Measurements of the dynamics of thermal plumes in turbulent mixed convection based on combined PIT and PIV

Measurements of the dynamics of thermal plumes in turbulent mixed convection based on combined... The dynamics of thermal plumes and their abundance is investigated in mixed convection in a cuboidal sample with respect to the characteristic numbers. The parameter range spans $$Ra=1.0{-}3.2\times 10^8$$ R a = 1.0 - 3.2 × 10 8 , $$Re=0.5{-}1.7\times 10^4$$ R e = 0.5 - 1.7 × 10 4 and $$Ar=1.1{-}7.6$$ A r = 1.1 - 7.6 . Combined particle image thermography and particle image velocimetry is conducted in a horizontal layer close above the bottom thermal boundary layer. This combination of measurement techniques, using thermochromic liquid crystals as tracer particles, which is novel for air flows, allows for simultaneous measurement of temperature and velocity fields. Details of the measurement technique are published in Schmeling et al. (Meas Sci Technol 25:035302, 2014). The fingerprints of sheet-like plumes and those of the stems of mushroom-like plumes are visible in the instantaneous temperature fields. A study of temperature PDFs reveals that the distributions can be well described by a sum of two Gaussian distributions. Analysing the ratio of the probabilities $$P_2/P_1$$ P 2 / P 1 reveals a sudden change at a critical Ra c  ≈ 2.3 × 108. Here, $$P_1$$ P 1 denotes the abundance of fluid temperatures imprinted by the bulk flow, while $$P_2$$ P 2 represses the abundance of temperatures ascribed to warm thermal plumes. Accordingly, $$P_2/P_1$$ P 2 / P 1 is a measure for the plume fraction in the measurement plane. The change occurs in the $$Ar$$ A r regime $$2.7\,\lesssim\, Ar\,\lesssim\, 3.3$$ 2.7 ≲ A r ≲ 3.3 , in which the interaction of buoyancy-induced large-scale circulations with the wall jet of the incoming air results in an instability reported already by Schmeling et al. (Exp Fluids 54:1517, 2013). A combined evaluation of the temperature and velocity fields reveals a change in the horizontal heat fluxes at $$Ar\approx 2.7{-}3$$ A r ≈ 2.7 - 3 . Furthermore, the total amount of heat transported in x direction within the measurement layer increases with $$Ra$$ R a in bulk-dominated regions, while it stays almost constant for plume-dominated ones. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Experiments in Fluids Springer Journals

Measurements of the dynamics of thermal plumes in turbulent mixed convection based on combined PIT and PIV

Loading next page...
 
/lp/springer_journal/measurements-of-the-dynamics-of-thermal-plumes-in-turbulent-mixed-iGrl0jJC74
Publisher
Springer Berlin Heidelberg
Copyright
Copyright © 2015 by Springer-Verlag Berlin Heidelberg
Subject
Engineering; Engineering Fluid Dynamics; Fluid- and Aerodynamics; Engineering Thermodynamics, Heat and Mass Transfer
ISSN
0723-4864
eISSN
1432-1114
D.O.I.
10.1007/s00348-015-1981-z
Publisher site
See Article on Publisher Site

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 12 million articles from more than
10,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

Monthly Plan

  • Read unlimited articles
  • Personalized recommendations
  • No expiration
  • Print 20 pages per month
  • 20% off on PDF purchases
  • Organize your research
  • Get updates on your journals and topic searches

$49/month

Start Free Trial

14-day Free Trial

Best Deal — 39% off

Annual Plan

  • All the features of the Professional Plan, but for 39% off!
  • Billed annually
  • No expiration
  • For the normal price of 10 articles elsewhere, you get one full year of unlimited access to articles.

$588

$360/year

billed annually
Start Free Trial

14-day Free Trial