Abstract
A new measuring method is suggested for determining the time constant of a thermocouple wire to be applied for the measurement of the true fluid temperatures in varying flow states. Based on the techniques of internal heating which are commonly used to measure mean time constants, we extend the existing method to measure instantaneous time constants continuously. A method of measurement and analysis is presented and verified experimentally.
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Abbreviations
- A s :
-
surface area [m2]
- c :
-
specific heat [J/kg K]
- D :
-
diameter [m]
- h :
-
heat transfer coefficient [W/m2 K]
- I :
-
current [A]
- k :
-
thermal conductivity [W/m K]
- L :
-
length [m]
- r :
-
resistance per unit length [Ω/m]
- T :
-
temperature [°C]
- t :
-
time [s]
- t c :
-
characteristic time to reach uniform state [s]
- u :
-
velocity of stream [m/s]
- V :
-
volume [m3]
- x :
-
axial coordinate [m]
- α:
-
thermal diffusivity [m2/s]
- θ :
-
normalized temperature (≡TθT ∞)/(T RθT ∞))
- ϱ :
-
density [kg/m3]
- τ:
-
time constant [s]
- ω :
-
angular velocity [rad/s]
- a :
-
amplitude
- i :
-
initial condition
- j :
-
junction of thermocouple
- R :
-
reference point
- ∞:
-
surrounding
References
Ballantyne A; Moss JB (1977) Fine wire thermocouple measurements of fluctuating temperature. Combust Sci Tech 17: 63–72
Bradbury LJS; Castro IP (1971) A pulsed-wire technique for velocity measurements in highly turbulent flows. J Fluid Mech 49: 657–691
Cambray P (1986) Measuring thermocouple time constants: A new method. Combust Sci Tech 45: 221–224
Carslaw HS; Jaeger JC (1959) Conduction of heat in solids, 2nd ed., Chap. 2. London: Oxford University Press
Collis DC; Williams NJ (1959) Two-dimensional convection from heated wires at low Reynolds numbers. J Fluid Mech 6: 357–384
Katsuki M; Mizutani Y; Matsumoto Y (1987) An improved thermocouple technique for measurement of fluctuating temperatures in flames. Combust Flame 67: 27–36
Lockwood FC; Moneib HA (1981) A new on-line pulsing technique for response measurements of thermocouple wires. Combust Sci. Tech 26: 177–181
Mathioulakis E; Grignon M; Poloniecki JG (1994) A pulsed-wire technique for velocity and temperature measurements in natural convection flows. Exp Fluids 18: 82–86
Ražnjevic' K (1987) Handbook of thermodynamic tables and charts. Washington DC: Hemisphere Publishing
Talby R; Anselmet F; Fulachier L (1990) Temperature fluctuation measurements with fine thermocouples. Exp Fluids 9: 115–118
Tanaka M; Yamashita I; Chisaka F (1990) Flow and heat transfer characteristics of the Stirling engine regenerator in an oscillating flow. JSME Int J II 33: 283–289
Simon TW; Seume JR (1988) A survey of oscillating flow in Stirling engine heat exchangers. NASA CR-182108
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The work was supported by Turbo and Power Machinery Research Center at Seoul National University and the authors are grateful to Mr. M. H. Yang for his assistance in the experiment.
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Park, S.J., Ro, S.T. A new method for measuring time constants of a thermocouple wire in varying flow states. Experiments in Fluids 21, 380–386 (1996). https://doi.org/10.1007/BF00189059
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DOI: https://doi.org/10.1007/BF00189059