SESSION 9
EXPERIMENTAL STUDIES AND DATA ANALYSIS
EXPERIMENTAL INVESTIGATION OF UNSTEADY TURBULENT FORCED CONVECTION IN A RECTANGULAR DUCT WITH ARRAYS OF BLOCK-LIKE ELECTRONIC COMPONENTS
Nedim SÖZBİR+, Mehmet ARIK++, Sadık KAKAÇ++, H. İbrahim SARAÇ$ and İsmail ÇALLI+
+Department of Mechanical Engineering, Sakarya University, Sakarya,
++Department of Mechanical Engineering, University of Miami, Coral Gables, FL, 33124, USA
$Department of Mechanical Engineering, Kocaeli University, Kocaeli,
This work focuses on an experimental study of unsteady turbulent forced convection in a rectangular duct with arrays of block-like electronic components, subjected to a periodically varying inlet temperature with hydrodynamically developed and thermally developing air flow. The modules are positioned both inlined and staggered arrangements to simulate the electric heating and cooling inside the computer. The study is conducted in turbulent forced flows with approach Reynolds number ranging from 11240 to 21580 with geometric parameters fixed at H/2b=0.1875, S/2b=4.26 while the inlet heat input frequency varied from 0.02 Hz to 0.24 Hz. The experiments are carried out in the thermal entrance region with the fully developed velocity profile. The temperature variation at the several locations along the duct was measured and recorded. The temperature amplitude decayed exponentially along the duct. The decayed indexes are obtained from the experimental investigation under different conditions are presented in tabular and graphical forms.
CONVECTIVE HEAT TRANSFER ANALYSIS AT INDUSTRIAL FURNACES
Dr. T. Kapros C. Sc., Dr. J. Sólyom and Dr. I. Török
TÜKI Research and Developing Company for Combustion Technology
The heat transfer process at the aluminium heat treatment furnaces can be characterised basically through the forced convection. In order to determine the heating up time and to estimate the maximum temperature difference a serial experience has been carried out at a model of a most often applied furnace.
The model was able to simulate the heat transfer of air/flue gas among the opening of aluminium slab-charge in heat treatment furnaces. In this parametric study the following parameters were considered: the Reynolds number, the slot among the charge and the length of flow. We paid attention particularly to the heat transfer phenomena at the beginning, transient phase of heating up process.
The discussion of the experimental results led to the determination of coefficient  as a function of above mentioned parameters taking into account the temperature-time relationship as well.
The investigated parameters had been chosen according to the conditions of most often applied industrial furnaces. The changing of heat transfer coefficient during the whole process and its local distribution made possible a more exact calculation. The results were applied at an operating aluminium heat treatment furnace of 60 t capacity.
VORTEX SHEDDING CHARACTERISATION IN A SHEAR LAYER WITH VARIABLE BOUNDARY CONDITIONS
Frédéric PLOURDE, Dominique COUTON, Son DOAN KIM
Laboratoire d'Etudes Thermiques
ENSMA, Site du FUTUROSCOPE
BP 109
86960 FUTUROSCOPE Cedex France.
The aim of this paper is to characterise the hydrodynamic development of a particular shear layer, created in the wake of an obstacle. An highly sheared flow can create periodic shedding vortices. Different boundary conditions have been tested in order to evaluate directly their influences on the shedding phenomenon. A fixed obstacle, creating the shear layer, has been studied and the response pressure data present clearly excitation of the first (250 Hz). the second (510 Hz) and the third (750 Hz) longitudinal modes. Two other different boundary conditions have been experimented : a flexible obstacle, offering a free vibration under flow field, and a variable and additional acoustic field. In the first case, the free vibration obstacle generates smaller energies of the acoustic modes, and in the second case, the additional acoustic field has entirely controlled the flow organisation.
NEW METHODS IN DATA ANALYSIS: POTENTIALS OFFERED FOR THE STUDY OF
VARIABLE PHENOMENA
Colette PADET, J. M. ROCHE
Laboratoire de Thermomécanique
Faculté des Sciences, Moulin de la Housse
B.P. 1039,51687 REIMS Cedex2 FRANCE
Interconnection between different domains of science has led to suggesting a new approach in the problems of measurements in physics. In this lecture, we propose an analysis of the applicability of different methods of data analysis (informational observation theory, trends of variable phenomena associated to time or space scales, outlines in pictures,....). We shall demonstrate their respective use in transient or chaotic convective heat transfer and follow by discussing some applications.
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