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Differential interferometry in heat transfer

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Abstract

In this paper the optical methods in heat transfer applications are described briefly. In particular, interferometric methods are discussed in detail as applied to the study of natural convection heat transfer. Of the most popular interferometers, viz. the Mach Zehnder Interferometer (mzi) and the Differential Interferometer (di), thedi is considered in detail. The theoretical and constructional features of adi are outlined. The procedures of heat transfer measurement and the temperature profile estimation are explained. The advantages and limitations of the two interferometers are compared with the help of a sample calculation. The experimental analyses of three cases, viz. (1) isothermal vertical flat plate, (2) single vertical fin attached to a heated horizontal base, and (3) horizontal fin array, are described. Typical heat transfer and temperature profile results are presented. Using the estimated temperature profiles isotherms are plotted. It is possible to get fairly good heat transfer and temperature profiles using adi. The instrument is specially useful in applications involving short optical path lengths because of its superior resolution as compared tomzi.

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Abbreviations

a :

constant appearing in (18);

C :

specific refractive index or Gladstone-Dale constant (for air 0.1506 × 10−3, m3/kg);

d :

distance from the Wollaston prism to the test object (m);

Gr x :

Grashof number based on local coordinatex;

h :

heat transfer coefficient (W/m2K);

k :

thermal conductivity (W/mK);

k′ :

a constant explained in §6.4;

L :

length of the test object (path length) (m);

m :

fringe shift factor = fringe shift/fringe spacing;

n :

refractive index;

P :

absolute pressure (Pa);

q :

heat flux (W/m2);

R :

gas constant (287, N m/kg K);

S :

interference line number (Hauf & Grigull 1970);

T :

absolute temperature (K);

w :

thickness of the wedge in the Wollaston prism (m);

x :

coordinate along the height of the test object;

ΔX :

local fringe deflection, (m);

y :

coordinate normal to the test surface;

ΔY :

fringe spacing, (m);

z :

distance measured along the light path, (m);

δ :

Wollaston prism angle;

λ :

wavelength of the light used (m);

ρ :

density of the medium (kg/m3)

w :

referred to the wall conditions;

∞:

referred to the ambient conditions;

o :

ordinary ray;

e :

extraordinary ray

References

  • Black W Z, Carr W W 1971 Application of differential interferometer to the measurement of heat transfer coefficients.Rev. Sci. Instrum. 42: 337–340

    Article  Google Scholar 

  • Black W Z, Norris J K 1974 Interferometric measurement of fully turbulent free convective heat transfer coefficient.Rev. Sci. Instrum. 45: 216–218

    Article  Google Scholar 

  • Chapman A J 1984Heat transfer (4th edn.) (London: Macmillan)

    Google Scholar 

  • Dosanjh D S (ed.) 1971Modern optical methods in gas dynamic research (New York: Plenum)

    Google Scholar 

  • Dyson J 1970Interferometry as a measuring tool (London: The Machinery Publication Co.)

    Google Scholar 

  • Edser E 1949Light for students (London: Macmillan)

    Google Scholar 

  • Hauf W, Grigull U 1970 Optical methods in heat transfer.Adv. Heat Transfer 6: 134–365

    Google Scholar 

  • Rammohan Rao V, Venkateshan S P 1990 Natural convection heat transfer and associated temperature fields in fins and horizontal fin arrays, to be presented at the 3rdASME-jsme Thermal Engineering Joint Conference, 1991

  • Schrader W 1978Manual on differential interferometer (Braunschweig: Spindler & Hoyer)

    Google Scholar 

  • Smith F G, Thomson J H 1977Optics (London: ELBS/John Wiley)

    Google Scholar 

  • Sobhan C B 1989Free convection studies on horizontal fins and fin arrays via differential interferometry, Doctoral thesis, Indian Institute of Technology, Madras

    Google Scholar 

  • Sobhan C B, Venkateshan S P, Seetharamu K N 1989 Experimental analysis of unsteady free convection heat transfer from horizontal fin arrays.Warme und Stoffubertragung 24: 155–160

    Article  Google Scholar 

  • Sobhan C B, Venkateshan S P, Seetharamu K N 1990 Experimental studies on steady free convection heat transfer from fins and fin arrays.Warme und Stoffubertragung 25: (in press)

  • Starling S G, Woodall A J 1963Physics (London: ELBS/Longman Green)

    Google Scholar 

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Author notes

  1. C B Sobhan

    Present address: Department of Mechanical Engineering, Regional Engineering College, 673 601, Calicut, India

Authors and Affiliations

  1. Department of Mechanical Engineering, Indian Institute of Technology, 600 036, Madras, India

    V Rammohan Rao, C B Sobhan & S P Venkateshan

Authors
  1. V Rammohan Rao
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  2. C B Sobhan
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  3. S P Venkateshan
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Rao, V.R., Sobhan, C.B. & Venkateshan, S.P. Differential interferometry in heat transfer. Sadhana 15, 105–128 (1990). https://doi.org/10.1007/BF02760470

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  • DOI: https://doi.org/10.1007/BF02760470

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