C-4 超音速ビジネスジェット機用推進機のためのサイクル検討(サイクル,一般講演)

概要

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When core duct exit area right downstream of a low-pressure turbine is changed by moving a tail cone back and forth, the low-pressure turbine expansion ratio changes and bypass ratio thereby changes. Operability of engine was analyzed based on cycle calculation for the purpose of fundamentally clarifying the physical mechanism of why a low-pressure turbine expansion ratio changes by changing core duct exit area. The result discovered that kinetic energy of working gas in core duct is converted to turbine work through momentum change. The following advantages on the cycle were obtained by using this simple variable mechanism for small-size engine for SSBJ. 1) Expansion of core duct exit area can increase fan speed and thrust without increasing fuel. Therefore, thrust loss generated by noise-reduction device at take-off can be recovered. 2) Fan over-speed can be prevented by narrowing core duct exit area when increasing thrust with higher fuel flow and higher overall pressure ratio at transonic climb. Therefore, it is possible to obtain large thrust that enables supersonic flight.
2011-07-06