In commercial aviation, it seems jet engines grow and by-pass ratio increase with newer engines. Here is some examples:
- 1963: by-pass ratio: 0.96 (P&W JT8D)
- 1970: by-pass ratio: 5.0 (P&W JT9D)
- 1984: by-pass ratio: 5.3 (P&W PW4000)
- 1984: by-pass ratio: 6.0 (P&W PW2000)
- 2004: by-pass-ratio: 8.5 (Rolls-Royce Trent900)
- 2007: by-pass ratio: 10.8 (Rolls-Royce Trent1000)
- 2015: by-pass ratio: 12.0 (P&W PW1124G)
The by-pass ratio has been multiplied by nearly 2 in 30 years (1970 -> 2015). I understand the need of really high by-pass ratio to decrease fuel consumption while increasing thrust. To have big by-pass ratio, the high pressure part of the engine must be small compare to the overall size of the engine.
- What prevent jet engine designer to design smaller high pressure part or bigger jet engines to increase the by-pass ratio?
- Is there someone that has made prediction about the increasing by-pass ratio in the next decades and written it in a serious article?