The effects of internal occupants and supplement heating make up an essential issue for the prediction and
control of fresh ventilating air distribution in an enclosure. The influence from livestock is complex, since they are mobile
obstacles, producing heat and contaminants in irregular geometry. As a part of the basic studies of these influences, the
investigations of air motion in a thermal buoyant flow caused by free convection around a livestock body are reported in
this article. A simulated pig, made of a painted metal tube (1 m long and 0.5 m in diameter) with covered ends and heat
elements inside, was used as the heat source in the experiments. The experiments were carried out in a full-scale room, 5
m iA11 m in floor area, with a 2.4 m side wall height, and sloped ceiling to center (height: 4.8 m). The simulated pig was
placed near the center of the floor. The vertical temperature difference in the room space was less than 0.3iaC. The
velocity and temperature in the thermal plume were measured with six sensors (each has both temperature and velocity
elements) placed at 0.2 m horizontal intervals. Data were acquired at 14 levels from 0.2 to 2.4 m above the top surface of
the simulated pig. The data-sampling period was 30 min in steady state for each measurement.
The results show that the plume was quite thin at the beginning (yd iU 0.6 m) in the central radial plane of the model.
Observations showed that the laminar flow at the beginning remained for some distance before it became turbulent and
spread. When the distance from the top of the model increased (yd iÝ 0.8 m), the temperature and velocity profile of the jet
fit Gaussian distributions. The temperature profiles were slightly wider than the velocity profiles. Numerical simulations
(Computational Fluid Dynamics) were applied for the same experimental set-up in computing the airflow over the pig
simulator. Transient simulation with fixed time stepping provided similar results to the measurements, indicating the CFD
simulation method used in the study has potential for prediction of buoyant flow generated by this type heat source.
[1]
Wolfgang Rodi,et al.
Vertical turbulent buoyant jets : a review of experimental data
,
1980
.
[2]
Soonil Nam,et al.
Numerical simulation of thermal plumes
,
1993
.
[3]
Hunter Rouse,et al.
Gravitational Convection from a Boundary Source
,
1952
.
[4]
Y. Jaluria,et al.
On the buoyancy-induced flow arising from a heated hemisphere
,
1975
.
[5]
Peter V. Nielsen,et al.
Thermal plumes in ventilated rooms: Measurements in stratified surroundings and analysis by use of an extrapolation method
,
1990
.
[6]
A. Tolpadi,et al.
Experimental investigation of conjugate natural convection heat transfer from a horizontal isothermal cylinder with a nonisothermal longitudinal plate fin at various angles
,
1985
.
[7]
Fujii Tetsu,et al.
BUOYANT PLUME ABOVE A HORIZONTAL LINE HEAT SOURCE
,
1973
.
[8]
C. H. Chen,et al.
On Prediction and Unified Correlation for Decay of Vertical Buoyant Jets
,
1979
.
[9]
M. Manzan,et al.
Natural convection from a horizontal cylinder in a rectangular cavity
,
1999
.