SUPPORT STRUCTURE FOR RADIAL INLET OF GAS TURBINE ENGINE

The compressor inlet can have two walls forming an annular fluid path with a radial inlet end, and a support structure extending axially between the two walls, the support structure having a plurality of circumferentially-interspaced supports, each one of the plurality of supports extending freely between the two walls across the radial inlet end of the annular fluid path, each support having at least one node at an intermediary location between the two walls, at least one branch extending from the node to a first one of the walls, and at least two branches branching off from the node and leading to the second one of the walls.

TECHNICAL FIELD

The application related generally to gas turbine engines and, more particularly, to a support structure for a radial inlet of a gas turbine engine.

BACKGROUND OF THE ART

Compressor inlet support structures are designed to maintain structural integrity of the compressor inlet while supporting the assembly under structural and thermal loads experienced during typical mission conditions, or off-design, extreme conditions. In gas turbine engines having radial inlets, it was known to provide a support structure in the form of a plurality of circumferentially interspaced columns. The columns all extended along an axial orientation between opposite walls of the radial inlet. To minimize aerodynamic losses, the columns were typically airfoil shaped along the radial orientation. While these structures were satisfactory to a certain degree, there remained room for improvement in terms of stress distribution, peak stress, and/or weight.

SUMMARY

In one aspect, there is provided a compressor inlet for a gas turbine engine, the compressor inlet having two walls forming an annular fluid path with a radial inlet end, and a support structure extending axially between the two opposite walls, the support structure having a plurality of circumferentially-interspaced supports, each one of the plurality of supports extending freely between the two walls across the radial inlet end of the annular fluid path, each support having at least one node at an intermediary location between the two walls, at least one branch extending from the node to a first one of the walls, and at least two branches branching off from the node and leading to the second one of the walls.

In another aspect, there is provided a gas turbine engine comprising, in serial flow communication, a compressor inlet, a compressor stage, a combustor, and a turbine stage, the compressor inlet having two walls leading to the compressor stage, and a support structure extending axially between the two walls, the support structure having a plurality of circumferentially-interspaced supports, each one of the plurality of supports extending freely between the two walls, each support having at least one node at an intermediary location between the two walls, at least one branch extending from the node to a first one of the walls, and at least two branches branching off from the node and leading to the second one of the walls.

DETAILED DESCRIPTION

FIG. 1illustrates an example of a turbine engine. In this example, the turbine engine10is a turboshaft engine generally comprising in serial flow communication, a compressor inlet11, a multistage compressor12for pressurizing the air, a combustor14in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section16for extracting energy from the combustion gases. The compressor inlet11has a generally annular structure having two opposite walls13,15which guide the intake air from a generally radial orientation to a generally axial orientation.

FIG. 2schematizes example stresses to which the compressor inlet11can be subjected during use of the gas turbine engine10. For instance, the compressor inlet11can be subjected to axial loads when the compressor inlet11is supported between two engine mounts24,26. In some circumstances only one engine mount location is present (24or26). Bending loads tend to deform the compressor inlet by bending, or curving the axis, such as schematized by curved axis20(exaggerated for the purpose of clarity). Such bending loads can be experimented during vibrations, manoeuvres and shocks (e.g. landing), and can be influenced by the weight of the engine.

The compressor inlet11can also be subjected to moment loads22. Such moment loads represent a relative torsion around the axis of the engine between two components, and can be experimented during vibrations, and be influenced by the operation of the engine, for instance. For instance, a torsion can occur between the first wall13and the second wall15of the turbine engine10.

The compressor inlet11can also be subjected to thermal loads. One source of thermal loads is heat expansion/contraction of the components during different scenarios (e.g. high altitude cruising, sea level parking, takeoff).

FIG. 3shows an example of a compressor inlet11for a gas turbine engine10having a radial inlet. The compressor inlet11has a support structure30having plurality of circumferentially interspaced columns32. The columns32all extend along an axial orientation, between opposite walls13,15of the compressor inlet. To minimize aerodynamic losses, the columns32can be airfoil shaped along the radial orientation, so as to offer minimal resistance to the incoming radial airflow. The columns32have a given radial depth36and a given axial length34. The radial depth of the columns32extend from a radially outer portion of the compressor inlet11, and radially into the compressor inlet11, along a curved portion of the wall15which transitions the incoming flow from radial to axial. The radial length of the columns is comparable to the axial length of the columns32, and the columns32have an associated weight.

In one embodiment, engineering knowledge was used in conjunction with computer-assisted analysis using topology optimization techniques in a manner to evaluate the possibility of further optimizing features such as peak load, load distribution, and weight of the support structure30. In the example presented below, the analysis was conducted using the software tool Inspire™ which can be obtained from solidThinking, inc., an Altair company.

