Patent Description:
Gas turbine engines typically include a compressor section to pressurize airflow, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases. The combustion gases commonly exceed <NUM> degrees F (<NUM> degrees C).

Cooling of engine components such as the high pressure turbine vane may be complicated by the presence of entrained particulates in the secondary cooling air that are carried through the engine. During engine operation a single point feed passage to each airfoil cooling circuit may be prone to blockage by foreign object particles. If these single source feed apertures become blocked, the associated downstream airfoil cooling circuit is starved of cooling air which may result in airfoil distress.

<CIT> discloses a prior art vane ring, wherein the vanes are internally cooled and the internal cooling circuit receives cooling air through a feed passage connected to a metering passage. Secondary passages feeding the metering passage are formed on an impingement plate.

<CIT> discloses a prior art cooling system for a turbine engine.

<CIT> discloses a prior art axial transfer tube.

<CIT> discloses a prior art debris-filtering technique for a gas turbine engine component air cooling system.

From a first aspect, there is provided a vane ring for a gas turbine engine component as recited in claim <NUM>.

It should be appreciated; however, the following description and drawings are intended to be exemplary in nature and non-limiting.

The gas turbine engine <NUM> is disclosed herein as a two-spool turbo fan that generally incorporates a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM> and a turbine section <NUM>. The fan section <NUM> drives air along a bypass flowpath while the compressor section <NUM> drives air along a core flowpath for compression and communication into the combustor section <NUM> then expansion through the turbine section <NUM>. Although depicted as a turbofan in the disclosed non-limiting embodiment, the concepts described herein may be applied to other turbine engine architectures such as turbojets, turboshafts, and three-spool (plus fan) turbofans.

The engine <NUM> generally includes a low spool <NUM> and a high spool <NUM> mounted for rotation about an engine central longitudinal axis A relative to an engine case structure <NUM> via several bearing structures <NUM>. The low spool <NUM> generally includes an inner shaft <NUM> that interconnects a fan <NUM>, a low pressure compressor ("LPC") <NUM> and a low pressure turbine ("LPT") <NUM>. The inner shaft <NUM> drives the fan <NUM> directly or through a geared architecture <NUM> to drive the fan <NUM> at a lower speed than the low spool <NUM>. An exemplary reduction transmission is an epicyclic transmission, namely a planetary or star gear system.

The high spool <NUM> includes an outer shaft <NUM> that interconnects a high pressure compressor ("HPC") <NUM> and high pressure turbine ("HPT") <NUM>. A combustor <NUM> is arranged between the high pressure compressor <NUM> and the high pressure turbine <NUM>. The inner shaft <NUM> and the outer shaft <NUM> are concentric and rotate about the engine central longitudinal axis A which is collinear with their longitudinal axes.

Core airflow is compressed by the LPC <NUM> then the HPC <NUM>, mixed with the fuel and burned in the combustor <NUM>, then the combustion gasses are expanded over the HPT <NUM> and the LPT <NUM>. The turbines <NUM>, <NUM> rotationally drive the respective low spool <NUM> and high spool <NUM> in response to the expansion. The main engine shafts <NUM>, <NUM> are supported at a plurality of points by bearing assemblies <NUM> within the engine case structure <NUM>.

With reference to <FIG>, an enlarged schematic view of a portion of the turbine section <NUM> is shown by way of example; however, other engine sections will also benefit herefrom. A full ring shroud assembly <NUM> within the engine case structure <NUM> supports a blade outer air seal (BOAS) assembly <NUM>. The blade outer air seal (BOAS) assembly <NUM> contains a multiple of circumferentially distributed BOAS proximate to a rotor assembly <NUM>. The full ring shroud assembly <NUM> and the blade outer air seal (BOAS) assembly <NUM> are axially disposed between a forward stationary vane ring <NUM> and an aft stationary vane ring <NUM>. Each vane ring <NUM>, <NUM> includes an array of vanes <NUM>, <NUM> that extend between a respective inner vane platform <NUM>, <NUM> and an outer vane platform <NUM>, <NUM>. The inner vane platforms <NUM>, <NUM> and the outer vane platforms <NUM>, <NUM> attach their respective vane ring <NUM>, <NUM> to the engine case structure <NUM>.

The blade outer air seal (BOAS) assembly <NUM> is affixed to the engine case structure <NUM> to form an annular chamber between the blade outer air seal (BOAS) assembly <NUM> and the engine case structure <NUM>. The blade outer air seal (BOAS) assembly <NUM> bounds the working medium combustion gas flow in a primary flow path <NUM>. The vane rings <NUM>, <NUM> align the flow of the working medium combustion gas flow while the rotor blades <NUM> collect the energy of the working medium combustion gas flow to drive the turbine section <NUM> which in turn drives the compressor section <NUM>.

