Patent Description:
An airfoil utilized within a gas turbine engine includes a cooling chamber within which cooling air flows to remove heat from an inner surface of a wall exposed to extreme temperatures. A baffle within the cooling chamber includes a plurality of openings for directing air to impinge directly against the inner surface of the hot wall. The impingement of the cooling air against the hot wall improves cooling efficiencies.

Cooling efficiencies are further improved with heat transfer features formed on the surfaces of the cooling chamber. Some materials that include favorable temperature performance properties are not easily manufactured to include heat transfer features. Moreover, some materials may experience undesirable heat distributions with heat transfer features formed within a surface or structure exposed to high temperature gas flows.

Accordingly, it is desirable to design and develop features that improve cooling air efficiency and provide uniform cooling air temperatures along the airfoil.

<CIT> discloses a turbine engine vane as set forth in the preamble of claim <NUM>.

<CIT> discloses gas turbine engine airfoil impingement cooling.

<CIT> discloses air cooled turbine vanes.

<CIT> discloses a method of making an air cooled vane with a film cooling pocket construction.

From a first aspect, the present invention provides a turbine engine vane as recited in claim <NUM>.

In an embodiment of the foregoing turbine engine vane, of flat plate insert scoops are configured to generate turbulent cooling airflow on the first side of the flat plate insert.

In a further embodiment of any of the foregoing turbine engine vanes, the baffle insert divides the leading edge cavity into separate channels comprising an interior channel for receiving cooling airflow and an exterior channel defined between the inner surface and the insert that receives cooling airflow through the plurality of scoops.

In a further embodiment of any of the foregoing turbine engine vanes, the plurality of baffle insert scoops are arranged in rows across the insert and each of the rows is staggered relative to adjacent rows.

In a further embodiment of any of the foregoing turbine engine vanes, the airfoil includes a plurality of film cooling holes for communicating cooling airflow from the leading and trailing edge cavities to an outer surface of the airfoil.

The invention also provides turbine engine as recited in claim <NUM>.

The invention also provides a method of cooling a turbine engine vane as recited in claim <NUM>.

Features of embodiments of the disclosure are set forth in the dependent claims.

It should be understood that various bearing systems <NUM> at various locations may alternatively or additionally be provided and the location of bearing systems <NUM> may be varied as appropriate to the application.

The geared architecture <NUM> may be an epicycle gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about <NUM>:<NUM>.

The fan section <NUM> of the engine <NUM> is designed for a particular flight condition -- typically cruise at about <NUM> Mach and about <NUM>,<NUM> feet (<NUM>). The flight condition of <NUM> Mach and <NUM>,<NUM> ft (<NUM>), with the engine at its best fuel consumption - also known as "bucket cruise Thrust Specific Fuel Consumption ('TSFC')" - is the industry standard parameter of Ibm of fuel being burned divided by Ibf of thrust the engine produces at that minimum point. The "Low corrected fan tip speed" as disclosed herein according to one non-limiting embodiment is less than about <NUM> ft / second (<NUM>/second).

The example gas turbine engine includes the fan <NUM> that comprises in one non-limiting embodiment less than about twenty-six (<NUM>) fan blades. In another non-limiting embodiment, the fan section <NUM> includes less than about twenty (<NUM>) fan blades. Moreover, in one disclosed embodiment the low pressure turbine <NUM> includes no more than about six (<NUM>) turbine rotors schematically indicated at <NUM>. In another non-limiting example embodiment the low pressure turbine <NUM> includes about three (<NUM>) turbine rotors. A ratio between the number of fan blades <NUM> and the number of low pressure turbine rotors is between about <NUM> and about <NUM>. The example low pressure turbine <NUM> provides the driving power to rotate the fan section <NUM> and therefore the relationship between the number of turbine rotors <NUM> in the low pressure turbine <NUM> and the number of blades <NUM> in the fan section <NUM> disclose an example gas turbine engine <NUM> with increased power transfer efficiency.

The turbine section <NUM> operates at elevated temperatures and therefore features for active cooling are provided. In this example cooling air from the compressor section <NUM> is communicated through a conduit <NUM> to the turbine section <NUM>. In this example, cooling air is communicated to a stationary stage including vanes <NUM> that are part of the low pressure turbine <NUM>. It should be understood, that although in this disclosed example cooling air is communicated to the fixed vane <NUM> of the low pressure turbine <NUM> that it is within the contemplation of this disclosure that cooling air may be supplied to other aircraft components, vane stages, blades and structures that are supplied with cooling airflow.

