Airflow in the context of "Human voice"

Schlieren photography is a process for photographing fluid flow. Invented by the German physicist August Toepler in 1864 to study supersonic motion, it is widely used in aeronautical engineering to photograph the flow of air around objects.

The process works by imaging the deflections of light rays that are refracted by a moving fluid, allowing normally unobservable changes in a fluid's refractive index to be seen. Because changes to flow rate directly affect the refractive index of a fluid, one can therefore photograph a fluid's flow rate (as well as other changes to density, temperature, and pressure) by viewing changes to its refractive index.

An obstruent (/ˈɒbstruənt/ OB-stroo-ənt) is a speech sound such as [k], [d͡ʒ], or [f] that is formed by obstructing airflow. Obstruents contrast with sonorants, which have no such obstruction and so resonate. All obstruents are consonants, but sonorants include vowels as well as consonants.

A damper is a valve or plate that stops or regulates the flow of air inside a duct, chimney, VAV box, air handler, or other air-handling equipment. A damper may be used to cut off central air conditioning (heating or cooling) to an unused room, or to regulate it for room-by-room temperature and climate control - for example, in the case of Volume Control Dampers. Its operation can be manual or automatic. Manual dampers are turned by a handle on the outside of a duct. Automatic dampers are used to regulate airflow constantly and are operated by electric or pneumatic motors, in turn controlled by a thermostat or building automation system. Automatic or motorized dampers may also be controlled by a solenoid, and the degree of air-flow calibrated, perhaps according to signals from the thermostat going to the actuator of the damper in order to modulate the flow of air-conditioned air in order to effect climate control.

In a chimney flue, a damper closes off the flue to keep the weather and animals (e.g. birds) out and warm or cool air in. This is usually done in the summer, but also may be done in the winter between uses. In some cases, the damper may also be partly closed to help control the rate of combustion. The damper may be accessible only by reaching up into the fireplace by hand or with a woodpoker, or sometimes by a lever or knob that sticks down or out. On a wood-burning stove or similar device, it is usually a handle on the vent duct as in an air conditioning system. Forgetting to open a damper before beginning a fire can cause serious smoke damage to the interior of a home, if not a house fire.

A scramjet (supersonic combustion ramjet) is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully before combustion (hence ramjet), but whereas a ramjet decelerates the air to subsonic velocities before combustion using shock cones, a scramjet has no shock cone and slows the airflow using shockwaves produced by its ignition source in place of a shock cone. This allows the scramjet to operate efficiently at extremely high speeds.

Although scramjet engines have been used in a handful of operational military vehicles, scramjets have so far mostly been demonstrated in research test articles and experimental vehicles.

In fluid dynamics, the wetted area is the surface area that interacts with the working fluid or gas.

• In maritime use, the wetted area is the area of the watercraft's hull which is immersed in water. This has a direct relationship on the overall hydrodynamic drag of the ship or submarine.
• In aeronautics, the wetted area is the area which is in contact with the external airflow. This has a direct relationship on the overall aerodynamic drag of the aircraft. See also: Wetted aspect ratio.
• In motorsport, such as Formula One, the term wetted surfaces is used to refer to the bodywork, wings and the radiator, which are in direct contact with the airflow, similarly to the term's use in aeronautics.

Lift-induced drag, induced drag, vortex drag, or sometimes drag due to lift, in aerodynamics, is an aerodynamic drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or a lifting body redirecting air to cause lift and also in cars with airfoil wings that redirect air to cause a downforce. It is symbolized as ${\textstyle D_{\text{i}}}$, and the lift-induced drag coefficient as ${\textstyle C_{D,i}}$.

For a constant amount of lift, induced drag can be reduced by increasing airspeed. A counter-intuitive effect of this is that, up to the speed-for-minimum-drag, aircraft need less power to fly faster. Induced drag is also reduced when the wingspan is higher, or for wings with wingtip devices.