Patent Description:
At least some known aircraft include a ram air system that provides ram air to at least one air conditioning pack of an aircraft environmental control system (ECS). In some known aircraft, the air conditioning pack is positioned within a pack bay of the aircraft along with other aircraft components. The air conditioning pack uses ram air to provide cooling to the high-temperature pneumatic air that is delivered to a passenger cabin of the aircraft. However, the ram air does not extract all of the internal heat load and, as a result, the heat may be transferred to the components within the pack bay and to the surrounding aircraft structure. At least some aircraft include a layer of insulation around the air conditioning packs to reduce the discharge of heat from the air conditioning packs to within the pack bay. However, such insulation increases the overall weight and spatial envelope of the aircraft, and may have a limited service life.

This section is intended to introduce the reader to various examples of art that may be related to various examples of the disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various examples of the present disclosure.

<CIT>, in accordance with its abstract, states a ram air system includes a bay comprising an exterior wall defining an interior volume that at least partially encloses a ram air duct. The ram air duct includes an outlet configured to discharge an exhaust airflow at a first temperature. At least one of the exterior wall and the ram air duct defines an aperture therein providing for flow communication between the interior volume and the exhaust airflow such that cooling air flows from the interior volume to form a boundary layer between the exhaust airflow and the exterior wall downstream of the outlet. The boundary layer is at a second temperature that is lower than the first temperature.

<CIT>, in accordance with its abstract, states an air duct arrangement for an aircraft. The arrangement comprises an environmental control system (ECS). The ECS comprises an air inlet arranged to ingest a low velocity portion of a boundary layer flow adjacent the aircraft fuselage, and to deliver a flow of air to an environmental control system air intake. The arrangement further comprises an ejector arranged to receive an ECS exhaust, and boundary layer air from an aft region of the aircraft, and to exhaust air to the ambient airstream at an aft portion of the aircraft.

<CIT>, in accordance with its abstract, states A laminar flow control surface having a foraminous section (also referred to below as a foraminous portion) of a skin of a vehicle to permit low temperature fluid to flow through the foraminous section to a heat exchanger, to reduce drag of the vehicle and to dissipate heat from the heat exchanger. The foraminous section and the heat exchanger synergistically reduce drag and transfer heat from the heat exchanger. The vehicle may be an aircraft with a laminar flow control system including a foraminous portion on a leading edge of the aircraft. While the aircraft is in flight, a portion of air impinging near the foraminous portion may flow laminarly about the leading edge, and another portion of the impinging air may flow through the foraminous portion to a heat exchanger to transfer heat from the heat exchanger to the air.

<CIT>, in accordance with its abstract, states aircraft environmental control systems having a single ram air inlet providing air to both cabin compressors and associated heat exchangers are disclosed herein. In one embodiment, and environmental control system for use with an aircraft includes a ram air inlet, an air conditioning pack, and an associated heat exchanger. In this embodiment, the ram air inlet provides a first portion of air to the air conditioning pack, and a second portion of air to the associated heat exchanger. The first portion of air flows from the air conditioning pack and through the heat exchanger before flowing into an aircraft cabin. The second portion of air from the ram air inlet cools the first portion of air in the heat exchanger before exiting the aircraft through a ram air outlet. The inlet and outlet can be modulated on an optimized schedule to minimize the net drag of the ram system. A system with two ram air inlets is also disclosed.

Examples of an aircraft are described. The aircraft includes a pack bay defined on an underside of the aircraft, comprising an interior; an air conditioning pack positioned within interior configured to discharge heat, and an exterior panel in close proximity to the air conditioning pack. The exterior panel comprises an opening defined therein, a first side facing towards the air conditioning pack, and a second side defining an exterior aircraft surface. The exterior aircraft surface is configured to be in communication with a free stream airflow past the aircraft. At least a portion of the air conditioning pack is disposed within the opening to facilitate transferring heat from the air conditioning pack to the free stream airflow. The air conditioning pack comprises a bottom wall. At least a portion of the bottom wall extends through the opening in the exterior panel for exposing the bottom wall to free stream airflow.

Examples of a method of assembling an aircraft are described. The method includes defining a pack bay on an underside of the aircraft, wherein the pack bay includes an interior, positioning an air conditioning pack within the interior, wherein the air conditioning pack is configured to discharge heat, and positioning an exterior panel in close proximity to the air conditioning pack to at least partially define the interior. The exterior panel includes an opening defined therein, and the exterior panel is positioned such that a first side thereof faces towards the air conditioning pack, and such that a second side thereof defines an exterior surface of the aircraft configured to be in communication with a free stream airflow. The method also includes disposing at least a portion of the air conditioning pack within the opening to facilitate transferring heat from the air conditioning pack to the free stream airflow.

