Pump inducer

An inducer is the axial inlet portion of a centrifugal pump rotor, the function of which is to raise the inlet head by an amount sufficient to prevent significant cavitation in the following pump stage.[1] It is used in applications in which the inlet pressure of a pump is close to the vapor pressure of the pumped liquid. Inducers are frequently included in design of turbopumps for liquid propellant rocket engines, although they are used in other applications which require high suction performance.[2] It does not increase NPSHa but increases NPSHr for Pump.

An inducer operating in an experimental water tunnel. The tip vortex cavitation phenomenon can be clearly identified.
For inducers in molecular biology, see Inducer.
An inducer designed for testing in water tunnels

Use in rocketry

In order to achieve high delta-v, the structural mass of a launch vehicle should be as low as possible. Liquid fuel tanks can be constructed lighter if the pressure within those tanks is kept low. Typically, for pump-fed rocket engines, the propellant tank pressures (and masses) are 1/10 to 1/40 of those in a pressure-fed rocket.[3] The structural weight constraint also makes the rotating speed of the turbopump rotor as high as possible. For example, the rotating speed of the oxygen turbopump of the Japanese LE-7 rocket engine is 18300rpm.[3] These two factors above combine to make the pump impeller very susceptible to cavitation. If cavitation occurs in the impeller, the performance of the pump will be severely degraded and the pump itself may be damaged.

gollark: Perhaps they're semirandom. Perhaps I devise bespoke bluffs by myself and then share them. Perhaps my bluffs are optimized automatically via testing against high-fidelity computer simulations of all other participants. Perhaps I don't make bluffs but merely disseminate cognitohazards causing perception of bluffs. Perhaps my every word and bluff is meticulously generated to produce minimum guessing of me. Perhaps I never bluff and every word I say is accurate.
gollark: I generate my bluffs via RNG now to avoid the terribleness of human random number generation (heavpoot has data on this), unless I don't and am trying to trick you into not making inferences from them.
gollark: Unless I didn't but am *not* trying to fool you all.
gollark: Unless I didn't and am trying to fool you all, of course.
gollark: I attempted to completely leave any chat here in the guessing phase out of my decision-making.

References
  1. NASA SP-8052 Liquid rocket engine turbopump inducers. NASA.
  2. Japikse, David. "Overview of Industrial and Rocket Turbopump Inducer Design" (PDF). Concepts NREC. Retrieved 17 May 2014.
  3. Sutton, George P. (2001). Rocket propulsion elements (7th ed.) (PDF). John Wiley&Sons. pp. 218, 363. Archived from the original (PDF) on 2013-01-02.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.