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When possible, dampers, extractors, and other flow control devices should not be placed near diffusers' inlets (necks), either not being used at all or being placed far upstream. They have been shown to dramatically increase noise production. For as-cataloged diffuser performance, a straight
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Diffusers can be as a shape of round, rectangular, or can be as linear slot diffusers (LSDs). E.g., linear slot diffusers take the form of one or several long, narrow slots, mostly semi-concealed in a fixed or suspended ceiling with
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A supersonic diffuser is a duct that decreases in area in the direction of flow which causes the fluid temperature, pressure, and density to increase, and velocity to decrease. These changes occur because the fluid is compressible.
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Occasionally, diffusers are mostly used in a reverse fashion, as air inlets or returns. This is especially true for a linear slot diffuser and 'perf' diffusers. But more commonly,
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Frictional effects during analysis can sometimes be important, but usually they are neglected. Ducts containing fluids flowing at low velocity can usually be analyzed using
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of a fluid passing through a systemā. The fluid's static pressure rise as it passes through a duct is commonly referred to as pressure recovery. In contrast, a
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needs serve a diffuser. An elbow, or kinked flex duct, just before a diffuser often leads to poor air distribution and increased noise.
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that increases in area in the direction of flow. As the area increases, fluid velocity decreases, and static pressure rises.
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is used to increase the discharge velocity and lower the pressure of a fluid passing through it.
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Often to cause the air jet(s) to attach to a ceiling or other surface, taking advantage of the
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systems. Diffusers are used in both all-air and air-water HVAC systems, as part of
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To create low-velocity air movement in the occupied portion of room
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To enhance mixing of room air into the primary air being discharged
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behind the slots directing the airflow in the desired direction.
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Evenly distribute the flow of air, in the desired directions
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Accomplish the above while producing the minimum amount of
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may also play an important role in a supersonic diffuser.
42:. Analyzing ducts flowing at higher velocities with
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98:To deliver both conditioning and ventilating air
258:Designer's Guide to Ceiling-Based Air Diffusion
239:. National Aeronautics and Space Administration
143:are used as return or exhaust air inlets.
88:heating, ventilating, and air-conditioning
94:subsystems, and serve several purposes:
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260:, ASHRAE, Inc., Atlanta, GA, USA, 2002
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82:A round diffuser in an HVAC system
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53:A typical subsonic diffuser is a
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23:is "a device for reducing the
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86:Diffusers are very common in
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212:MerriamāWebster Dictionary
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153:Bernoulli's principle
92:room air distribution
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40:Bernoulli's principle
282:Building engineering
61:Supersonic diffusers
16:Thermodynamic device
27:and increasing the
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158:Compressible flow
48:compressible flow
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241:. Retrieved
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215:. Retrieved
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74:Applications
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44:Mach numbers
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277:Ventilation
163:Duct (flow)
124:section of
68:Shock waves
50:relations.
271:Categories
208:"diffuser"
194:References
243:5 August
217:5 August
147:See also
134:airfoils
25:velocity
21:diffuser
141:grilles
188:Nozzle
183:SMACNA
178:ASHRAE
33:nozzle
118:noise
245:2016
237:NASA
219:2016
126:duct
55:duct
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19:A
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