Various refinements exist of the features noted in relation to the above-mentioned examples of the present disclosure. Further features may also be incorporated in the above-mentioned examples of the present disclosure as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated examples of the present disclosure may be incorporated into any of the above-described examples of the present disclosure, alone or in any combination.

The examples described relate to an air conditioning pack and pack bay assembly with improved heat dissipation capabilities. As described herein, the assembly includes an air conditioning pack configured to discharge heat, and an exterior panel positioned in close proximity to the air conditioning pack. The exterior panel has an opening defined therein, which provides a flow communication path between the pack bay and an ambient environment. At least a portion of the air conditioning pack is disposed within the opening such that the air conditioning pack is exposed to the ambient environment. The portion of the air conditioning pack disposed within the opening has no intervening layer of thermally insulating material positioned between the air conditioning pack and the exterior panel. The air conditioning pack has a bottom wall that extends through the opening to be in direct flow communication with the ambient environment. The bottom wall may have an airfoil cross-sectional shape to facilitate preserving the aerodynamic efficiency of the aircraft. In these and other examples, the heat generated by the air conditioning pack is dischargeable to the ambient environment in an efficient, space-saving, and weight-reducing manner that enhances heat rejection from the internal flow.

As used herein, an element or step recited in the singular and preceded with the word "a" or "an" should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "example" or "examples" of the present disclosure are not intended to be interpreted as excluding the existence of additional examples that also incorporate the recited features.

<FIG> is a schematic view of an example aircraft <NUM>. Aircraft <NUM> includes pressurized areas <NUM> and unpressurized areas <NUM>. Pressurized areas <NUM> include, but are not limited to, a cockpit <NUM>, and a passenger cabin <NUM>. Unpressurized areas <NUM> include, but are not limited to, a pack bay <NUM> defined on an underside <NUM> of aircraft <NUM>. Pack bay <NUM> has an interior <NUM>, and an air conditioning pack <NUM> is positioned within interior <NUM>. In operation, air conditioning pack <NUM> receives airflow from the engines, an auxiliary power unit, or electrically driven compressors (all not shown) on aircraft <NUM>, for example. Air conditioning pack <NUM> then cools the airflow, and discharges the cooled airflow for distribution within pressurized areas <NUM>. Thus, air conditioning pack <NUM> generates and dissipates heat during operation thereof.

<FIG> is a bottom view of a portion of aircraft <NUM>, and <FIG> is a sectional view of a portion of aircraft <NUM> taken along line <NUM>-<NUM>. Aircraft <NUM> includes an exterior panel <NUM> in close proximity to air conditioning pack <NUM> positioned within pack bay <NUM>. Exterior panel <NUM> has an opening <NUM> defined therein. Exterior panel <NUM> also has a first side <NUM> that faces towards air conditioning pack <NUM>, and a second side <NUM> that defines an exterior surface <NUM> of aircraft <NUM>. First side <NUM> faces towards air conditioning pack <NUM> in that at least a portion of air conditioning pack <NUM> extends in the direction in which first side <NUM> faces. Exterior surface <NUM> is in communication with a free stream airflow <NUM> that is channeled past exterior panel <NUM>. Free stream airflow <NUM> is defined by an ambient environment <NUM> defined exterior of aircraft <NUM>. In addition, the velocity and cooling capacity of free stream airflow <NUM> is (generally) directly proportional to the velocity of aircraft <NUM>, and free stream airflow <NUM> is channeled past exterior panel <NUM> in a rearward direction (RWD) or substantially rearward direction when aircraft <NUM> is in motion. As used herein, the term "close proximity" refers to when exterior panel <NUM> is either in contact with, or is minimally spaced apart from, any portion of air conditioning pack <NUM>.

Air conditioning pack <NUM> includes a heat exchanger <NUM> defining an enclosure <NUM>, and a plurality of ducts <NUM> are in flow communication with heat exchanger <NUM>. Airflows are channeled to heat exchanger <NUM> via one or more ducts <NUM> to facilitate transferring heat between the airflows, and an airflow is discharged from heat exchanger <NUM> for distribution within pressurized areas <NUM> (shown in <FIG>), for example. Heat exchanger <NUM> has a top side <NUM>, a bottom side <NUM>, and a plurality of lateral sides <NUM> extending therebetween. As noted above, air conditioning pack <NUM> generates heat during operation thereof. For example, as illustrated in <FIG>, heat <NUM> is discharged from each side <NUM>, <NUM>, and <NUM> of air conditioning pack <NUM>.

