aerodynamic force


Also found in: Dictionary, Thesaurus.

Aerodynamic force

The force exerted on a body whenever there is a relative velocity between the body and the air. There are only two basic sources of aerodynamic force: the pressure distribution and the frictional shear stress distribution exerted by the airflow on the body surface. The pressure exerted by the air at a point on the surface acts perpendicular to the surface at that point; and the shear stress, which is due to the frictional action of the air rubbing against the surface, acts tangentially to the surface at that point. The distribution of pressure and shear stress represent a distributed load over the surface. The net aerodynamic force on the body is due to the net imbalance between these distributed loads as they are summed (integrated) over the entire surface. See Boundary-layer flow, Fluid flow

For purposes of discussion, it is convenient to consider the aerodynamic force on an airfoil (see illustration). The net resultant aerodynamic force R acting through the center of pressure on the airfoil represents mechanically the same effect as that due to the actual pressure and shear stress loads distributed over the body surface. The velocity of the airflow V is called the free-stream velocity or the free-stream relative wind. By definition, the component of R perpendicular to the relative wind is the lift, L, and the component of R parallel to the relative wind is the drag D. The orientation of the body with respect to the direction of the free stream is given by the angle of attack, α. The magnitude of the aerodynamic force R is governed by the density &rgr; and velocity of the free stream, the size of the body, and the angle of attack. See Airfoil

Resultant aerodynamic force ( R ), and its resolution into lift ( L ) and drag ( D ) componentsenlarge picture
Resultant aerodynamic force (R), and its resolution into lift (L) and drag (D) components

An important measure of aerodynamic efficiency is the ratio of lift to drag, L/D. The higher the value of L/D, the more efficient is the lifting action of the body. The value of L/D reaches a maximum, denoted by (L/D)max, at a relatively low angle of attack. Beyond a certain angle the lift decreases with increasing α. In this region, the wing is said to be stalled. In the stall region the flow has separated from the top surface of the wing, creating a type of slowly recirculating dead-air region, which decreases the lift and substantially increases the drag.

aerodynamic force

[‚e·ro·dī′nam·ik ′fȯrs]
(fluid mechanics)
The force between a body and a gaseous fluid caused by their relative motion. Also known as aerodynamic load.

Aerodynamic force

The force exerted on a body whenever there is a relative velocity between the body and the air. There are only two basic sources of aerodynamic force: the pressure distribution and the frictional shear stress distribution exerted by the airflow on the body surface. The pressure exerted by the air at a point on the surface acts perpendicular to the surface at that point; and the shear stress, which is due to the frictional action of the air rubbing against the surface, acts tangentially to the surface at that point. The distribution of pressure and shear stress represent a distributed load over the surface. The net aerodynamic force on the body is due to the net imbalance between these distributed loads as they are summed (integrated) over the entire surface.

For purposes of discussion, it is convenient to consider the aerodynamic force on an airfoil (see illustration). The net resultant aerodynamic force R acting through the center of pressure on the airfoil represents mechanically the same effect as that due to the actual pressure and shear stress loads distributed over the body surface. The velocity of the airflow V is called the free-stream velocity or the free-stream relative wind. By definition, the component of R perpendicular to the relative wind is the lift, L, and the component of R parallel to the relative wind is the drag D. The orientation of the body with respect to the direction of the free stream is given by the angle of attack, α. The magnitude of the aerodynamic force R is governed by the density &rgr; and velocity of the free stream, the size of the body, and the angle of attack.

Resultant aerodynamic force ( R ), and its resolution into lift ( L ) and drag ( D ) componentsenlarge picture
Resultant aerodynamic force (R), and its resolution into lift (L) and drag (D) components

An important measure of aerodynamic efficiency is the ratio of lift to drag, L/D. The higher the value of L/D, the more efficient is the lifting action of the body. The value of L/D reaches a maximum, denoted by (L/D)max, at a relatively low angle of attack. Beyond a certain angle the lift decreases with increasing α. In this region, the wing is said to be stalled. In the stall region the flow has separated from the top surface of the wing, creating a type of slowly recirculating dead-air region, which decreases the lift and substantially increases the drag.

References in periodicals archive ?
The components of the aerodynamic forces projected on the vehicle axis are the drag in the streamwise direction, the side force in the lateral direction, and the lift in the upward vertical direction.
The relationship between aerodynamic force and instantaneous flapping angle was shown fig5.
The velocity induced on each element is determined using the momentum equation; the aerodynamic forces on the element are calculated using the lift and drag coefficients of the considered profile section [3-5].
First, the goal of this work is to offer a simple mathematical model, valid in the thin-film limit, for the FBP including the aerodynamic force that is applied from the air to the film, and second, to present the effect of the air jet on a highly viscoelastic film.
Aerodynamic forces and the requirement to clear the crossbar were expected to have only a small influence on the player's optimum projection angle (Linthorne and Everett, 2006; Linthorne and Patel, 2011).
A top-mounted carbon fibre rear wing provides rear downforce and stability, while a carbon fibre splitter balances the aerodynamic forces at the front of the car.
04 release includes a new model to predict the formation and transport of a thin liquid film on a solid surface, and its subsequent stripping and break-up under aerodynamic forces.
4) In addition to a new CONOPS, electric propulsion, and a small platform, the third phase will demand a vehicle capable of manipulating aerodynamic forces (similar to the space shuttle and X-37).
As a result, at top speed, aerodynamic forces exert an additional 190kg pushing the 911 GT3 RS 4.
The data confirm that the fish control aerodynamic forces by altering the angle of their pectoral fins, which changes the effective "wingspan" and the lift force.
Numerical and experimental investigations of fluid dynamics of high speed flows, the determination of aerodynamic forces on sails, large-eddy simulation of free shear and wall-bounded turbulent flows, and a semi-analytic model of fog effects on visions are some areas discussed.

Full browser ?