How to Extract Energy from Turbulence in Flight by Fast Tracking
arXiv:2011.03511 · doi:10.1017/jfm.2021.499
Abstract
We analyze a way to make flight vehicles harvest energy from homogeneous turbulence by fast tracking in the way that falling inertial particles do. Mean airspeed increases relative to flight through quiescent fluid when turbulent eddies sweep particles and vehicles along in a productive way. Once swept, inertia tends to carry a vehicle into tailwinds more often than headwinds. We introduce a forcing that rescales the effective inertia of rotorcraft in computer simulations. Given a certain thrust and effective inertia, we find that flight energy consumption can be calculated from measurements of mean particle settling velocities and acceleration variances alone, without need for other information. In calculations using a turbulence model, we optimize the balance between the work performed to generate the forcing and the advantages induced by fast tracking. The results show net energy reductions of up to about 10% relative to flight through quiescent fluid and mean velocities up to 40% higher. The forcing expands the range of conditions under which fast tracking operates by a factor of about ten. We discuss how the mechanism can operate for any vehicle, how it may be even more effective in real turbulence and for fixed-wing aircraft, and how modifications might yield yet greater performance.
arXiv comment29 pages, 10 figures, submitted to the Journal of Fluid Mechanics
References in corpus (10)
- Unmanned Aerial Vehicles: A Survey on Civil Applications and Key Research Challenges
- Fluid Particle Accelerations in Fully Developed Turbulence
- Experimental Lagrangian Acceleration Probability Density Function Measurement
- Thermal soaring flight of birds and unmanned aerial vehicles
- Observation of the sling effect
- Multiscale preferential sweeping of particles settling in turbulence
- Wind profiling in the lower atmosphere from wind-induced perturbations to multirotor UAS
- Turbulence explains the accelerations of an eagle in natural flight
- Differential Evolution for Efficient AUV Path Planning in Time Variant Uncertain Underwater Environment
- On the least common multiple of several random integers