At least a portion of air conditioning pack <NUM> is disposed within opening <NUM> of exterior panel <NUM> to facilitate transferring heat <NUM> from air conditioning pack <NUM> to free stream airflow <NUM>. For example, bottom side <NUM> of heat exchanger <NUM> and at least a portion of ducts <NUM> are disposed within opening <NUM>, and are directly exposed to ambient environment <NUM>. As such, air conditioning pack <NUM> and ducts <NUM> are positioned to discharge heat <NUM> directly to free stream airflow <NUM>. In addition, bottom side <NUM> and the portion of ducts <NUM> are disposed to be flush or substantially flush with exterior surface <NUM> of aircraft <NUM>. As such, bottom side <NUM> and the portion of ducts <NUM> are exposed to ambient environment <NUM> while still maintaining or substantially maintaining the aerodynamic efficiency of aircraft <NUM>.

In some examples, a layer <NUM> of thermally insulative material extends over at least a portion of heat exchanger <NUM>. For example, as described above, bottom side <NUM> of heat exchanger <NUM> is directly exposed to ambient environment <NUM> to facilitate heat discharge to free stream airflow <NUM>. However, the remaining sides of heat exchanger <NUM>, such as top side <NUM> and lateral sides <NUM>, are covered by layer <NUM> to facilitate reducing heat transfer between air conditioning pack <NUM> and interior <NUM> of pack bay <NUM>. As such, components (not shown) within pack bay <NUM>, electronic or otherwise, and the aircraft structure, are protected from exposure to increased heat and temperature variations. Examples of thermally insulative material include, but are not limited to, a fiberglass material, such as in blanket form, or a closed cell foam material such as polyvinylidene fluoride or polyvinylidene difluoride (PVDF).

Referring now to <FIG>, air conditioning pack <NUM> includes a bottom wall <NUM> disposed on bottom side <NUM> of heat exchanger <NUM>. At least a portion of bottom wall <NUM> extends through opening <NUM> in exterior panel <NUM> for positioning exterior of pack bay <NUM>. That is, in some examples, bottom wall <NUM> is coupled to first side <NUM> of exterior panel <NUM> and the portion of bottom wall <NUM> extends from first side <NUM> through opening <NUM>. Alternatively, bottom wall <NUM> is formed separately from heat exchanger <NUM> and coupled to second side <NUM> of exterior panel <NUM>. In these and other examples, bottom wall <NUM> is oriented to be in flow communication with free stream airflow <NUM> to facilitate defining a thermal communication pathway for heat <NUM> discharged from air conditioning pack <NUM>. In addition, opening <NUM> is at least partially defined by a forward edge <NUM> and a rearward edge <NUM> of exterior panel <NUM>. In these and other examples, bottom wall <NUM> extends between forward edge <NUM> and rearward edge <NUM> to facilitate sealing interior <NUM> from ambient environment <NUM>.

In addition, exposing bottom wall <NUM> to free stream airflow <NUM> facilitates reducing the aerodynamic efficiency of aircraft <NUM> (shown in <FIG>). As such, the portion of bottom wall <NUM> extending through opening <NUM> has an airfoil cross-sectional shape to reduce the amount of drag induced to aircraft <NUM> by bottom wall <NUM> during flight. The shape of bottom wall <NUM> facilitates defining an open space <NUM> between heat exchanger <NUM> and bottom wall <NUM>, and between ducts <NUM> and bottom wall <NUM>. In some examples, open space <NUM> contains air, which receives heat <NUM> from heat exchanger <NUM>, and facilitates its passage through bottom wall <NUM>, for transfer to free stream airflow <NUM>. Alternatively, thermally conductive material <NUM> is positioned between air conditioning pack <NUM> and bottom wall <NUM>, and between ducts <NUM> and bottom wall <NUM>. Thermally conductive material <NUM> facilitates enhancing heat transfer from air conditioning pack <NUM> and ducts <NUM> to free stream airflow <NUM>. Example thermally conductive materials include, but are not limited to, a thermally conductive foam material, heat pipes, or a non-structural and lightweight metallic material such as aluminum.

<FIG> is a schematic sectional view of a portion of the aircraft <NUM> including an example sealing system <NUM> in which exterior panel <NUM> provides a primary load path for the installation of air conditioning pack <NUM>. Sealing system <NUM> is configured to restrict the inflow of free stream airflow <NUM> and debris (not shown) through opening <NUM>. In the example, exterior panel <NUM> includes an indent <NUM>, and air conditioning pack <NUM> includes a flange <NUM> sized to be received within indent <NUM>. For example, indent <NUM> and flange <NUM> are sized such that an exterior surface <NUM> of air conditioning pack <NUM> is flush or substantially flush with exterior surface <NUM> of exterior panel <NUM> at an interface <NUM> defined therebetween.

