External turning vane for IFS-mounted secondary flow systems

An external turning vane includes a vane body extending radially from the inner cowl and disposed upstream from an inlet of the secondary flow system, the vane body configured to turn an airflow in a bypass flow path towards an axial direction to minimize separation between the airflow and the secondary flow system.

FIELD

This disclosure relates generally to gas turbine engines, and more particularly to secondary flow system arrangements for gas turbine engines.

BACKGROUND

A gas turbine engine may employ secondary flow system inlets that are positioned about the low pressure compressor in the inner fixed structure section of the inner cowl in general fluid communication with a fan duct of the gas turbine engine. More specifically, the inner surface of the outer nacelle and the outer surface of the inner cowl at the low pressure compressor section define a fan duct through which fan airflow is received. This fan duct is the source of airflow for IFS-mounted secondary flow systems.

SUMMARY

An external turning vane for a gas turbine engine having at least an inner cowl, and a secondary flow system is disclosed. The external turning vane comprises a vane body extending radially from the inner cowl and disposed upstream from an inlet of the secondary flow system, the vane body configured to turn an airflow in the bypass flow path towards an axial direction and to introduce higher momentum flow of a vortex into the inlet to minimize flow separation on a sidewall of the inlet.

In various embodiments, the vane body is oriented at a non-zero angle with respect to a centerline axis of the inlet.

In various embodiments, a first height of the vane body is less than a second height of the inlet.

In various embodiments, the inner cowl comprises an inner fixed structure (IFS).

In various embodiments, the vane body is disposed relative to the inlet such that a wake vortex generated by the vane body during operation of the gas turbine engine is completely or nearly completely ingested by the inlet.

In various embodiments, the vane body is configured to convert kinetic energy associated with a circumferential flow direction into a vortex to introduce a higher momentum flow of the vortex into the inlet of the secondary flow system to minimize propagation of a flow separation off a sidewall of the inlet.

In various embodiments, the vane body is configured to straighten the airflow diverted by a bifurcation of the gas turbine engine.

In various embodiments, the first height is a maximum height of the vane body and the second height is a maximum height of the inlet.

A secondary flow system for a gas turbine engine having an inner cowl is disclosed. The secondary flow system comprises an inlet disposed on the inner cowl, the inlet in fluid communication with a bypass flow path, and an external turning vane comprising a vane body extending radially from the inner cowl and disposed upstream from the inlet of the secondary flow system, the vane body configured to turn an airflow in the bypass flow path towards an axial direction and to introduce higher momentum flow of a vortex into the inlet to minimize flow separation on a sidewall of the inlet.

In various embodiments, the vane body is oriented at a non-zero angle with respect to a centerline axis of the inlet.

In various embodiments, a first height of the vane body is less than a second height of the inlet.

In various embodiments, the inner cowl comprises an inner fixed structure (IFS).

In various embodiments, the vane body is disposed relative to the inlet such that a wake vortex generated by the vane body during operation of the gas turbine engine is completely or nearly completely ingested by the inlet.

In various embodiments, the vane body is configured to convert kinetic energy associated with a circumferential flow direction into a vortex to introduce a higher momentum flow of the vortex into the inlet of the secondary flow system to minimize propagation of a flow separation off a sidewall of the inlet.

In various embodiments, the vane body is configured to straighten the airflow diverted by a bifurcation of the gas turbine engine.

A gas turbine engine is disclosed, comprising an outer nacelle, an inner cowl defining a bypass flow path along with the outer nacelle for receiving fan airflow, an inlet for a secondary flow system disposed on the inner cowl, the inlet in fluid communication with the bypass flow path, and an external turning vane comprising a vane body extending radially from the inner cowl and disposed upstream from the inlet of the secondary flow system, the vane body configured to turn an airflow in the bypass flow path towards an axial direction and to introduce higher momentum flow of a vortex into the inlet to minimize flow separation on a sidewall of the inlet.

In various embodiments, the vane body is oriented at a non-zero angle with respect to a centerline axis of the inlet.

In various embodiments, a first height of the vane body is less than a second height of the inlet.

In various embodiments, the inner cowl comprises an inner fixed structure (IFS).

In various embodiments, the vane body is disposed relative to the inlet such that a wake vortex generated by the vane body during operation of the gas turbine engine is completely or nearly completely ingested by the inlet.

In various embodiments, the vane body is configured to convert kinetic energy associated with a circumferential flow direction into a vortex to introduce a higher momentum flow of the vortex into the inlet of the secondary flow system to minimize propagation of a flow separation off a sidewall of the inlet.

In various embodiments, the vane body is configured to straighten the airflow diverted by a bifurcation of the gas turbine engine.

DETAILED DESCRIPTION

An external turning vane of the present disclosure is provided forward from a secondary flow system inlet. A wake vortex generated by the external turning body may be completely or nearly completely ingested by the inlet for improving secondary flow system inlet total pressure recovery. An external turning vane of the present disclosure may minimize air flow separation inside of the inlet.

FIG. 1illustrates a schematic view of a gas turbine engine, in accordance with various embodiments. An xyz-axis is provided for ease of illustration. Gas turbine engine100may include core engine120. Core air flow C flows through core engine120and is expelled through exhaust outlet118surrounding tail cone122.

Core engine120drives a fan112arranged in a bypass flow path B. Air in bypass flow path B flows in the aft direction (z-direction) along bypass flow path B. At least a portion of bypass flow path B may be defined by outer nacelle104and inner cowl106(also referred to herein as an inner fixed structure (IFS)). Fan case132may surround fan112. Fan case132may be housed within outer nacelle104.

