FREE FALL EXPERIMENTS IN THE MINES OF LINARES |
Three mining shafts which belong to the old mining district
of Linares have been used to carry out free fall experiment by using
smooth spheres of both different types and sizes. The purpose of
these experiences has been the evaluation of the drag coefficient of a
smooth sphere moving at laminar regime with Reynolds numbers in the interval
103 - 2·105. Firsty, a selection
of the more suitable shafts was carried out taking into account the state
of each mine in order to limit the risk of landslide during the measurements.
There was verified the diverse degree of flood of the shafts. The effective
deep of the shafts (the distance from the shaft entrance to the free surface
of the water) was measured by using a bore. The experiments were carried
out by measuring the interval of time from the initial free movement of
the sphere to the recording of the impact sound of the sphere with the
water. A number of previous measurements showed that the tubular shape
of the shafts provides a wide transmission of the sound. This fact made
feasible the recording of the impact sound of the spheres with the water
at distances up to approximately 200 m.
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The authors of this work are:
Dr. José Alberto Maroto Centeno (Department of Physics, Polytechnic School of Linares, University of Jaén, Spain) Prof. José Dueñas Molina (Department of Graphic Engineering and Design, Polytechnic School of Linares, University of Jaén, Spain) D. Jorge de Dios Espí (Technical industrial engineer,
APCAR, La Carolina, Jaén, Spain)
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