Managing the costs of system unavailability in long-term maintenance contracts for hydraulic structures

Construction Management and EngineeringStructural EngineeringCivil Engineering and Geoscience

Aerodynamic and Static Coupling Simulations of the Pazy Wing with Transitional CFD for the Third Aeroelastic Prediction Workshop

The Pazy Wing test case is a benchmark for the investigation of aeroelastic effects at very large deflections. Tip deformations in the order of 50% span were measured in wind tunnel tests which renders this model highly attractive for the validation of numerical aeroelastic methods and tools for geometrically nonlinear, large deflection analyses. The present work is focused on high fidelity aerodynamic and aeroelastic simulations of the wing using RANS and URANS with transition modeling in order to capture nonlinear effects originating from the shape of the wing and the low Reynolds number. Steady and unsteady aerodynamic as well as static coupling simulations with a nonlinear structural model are presented, the impact of the different transition and turbulence modeling techniques is depicted. This work supports the Large Deflection Working Group (LDWG), which is one of the sub-groups of the 3rd Aeroelastic Prediction Workshop (AePW3).Aerodynamic

An Avionics Touch Screen based Control Display Concept

In many cockpits, control display units (CDUs) are vital input and information devices. In order to improve the usability of these devices, Barco, in cooperation with TU-Delft, created a touch screen control unit (TSCU), consisting of a high-quality multi-touch screen. The unit fits in the standard dimensions of a conventional CDU and is thus suitable for both retrofit and new installations. The TSCU offers two major advantages. First, the interface can be reconfigured to enable consecutive execution of several tasks on the same display area, allowing for a more efficient usage of the limited display real-estate as well as a potential reduction of cost. Secondly, advanced graphical interface design, in combination with multi-touch gestures, can improve human-machine interaction. To demonstrate the capabilities of this concept, a graphical software application was developed to perform the same operations as a conventional CDU, but now using a direct manipulation interface (DMI) of the displayed graphics. The TSCU can still be used in a legacy CDU mode, displaying a virtual keyboard operated with the touch interface. In addition, the TSCU could be used for a variety of other cockpit functions. The paper concludes with a report of pilot and non-pilot feedback.Control and OperationsAerospace Engineerin

CFD Simulations of the Pazy Wing in Support of the Third Aeroelastic Prediction Workshop

The Pazy Wing test case is a benchmark for the investigation of aeroelastic effects at very large deflections. Tip deformations in the order of 50% span were measured in wind tunnel tests, which renders this model highly attractive for the validation of numerical aeroelastic methods and tools for geometrically nonlinear, large deflection analyses. Due to the low flow velocity (up to 60 m/s) and the simple geometry of the wing, simulation programs based on subsonic, linear potential aerodynamic solvers (such as VLM and UVLM) are an ideal basis for static coupling and flutter simulations. However, more comprehensive analyses with focus on aerodynamic nonlinearities such as stall and limit cycle oscillations (which have been observed in several wind tunnel tests) are attractive research topics but call for advanced aerodynamic methods. The present work is thus focused on high fidelity aerodynamic simulations of the Pazy Wing using RANS with transition modeling in order to capture nonlinear effects originating from the particular shape of the wing and the low Reynolds number. It is a collaborative activity of DLR, NASA, and TU Delft and supports the Large Deflection Working Group (LDWG), which is one of the sub-groups of the 3rd Aeroelastic Prediction Workshop (AePW3).Aerodynamic

Vers les Pays Vert: The metamorphosis of Charleroi territory

The territory is the result of several and simultaneous process of transformations, that independently from intensity and quality leave behind some traces. An a posteriori observation of these remains as inert and latent spaces in the territory enables the comprehension of what resists to the flow of time, what adapts or opposes itself to it. Therefore, this paper is based on idea of study the transformation of the territory, by observing the present situation, in which past and future converge. Reading the metamorphosis of the Charleroi region, by starting from the observation of the signs left on the territory is not a linear process. In less than a century, indeed, Charleroi region has been strongly manipulated to host the mining, glass and steel industries. Only after the second world war the long decline of this territory begun. Several successive phases of transformation and the decline of the mining, glass and steel industries have radically changed Charleroi’s territory, leaving a legacy of different levels of abandoned spaces. However, sixty years of abandonment slowly and silently changed these spaces, allowing the infiltration of ruderal vegetation, new form of appropriation and consequently supposing the beginning of a new life cycle for the region. In order to address this issue, the paper is divided in two main parts. In the first part the article briefly reconstructs the transformations of the industrial productions of Charleroi starting from the traces left on the territory. Finally, the second part aims to observe these traces from an ecological perspective, highlighting a different value.Environmental Technology and Desig

Non-intrusive determination of the unsteady surface pressure and aerodynamic loads on a pitching airfoil

