Bioinspired morphing for novel propulsor design

Project Summary

Aerodynamic performance depends on appropriate geometries for both section and planform. Optimal designs are quite profoundly different with changeable fluid densities (e.g. with increasing altitude or in water-to-air transitions), and also in unsteady operational states (such as variable forward speed). However, traditional fixed wings, rotor blades and propellers are typically limited by single point optimisation, with inherent inefficiencies at different rotational speeds or forward velocities. Variable-pitch propellers are an insufficient solution, ignoring the consequential effects of planform and twist and necessitating prolonged periods of off-design operation. Passive mechanisms that result in context-appropriate adoption of effective geometries have potential advantages in terms of simplicity, weight and speed; they need not depend on sensing, processing and actuation. Reconfiguration under aerodynamic or inertial forces has long been discussed in swimming fish and flying insects and birds, and advantages are often inferred, particularly in terms of efficiency but sometimes also stability. We will develop numerical simulations using Computational Fluid Dynamics, Computational Solid Dynamics, and combined Fluid-Structure Interactions (FSI; within ANSYS workbench) to explore both established and unpublished biological mechanisms of adaptive aeroelastic foil morphing. This builds on our previous work on birds and insects. The ambitious and potentially transformative scientific challenge addressed here is to exploit these mechanisms for for fixed wing, pitching/plunging and rotary propulsors and energy harvesters. Both propulsors and energy harvesters experience – withstand and exploit – air and water motions at a range of flow speeds, amplitudes and frequencies. We expect to arrive at working prototypes demonstrating superior characteristics across an expanded range of operating conditions. This project will assess biologically inspired flexible and morphing foil designs in silico before creating functional benchtop demonstrators.