# aerodynamic trail

## aerodynamic trail

[‚e·ro·dī′nam·ik ′trāl]
(fluid mechanics)
A condensation trail formed by adiabatic cooling to saturation (or slight supersaturation) of air passing over the surfaces of high-speed aircraft.

## aerodynamic trail

A condensation trail formed by adiabatic cooling to saturation (or slightly supersaturation) of air passing over the surfaces of high-speed aircraft. Aerodynamic trails form off the tips of wings, propellers, and other points of maximum pressure decrease. They are relatively rare and of short duration compared with exhaust trails.
Mentioned in ?
References in periodicals archive ?
Acceleration or deceleration in the flow that moves around the cylinder causes significant change to the structure of the boundary layer and, correspondingly, change to the position of the point of boundary layer separation: during acceleration of the flow around the cylinder ([partial derivative]W/[partial derivative][tau]) > 0, the point of separation shifts backwards, causing a decrease in aerodynamic trail width and as a result profile drag caused by viscous forces in the flow (the coefficient of profile drag [C.sub.x] decreases); during deceleration in the flow ([partial derivative]W/[partial derivative][tau]) < 0, the point of boundary layer separation shifts forward, widening the aerodynamic trail behind the cylinder and increasing profile drag.
Research has established that the frequency of the separation of vortices (the frequency of the velocity pulsations in the aerodynamic trail behind the cylinder) corresponds to the values of Strouhal number [S.sub.[eta]] = ([[omega].sub.1]d/W) > 0.2 - 0.4 at values of the Reynolds number that are contained within the range of 0.3 x [10.sup.6] < Re < 0.8 x [10.sup.6], where [[omega].sub.1] is frequency of the separation of vortices, d is diameter of a cylinder, and W is speed of incoming airflow (Schlichting 1969; Kestin et al.
At Strouhal number [S.sub.r] > 0.28, there is no research or recommendations regarding the behaviour of the flow on the cylinder surface and in the aerodynamic trail behind it.

Site: Follow: Share:
Open / Close