1
$\begingroup$

Vane device comprises inner shroud, outer shroud, aerofoils. I cannot understand what shrouds are, and their function.

$\endgroup$
2
  • $\begingroup$ Do you have a reference where this phrase is used? I’ve heard of a screech liner, but that’s something totally different. $\endgroup$ Commented Oct 25, 2023 at 22:58
  • $\begingroup$ Sorry, this phrase is used in a patent which I don't want to quote in greater detail, due to confidentiality reasons. It is exactly as i reported it. Thank you anyway $\endgroup$ Commented Oct 27, 2023 at 8:24

1 Answer 1

2
$\begingroup$

Generally speaking the shroud in a turbine engine is a flat plate located at the end of the blades which helps to keep the gases from "leaking" past the tips of the blades for better flow, and also to minimize vibration. A more detailed description can be found on the WENZEL America website.

In this photo of an interior blade of an RB199 turbofan engine the shroud is on the right.

RB199 blade RB199 blade (author: Stahlkocher, via Wikimedia Commons, CC-BY-SA-3.0)

Even though in most cases there is an individual shroud for each blade which butt up against each other, the entire structure is often referred to in the singular as a shroud. This diagram shows how it looks when the individual blade-tip shrouds fit together.

Turbine shroud
Turbine shroud (author: unknown, this diagram appears unattributed on multiple websites)

Turbofan engines essentially use the wall of the engine inlet as a shroud for the fan blades, as seen in this photo:

GE90 GE90 (author: Dysanovic, via Wikimedia Commons, CC-BY-2.0)

Although there was a question here about why the fan blades of turbofan engines don't have individual shrouds, and one of the answers included a photo of one that does, the F108 (CFM-56) engines that are used on the reengined KC-135 tankers.

F108 engine F108 turbofan engine (Tinker Air Force Base)

I have seen the blade tip type of shroud referred to as an "outer shroud". I couldn't find anything explaining what an inner shroud is.

$\endgroup$
4
  • $\begingroup$ Very clear and exhaustive explanation. As regards the "inner shroud" the phase I submitted relates to stationary vanes, not to rotor blades. I think that it is something like a vane supporting ring, formed by indvidual foot platforms or "shrouds" of the blades. At least, this is what I understand. In any case,thank you very much $\endgroup$ Commented Oct 27, 2023 at 8:35
  • $\begingroup$ Luciano Grazzini - while for jet engines the term vane is normally used to refer to the stator (stationary) vanes, in discussions about gas turbines in general it also seems to often be used to refer to both stationary vanes and rotating vanes, aka blades. So as you do your research make sure that it's clear which type of vane is being referred to as you look at various sources. If you find an answer regarding stator vane shrouds you can post it here as an answer, it is allowed to answer your own question in Stack Exchange. $\endgroup$ Commented Oct 27, 2023 at 12:56
  • $\begingroup$ EP 1956196, among others, "is directed to a vane shroud of a gas turbine engine §[0004]. In same source, it is stated, e.g., §[0001] that "compressors and turbines are comprised of alternating stages of stator vanes and rotor blades..." and in Claim 1 "A vane shroud of a gas turbine engine..." So, may I infer that the phrase "vane shroud" can refer to a shroud (an individual or common annular component) associated to one or more (stator) vanes in gas turbine of jet engines, as well as for stationary use (power plant)? I understand that this terminology is commonly used in patent literature. $\endgroup$ Commented Nov 1, 2023 at 10:49
  • $\begingroup$ Luciano Grazzini - seems like the term can have multiple meanings. Omniseal sells what seems to be a fixed ring shroud around the fan blades. In this Rolls Royce patent it seems to mention a wall and a skin shroud used for cooling. Another Rolls Royce patent is an inner shroud for a stator vane. A Raytheon patent is for an inner shroud for a variable vane system. $\endgroup$ Commented Nov 1, 2023 at 13:16

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .