Patent Description:
Many cases in turbine engines have very restrictive geometry for placing probes to collect Non-Intrusive Stress Measurement System (NSMS) data for vibratory modes on rotating airfoils. Some of the geometries are very thin and also placed between gas paths, as in engines with multiple gas paths. Current probe designs block or obstruct outer gas paths in order to gather data on the inner blades. Not only are the re-operated cases compromised, but the performance of the asset is not indicative of BOM expectations. This is especially important when development engines are tasked with gathering both sets of data (stress and operability) simultaneously.

<CIT> discloses a high temperature uncooled optical probe.

According to a first aspect, there is provided an optical probe as described in claim <NUM>.

The outer tube may be brazed to the housing.

An axial position of the optical head may be fixed with an optical head retention pin extending through the housing and into the optical head.

The optical head may define a plurality of holes proximate the fiber holders to secure the fiber holders thereto with an adhesive.

A forward end of the optical head may be disposed within a view window defined by the housing.

A mirror may be operatively coupled to the housing within the view window. The mirror may be operatively coupled to the housing with a mirror retention pin extending through the housing and into the mirror.

The cap may be welded to the optical head.

The cap may be brazed to the inner tube.

The cap may include channels for fluidly coupling the annulus defined by the inner and outer tubes with an interior of the optical head.

Also disclosed is gas turbine engine as described in claim <NUM>.

The gas turbine engine <NUM> is disclosed herein as a two-spool turbofan that generally incorporates a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM>, a turbine section <NUM>, an augmenter section <NUM> and a nozzle section <NUM>. The sections are defined along a central longitudinal engine axis A. Although depicted as an augmented low bypass gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are applicable to other gas turbine engines including geared architecture engines, direct drive turbofans, turboshaft engines and others.

The compressor section <NUM>, the combustor section <NUM> and the turbine section <NUM> are generally referred to as the engine core. The fan section <NUM> and a low pressure turbine <NUM> of the turbine section <NUM> are coupled by a first shaft <NUM> to define a low spool. The compressor section <NUM> and a high pressure turbine <NUM> of the turbine section <NUM> are coupled by a second shaft <NUM> to define a high spool.

An outer engine case structure <NUM> and an inner engine structure <NUM> define a generally annular secondary flow path <NUM> around a core flow path <NUM> of the engine core. It should be understood that various structure within the engine may define the outer engine case structure <NUM> and the inner engine structure <NUM> which essentially define an exoskeleton to support the core engine therein.

Air which enters the fan section <NUM> is divided between a core flow through the core flow path <NUM> and a secondary flow through the secondary flow path <NUM>. The core flow passes through the combustor section <NUM>, the turbine section <NUM>, then the augmentor section <NUM> where fuel may be selectively injected and burned to generate additional thrust through the nozzle section <NUM>. The secondary flow may be utilized for a multiple of purposes to include, for example, cooling and pressurization. The secondary flow as defined herein is any flow different from the primary combustion gas exhaust core flow. The secondary flow passes through an annulus defined by the outer engine case structure <NUM> and the inner engine structure <NUM> then may be at least partially injected into the core flow adjacent the nozzle section <NUM>.

The outer engine case structure <NUM> and the inner engine structure <NUM> as well as other engine structures are often manufactured of Ceramic Matrix Composite, Organic Matrix Composite materials and combinations thereof which are moisture sensitive. The Ceramic Matrix Composite and the Organic Matrix Composite materials will hereinafter be referred to herein as composite materials but it should be understood that any such moisture sensitive materials and structured are also contemplated.

Referring now to <FIG>, with continued reference to <FIG>, a portion of the gas turbine engine <NUM> is illustrated in greater detail. In particular, a radial flow separation wall is shown. The radial flow separation wall <NUM> is configured to separate a first flow path FP1 of the gas turbine engine <NUM> from a second flow path FP2 of the gas turbine engine <NUM>. The first flow path FP1 flows through blades <NUM> of the gas turbine engine <NUM> and the second flow path FP2 flows through guide vanes, also referred to as stators <NUM>, of the gas turbine engine <NUM>. The first flow path FP1 may be the core flow path <NUM> seen in <FIG> and the second flow path FP2 may be the secondary flow path <NUM> seen in <FIG>. It is understood that embodiments disclosed herein are also applicable to gas turbine engines with more than two flow paths. The radial flow separation wall <NUM> may be composed of one or more components of the gas turbine engine <NUM>.

