Conceptual-level evaluation of a variable stiffness skin for a morphing wing leading edge

A morphing leading edge produces a continuous aerodynamic surface that has no gaps between the moving and fixed parts. The continuous seamless shape has the potential to reduce drag, compared to conventional devices, such as slats that produce a discrete aerofoil shape change. However, the morphing leading edge has to achieve the required target shape by deforming from the baseline shape under the aerodynamic loads. In this paper, a conceptual-level method is proposed to evaluate the morphing leading edge structure. The feasibility of the skin design is validated by checking the failure index of the composite when the morphing leading edge undergoes the shape change. The stiffness of the morphing leading edge skin is spatially varied using variable lamina angles, and comparisons to the skin with constant stiffness are made to highlight its potential to reduce the actuation forces. The structural analysis is performed using a two-level structural optimisation scheme. The first level optimisation is applied to find the optimised structural proper- ties of the leading edge skin and the associated actuation forces. The structural properties of the skin are given as a stiffness distribution, which is controlled by a B spline interpolation function. In the second level, the design solution of the skin is investigated. The skin is assumed to be made of variable stiffness composite. The stack sequence of the composite is optimised element-by-element to match the target stiffness. A failure criterion is employed to obtain the failure index when the leading edge is actuated from the baseline shape to the target shape. Test cases are given to demonstrate that the optimisation scheme is able to provide the stiffness distribution of the leading edge skin and the actuation forces can be reduced by using a spatially variable stiffness skin

Design of a Rear BLI Non-Axisymmetric Propulsor for a Transonic Flight Experiment

Nowadays, the increasing demand for reducing the environmental impact of civil aviation is leading to more sustainable aircraft technologies. In the context of aircraft propulsion, Boundary Layer Ingestion (BLI) is considered one of the most promising solutions, although the high level of integration between the airframe and propulsors becomes a major challenge in the design process. The present work deals with a CFD based shape optimization of a BLI-360 propulsor, starting from a simplified two-dimensional axisymmetric model as a basis for the three-dimensional design

Landslide-related sediment yield of a large apenninic catchment

Diverse sources of information, which describes landslide movement, hillslope-channel connectivity and sedimentation rates, are analyzed to detect trends that took place during the last 12 thousands years. We estimate the landslide-related sediment production rates by combining measured landslide velocities and geometries and historical landslide frequency. Coarse sediment deposition rates are measured throughout the Holocene by means of dating and stratigraphy of the alluvial fan and terraced deposits. The comparison between present-day hillslope sediment production and Holocene averaged sediment deposition rates confirms that landsliding is the main agent conveying sediments to higher order trunk streams. The connectivity between hillslopes and the stream network is well developed and no significant sediment sinks influence the sediment transport process. However fluctuations of sediment delivery rates at the outlet of the catchment took place during Holocene and are likely associated to periods of increased hillslope sediment production and channel discharge caused by climatic forcin

Performance Optimization of a Heavy Class Helicopter Engine Installation Using Genetic Algorithms Coupled With CFD Simulations

Aerodynamic design and optimization of engine installation is a pivotal part of the helicopter design process. To this purpose, an adaptive problem-independent and reliable optimization methodology would be particularly valuable for accomplishment of such goal. The application of advanced evolutionary algorithms coupled with CFD solvers for the accurate flow solution of validated numerical models represents a very powerful tool for the parametric design and optimization of engine installation components. Within the JTI Clean Sky FP7 project \u201cHeavyCopter\u201d the consortium constituted by the University of Padova (UNIPD) and the spin-off company HIT09 developed an automatic optimization loop based on an in-house genetic algorithm called GeDEA, and applied it to engine installation design of a heavy-class helicopter. This paper illustrates the application of the above mentioned optimization loop both at cruise and hover reference flight conditions for such a helicopter. The algorithm pursues the minimization of the total pressure losses at the air intakes while keeping the flow distortion at the engine inlet at the lowest level; regarding the exhausts, the back-pressure is minimized in order to increase the power output of the engine while preserving the entrainment ratio. The results highlight significantly improved performance margins with respect to the baseline both for intakes and exhaust