Fluidic Compressor Bleed Valve.

Changing compression ratio with compressor corrected speed change, causes changes in relative air densities and flow velocities in the stages. At less than design speed, the increased relative flow velocities needed in the later stages causes them to act as a throttle on the early stages, tending to drive them into compressor stall. Bleeding air from the front stages averts this. The required bleeding is most precisely determined by the relation of the compression ratio of the final stages to the over-all compression ratio. Fluidic technology readily provides this - using flowing air computation circuits and an amplifier to position a diaphragm operated poppet type bleed valve. The computer modeling, design, and successful bench substantiation tests of the Mode AV-N2 fluidic compressor bleed valve for the Teledyne CAE Model 472-11D engine, are described. Planned engine testing was cancelled when engine development was stopped. An application survey was made, with requirements for six other small engines being studied. The survey indicated 1 the fluidic approach could meet the requirements for all the engines, and 2 its superior accuracy potential could benefit by either reducing excessive parasitic air bleeding or allowing design trade-offs for size, weight, response, etc. Author