GASEOUS OXYGEN COOLING OF THE SPACE TRANSPORTATION SYSTEM LAUNCH PAD ENVIRONMENT

The external tank (ET) of the Space Transportation System (STS) contains liquid oxygen and hydrogen as oxidizer and fuel for the Space Shuttle main engines (SSMEs). During and subsequent to the loading of the ET prior to the launch of an STS, the cryogens boil in the near atmospheric conditions existing within their respective tanks. The gaseous oxygen (GOX) formed as a result of this boiling is vented overboard, mixes with air, and may, under certain wind conditions, be transported toward the STS to cause a cooling of its environment. This paper describes a two-dimensional computational fluid dynamics analysis to determine the magnitude of this cooling effect by determining the temperature depression and stratification caused by this GOX/air mixture in the region around the east redesigned solid rocket motor (RSRM), the ET, and below the STS assembly. For a severe wintertime launch temperature of 24-degrees-F (-4.44-degrees-C), the maximum local temperature depression of the mixture was calculated to be 58-degrees-F (32.22-degrees-C) in the inboard region next to the ET surface, and a surface temperature on the east RSRM was found to be as much as 25-degrees-F (13.89-degrees-C) colder than ambient. The computed average surface temperatures on either side of the RSRM were in excellent agreement with a temperature determined from a correlation of prelaunch temperature measurements.