Gas turbine engine including a pre-diffuser heat exchanger

According to an example embodiment, a gas turbine engine assembly includes, among other things, a compressor. A strut near the compressor includes a flow passage through a portion of the strut. The flow passage is configured to direct air from the compressor to another portion of the gas turbine engine. The flow passage has at least one surface feature that at least partially hinders some airflow through the flow passage.

BACKGROUND

There are various aspects of gas turbine operation that require or would benefit from temperature control. For example, it is useful to provide cooling air to the turbine section. Providing sufficiently cool air to the turbine section tends to increase the lifetime of the turbine hardware.

SUMMARY

According to an example embodiment, a gas turbine engine assembly includes, among other things, a compressor. A strut near the compressor includes a flow passage through a portion of the strut. The flow passage is configured to direct air from the compressor to another portion of the gas turbine engine. The flow passage has at least one surface feature that at least partially augments heat transfer within the flow passage.

In a further non-limiting embodiment according to the foregoing gas turbine engine assembly, the surface feature comprises a rough surface within the flow passage.

In a further non-limiting embodiment according to any of the foregoing gas turbine engines assemblies, the surface feature comprises a baffle within the flow passage.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the flow passage has a cross-sectional dimension in a direction that is transverse to a primary direction of airflow through the flow path. The baffle comprises a plurality of walls within the flow passage. Each of the walls has a length oriented transverse to the primary direction of airflow. The length of each wall is less than the cross-sectional dimension.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the baffle comprises the plurality of pegs situated in the flow passage. Each of the pegs has a length along a direction that is transverse to a direction of airflow through the flow passage.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the baffle comprises an insert that is situated within a portion of the strut that includes the flow passage.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the baffle establishes a tortuous path for airflow through the flow passage.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the surface feature provides an increased surface area for contacting at least some airflow through the flow passage.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the strut is operative as a heat exchanger such that at least some air entering the flow passage has a higher temperature than at least some air exiting the flow passage.

According to another example embodiment, a gas turbine engine assembly includes, among other things, a compressor. A strut near the compressor includes a flow passage through a portion of the strut. The flow passage is configured to direct air from the compressor to another portion of the gas turbine engine. The flow passage has at least one surface feature that provides an increased surface area for contacting at least some airflow through the flow passage.

In a further non-limiting embodiment according to the foregoing gas turbine engine assembly, the surface feature comprises a rough surface within the flow passage.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the surface feature comprises a baffle within the flow passage.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the flow passage has a cross-sectional dimension in a direction that is transverse to a primary direction of airflow through the flow path. The baffle comprises a plurality of walls within the flow passage. Each of the walls has a length oriented transverse to the primary direction of airflow. The length of each wall is less than the cross-sectional dimension.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the baffle comprises a plurality of pegs situated in the flow passage. Each of the pegs has a length along a direction that is transverse to a direction of airflow through the flow passage.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the baffle comprises an insert that is situated within a portion of the strut that includes the flow passage.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the baffle establishes a tortuous path for airflow through the flow passage.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the surface feature at least partially augments heat transfer within the flow passage.

In a further non-limiting embodiment according to any of the foregoing gas turbine engine assemblies, the strut is operative as a heat exchanger such that at least some air entering the flow passage has a higher temperature than at least some air exiting the flow passage.

According to an embodiment, a method of operating a gas turbine engine includes, among other things, directing airflow from a compressor into a flow passage through a strut near the compressor. A temperature of the airflow in the flow passage is at least partially reduced. Air from the flow passage is directed toward a turbine portion of the gas turbine engine.

In a further non-limiting embodiment according to the foregoing method, the temperature of the airflow in the flow passage is at least partially reduced by using the strut as a heat exchanger for at least partially cooling the airflow.

The various features and advantages of at least one disclosed embodiment will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.

DETAILED DESCRIPTION

A mid-turbine frame58of the engine static structure36is arranged generally between the high pressure turbine54and the low pressure turbine46. The mid-turbine frame58further supports bearing systems38in the turbine section28as well as setting airflow entering the low pressure turbine46.

In one disclosed embodiment, the gas turbine engine20includes a bypass ratio greater than about ten (10:1) and the fan diameter is significantly larger than an outer diameter of the low pressure compressor44. It should be understood, however, that the above parameters are only exemplary of one embodiment of a gas turbine engine including a geared architecture and that the present disclosure is applicable to other gas turbine engines.

