THE EFFECTS OF FREESTREAM AND KINEMATIC PERTURBATIONS ON OSCILLATING WINGS AT LOW REYNOLDS NUMBERS
Abstract
While flying in outdoor conditions miniature crafts with flapping wings, that exploit dynamic stall to produced enhanced lift, will be required to not only perform robustly when encountering variations in ambient flows (gusts) but also be capable of producing rapid changes in aerodynamic forces during voluntary aerial manoeuvres. Our knowledge of the receptivity of unsteady flow occurring over dynamically stalling wings to freestream-induced perturbations remains limited yet the likelihood of such interactions is high due to the ubiquitousness of wind unsteadiness in the outdoor environment across all atmospheric regimes. In this project we will systematically study the effects of frontal and vertical gusts on the performance of flapping/oscillating wings. We will also seek insights into the transient forces and flow profile over the wings due to variations in kinematics like those performed during manoeuvres consisting of rapid variation in flapping frequency, amplitude and wing rotation angles. This will be accomplished by conducting experiments on a Reynolds scaled flapping wing apparatus capable of producing arbitrary prescribed kinematics. The flapping wings of the robot will be subjected to gusts of varying magnitude and orientation while mean and transient forces and moments can be measured in situ. Various manoeuvring kinematics will also be introduced while the variation in forces will be analysed. The flow structure that develops due to the ensuing interaction with flow perturbations will be quantified using a combination of dye visualization and planar and stereoscopic particle image velocimetry. These measurements will be used to develop parametric representations consisting of analytical and empirical modelling that will relate the profile of the perturbation and to its effect on the lift and drag performance of flapping wings.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 11, 2021
- Source ID
- FA23862014084
Entities
People
- Sridhar Ravi
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of New South Wales