Figure 1.2.1: SSME Oxidizer System Schematic ^{[1, 2]}

The SSME oxidizer system routes high-pressure oxygen to the engine’s three combustion chambers.

Liquid oxygen enters the Low Pressure Oxidizer Turbopump at Station 17 from the External Tank. This pump raises the pressure of the incoming fluid to a modest level before routing it to the High Pressure Oxidizer Turbopump (HPOTP) at Station 19 where the pressure is raised to a level suitable for combustion.

After departing the HPOTP at Station 20, the flow splits into two branches. The first branch (Branch “D”) runs directly to the Large Throat Main Combustion Chamber (LTMCC) inlet at Station 21. Just prior to reaching this station, the flow splits off (Branch “E”) and returns toward the Preburner Oxidizer Boost Pump (Station 24). This pump is mounted directly beneath the HPOTP and is used to pressurize the oxygen to a level appropriate for entry into the Oxidizer Preburner oxygen inlet (Station 26) and the Fuel Preburner oxygen inlet (Station 27).

The second branch departing the HPOTP at Station 20 (Branch “F”) flows to the Low Pressure Oxidizer Turbine Inlet (Station 22). This turbine drives the Low Pressure Oxidizer Turbopump, thus sustaining the overall mass flow rate of liquid oxygen into the system. Flow departs the Low Pressure Oxidizer Turbine at Station 23 and mixes with the outflow from the Low Pressure Oxidizer Turbopump at Station 18.

Station 28 represents the small quantity of oxygen that is routed back to the external oxygen tank as an ullage pressurant.

Table 1.2.1 displays several key thermodynamic properties of the flow as it progresses through these stations. The mass flow rates, temperatures, and pressures listed below were tabulated from Reference [2]. Densities and enthalpies were calculated utilizing the procedure discussed in Section 2.3.

Table 1.2.1

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