The aerodynamic forces and pressure distribution of a revolving pigeon wing |
| |
Authors: | James R Usherwood |
| |
Institution: | (1) Structure and Motion Lab, The Royal Veterinary College, North Mymms, Hatfield, Herts, AL9 7TA, UK |
| |
Abstract: | The aerodynamic forces acting on a revolving dried pigeon wing and a flat card replica were measured with a propeller rig,
effectively simulating a wing in continual downstroke. Two methods were adopted: direct measurement of the reaction vertical
force and torque via a forceplate, and a map of the pressures along and across the wing measured with differential pressure
sensors. Wings were tested at Reynolds numbers up to 108,000, typical for slow-flying pigeons, and considerably above previous
similar measurements applied to insect and hummingbird wing and wing models. The pigeon wing out-performed the flat card replica,
reaching lift coefficients of 1.64 compared with 1.44. Both real and model wings achieved much higher maximum lift coefficients,
and at much higher geometric angles of attack (43°), than would be expected from wings tested in a windtunnel simulating translating
flight. It therefore appears that some high-lift mechanisms, possibly analogous to those of slow-flying insects, may be available
for birds flapping with wings at high angles of attack. The net magnitude and orientation of aerodynamic forces acting on
a revolving pigeon wing can be determined from the differential pressure maps with a moderate degree of precision. With increasing
angle of attack, variability in the pressure signals suddenly increases at an angle of attack between 33° and 38°, close to
the angle of highest vertical force coefficient or lift coefficient; stall appears to be delayed compared with measurements
from wings in windtunnels. |
| |
Keywords: | |
本文献已被 PubMed SpringerLink 等数据库收录! |
|