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I understand mass diffusion. But what is the meaning of 'diffusion' which converts the kinetic energy to rise in pressure in a stator/diffuser?

GRANZER
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  • I find this a good source: Engineering Thermodynamics, Work and Heat Transfer by Rogers and Mayhew. – Solar Mike May 23 '20 at 07:27
  • @SolarMike Thank you. But I don't have access to that book and am not finding any pdf version. – GRANZER May 23 '20 at 08:20
  • 4th edition easily available on Amazon.com, see https://www.amazon.com/Engineering-Thermodynamics-Work-Heat-Transfer/dp/0582045665/ref=sr_1_1?dchild=1&keywords=engineering+thermodynamics+work+and+heat+transfer&qid=1590232741&sr=8-1 – Solar Mike May 23 '20 at 11:19
  • @SolarMike Yes and I am sure it's worth the price, but I can't afford it right now. – GRANZER May 23 '20 at 11:32
  • It explains what you are asking... so what value is that worth? – Solar Mike May 23 '20 at 11:45
  • @SolarMike Well professor I would love to buy it, but still can't afford it at the moment. If you know the answer it would mean a lot to me if you could explain it. Thank you. – GRANZER May 23 '20 at 11:54

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The word "diffuse" is used in different contexts in both engineering and in the vernacular. A general definition would be similar to, as a verb, "spread out over a larger area, space, or number of participants or carriers."

With momentum diffusion, a more concentrated area of fluid momentum is spread out to a larger flow volume and to more fluid particles that have their mean velocity increased.

With heat diffusion, a concentrated area of molecular motion is likewise spread out, with larger numbers of molecules assuming more vibrational energy.

With mass diffusion, a concentration of molecular species among other species is spread out to a larger or more distant region, reducing the concentrations of the named species.

With a fluid diffuser, a concentrated area of kinetic energy of fluid motion gets directed to a region where the kinetic energy is converted (diffuses) to a higher static pressure. With subsonic flow, this requires an increase in flow area, but with supersonic flow, this requires a drop in flow area.

ttonon
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