A Classification of Hyper-heuristic Approaches

The current state of the art in hyper-heuristic research comprises a set of approaches that share the common goal of automating the design and adaptation of heuristic methods to solve hard computational search problems. The main goal is to produce more generally applicable search methodologies. In this chapter we present and overview of previous categorisations of hyper-heuristics and provide a unified classification and definition which captures the work that is being undertaken in this field. We distinguish between two main hyper-heuristic categories: heuristic selection and heuristic generation. Some representative examples of each category are discussed in detail. Our goal is to both clarify the main features of existing techniques and to suggest new directions for hyper-heuristic research

Numerical analysis of active chordwise flexibility on the performance of non-symmetrical flapping airfoils

10.1016/j.jfluidstructs.2009.10.005Journal of Fluids and Structures26174-9

Numerical simulation of 'X-wing' type biplane flapping wings in 3D using the Immersed Boundary Method (IBM)

The numerical simulation of a “X-wing” type biplane flapping wings, has been performed in 3D using the Immersed Boundary Method (IBM). This “X-wing” type flapping configuration draws its inspiration from Delfly [1], a family of ornithopters developed by the Delft University of Technology, as shown in Figure 1. The unique “X-wing” design features a biplane flapping wings where two sets of wings were are placed above each other moving in counter phase. On comparison with configurations using a single pair of wings or two sets of wings in tandem, experiments showed that the “X-wing” configuration gives lower power requirement and zero rocking amplitude, which is a beneficial property for a Flapping Micro Aerial Vehicle (FMAV) to be used as a camera platform.Aerodynamics, Wind Energy & PropulsionAerospace Engineerin

Analysis of biplane flapping flight with tail

Numerical simulations have been performed to examine the interference effects between an upstream flapping biplane airfoil arrangement and a downstream stationary tail at a Reynolds number of 1000, which is around the regime of small flapping micro aerial vehicles. The objective is to investigate the effect of the relative distance and angle of attack between the airfoils and its tail on the overall propulsive efficiency, thrust and lift. An immersed boundary method Navier-Stokes solver is used for the simulation. Results show that overall efficiency and average thrust per airfoil can be increased up to 17% and 126% respectively when the top and bottom airfoils come into contact during flapping. When placing the tail at a strategic position, the overall configuration generates much higher lift, although at the expense of decreased efficiency and thrust. Increasing the angle of attack of the tail also helps to increase the lift. Analysis of the vorticity plots reveals the interaction between the vortices and the airfoils and the reason behind the high thrust and lift. The results obtained from this study can be used to optimize the performance of small flapping MAVs.Aerodynamics, Wind Energy & PropulsionAerospace Engineerin

Analysis of tail effects in flapping flight

Numerical simulations have been performed to examine the interference effects between an upstream flapping airfoil and a downstream stationary airfoil in a tandem configuration at a Reynolds number of 1000, which is around the regime of small flapping micro aerial vehicles. The objective is to investigate the effect of the distance of the tail and its angle of attack on the overall propulsive efficiency, thrust and lift. An immersed boundary method Navier-Stokes solver is used for the simulation. Results show that efficiency and average thrust can be increased up to 10% and 25% respectively when a stationary airfoil is placed downstream. The simulations reveal how the vortex-shedding pattern of the airfoils are affected by the interaction between them. As the angle of attack of this airfoil increases from 0 to 45o, high lift is generated at the expense of rapidly decreasing efficiency and thrust. The results are not very sensitive to the shape of the airfoil; similar results are obtained with a flat plate airfoil. Lastly, a simple optimization study is performed to obtain the configuration which gave the best performance based on the range of parameters studied. The results obtained from this study can be used to optimize the performance of small flapping MAVs.Aerodynamics and Wind EnergyAerospace Engineerin

Analysis of tail effects in flapping flight

Numerical simulations have been performed to examine the interference effects between an upstream flapping airfoil and a downstream stationary airfoil in a tandem configuration at a Reynolds number of 1000, which is around the regime of small flapping micro aerial vehicles. The objective is to investigate the effect of the distance of the tail and its angle of attack on the overall propulsive efficiency, thrust and lift. An immersed boundary method Navier-Stokes solver is used for the simulation. Results show that efficiency and average thrust can be increased up to 10% and 25% respectively when a stationary airfoil is placed downstream. The simulations reveal how the vortex-shedding pattern of the airfoils are affected by the interaction between them. As the angle of attack of this airfoil increases from 0 to 45o, high lift is generated at the expense of rapidly decreasing efficiency and thrust. The results are not very sensitive to the shape of the airfoil; similar results are obtained with a flat plate airfoil. Lastly, a simple optimization study is performed to obtain the configuration which gave the best performance based on the range of parameters studied. The results obtained from this study can be used to optimize the performance of small flapping MAVs

Effect of chordwise deformation on unsteady aerodynamic mechanisms in hovering flapping flight

A three-dimensional simulation of hovering flapping wings was performed using an immersed boundary method. This was done to investigate the effects of chordwise wing deformation on three important unsteady aerodynamic mechanisms found in flapping flight, namely Leading Edge Vortex (LEV) shedding, wake capture and clap and fling. A wing was modeled as a flat plate, flapping close to a symmetry plane. Three different deforming chords were defined, a rigid case, a case with maximum deformation at the trailing edge and increased angle of attack (AoA) near the leading edge, and a case with the maximum deformation in the center of the chord and decreased AoA near the leading edge. All cases had zero deformation at the wing root and maximal deformation at the wing tip. A higher AoA near the leading edge resulted in faster LEV buildup and faster buildup of lift. No shedding of the LEV was observed in any of the cases even when deformation caused a high AoA near the leading edge. A distinct dip in lift buildup was observed and shown to be caused by the interaction between the previously shed vortex and the newly developing LEV. This interaction occurred faster when the AoA at the leading edge was increased, and slower when the angle of attack was decreased. Moving the wing closer to the symmetry plane had a positive effect on the cycle average value of CL. This positive effect was reduced however by the earlier interaction between the LEV and the previously shed vortex.Aerodynamics, Wind Energy & PropulsionAerospace Engineerin

Numerical analysis of the s1020 airfoils in tandem under different flapping configurations

10.1007/s10409-009-0302-2Acta Mechanica Sinica/Lixue Xuebao262191-207AMSN