In a first scenario, the compressor inlet11was analyzed in a scenario dominated by axial and bending loads for both mission and off design conditions. A support structure was designed which could satisfactorily withstand the structural and thermal loads, while minimizing weight and stress and optimizing stress distribution. For the same general compressor inlet configuration as the one shown inFIG. 3, the design technique led to the support structure40shown inFIG. 4.

In the support structure40shown inFIG. 4, the support structure40includes a plurality of identical supports42which are each circumferentially interspaced from one another. The supports42extend freely from a first wall13of the compressor inlet41to a second wall15of the compressor inlet41. The supports42can be said to have a length extending from the first wall13to the second wall15, and a width which extends circumferentially. The supports42are all identical. The supports42have a first branch44leading from the first wall13to a node46, and two branches48,50branching off from the node46and leading to the second wall15, forming a fork. Overall, the supports42inFIG. 4can be seen to generally have a Y shape. The first one of the branches44has a length52which is shorter than an axial length54of the two other branches48,50, and the intermediary location56of the node46can be seen to be closer to the first wall13than to the second wall15. The length of the supports is generally oriented axially, and is also inclined relative to an axial orientation in the radially-inner direction along angle α, from the first wall13to the second wall15.

In a second scenario, the compressor inlet11was analysed in a scenario dominated by moment loads for both mission and off design conditions. The design technique was used to generate a support structure shape which could satisfactorily withstand the moment loads, while minimizing weight and stress and optimizing stress distribution. For the same general compressor inlet configuration as the one shown inFIGS. 3 and 4, the design technique led to the support structure60shown inFIG. 5.

In the support structure60shown inFIG. 5, the support structure60also includes a plurality of identical supports62which are each circumferentially interspaced from one another. The supports extend freely from a first wall13of the compressor inlet61to the second wall15of the compressor inlet15. The supports62extend generally in an axial orientation. The supports have two branches64,66leading from the first wall to a node65, and two branches68,70branching off from the node65and leading to the second wall15, forming two opposed forks, or a general X-shape. In this embodiment, the supports62are symmetrical both along a radially-axial plane72and along a radially-transversal plane74. The intermediary location72of the node can be seen to be halfway between the first wall13and the second wall15. The length of the supports is inclined relative to an axial orientation in the radially-inner direction along angle α, from the first wall13to the second wall15.

In a third scenario, the compressor inlet was analysed in a scenario of balanced moment and axial loads for both mission and off design conditions. The design technique was used to generate a support structure shape which could satisfactorily withstand the moment loads, while minimizing weight and stress and optimizing stress distribution. For the same general compressor inlet configuration as the one show inFIGS. 3-5, the design technique led to the support structure80shown inFIG. 6.

In the support structure80shown inFIG. 6, the support structure80also includes a plurality of identical supports82which are each circumferentially interspaced from one another. The supports82extend freely from a first wall13to the second wall15of the compressor inlet81. The supports82extend generally in an axial orientation. Each support has main branches86,90and secondary branch84,88branching off from the node85to a corresponding wall13,15, on each axial side of the node85. The secondary branches84,88have a smaller cross-sectional area than the corresponding main branch86,90, and the relative circumferential directions of the main branch86,90and of the secondary branch84,88are inversed on the first side and on the second side. As seen, the main branch slopes downwardly on the left side, and upwardly on the right side inFIG. 6. The main branches86,90are used for compression resistance, whereas the secondary branches84,88are used for tension resistance. In this specific embodiment, both the main branch86and the secondary branch84are shorter on a side of the node85leading to the first wall13, compared to the main branch90and the secondary branch88on the side of the node85leading to the second wall15. The distance92between the first wall13and the node85is smaller than the distance between94the second wall15and the node85. The length of the supports is inclined relative to an axial orientation in the radially-inner direction, from the first wall13to the second wall15.

The shapes presented above can be further adapted to different embodiments of compressor inlets, and to different mission and off design conditions. For instance, icing, inlet distortion and noise can be taken into consideration in the determination of a particular support structure design.

Moreover, the structures can have different shapes in different embodiments. For instance, instead of having two branches leading from a node to a given wall, in a different embodiment, the supports can have three branches leading from a node to a given wall. A three branch embodiment can include two branches positioned adjacent the edge of the radial inlet, and sloping circumferentially relative to each other, and a third branch sloping in a radially-inward direction relative to the other two. Still other configurations are possible.

In practice, the branches will typically be hollow, which can provide weight reduction for a given mechanical resistance. The hollow branches can form a continuous gas path extending inside the support structure, and this gas path can be used to circulate hot air during use, to help withstand icing, if desired. The exact cross-sectional shape of the branches can be selected in a manner to optimize noise and aerodynamic performance. The cross-sectional shape and size can vary along a length of the branches to further reduce areas of peak stress and even out stress distribution. The supports can be formed by any suitable manufacturing process, such as casting or additive manufacturing (e.g. 3D printing), and can involve post processing.