Advertisement

Heat and Mass Transfer

, Volume 48, Issue 3, pp 541–554 | Cite as

Color schlieren deflectometry study of jet mixing: effect of buoyancy and perforation

  • Kaladhar Semwal
  • Rakesh Ranjan
  • P. K. PanigrahiEmail author
  • P. Munshi
Original

Abstract

Mixing of jets is crucial for optimal performance of many industrial applications and there is a need to optimize both nozzle geometry and flow conditions. The present study reports the influence of buoyancy and perforation on mixing between a jet and its environment. Optical techniques are ideal for the study of jet mixing due to their non-intrusive and inertia free properties. The present study gives an account of mixing between helium jet and the ambient fluid using a combination of color schlieren deflectometry and radial tomographic mathematics. Four different perforation sizes have been used and the experiments are performed for Reynolds numbers 21–676 and Richardson numbers 3.27–0.0015. Color schlieren images show distinct influence of perforation and flow conditions (Richardson number). Oxygen concentration and jet width quantify effectiveness of jet mixing. Buoyancy plays an important role in mixing at high Richardson number. Perforation improves jet mixing i.e. there is about 120% increase in jet width and the size of perforation plays an important role.

Keywords

Perforation Richardson Number Perforation Size Oxygen Mole Fraction Mole Fraction Profile 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols

Re

Reynolds number \( (\frac{{\rho_{a} UD}}{{\mu_{a} }}) \)

Ri

Richardson number \( (\frac{{|\rho_{g} - \rho_{a} |gD}}{{\rho_{g} U_{g}^{2} }}) \)

U

Average bulk velocity in axial direction

D

Internal diameter of the nozzle

g

Acceleration due to gravity

u

Axial local velocity

v

Radial local velocity

z

Axial direction

r

Radial direction

n

Refractive index

f

Focal length

M

Molecular weight

x

Mole fraction

P

Pressure

R

Universal gas constant

T

Temperature

K

Gladstone Dale constant

d

Filter plane displacement

Greek symbols

α

Entrainment coefficient

ρ

Density of the bulk fluid

μ

Viscosity of fluid

Angular deflection

η

Normalized refractive index

δ

Refractive index difference

Subscripts

a

Ambient fluid property

g

Jet fluid under consideration

References

  1. 1.
    Subbarao R, Cantwell BJ (1992) Investigation of a co-flowing buoyant jet: experiments on the effect of Reynolds number and Richardson number. J Fluid Mech 245:69–90CrossRefGoogle Scholar
  2. 2.
    Schwarz A, Becker A (1993) Tomographic temperature measurement of flames with the schlieren effect. Technisches Messen 60:tm-7/8Google Scholar
  3. 3.
    Schwarz A (1995) Three dimensional reconstruction of temperature and velocity fields in a furnace, Part. Part Syst Charact 12:75–80CrossRefGoogle Scholar
  4. 4.
    Mastorakos E, Shibasaki M, Hishda K (1996) Mixing enhancement in axisymmetric turbulent isothermal and buoyant jets. Exp Fluids 20:279–290CrossRefGoogle Scholar
  5. 5.
    Al-Ammar K, Agrawal AK, Gollahalli SR, Griffin D (1998) Application of rainbow schlieren deflectometry for concentration measurements in an axisymmetric helium jets. Exp Fluids 25:89–95CrossRefGoogle Scholar
  6. 6.
    Pasumarthi KS, Agrawal AK (2003) Schlieren measurement and analysis of concentration field in self excited helium jets. Phys Fluids 15:3683–3692CrossRefGoogle Scholar
  7. 7.
    Helmer DB, Su LK (2006) Imaging of turbulent buoyant jet mixing. In: 44th AIAA aerospace sciences meeting and exhibit, Reno, Nevada, 9–12 JanGoogle Scholar
  8. 8.
    Rubinstein R, Greenberg PS (1994) Rapid inversion of angular deflection data for certain axisymmetric refractive index distribution. Appl Opt 33:1141–1144CrossRefGoogle Scholar
  9. 9.
    Vasil’ev LA (1971) Schlieren methods. In: Baruch A (ed) Israel Program for Scientific Translations, New York, pp 176–177Google Scholar
  10. 10.
    Merzkirch W (1974) Flow visualization. Academic Press, New YorkzbMATHGoogle Scholar
  11. 11.
    Greenberg PS, Klimek RB, Buchele DR (1995) Quantitative rainbow schlieren deflectometry. Appl Opt 34(19):3810–3825CrossRefGoogle Scholar
  12. 12.
    Gupta AS, Panigrahi PK, Muralidhar K, Rajive Gupta (2010) Color schlieren deflectometry for characterization of crystal growth processes: KDP and lysozyme. J Cryst Growth 312:817–830CrossRefGoogle Scholar
  13. 13.
    Ramsey AT, Diesso M (1999) Abel inversions: error propagation and inversion reliability. Rev Sci Instrum 70:380–383CrossRefGoogle Scholar
  14. 14.
    Kolhe PS, Agrawal AK (2009) Abel inversion of deflectometric data: comparison of accuracy and noise propagation of existing techniques. Appl Opt 48:3894–3902CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Kaladhar Semwal
    • 1
  • Rakesh Ranjan
    • 1
  • P. K. Panigrahi
    • 1
    Email author
  • P. Munshi
    • 1
  1. 1.Department of Mechanical EngineeringIndian Institute of TechnologyKanpurIndia

Personalised recommendations