Referring to <FIG>, the illustrated turbine vane <NUM> according to the present invention includes an outer platform <NUM>, an inner platform <NUM>, and an airfoil that extends between the outer platform <NUM> and the inner platform <NUM>. The airfoil section <NUM> is hollow and defines a first or leading edge cavity <NUM> and a second or trailing edge cavity <NUM>. Cooling air is communicated through first and second openings <NUM> and <NUM> into corresponding cavities <NUM> and <NUM>.

The first cavity <NUM> includes a baffle <NUM> and the second cavity <NUM> includes a flat plate <NUM>. Each of the baffle <NUM> and plate <NUM> are inserts that direct cooling airflow supplied to each of the corresponding cavities <NUM>, <NUM>. The inserts direct cooling air to impinge on outer walls of each of the corresponding cavities <NUM>, <NUM>.

Referring to <FIG> with continued reference to <FIG>, the baffle insert <NUM> defines an interior channel <NUM> with an open top and includes a plurality of scoops <NUM> that extend into that interior space. In the disclosed example, the scoops <NUM> are arranged in a plurality of rows <NUM> and columns <NUM> along the length of the baffle <NUM>. The rows <NUM> and columns <NUM> of scoops <NUM> are staggered relative to an adjacent row and column. It is also within the contemplation of this disclosure that the scoops <NUM> could be distributed in other arrangements within either the baffle insert <NUM> or the flat plate <NUM>.

The plate <NUM> includes a first side <NUM> and a second side <NUM>. The plate also includes a plurality of scoops <NUM> that are arranged in rows <NUM> and columns <NUM>. Each of the scoops <NUM> include an opening <NUM> directed towards the direction of incoming cooling air flow. The baffle <NUM> and the plate <NUM> are assembled into the corresponding cavity and secured in place to provide and direct cooling air flow that is supplied from the compressor section <NUM>.

Referring to <FIG> and <FIG> with continued reference to <FIG>, the leading edge cavity <NUM> is shown in cross-section including baffle <NUM>. The baffle <NUM> is inserted into the leading edge cavity <NUM> such that it defines the interior channel <NUM> and an exterior channel <NUM> between the baffle <NUM> and the inner surface <NUM> of the cavity <NUM>. Cooling air indicated by arrow <NUM> is supplied through the first opening <NUM> into the interior channel <NUM>. Each of the plurality of scoops <NUM> includes the opening <NUM> that is directed upward to receive incoming air flow <NUM>. The cooling air flow <NUM> is then directed through each of the plurality of scoops <NUM> and impinged against the inner surface <NUM> of the cavity <NUM>. Cooling air flow <NUM> is then exhausted through film cooling holes <NUM> or through bottom openings <NUM> of channel <NUM> defined between the baffle <NUM> and inner surface <NUM> of cavity <NUM>.

Since opening <NUM> is aimed at incoming air flow <NUM>, the scoops <NUM> utilize total pressure, rather than static pressure, to drive the cooling flow <NUM> against inner surface <NUM> of cavity <NUM>. This increases the pressure delta across the baffle <NUM>, which increases impingement heat transfer on inner surface <NUM> of cavity <NUM>.

Referring to <FIG> and <FIG> with continued reference to <FIG>, the trailing edge cavity <NUM> is smaller and therefore includes the flat plate insert <NUM>. The flat plate insert <NUM> includes a plurality of the scoops <NUM> that extend from a first side <NUM>. Cooling air <NUM> directed into the cavity <NUM> is directed through the scoops <NUM> from the first side <NUM> to a second side <NUM>.

The flat plate insert <NUM> divides the cavity <NUM> into a first part <NUM> and a second part <NUM>. In this example, the parts <NUM> and <NUM> extend the radial length of the cavity <NUM>. Each of the scoops <NUM> includes the opening <NUM> directed upward to receive incoming cooling airflow <NUM> and direct that airflow <NUM> through the flat plate <NUM> from the first side <NUM> to the second side <NUM>. Cooling air flow directed through the plate <NUM> is impinged on an inner surface <NUM> of the cavity <NUM> within the second part <NUM>, using total pressure as the driving pressure. Air flow that remains within the first part <NUM> is disturbed to create a turbulent air flow that scrubs against the inner surface <NUM> of cavity <NUM> to generate improved heat transfer performance. The combination of impingement cooling airflow in the second part <NUM> and turbulent flow in the first part <NUM> provide improved heat transfer performance.

