An experimental study has been conducted to investigate the effects of vane-type vortex generators in affecting the flow pattern of the wake region using a 1:20 scale tractor-trailer model. The de Haviland wind tunnel of the University of Glasgow was employed in this study. Surface oil flow visualisation, smoke visualisation and twocomponent time-averaged particle image velocimetry measurements...

An analysis of ight measurements made near a wake vortex was conducted to explore the feasibility of providing a pilot with useful wake-avoidance information. The measurements were made with relatively low-cost ow and motion sensors on a light airplane ying near the wake vortex of a turboprop airplane weighing approximately 90 000 lb. Algorithms were developed which removed the response of the ...

The method of radial velocities (RV) is applied to estimate aircraft wake vortex parameters from measurements conducted with pulsed coherent Doppler lidar (PCDL). Operations of the Stream Line lidar and the 2-µm PCDL are simulated numerically to analyze the accuracy of the estimated wake vortex parameters with the RV method. The RV method is also used to estimate wake vortex trajectories and ci...

A von Karman vortex street generated in the usual way was subjected to a deceleration, thereby changing the ratio of longitudinal to lateral spacing between the vortices. Distortion of the individual vortices followed which resulted in annihilation of concentrated vortex regions and creation of a stationary wake flow. This wake flow was itself dynamically unstable and developed into a new vorte...

The lift-generated wake vortices trailing behind an aircraft present a danger to aircraft following the same or a nearby path. The degree of hazard to the following aircraft depends on the nature of the wake encountered in its flight path and on the ability of the aircraft to counter its effects. This report describes the current state of understanding of the factors that influence the motion a...

Introduction. The Karman-vortex street formed behind two-dimensional bluff bodies has attracted interest because of its beautiful flow pattern. It goes without saying that this beautifulness results from the alternative vortices regularly shed from the body. Vortex shedding induces aerodynamic force perpendicular to the mean flow. This force causing mechanical vibration of the model is accompan...

Vortex control is a new paradigm in fluid mechanics, with applications to propulsion and wake reduction. A heaving and pitching hydrofoil placed in a flow with an array of oncoming vortices can achieve a very high propulsive efficiency and reduced wake signature. The canonical example of flow with regular arrays of vortices is the Krman vortex street, and this is our model for the inflow to the...

The transfer of momentum from an animal to fluid in its wake is fundamental to many swimming and flying modes of locomotion. Hence, properties of the wake are commonly studied in experiments to infer the magnitude and direction of locomotive forces. The determination of which wake properties are necessary and sufficient to empirically deduce swimming and flying forces is currently made ad hoc. ...

The vortex wake is the fluid dynamic footprint of swimming and flying animals. When an animal moves through fluid, Newton’s second and third laws together dictate that the locomotive force exerted by the fluid on the animal has a magnitude equal to the rate at which the animal imparts momentum to the fluid. Often the animal delivers this momentum in the form of rotating fluid masses called vort...