optical Measurement Techniques for Wind Tunnel Testing of Flexible WingsOptical measurement technology has been gaining more and more traction in aerodynamic wind tunnel testing in recent years. Making these techniques available for the aeroelastic testing of flexible wings has a high potential but comes with certain challenges. This talk will present results from the application of optical measurement techniques to a highly flexible benchmark wing and will discuss the current limitations and potential improvements for the future of aeroelastic wind tunnel testing.Design and testing of subscale models of very flexible wings: lessons learntThe modelling, designing and testing of subscale flexible models present new challenges that did not exist for rigid models. These aspects, which characterise the model's behaviour, often lead to the nonlinear response of the model, which is difficult to predict and to replicate with consistency in the wind tunnel. This presentation will focus on the different elements that characterise the design of such flexible wings, from the design of the test matrix and prediction of the nonlinear behaviour of the model to more minor but essential aspects of the design, such as the impact of panel gaps, instrumentation layout and manufacturing technologies. Examples of different models will be presented to detail various approaches to the problem, stressing the benefits and limitations of the different techniques.