The HPFTP is a two stage turbine powered with hot, hydrogen rich gas. Hot gas is directed hrough the first and second stage blades, and is discharged into the hot gas manifold. The HPFTP raises the pressure of the hydrogen flowing to the engine combustion chambers sufficiently to ensure positive injection of hydrogen at all thrust levels.
The HPFTP rotor consists of a stack of three centrifugal Impellers held together by central tie bolt. These three impellers act as a three stage centrifugal pump when driven by the two stage hot gas turbine. The rotor is supported with in the HPFTP case by double ball bearings at either end, pump interstage seals, and a balance piston to limit axial translation.
The HPFTP is completely insulated to retain the hydrogen in a liquid state and prevent the formation of liquid air on the pump. Each impeller has front and back face labyrinth seals except number 3.
The second stage wheel is spline coupled to the third stage impeller, and the first stage wheel is bolted to the second-stage wheel through a curvic coupling.
The turbine and turbine bearings are cooled by extracting fuel from the fuel pump itself. The flow first splits through the coolant passage and the labyrinth seal. Then, through several circuitous pathways, it flows through and over all turbine structure and the turbine bearings.
