diffuser

diffuser

[də′fyüz·er]

(engineering)

A duct, chamber, or section in which a high-velocity, low-pressure stream of fluid (usually air) is converted into a high-velocity, high-pressure flow

Diffuser

In a forced-air heating/cooling system, the diffuser is a register or grille attached to ducting through which heated or air-conditioned air is delivered to the living space. In a tubular skylight or an electric light fixture, the diffuser is a cover plate through which scattered light is delivered.

Diffuser

 

in aerodynamics and hydrodynamics, the part of a channel or tube in which deceleration (expansion) of the flow and an increase in pressure take place. At speeds not exceeding the speed of sound, the cross-sectional area of a diffuser increases in the direction of flow; at supersonic speeds the area decreases. Diffusers are used in installations in which there is movement of liquids or gases (water, air, gas, or oil pipelines, wind tunnels, and jet engines).

In electroacoustics, a diffuser is a part of the mechanical vibration system of a loudspeaker; it is designed to generate sound waves in the surrounding air. It is usually made from special paper and is flexibly attached to the metal body of the loudspeaker.

In photographic technology, a diffuser is a device used to produce photographic images with softened definition. Such a diffuser consists of a plane-parallel glass plate with a tetragonal reticule or with concentric circles scored with a diamond stylus, 2-3 mm apart, or narrow glass strips having a width of 0.1 of the diameter of the lens and a thickness of 0.8-1.0 mm. The strips and plates are mounted in a frame that is placed on the lens of the camera or enlarger (after focusing for maximum sharpness of the image).

In the production of alumina a diffuser is an apparatus for flow leaching of crushed bauxite cake. Twelve to 14 such diffusers are usually joined in series to form a battery. A feature of the flow leaching process in diffusers is the fact that the cake remains stationary on the bottom grate of the diffuser, and the solution seeps through the cake successively in each diffuser. In this way the solution not only washes the surface of each particle but also permeates the particle through its pores, thus leaching out all soluble components. Hot water is fed into one end of the battery; a concentrated solution of sodium aluminate is removed at the other end. All of the diffusers are joined by pipelines in such a way that each diffuser can be disconnected by means of valves without interrupting the operation of the others. Diffusers containing fully leached cakes are periodically disconnected and other diffusers, containing fresh cakes, are connected at the other end of the battery. Typically, in a battery of 14 diffusers, 12 are in operation, one is being loaded, and one is being unloaded.

REFERENCES

Lainer, A. I. Proizvodstvo glinozema. Moscow, 1961.
Beliaev, A. I. Metallurgiia legkikh metallov, 6th ed. Moscow, 1970.

A. I. LAINER

diffuser

1. Any device, object, or surface that scatters light (or sound) from a source.

2. For air-conditioning systems, see air diffuser.

diffuser

Location of diffuser in axial and centrifugal flow engines.

A specially designed duct, chamber, or section, sometimes equipped with guide vanes, that decreases the velocity of a fluid, such as air, and increases its pressure, such as in a jet engine, a wind tunnel, etc. In a gas turbine engine, the diffuser converts the velocity energy of the air leaving the compressor into pressure energy before it passes into the combustion chamber. The diffuser may be formed as an integral part of the compressor casing or be bolted to it. It consists of a number of tangential vanes, whose inner edges are parallel to the direction of the resultant airflow from the rotating compressor. The passages between the vanes are proportioned so that air pressure attains the requisite entry value on entry to the combustion chambers.