The forward stationary vane ring <NUM> is mounted to the engine case structure <NUM> upstream of the blade outer air seal (BOAS) assembly <NUM> by a vane support <NUM>. The vane support <NUM>, for example, may include a rail <NUM> that extends from the outer vane platform <NUM> that is fastened to the engine case structure <NUM>. The rail <NUM> includes a multitude of apertures <NUM> spaced therearound to communicate cooling air "C" into the vanes <NUM> as well as downstream thereof. Cooling air "C", also referred to as secondary airflow, often contains foreign object particulates (such as sand). As only a specific quantity of cooling air "C" is required, the cooling air "C" is usually metered to minimally affect engine efficiency.

The aft stationary vane ring <NUM> is mounted to the engine case structure <NUM> downstream of the blade outer air seal (BOAS) assembly <NUM> by a vane support <NUM>. The vane support <NUM> extends from the outer vane platform <NUM> and may include an annular hooked rail <NUM> (also shown in <FIG>) that engages the engine case structure <NUM>.

The annular hooked rail <NUM> includes a feed passage <NUM> (also shown in <FIG> and <FIG>) for each vane <NUM>. The feed passage <NUM> supplies the cooling air "C" to an airfoil cooling circuit <NUM> distributed within the respective vane <NUM>. That is, each vane <NUM> receives cooling air "C" from one respective feed passage <NUM> (<FIG>) that feeds the airfoil cooling circuit <NUM>. In one example, the feed passage is about <NUM> inches (<NUM>) in diameter.

With reference to <FIG>, one example of the feed passage <NUM> includes an extension <NUM> with a metering passage <NUM> in communication with the feed passage <NUM>. The extension <NUM> projects from a surface <NUM> of the annular hooked rail <NUM>. The surface <NUM> is an annular face transverse to the engine axis A. In the disclosed embodiment, the extension <NUM> is generally cubic in shape, however, other shapes such as cylinders, polygons, and others may be utilized. The extension <NUM> may be a standalone feature or, alternatively, an anti-rotation feature for the stationary vane ring <NUM>. The extension <NUM> may be a cast integral with the outer vane platform <NUM> or may be separately machined and attached thereto in communication with the feed passage <NUM>. Cooling airflow "C" communicated to the plenum <NUM> (<FIG>) generally scrubs along the surface <NUM> such that foreign object particles therein have a lessened tendency to enter an entrance <NUM> to the metering passage <NUM> as the entrance <NUM> is displaced from the surface <NUM>.

With reference to <FIG>, another example of the feed passage <NUM> includes an extension <NUM> with a metering passage <NUM> and a multiple of secondary passages <NUM>, <NUM>, <NUM>, <NUM> in each face <NUM>, <NUM>, <NUM>, <NUM> of the extension <NUM> transverse to the metering passage <NUM>. The metering passage <NUM> is sized to meter the flow into the airfoil cooling circuit <NUM> within the vane <NUM> such that the secondary passages <NUM>, <NUM>, <NUM>, <NUM> need not be specifically sized to meter the cooling flow "C".

Cooling airflow within the plenum <NUM> adjacent the outer vane platform <NUM>, <NUM> generally scrubs along the surface <NUM> such that foreign object particles therein have a lessened tendency to enter the metering passage <NUM> and the secondary passages <NUM>, <NUM>, <NUM>, <NUM> as they are displaced from the surface <NUM>. Nonetheless, should one passage become blocked, the other passages permit unobstructed flow into the airfoil cooling circuit <NUM> within the vane <NUM>.

With reference to <FIG>, another example of the feed passage <NUM> includes an extension <NUM> with a metering passage <NUM> and a secondary passage <NUM> transverse to the metering passage <NUM>. The secondary passage <NUM> is a slot transverse to the metering passage <NUM>. If the foreign object particles that scrub along the surface <NUM> are of a size to block the metering passage <NUM>, the foreign objects will become stuck on the secondary passage <NUM> and not be allowed to enter the metering passage <NUM>. Additionally if the entrance of the metering passage <NUM> becomes blocked with a sizeable foreign object, cooling air can still enter the metering passage <NUM> through the secondary passage <NUM>.

