Redesign proposal for the space shuttle propellant cavity purge
A critical part of the Main Propulsion System (MPS) of the Space Shuttle includes the propellant umbilical cavity which is that volume enclosing the flanges of the external tank propellant lines and the orbiter feedlines. The initial design of this cavity allowed a ground supplied helium purge to maintain a positive inert pressure within the cavity. The main problems with this design include system insensitivity to purge leakage or to propellant leakage downstream of the distribution orifices and purge inadequacy to protect against a prope 11 ant 1 eakage. The purge's primary function is to protect pyrotechnic cannisters and electrical hardware, which share this interface area, from icing. Pressure sensors have been approved for installation into the cavity, providing limited sensitivity to propellant leaks. This work proposes a way to obtain satisfactory leak detection capability by adding temperature density sensors in tandem with the pressure sensor in the cavity. Hazardous gas detection sensors are of l itt le use in this area s i nee improper mixing reduces useful information. This solution assumes the gas mixture in the cavity can be approximated by a reduced equation of state with a correction factor in addition to using a reverse molar averaging estimate of the mixture ratio arrived at by determination of the pseudocritical pressure and temperature.
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Anderson, Loren A.
Master of Science (M.S.)
College of Engineering
Mechanical Engineering and Aerospace Sciences
Length of Campus-only Access
Masters Thesis (Open Access)
Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic
Stinson, William M., "Redesign proposal for the space shuttle propellant cavity purge" (1990). Retrospective Theses and Dissertations. 4083.