The unsteady surface pressure distribution and aerodynamic loads on a pitching airfoil are determined non-intrusively using PIV measurements. An experimental test case is considered where the flow around the airfoil is mostly attached while the unsteady effects on the aerodynamic loads are significant. The surface pressure is calculated from the flow velocity measurements in the vicinity of the airfoil surface, that are obtained with a robotic PIV system, by using relations from unsteady potential flow and thin airfoil theory. The proposed approach is a robust and computationally efficient approach to obtain non-intrusive measurements of the unsteady surface pressure distribution and the aerodynamic loads, that are in good agreement with reference data from installed pressure transducer sensors.AerodynamicsAerospace Structures & Computational Mechanic

Optimisation of Differential Infrared Thermography for Unsteady Boundary Layer Transition Measurement

Differential infrared thermography (DIT) is a method of analyzing infrared images to measure the unsteady motion of the laminar–turbulent transition of a boundary layer. It uses the subtraction of two infrared images taken with a short time delay. DIT is a new technique which already demonstrated its validity inapplications related to the unsteady aerodynamics of helicopter rotors in forward 2ight. The current study investigates a pitch–oscillating airfoil and proposes several optimizations of the original concept. These include the extension of DIT to steady test cases, a temperature compensation for long–term measurements,and a discussion of the proper infrared image separation distance. The current results also provide a deeper insight into the working principles of the technique. The results compare well to reference data acquired by unsteady pressure transducers, but at least for the current setup DIT results in an additional measurement–related lag for relevant pitching frequencies.Aerodynamic

Experimental characterization of an unsteady laminar separation bubble on a pitching wing

The laminar separation bubble (LSB) that forms on the suction side of a modified NACA 64 3-618 airfoil at a chord-based Reynolds number of Re = 200 , 000 is studied using wind tunnel experiments. First, the LSB is characterized over a range of static angles of attack, in terms of the locations of separation, transition and reattachment—using surface pressure measurements, particle image velocimetry (PIV) and infrared thermography (IT). For the conditions tested, excellent agreement between the techniques is obtained. Subsequently, a pitching motion is imposed on the wind tunnel model, with reduced frequencies up to k = 0.25. While surface pressure measurements and PIV are not affected by the change in experimental conditions, the infrared approach is impaired by the thermal response of the surface. To overcome this, an extension of the differential infrared thermography (DIT) method for detecting the three characteristics of an unsteady LSB is considered. All three experimental techniques indicate a hysteresis in bubble location between the pitch up and pitch down phases of the motion, caused by the effect of the aerodynamic unsteadiness on the adverse pressure gradient. However, the DIT measurements suggest a larger hysteresis, which is attributed to the thermal response time of the model surface. The experimental results measured with the pressure sensors reveal that the hysteresis in bubble location is larger than the hysteresis in lift, indicating that the observed bubble hysteresis is not purely due to instantaneous flow conditions, but has an inherent component as well. Aerodynamic

An integrated measurement approach for the determination of the aerodynamic loads and structural motion for unsteady airfoils

The structural motion and unsteady aerodynamic loads of a pitching airfoil model that features an actuated trailing edge flap are determined experimentally using a single measurement and data processing system. This integrated approach provides an alternative to the coordinated use of multiple measurement systems for simultaneous position and flow field measurements in large-scale fluid–structure interaction experiments. The measurements in this study are performed with a robotic PIV system using Lagrangian particle tracking. Flow field measurements are obtained by seeding the flow with helium-filled soap bubbles, while the structural measurements are performed by tracking fiducial markers on the model surface. The unsteady position and flap deflection of the airfoil model are determined from the marker tracking data by fitting a rigid body model, that accounts for the motion degrees of freedom of the airfoil model, to the measurements. For the determination of the unsteady aerodynamic loads (lift and pitching moment) from the flow field measurements, two different approaches are evaluated, that are both based on unsteady potential flow and thin airfoil theory. These methods facilitate an efficient non-intrusive load determination on unsteady airfoils and produce results that are in good agreement with reference measurements from pressure transducers.AerodynamicsAerospace Structures & Computational Mechanic

Experimental Aeroelastic Characterization of a Very Flexible Wing in Steady and Unsteady Inflow

The aeroelastic response of a very flexible wing in steady and unsteady inflow conditions is measured in a wind tunnel experiment. An integrated aeroelastic characterization is performed with a non-intrusive optical setup that allows simultaneous measurements of the structural motion and the flow field around the wing. The experimental aerodynamic loads that are inferred from the flow field measurements are in very good agreement with reference data from a force balance. Prior to the wind tunnel experiment, results of the numerical modal analysis of a structural model of the wing are compared with the experimental results from a ground vibration test. An aeroelastic model validation is achieved by applying the experimental aerodynamic loads to the structural model of the wing. The results of this structural analysis are compared with the measured structural response in the wind tunnel for steady inflow conditions, yielding differences of around 15% in tip displacements when using a linear structural model.AerodynamicsAerospace Structures & Computational Mechanic