FIG. 2illustrates selected portions of the high pressure compressor52of the example embodiment fromFIG. 1. A strut100is situated near the high pressure compressor52. In the illustration ofFIG. 2, the strut100is surrounded by a dashed line101. In the illustrated example, the strut100comprises a pre-diffuser strut and is positioned in the primary flowpath C at element90(illustrated inFIG. 1). The strut100includes an airflow passage102for cooling air that is eventually directed toward the high pressure turbine54. As shown inFIG. 2, some airflow104is bled from the high pressure compressor52and enters the airflow passage102. Before exiting the airflow passage102as schematically shown at106, a temperature of the air is at least partially reduced. The strut100operates as a heat exchanger for at least partially altering the temperature of airflow through the airflow passage102.

In some examples the airflow at104is hotter than the airflow at105. In those cases, the airflow at105can absorb heat from and cool the airflow at104. In some other examples, the airflow at104is cooler than the airflow at105. In those situations the airflow at104absorbs some heat from the airflow at105. In those cases the airflow at106is warmer than the airflow at104.

The airflow106is directed toward and eventually mixes with airflow schematically shown at108that is directed to the high pressure turbine54. Reducing the temperature of the air passing through the airflow passage102enhances the amount of cooling air provided to the components of the high pressure turbine54such as the second vane and the turbine rotor cover plates.

FIGS. 3A and 3Bare cross-sectional illustrations drawn along the plane defined by the dashed lines108, beginning at sectional line103and extending radially outward. The cross-sectional illustrations ofFIGS. 3A and 3Bshow an example configuration of an example airflow passage102. At least one surface feature120within the airflow passage102augments heat transfer within the airflow passage102. In this example, the surface feature augments heat transfer because it at least partially hinders at least some of the airflow through the passage102, which increases the amount of contact between the air and the airflow passage102. In this example, the surface feature120comprises a baffle. The example baffle includes a plurality of vanes or wall segments122that are situated to establish a tortuous path that the airflow must follow as it passes through the airflow passage102. InFIG. 3A, the airflow schematically shown at124follows a tortuous path as illustrated.

In the example ofFIG. 3A, the airflow passage102includes a cross-sectional dimension d. Each of the vanes122has a length L extending in a direction that is transverse to a primary direction of airflow through the airflow passage102. The primary direction of the airflow is schematically shown by the arrows104and106. The length L is less than the cross-sectional dimension d and the vanes122are situated as illustrated to establish the tortuous path for airflow shown at124.

As shown inFIG. 3A, this example also includes ribs or ridges126along the tortuous path that air follows as it passes through the flow passage102. Some examples include ridges formed as turbulentors or trip strips. The ribs or ridges126along with the vanes122increase an amount of surface area within the airflow passage102for contacting at least some of the air104before it exits at106. Increasing the amount of surface contact between the material of the airflow passage102and the air flowing through it enhances the ability of the strut100to operate as a heat exchanger.

FIG. 3Bshows the airflow passage102as seen along the lines3B-3B inFIG. 3A. The airflow passage102in the example is established by an insert128that is situated within the strut100. This configuration allows for the airflow104to pass through the airflow passage102in a direction from bottom to top (according to the drawing) and to allow other air schematically shown at105(FIG. 3A) to flow from the compressor52toward the combustor56. The inset128includes a central opening or through passage129A (FIG. 3B) to accommodate the airflow schematically shown at105.

FIG. 4illustrates another example arrangement. The example ofFIG. 4includes a surface feature120that is configured as a baffle within the airflow passage102. In this example, the airflow passage102extends to an end of the strut100. This example also includes an insert128that is situated within the strut100. A cover plate130establishes one edge of the insert128near an end of the strut100for establishing the airflow passage102as schematically shown. Depending on the configuration of the strut100and the desired amount of airflow through the passage102, an arrangement as shown inFIG. 3 or 4may be selected to meet the needs of a particular situation.

FIG. 5illustrates another example arrangement. In this example, the surface feature120comprises a baffle established by a plurality of posts132situated within the airflow passage102. The posts102interrupt or at least partially hinder airflow through the passage102resulting in air flowing in directions schematically shown at124. Another feature of the posts132is that they increase the amount of surface area contact between the air flowing through the passage102and the material of the passage102. Increased surface area contact increases the heat exchange capability of the strut100for cooling the air104before it exists at106.

FIG. 6illustrates another example arrangement. In this example, the surface feature120includes a rough surface140established on at least one of the sides within the airflow passage102. The rough surface140may have a variety of configurations such as a selected pattern or a random arrangement of surface imperfections or variations in thickness, for example. The rough surface140provides an increased amount of surface area for contact with the airflow through the passage102.

Each of the illustrated examples cool the relatively hot air schematically shown at104exiting from the compressor52. The strut100operates as a heat exchanger. The cooled air schematically shown at106has a lower temperature than the air schematically shown at104. Therefore, a lower temperature air mixture is established at108(FIG. 2). Increasing the heat exchanging capability of the strut100leads to cooler turbine cooling air temperatures. The illustrated examples decrease cooling air needs and increase the lifetime of components in the high pressure turbine54.