AIR FLOW PATTERNS IN AN AIR CONDITIONED MEASURING EQUIPMENT LABORATORY

Document Type : Original Article

Authors

1 Egyptian Air Force.

2 Mechanical Power Engineering Department , Faculty of Engineering, Cairo University, Cairo, Egypt.

Abstract

ABSTRACT
Calibration for the measuring instruments in the Air Force Measuring Equipment
Laboratories, are considered to be one of the reasons for flight success in Egyptian Air
Force. Hence, they should be preserved from the different factors that might cause
harm or decrease the accuracy in calibration for the measuring instruments. One of
these factors is the excessive relative humidity as it affects the mechanical and physical
properties of the standard instruments that are considered the reference. Measuring
instruments need to be calibrated from time to time to provide high accuracy in use that
occurs by comparing a measuring device (uncalibrated) against an equal or better
standard.
The present paper focuses on the heat transfer interactions on the air flow in Precision
Measuring Equipment Laboratories (PMEL). Many PMELs built or renovated in recent
years have not met minimum operating environment standards. The impact of flow
parameters on the air flow pattern were investigated. This offers the designer a better
view of design limits to enable him to adequately select the optimum design from a wide
number of alternative options and to use them in forecasting and even monitoring. Air
movement inside enclosures prediction via CFD is a strong tool for reaching better
designs for inlets and outlets positions in ventilated spaces. Fluent Computational
Software [1] was used to predict the parameters affecting the air distribution inside airconditioned
spaces. Continuity, momentum, energy, and species transport equations in
addition to k-epsilon model equations for turbulence closure were solved using finite
volume method. Furthermore the paper includes full-scale actual existing space
experiments, to obtain good documented full-scale measurements in actual ventilated
laboratory room that can be used for comparison with CFD-simulations.
Many of the reported comparisons were found in good agreement with experiments and
aided the assessment of the numerical procedure application to air-conditioned spaces.
Finally, it was found that the optimum airside system design should allow the air to pass
all the enclosure areas before being extracted. Temperature and humidity control are
crucial elements of laboratory design. Since temperature fluctuations also affect
humidity, its control is especially important. Also a restriction should be made for the
mechanical and optical disciplines, the internationally accepted temperature is not
exceed 20°C.

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