Abstract
During ascent of space launch vehicle in
atmosphere, the payload compartment pressure should be leveled
with the atmospheric pressure. At high altitudes, this pressure
difference becomes more destructive. It produces crushing or
bursting loads in the form of tension, compression or shear on
satellite and launch vehicle. Even small differentials may be
critical when imposed with compressive axial loads. In history of
launch vehicles, at least two flights were failed due to improper
depressurization of fairing [1]. Pressure equalization is attained
through venting ports located on the periphery of fairing. The
main constraint of depressurization system is to ensure the
minimal pressure difference between fairing payload
compartment and the atmosphere. However, fulfilling this
constraint is difficult due to the continuous variation in flow
velocity, from subsonic to hypersonic, during flight. The size,
location and number of venting ports dictate effectiveness of
depressurization system.
In this paper, an innovative approach is used for the design
and mathematical model development of depressurization system
of launch vehicle fairing. For this purpose,
MATLAB/SIMULINK toolbox Simscape is customized as per
requirement. The quantity and size of venting ports are estimated
by considering minimum pressure differential during
atmospheric flight and at fairing separation. The suitable
location of ports is estimated where static pressure at the port
location over the fairing surface and the uninterrupted
atmospheric pressure are equal.
In order to verify the results, a scale down experimental setup
is developed. One-way solenoid valves with three different orifice
sizes are used as venting ports. Depressurization is performed at
highest pressure difference, expected during flight. Numerical
and experimental results are compared and it is found that
numerical results are in good agreement with the experiment.
Muhammad Tanveer Iqbal, Abdul Majid. (2018) Design and Development of Depressurization System of Launch Vehicle Fairings, Journal of Space Technology , Volume 8, Issue 1.
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