Turbofan:Compressor: Difference between revisions
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Special care has to be given to the rotor, since it will spin at very high rotation speeds (not calculated yet). | Special care has to be given to the rotor, since it will spin at very high rotation speeds (not calculated yet). | ||
A blade mounting failure will likely cause the loss of the aircraft, given the constraints. | A blade mounting failure will likely cause the loss of the aircraft, given the constraints. The part that holds the blades is called the '''hub'''. We'll call the part of the blades that is hold by the blades at their root the '''insert'''. | ||
=== | ===Fan and compressor's fisrt stage blades mounting=== | ||
For the first compressor stage and the fan, blades are long enough to have a root parallel to the shaft. An innovative design for the hub would be to a use spacer part between each blade. The whole compressor stage fixation would be the result of all blades and spacer put together side by side. It would be like a pie chart, in which separations are the blades' inserts. This design is probably not used on real planes for two reasons: it's more heavy, since the inside of the compressor stage/shaft is full of metal, and it's too complicated for higher stages as we will see below. | |||
An alternative design would be to have the blades moving freely from the hub, and when assembled, a key of some sort would fix them on the hub. The hub and the blades would have a notch in the same place, in which a ring-shaped key would place to hold everything together. This is illustrated in the pictures below. | |||
===2nd and 3rd stage's compressor blade close-up and manufacturing=== | |||
Higher stages have shorter blades, and need to have the base of the blade non-parallel to the shaft for their twisting to be acceptable. That brings problems to the design and manufacturing of the blade socket and fixing: creating a part that can be duplicated to form a cylinder, but with a non-parallel-to-the-axis separation. | |||
We propose a more classical solution to this problem: the hub is a standalone part, in which are milled the inserts holes. Blades' inserts remain a linear part and the milling of the hub is thus linear too. Since it's a round part, this makes a strange effect, but allows the blades to be properly fixed on their sides, and if not enough, by a keyed design. The pictures below represent this mounting system, in exploded view in the first row (larger versions available). | |||
[[File:Interblade1.jpg|300px]] [[File:Interblade2.jpg|300px]] | [[File:Interblade1.jpg|300px]] [[File:Interblade2.jpg|300px]] | ||
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[[File:Blade_fixation1.jpg|300px]] [[File:Blade_fixation2.jpg|300px]] | [[File:Blade_fixation1.jpg|300px]] [[File:Blade_fixation2.jpg|300px]] | ||
==Stator design== | ==Stator design== | ||
Revision as of 00:02, 24 February 2011
Compressor design
Real-world engines can have nearly 20 compression stages. We will first build a 3-stage compressor, in a single-spool engine to assess how it can be scaled to a full power engine, or if it will require more stages (= quite costly). Blade design and manufacturing have a dedicated page.
Rotor design
Special care has to be given to the rotor, since it will spin at very high rotation speeds (not calculated yet).
A blade mounting failure will likely cause the loss of the aircraft, given the constraints. The part that holds the blades is called the hub. We'll call the part of the blades that is hold by the blades at their root the insert.
Fan and compressor's fisrt stage blades mounting
For the first compressor stage and the fan, blades are long enough to have a root parallel to the shaft. An innovative design for the hub would be to a use spacer part between each blade. The whole compressor stage fixation would be the result of all blades and spacer put together side by side. It would be like a pie chart, in which separations are the blades' inserts. This design is probably not used on real planes for two reasons: it's more heavy, since the inside of the compressor stage/shaft is full of metal, and it's too complicated for higher stages as we will see below.
An alternative design would be to have the blades moving freely from the hub, and when assembled, a key of some sort would fix them on the hub. The hub and the blades would have a notch in the same place, in which a ring-shaped key would place to hold everything together. This is illustrated in the pictures below.
2nd and 3rd stage's compressor blade close-up and manufacturing
Higher stages have shorter blades, and need to have the base of the blade non-parallel to the shaft for their twisting to be acceptable. That brings problems to the design and manufacturing of the blade socket and fixing: creating a part that can be duplicated to form a cylinder, but with a non-parallel-to-the-axis separation.
We propose a more classical solution to this problem: the hub is a standalone part, in which are milled the inserts holes. Blades' inserts remain a linear part and the milling of the hub is thus linear too. Since it's a round part, this makes a strange effect, but allows the blades to be properly fixed on their sides, and if not enough, by a keyed design. The pictures below represent this mounting system, in exploded view in the first row (larger versions available).
Below is a close-up on the mounted blades and on the key system from the yellow part.
Stator design
Even more complicated.