Referring to <FIG>, <FIG> and <FIG>, a plurality of film cooling holes <NUM> extend through the airfoil <NUM> between each of the cavities <NUM>, <NUM> to the outer surface <NUM>. Cooling air flows from each cavity <NUM>, <NUM> to the outer surface <NUM> of the airfoil <NUM> to provide film cooling airflow <NUM>. The film cooling airflow <NUM> provides additional cooling along the outer surface of the turbine vane <NUM>. Because the scoops <NUM> utilize total pressure rather than static pressure to direct cooling airflow, the pressure in channels <NUM> and <NUM> is also higher. This results in pressure across the film cooling holes <NUM> being increased without increasing supply pressure. The increased pressure of film cooling airflow <NUM> reduces the possibility of back flow through the film cooling holes <NUM> of hot exhaust gases. Cooling air flow that is not communicated through the film cooling holes <NUM> is directed through a bottom surface or opening <NUM> and will either be exhausted or supplied to other features for cooling purposes.

Accordingly, cooling of the disclosed turbine vane <NUM> is provided by inserting the baffle <NUM> and the flat plate <NUM> into a corresponding one of the cavities <NUM>, <NUM> within the airfoil <NUM>. The baffle <NUM> and plate <NUM> include the plurality of scoops <NUM> configured to direct cooling airflow <NUM> against the inner surface <NUM>, <NUM> of the corresponding cavity <NUM>, <NUM> using total pressure as the driving pressure. Cooling airflow is then directed through the plurality of film cooling holes <NUM> that define passages between the outer surface <NUM> of the airfoil <NUM> and the corresponding cavity <NUM>, <NUM>.

The example scoops <NUM> defined within the baffle <NUM> and the flat plate <NUM> are stamped features arranged in columns <NUM> and rows <NUM> spaced apart such that they provide total desired cooling air flow against the inner surfaces <NUM>, <NUM> of each cavity <NUM>,<NUM>. In certain turbine vane applications, the vanes are fabricated from material that is not favorable of the creation of integrally formed flow directing features. Accordingly, the example inserts <NUM>, <NUM> both direct cooling airflow for impingement and generate turbulence to improve heat transfer performance.

Claim 1:
A turbine engine vane (<NUM>) comprising:
an outer platform (<NUM>);
an inner platform (<NUM>);
an airfoil extending between the outer platform (<NUM>) and the inner platform (<NUM>) and including a hollow airfoil section (<NUM>) defining a leading edge cavity (<NUM>) in communication with a source of cooling air (<NUM>) through a first opening (<NUM>) in the leading edge cavity (<NUM>) and a trailing edge cavity (<NUM>) in communication with a source of cooling air (<NUM>) through a second opening (<NUM>) in the trailing edge cavity (<NUM>), wherein the trailing edge cavity (<NUM>) is smaller than the leading edge cavity (<NUM>);
a baffle insert (<NUM>) disposed within the leading edge cavity (<NUM>) and defining an interior channel (<NUM>) with an open top through which cooling air (<NUM>) flows,
wherein the baffle insert (<NUM>) includes a plurality of baffle insert scoops (<NUM>) for directing cooling air (<NUM>) through the insert (<NUM>) and against an inner surface (<NUM>) of the leading edge cavity (<NUM>), characterised in that the plurality of baffle insert scoops (<NUM>) protrude into the interior channel (<NUM>) and in that an opening (<NUM>) of each of the plurality of baffle insert scoops (<NUM>) is directed towards an incoming flow of cooling air (<NUM>) to capture total pressure of the cooling air (<NUM>) which is directed to impinge on the inner surface (<NUM>) of the leading edge cavity (<NUM>); and
a flat plate insert (<NUM>) disposed within the trailing edge cavity (<NUM>), the flat plate insert (<NUM>) including a first side (<NUM>) and a second side (<NUM>) and a plurality of flat plate insert scoops (<NUM>) configured to direct cooling air flow (<NUM>) through the flat plate insert (<NUM>) from the first side (<NUM>) to the second side (<NUM>) against an inner surface (<NUM>) of the trailing edge cavity (<NUM>),
wherein the plurality of flat plate insert scoops (<NUM>) extends from the flat plate insert (<NUM>) on the first side (<NUM>) and an opening (<NUM>) of each of the plurality of flat plate insert scoops (<NUM>) is directed towards an incoming flow of cooling air (<NUM>) to capture total pressure of the cooling air (<NUM>) which is directed to impinge on the inner surface (<NUM>) of the trailing edge cavity (<NUM>).