Referring now to <FIG>, an optical probe <NUM> is embedded in a channel <NUM> of the radial flow separation wall <NUM> of a gas turbine engine <NUM> proximate a base wall of the stator <NUM>, in accordance with an embodiment of the disclosure. The optical probe <NUM> is configured to collect Non-Intrusive Stress Measurement System (NSMS) data for vibratory modes on the blade <NUM>. The optical probe <NUM> can be fully embedded in the flow separation wall <NUM> to collect NSMS data without any impact to the BOM hardware in the embodiments described herein. The low profile design is facilitated by the elimination of typical components required for other probe designs, with the low profile design avoiding gas path obstruction for more accurate testing.

Referring to <FIG>, illustrated is an exterior view of the optical probe <NUM> in an assembled condition. The optical probe <NUM> includes a housing <NUM> having a main body <NUM> and a pair of flanges <NUM>. In some embodiments, the housing <NUM> is a single, uniformly manufactured component, but it is contemplated that an assembled housing may be utilized. The flanges <NUM>, and/or any other part of the housing <NUM>, may be operatively coupled to the flow separation wall <NUM> within the channel <NUM> in any suitable manner. Coupling may include the use of mechanical fasteners, welding, brazing or any other suitable securing technique.

The housing <NUM> contains a number of internal components which are described herein and illustrated in at least <FIG>. In <FIG>, an outer tube <NUM> containing fibers and a cooling passage is shown extending from an aft end <NUM> of the housing <NUM>. A view window <NUM> is defined proximate the forward end <NUM> of the housing <NUM>. Disposed near or within the view window <NUM> is a portion of an optical head <NUM> and a mirror <NUM>. The position of the optical head <NUM> is fixed with an optics head retention pin <NUM> and the position of the mirror <NUM> is fixed with a mirror retention pin <NUM>. Each pin <NUM>, <NUM> extends through the housing <NUM> to secure the optical head <NUM> and the mirror <NUM>, respectively, to the housing <NUM>.

Referring now to <FIG>, illustrated are fiber holders <NUM> holding optical fibers <NUM>. One of the optical fibers is a transmit fiber to route light from a laser source and the other fiber is a receive fiber to route light to a photo detector. Disposed at an end of each fiber holder <NUM> is an optical lens <NUM>. An adhesive is used to hold the optical lenses <NUM>, fiber holders <NUM>, and optical fibers <NUM> in place. The optical fibers <NUM> may be coated in a high temperature material to withstand temperatures up to <NUM> degrees Fahrenheit (<NUM> degrees Celcius), making high temperature uncooled optical probe employable in every stage of high pressure compressors and low pressure compressors of a gas turbine engine. The optical fibers proximate the lens <NUM> are polished to have a flush surface with the end of the fiber holders <NUM>.

The optical lens <NUM> may be convex or may be a gradient index of refraction (GRIN) lens. The optical lenses <NUM> may be made of a transparent material, such as sapphire or silica. As a result, high temperature optical lenses <NUM> may withstand temperatures of up to <NUM> degrees Fahrenheit (<NUM> degrees Celcius). In one embodiment, the optical lens <NUM> collimates the light from the fiber <NUM>.

The fiber holders <NUM> may be made of a superalloy, such as Incoloy®. In alternative embodiments, the fiber holders <NUM> may be made of an alloy or a superalloy, such as Haynes® <NUM>® or Waspaloy®. The adhesive used to hold the optical lenses <NUM>, fiber holders <NUM>, and optical fibers <NUM> in place may be a high temperature adhesive, such as a Cotronics Resbond 907TS variant, which can withstand temperatures of up to <NUM> degrees Fahrenheit (<NUM> degrees Celcius).