With reference to <FIG>, another example of the feed passage <NUM> includes an extension <NUM> with a multiple of secondary passages <NUM>. The extension <NUM> may be separately machined and attached to the surface <NUM>. In this embodiment the multiple of secondary passages <NUM> operate to meter the cooling air "C".

With reference to <FIG>, another example of the feed passage <NUM> includes a metering passage <NUM> and a secondary passage <NUM> transverse to the metering passage <NUM>. The secondary passage <NUM>, in one example is a (feed) slot recessed into the surface <NUM>. In one example, the feed slot <NUM> provides a recessed area approximately equivalent to an area of the entrance <NUM> to the metering passage <NUM>. Although one slot is illustrated in the disclosed example, according to the invention a plurality of secondary passages <NUM> is provided (<FIG>).

Should the metering passage <NUM> become blocked, cooling air "C" may readily pass through the secondary passage <NUM> under the foreign object stuck in the entrance <NUM> and thereby pass into the feed passage <NUM>.

With reference to <FIG>, another example of the feed passage <NUM> includes a non-circular metering passage <NUM>. The non-circular metering passage <NUM> is less likely to be completely blocked by foreign object particles in the cooling flow, thus assuring cooling flow "C".

With reference to <FIG>, another example of the feed passage <NUM> includes a metering passage <NUM>, and a secondary passage <NUM> that intersects with the metering passage <NUM>. That is, the secondary passage <NUM> is a branch from the metering passage <NUM>. In one example, the secondary passage <NUM> forms an angle of about <NUM> degrees with respect to the metering passage <NUM>. The metering passage <NUM> may be sized to meter the cooling flow "C" such that the secondary passage <NUM> need not be specifically sized to meter the cooling flow "C". Should the metering passage <NUM> become blocked, cooling air may readily pass through the secondary passage <NUM> then into the metering passage <NUM> downstream of the entrance <NUM>. The secondary passage <NUM> may be circumferentially located with respect to the metering passage <NUM> to minimize ingress of the foreign object particles based on the expected cooling flow adjacent each vane <NUM>.

With reference to <FIG>, another example of the feed passage <NUM> includes a metering passage <NUM> and a multiple of raised areas <NUM> that are located around the metering passage <NUM>. The raised areas <NUM> extend from the surface <NUM>. The multiple of raised areas <NUM> disrupt the flow and allows the foreign particles to collect outside the metering passage <NUM> rather than entering. Various shapes may alternatively be provided such as an asterisk shape.

During operation of the engine, cooling flow "C" from the high pressure compressor flows around the combustor and into the first vane cavity <NUM>. This cooling air has particulates entrained in it. These particulates are present in the working medium flow path as ingested from the environment by the engine. The majority of the particulates are very fine in size, thus they are carried through the sections of the engine as the working medium gases flow axially downstream. Should a particle be of a size to block the metering passage, the secondary flow passages necessarily permit communication of at least a portion of the cooling air which significantly reduces the risk of damage to the airfoil and increases component field life.

Although particular step sequences are shown, described, and claimed, it should be appreciated that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure.

Claim 1:
A vane ring (<NUM>; <NUM>) for a gas turbine engine component, comprising:
an inner vane platform (<NUM>: <NUM>) around an axis (A);
an outer vane platform (<NUM>; <NUM>) around the axis (A);
a multiple of vanes (<NUM>; <NUM>) that extend between the inner vane platform (<NUM>; <NUM>) and the outer vane platform (<NUM>; <NUM>), each of the multiple of vanes (<NUM>; <NUM>) contains an airfoil cooling circuit (<NUM>) that receives cooling airflow (C) through a respective one of a multiple of feed passages (<NUM>); and
a multiple of metering passages (<NUM>) in the outer vane platform (<NUM>; <NUM>), each of the multiple of metering passages (<NUM>) in communication with one of the multiple of feed passages (<NUM>), wherein the cross section of each of the multiple of metering passages (<NUM>) is circular; and characterised by :
a multiple of secondary passages (<NUM>) recessed in the outer vane platform (<NUM>; <NUM>), wherein a plurality of the multiple of secondary passages (<NUM>) are in communication with each respective one of the multiple of metering passages (<NUM>), wherein each of the multiple of secondary passages (<NUM>) provides a recessed area equal to an area of the entrance (<NUM>) of each of the multiple of metering passages (<NUM>) ;
wherein
each of the multiple of secondary passages (<NUM>) is a slot (<NUM>); and wherein
each of the plurality of the multiple of secondary passages (<NUM>) is transverse to said respective one of the multiple of metering passages (<NUM>).