Aerodynamic research of Flapping MAV

Background

Flapping Micro Air Vehicles (FMAVs) as the most intriguing type of MAVs family have obtained a great interest due to their outstanding efficiency and maneuverability. The flapping wings can generate both lift and thrust for an available flight. With onboard cameras and sensitive devices, these radio-controlled FMAVs are capable to implement tasks of surveillance, exploration and rescue. The inherent low Reynolds and unsteady aerodynamics caused by flapping motion results an uncomfortable aerodynamic behavior, conventional aerodynamic theories and analysis methods are no longer applicable on FMAVs. Ultimately, it is always essential to offer the designers and engineers a clear picture about the overall aerodynamic knowledge and useful tool to organize the FMAVs for specific mission objective and flight envelop.

This sub-project is now embedded in the STW project:“Insect Flight Inspired New Generation of Flapping -Wing Micro- Aircraft”

Progress and Objectives

During the past period, a great deal of progress has been accomplished on the research on Flapping MAVs. Fundamental theoretical knowledge and previous research have been systematically referred. Meanwhile, staff from MAVLab provide a lot assistance on the fabrication of micro parts, which now results in other prototypes for both free flight and wind tunnel measurements.

An efficient and accuracy N-S solver coupled of the ability of dynamic mesh strategies has been developed. For the inherent unsteady aerodynamics of flapping motion, two optional dynamic mesh methods are employed. Overset grid is responsible for large scale movement to guarantee the mesh quantity, while fast grid deformation based on Delaunay graph mapping will take care of small deformation, such as flexibility and Fluid-Structure interaction due to its notable computational efficiency. Such numerical tool can provide a reliable prediction and optimization of flapping motion by parametric test.

Experimental, computational and analytical methods are used in combination to further describe and investigate the characteristics. This will reveal to what extent beneficial unsteady aero-elastic phenomena are present in the current designs and how they may be further improved.

Further campaign will be conducted on the Wind Tunnel measurement on the Delfly Micro prototype which can collect sufficient data for next optimization and minimization. Also flow visualization techniques PIV (Particle Image Processing) will be performed on Delfly Micro to provide a detail insight into the flow behavior around the flapping wing. Results of the experiments will provide feedback and input for further optimization. Alternatively, the data from experiments can provide specific validation data for testing the CFD method.

Certain PhD project will be especially dedicated to the further development and miniaturization of the Delfly MAV concept, along the lines of the existing Delfly Micro design. With an ambitious destination that establishing an overall FMAV design concept and its system integration.

Publications

-S.Deng, B.W.van Oudheusden, T.Xiao, H.Bijl: “A Computational Study on the Aerodynamic Influence of a Propeller on an MAV by Unstructured Overset Grid Technology and Low Mach Number Preconditioning”. The Open Aerospace Engineering Journal, vol 5 (2012), 11-21.

-S.Deng, T.Xiao, W.B.Tay, B.W. van Oudheusden, H.Bijl: “Numerical Investigation of Flexible Flapping Wing Propulsion at Low-Reynolds Numbers”. International Micro Air Vehicle Conference and Flight Competition (IMAV 2012), 3-6 July 2012, Braunschweig, Germany.

Delfly Micro ProtoType

Research Methodology

Experimental Methods• Free flight test will be conducted on the

prototype Delfly Micro to obtain the flight performance such as control ability, stability and Duration.

• Wind-Tunnel Experiments can provide a quantitative measurement for Delfly ornithopter. Knowledge based on wind tunnel results will guide for further optimizations. Flow visualization can be obtained by PIV(Particle Image Velocimetry) technique.

Numerical Methods• Quasi-Steady Model based on blade element

theory for roughly estimation of the forces on a flapping wing.

• Complete Navier- Stroke simulations will give a detailed flow performance and topology on flapping motion Movement during flapping motion.

• Dynamic mesh strategies are capable to realize motion of objects with temporal unsteady aerodynamics.

Different Configurations of Ornithopters

Gallery3D unsteady Navier-Stoke equations in ALE scheme with dual-time preconditioning technique for all-speed flow as:

PhD Candidate: S. DengDepartment: AWEPSection: AerodynamicsSupervisor: B. van OudheusdenCo-Supervisors: B. Remes R. RuijsinkPromoter: H.BijlStart date: 10-1-2011Funding: STW

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Validation on N-S Solver we developed

Fast mesh deformation on Delaunay Graph Mapping

Overset Grid Schematics

Wake Topology of Plunge Airfoil

Vorticity Contour Behind Flexible Airfoil