Referring now to <FIG>, the optical fibers <NUM> are routed through respective channels of a cap <NUM>. The cap <NUM> provides a connection between an inner tube <NUM> that houses an aft portion the optical fibers <NUM>, while also providing integrated channels for cooling and/or purging of the interior of the housing <NUM>. The cap <NUM> is brazed to the inner tube <NUM> and then slid over the fibers <NUM> during assembly.

Referring to <FIG>, the optical head <NUM> is illustrated in detail. The optical head <NUM> includes through holes <NUM> extending axially in a longitudinal direction of the optical head <NUM>. The optical lenses <NUM> and the fiber holders <NUM> are inserted into an aft side <NUM> of the optical head <NUM> and the cap <NUM> is welded to the aft side <NUM>. A pocket <NUM> or other location feature of the optical head <NUM> at the aft side <NUM> provides a feature to assist with proper locating of the cap <NUM> relative to the optical head <NUM>. Multiple holes <NUM> are provided along optical head <NUM> to allow for the optical lenses <NUM> and the fiber holders <NUM> to be glued into place within the optical head <NUM>.

<FIG> illustrate the optical head <NUM> and the cap <NUM> disposed within the housing <NUM>. The optical head <NUM> is inserted and slid into the housing <NUM> to place the forward end <NUM> of the optical head <NUM> within the view window <NUM>. Once the optical head <NUM> is in the desired position within the housing <NUM>, the optics head retention pin <NUM> or a similar mechanical fastener is inserted through the housing <NUM> and into the optical head <NUM> to fix the position of the optical head <NUM>. The inner tube <NUM> is also shown in <FIG> to be at least partially inserted into the housing <NUM>. The outer tube <NUM> is placed concentrically around the inner tube <NUM> and brazed to the housing <NUM>. The inner tube <NUM> and the outer tube <NUM> are radially spaced from each other to define an annulus <NUM> that allows for cooling air to be routed therethrough or to purge the interior of the housing <NUM>.

Referring to <FIG>, a final assembled condition of the optical probe <NUM> is illustrated. The mirror <NUM> is installed at a forward end <NUM> of the housing <NUM> in a desired position. The mirror retention pin <NUM> or a similar mechanical fastener is inserted through the housing <NUM> and into the mirror <NUM> to fix the position of the mirror <NUM>.

The optical fibers are electrically connected to a measurement device <NUM>, as shown in <FIG>. The measurement device <NUM> is configured to determine various vibratory modes. The measurement device <NUM> may include a processor and a memory. The processor can be any type or combination of computer processors, such as a microprocessor, microcontroller, digital signal processor, application specific integrated circuit, programmable logic device, and/or field programmable gate array. The memory is an example of a non-transitory computer readable storage medium tangibly embodied in or operably connected to the path determination system including executable instructions stored therein, for instance, as firmware.

The transmit fiber is optically connected to a laser source controlled at the measurement device <NUM>. The receive fiber is optically connected to a photo-detector which is electrically connected to the measurement device <NUM>.

The embodiments described herein provides a probe that can be fully embedded in the radial flow separation wall <NUM> to collect NSMS data without any impact to the BOM hardware.

While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made without departing from the scope of the present disclosure.

Claim 1:
An optical probe (<NUM>) for a gas turbine engine (<NUM>) comprising:
a housing (<NUM>);
a plurality of optical fibers (<NUM>), a portion of each of the optical fibers secured to fiber holders (<NUM>);
an optical head (<NUM>) disposed within the housing and having channels extending in a longitudinal direction of the optical head, the fiber holders disposed within the channels;
a cap (<NUM>) disposed within the housing and operatively coupled to the optical head, the plurality of optical fibers extending through the cap; and
an inner tube (<NUM>) operatively coupled to the cap, the plurality of fibers extending through the inner tube; and
an outer tube (<NUM>) surrounding a portion of the inner tube, the inner tube and the outer tube being radially spaced from each other to define an annulus (<NUM>) therebetween arranged to allow cooling air to be routed therethrough or to purge the interior of the housing, the outer tube being operatively coupled to the housing.