Outer nacelle104typically comprises two halves which are typically mounted to a pylon. According to various embodiments, multiple guide vanes114may extend radially between core engine120and fan case132. Upper bifurcation144and lower bifurcation142may extend radially between the outer nacelle104and inner cowl106in locations opposite one another to accommodate engine components such as wires and fluids, for example.

Inner cowl106may surround core engine120and provide core compartment124. Various components may be provided in core compartment124such as fluid conduits, compressed air ducts, and/or air-oil coolers, for example.

With respect toFIG. 2, elements with like element numbering, as depicted inFIG. 1, are intended to be the same and will not necessarily be repeated for the sake of clarity.

Referring toFIG. 2, the front section of a gas turbine engine100having an example secondary flow system102constructed in accordance with the present disclosure is provided. Among other things, the front section of the gas turbine engine100may generally include outer nacelle104, inner cowl106, a splitter108, fan blades112, exit guide vanes114and a fan duct110associated therewith. Moreover, airflow entering into the gas turbine engine100may be split by the splitter108into bypass flow path B flowing through the fan duct110and core air flow C flowing into the low pressure compressor.

The secondary flow system102of the gas turbine engine100ofFIG. 2may be disposed on an outer surface of the inner fixed structure, and generally composed of at least one secondary flow system152and an external turning vane162adjacent thereto. In various embodiments, the external turning vane is disposed downstream, or aft, of exit guide vanes114.

With reference toFIG. 3A, secondary flow system152receives bypass air through an inlet354. In this regard, inlet354is in fluid communication with bypass flow path B. The upper bifurcation144may divert airflow through bypass flow path B around the upper bifurcation144. The upper bifurcation144may tend to turn the bypass air, illustrated by arrow398inFIG. 3A, in the circumferential direction, causing the bypass air to enter inlet354at an angle with respect to a centerline axis390of inlet354. This circumferential flow migration of the bypass air may tend to cause flow separation at a sidewall located circumferentially adjacent upper bifurcation144, such as the upper side302, of inlet354, which may result in a total pressure deficit and decreased system mass air flow. In this regard, an external turning vane is provided, which may improve total pressure distribution across the inlet354and maximize system mass air flow.

In various embodiments, external turning vane162is disposed in front of inlet354. That is, external turning vane162is disposed upstream from inlet354. In various embodiments, external turning vane162is formed as a plate. In this regard, external turning vane162comprises a vane body163extending radially from the IFS106. In various embodiments, external turning vane162is made of a metal such as a steel alloy, stainless steel, titanium, aluminum, or any other metal or alloy thereof. In various embodiments, external turning vane162comprises one or more machined metal parts. In various embodiments, external turning vane162comprises a fiber-reinforced composite material. External turning vane162may be configured to turn bypass air in an axial direction (e.g., parallel to a centerline axis A-A′ of the gas turbine engine100(seeFIG. 2)), illustrated by arrow399, entering inlet354, for example, such that the bypass air enters inlet354substantially parallel to centerline axis390.

With reference toFIG. 3B, due to the aerodynamic effects of external turning vane162, wake vortices395may be generated by external turning vane162and ingested by inlet354. In this regard, external turning vane162may be placed in front of inlet354such that the wake vortices395generated thereby are completely ingested by inlet354. In various embodiments, external turning vane162is placed in front of inlet354such that the wake vortices395generated thereby are completely or nearly completely ingested by inlet354at or near upper side302, which may tend to minimize flow separation from upper side302, improve total pressure distribution across the inlet354, and maximize system mass air flow through secondary flow system152. External turning vane162may be configured to turn the airflow (e.g., see bypass air398ofFIG. 3A) in the bypass flow path such that the wake vortices395of the external turning vane162are directed at the portion of the inlet354challenged by flow separation. External turning vane162may be configured to convert kinetic energy associated with a circumferential flow direction (e.g., see bypass air398ofFIG. 3A) into a vortex (e.g., wake vortices395) to introduce a higher momentum flow of the vortex into the inlet354of the secondary flow system152to minimize propagation of a flow separation off a sidewall (e.g., upper side302) of the inlet354. As used herein, the term “higher momentum flow” means that the momentum of the wake vortices395is greater than the local momentum of the circumferential flow of bypass air398.

In various embodiments, the aerodynamic effects of external turning vane162are further enhanced by optimizing the angle of the external turning vane162relative to centerline axis390to provide optimal vortex size and sidewall (e.g., upper side302) interaction. In various embodiments, external turning vane162is oriented at a non-zero angle with respect to centerline axis390. In various embodiments, external turning vane162is angled towards centerline axis390. External turning vane162may be angled towards centerline axis390with the forward edge364pointed towards centerline axis390. In various embodiments, a height381(also referred to herein as a first height), as measured in the radial direction, of external turning vane162may be less than or equal to a height382(also referred to herein as a second height) of the inlet354. In this manner, the aerodynamic effects of external turning vane162are minimized or eliminated at locations radially outward from inlet354. In various embodiments, height381is the maximum height of external turning vane162. In various embodiments, height382is the maximum height of inlet354. In various embodiments, the length383of external turning vane162is greater than the height381of external turning vane162.

External turning vane162may be attached to IFS106via any known method suitable for attaching vanes to a cowl structure. For example, external turning vane162may be attached to IFS106via one or more fasteners, such as a rivet, a threaded fastener, a bolt, or a screw, among other types of fasteners. Furthermore, external turning vane162may be bonded to IFS106via an adhesive.

Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment”, “an embodiment”, “various embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.