Advertisement

Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

An efficient way of convection heat transfer measurement on a curved surface

  • 140 Accesses

Abstract

Accurate determination of convective heat transfer coefficients on complex surfaces with high spatial resolution is essential in the design and analysis of thermal systems. This study focuses on the implementation of a recently developed true color image-processing technique for the quantitative interpretation of liquid crystal images obtained from a curved surface. The interpretation includes the use of a linear hue versus temperature relation as an accurate temperature measuring tool, a color image analysis system and a transient heat transfer model for the conversion of time accurate temperature information into heat transfer coefficient maps. A square to rectangular transition duct is used as a heat transfer model representative of a curved geometry. The transient heat transfer experiments are performed with ambient temperature air in the transition duct model which is preheated by a custom designed electric heater. The measurements are performed on the curved bottom surface of the transition duct. Two dimensional surface distributions of heat transfer coefficient on the curved surface are presented with high spatial resolution. The hue-capturing technique provides extremely fine details of heat transfer coefficient when compared to other conventional discrete sensor methods. The technique is a highly automated heat transfer measurement method which reduces lengthy data reduction processes and significantly improves spatial resolution.

This is a preview of subscription content, log in to check access.

Abbreviations

c :

Specific heat

CCD:

Charge coupled device

h :

Convective heat transfer coefficienth=q/(T w−T)(W/m2K)

HSI :

Normalized hue, saturation and intensity

k :

Thermal conductivity

NTSC:

National Television System Committee

q :

Heat flux,q=−k∂T/∂y(W/m2)

RGB :

Normalized red, green and blue

R35C1W:

Chiral nematic liquid crystal starting to respond at about 35°C with an approximate bandwidth of 1°C

T :

Static temperature

t :

Time

y :

Normal distance from the wall surface

α:

Thermal diffusivity of air, α=k/(ρCp)

β:

Nondimensional time, β=h√t/√ϱck

θ:

Normalized temperature θ=(T−T i)/(T −Ti)

ρ:

Density

i :

Initial condition

p :

At constant pressure

w :

Wall condition

°:

Free stream value

References

  1. Akino, N., Kunugi, T., Ichimiya, K., Mitsushiro, K. and Ueda, M., 1989, “Improved Liquid-Crystal Thermometry Excluding Human Color Sensation,” Trans. of the ASME, J. of Heat Transfer, Vol. 111, pp. 558–565.

  2. Baughn, J.W., Ireland, P.T., Jones, T.V. and Saniei, N., 1988, “A Comparison of the Transient and Heated-Coating Methods for the Measurement of Local Heat Transfer Coefficients on a Pin Fin,” ASME Paper 88-GT-180.

  3. Bunker, R.S., Metzger, D.E. and Wittig, S., 1990, “Local Heat Transfer in Turbine Disk-Cavities. Part I: Rotor and Stator Cooling with Hub Injection of Coolant,” ASME Paper 90-GT-25.

  4. Camci, C., Kim, K. and Hippensteele, S.A., 1992, “A New Hue Capturing Technique for the Quantitative Interpretation of Liquid Crystal Images Used in Convective Heat Transfer Studies,” Trans. of the ASME, J. of Turbomachinery, Vol. 114, pp. 765–775.

  5. Hippensteele, S.A., Russell, L.M. and Stepka, F.S. 1983, “Evaluation of a Method for Heat Transfer Measurements and Thermal Visualization Using a Composite of a Heater Element and Liquid Crystals,” Trans. of the ASME, J. of Heat Transfer, Vol. 105, pp. 184–189.

  6. Ireland, P.T. and Jones, T.V., 1985, “The Measurement of Local Heat Transfer Coefficients in Blade Cooling Geometries,” AGARD CP-390, Paper 28, Bergen.

  7. Jones, T.V. and Hippensteele, S.A., 1985, “High-Resolution Heat Transfer Coefficient Maps Applicaple to Compound-Curve Surfaces Using Liquid Crystals in a Transient Wind Tunnel,” Developments in Experimental Techniques in Heat Transfer and Combustion, HTD-Vol. 71, ASME.

  8. Klein, E.J., 1968, “Liquid Crystals in Aerodynamic Testing,” Astronautics and Aeronautics, Vol. 6, pp. 70–73.

  9. Kline, S.J. and McClintock, F.A., 1953, “Describing Uncertainties in Single Sample Experiments,” Mechanical Engineering, Vol. 75, pp. 3–8.

  10. Parsley, M., 1991, “The Use of Thermochromic Liquid Crystals in Research Applications, Thermal Mapping and Non-destructive Testing,” Seventh IEEE SEMI-THERM Symposium, pp. 53–58.

  11. Schultz, D.L. and Jones, T.V., 1973, “Heat Transfer Measurements in Short Duration Hypersonic Facilities,” AGARD-AG-165.

Download references

Author information

Correspondence to Kui-Soon Kim.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Kim, K. An efficient way of convection heat transfer measurement on a curved surface. KSME Journal 7, 349–363 (1993). https://doi.org/10.1007/BF02953205

Download citation

Key Words

  • Convection
  • Curved Surface
  • Liquid Crystal