Turbulent Air Flow Characteristics in a Ventilated
Hospital
Railway Coach
A. de Lieto
Vollaro, P. Gori and A. Vallati
Fisica
Tecnica Department, University of Rome‘La Sapienza’,
via Eudossiana 18, 00184 Rome, Italy.
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Abstract
The aim of this work is to
investigate turbulent air flows, through measurements inside railway
coaches employed for the transport of sick persons. In this kind of
environment, assuring occupant comfort and eliminating potentially
annoying draught is necessary for safeguarding patients inside the train.
As it is known, air velocity is not uniform but, instead, it fluctuates.
It is these fluctuations that are the origin of local discomfort. This can
result in a draught, which is defined as a local undesired cooling of the
body. Since draught is one of the most common causes of complaint in a
ventilated or air-conditioned space, understanding the turbulent air flow
in these spaces and the impact of this flow on the sensation of draught is
very important. The characteristics of turbulent air flow have been
investigated through experimental measurements inside a railway coach
provided with stretchers. In particular, in order to characterise these
air flows, some parameters have been used, including mean velocity,
standard deviation of velocity, turbulence intensity, and energy spectrum,
etc. These parameters have been introduced by making use of the
statistical analysis of instantaneous velocity measurements performed at
several points. These were taken to be representative of the whole space
actually occupied. This analysis showed that micro-nozzle diffusers gave
optimum comfort conditions for patients in this type of hospital train.
Key words: railway
coach, hospital, comfort conditions, measurements, turbulence parameters.
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