Sealing system <NUM> includes at least one seal member positioned about the periphery of opening <NUM>. For example, sealing system <NUM> includes a first seal member <NUM> and a second seal member <NUM> positioned between air conditioning pack <NUM> and exterior panel <NUM>. Exterior panel <NUM> includes a side edge <NUM> that is spaced from lateral side <NUM> of air conditioning pack <NUM> such that a cavity <NUM> is defined therebetween. First seal member <NUM> is positioned within cavity <NUM>, and is pre-loaded before being positioned within cavity <NUM> to facilitate sealing interior <NUM> of pack bay <NUM> from ambient environment <NUM>. Second seal member <NUM> is coupled to air conditioning pack <NUM> and exterior panel <NUM> to facilitate sealing cavity <NUM>. That is, second seal member <NUM> is coupled to lateral side <NUM> of air conditioning pack <NUM>, and extends across cavity <NUM> to further couple to first side <NUM> of exterior panel <NUM>. A fastener <NUM> extends through second seal member <NUM>, exterior panel <NUM>, and flange <NUM> of air conditioning pack <NUM> to facilitate installing air conditioning pack <NUM> on aircraft <NUM>. As such, second seal member <NUM> statically affixed between air conditioning pack <NUM> and exterior panel <NUM> to facilitate enhancing the seal provided between interior <NUM> of pack bay <NUM> and ambient environment <NUM>. In some examples, a second fastener is insertable, and is accessible for removal and installation, from the exterior side of aircraft <NUM>. As such, pack bay <NUM> is accessible from exterior of aircraft <NUM> when air conditioning pack <NUM> is uncoupled from exterior panel <NUM>.

First seal member <NUM> and second seal member <NUM> are fabricated from any material that enables aircraft <NUM> to function as described herein. An example seal material includes, but is not limited to, an elastomeric material. When fabricated from elastomeric material, first seal member <NUM> and second seal member <NUM> are capable of accommodating relative movement between air conditioning pack <NUM> and exterior panel <NUM>.

<FIG> illustrates the schematic sectional view shown in <FIG> and including an additional sealing system <NUM>. Aircraft <NUM> includes a lower panel <NUM>, and an attachment mechanism <NUM> coupled between air conditioning pack <NUM> and lower panel <NUM>. Attachment mechanism <NUM> provides the primary load path for installing air conditioning pack <NUM> on aircraft <NUM>, thereby reducing a load induced on exterior panel <NUM> by air conditioning pack <NUM> when attachment is made therebetween. As such, air conditioning pack <NUM> is held stationary or substantially stationary relative to lower panel <NUM>.

Air conditioning pack <NUM> is spaced from exterior panel <NUM> such that a gap <NUM> is defined between flange <NUM> of air conditioning pack <NUM> and side edge <NUM> of exterior panel <NUM>. First seal member <NUM> is positioned within gap <NUM>, and a second seal member <NUM> and a third seal member <NUM> are positioned on opposing sides of gap <NUM>. Second seal member <NUM> is adapted to seal gap <NUM> and to also accommodate movement of exterior panel <NUM> relative to air conditioning pack <NUM>. For example, a layer <NUM> of a low friction coating material is applied to flange <NUM>, and second seal member <NUM> has a sacrificial layer <NUM> of material formed thereon. In operation, exterior panel <NUM> is translatable relative to air conditioning pack <NUM> as a result of the sliding interface between layer <NUM> of low friction coating material and sacrificial layer <NUM>. As such, sealing system <NUM> is capable of accommodating a greater degree of relative motion between air conditioning pack <NUM> and exterior panel <NUM>.

<FIG> illustrates the schematic sectional view shown in <FIG> and including an additional sealing system <NUM> in which exterior panel <NUM> provides a primary load path for the installation of air conditioning pack <NUM>. Air conditioning pack <NUM> is spaced from exterior panel <NUM> such that a gap <NUM> is defined between flange <NUM> of air conditioning pack <NUM> and side edge <NUM> of exterior panel <NUM>. In addition, flange <NUM> includes a lip member <NUM> oriented to extend into interior <NUM> of pack bay <NUM>. Sealing system <NUM> includes a seal member <NUM> positioned within gap <NUM>, and having a first portion <NUM> and a second portion <NUM> positioned on opposing sides of gap <NUM>. Second portion <NUM> of seal member <NUM> is coupled to, and encloses at least a portion of lip member <NUM>. As such, lip member <NUM> facilitates retaining seal member <NUM> in place relative to air conditioning pack <NUM> and exterior panel <NUM>.

<FIG> illustrates the schematic sectional view shown in <FIG> and including an additional sealing system <NUM> in a first operational mode, and <FIG> illustrates additional sealing system <NUM> in a second operational mode. Air conditioning pack <NUM> and exterior panel <NUM> are spaced from each other such that a gap <NUM> is defined therebetween. Sealing system <NUM> includes a spring-seal member <NUM> positioned within gap <NUM>. Spring-seal member <NUM> is pre-loaded within gap <NUM> when in the first operational mode to enable spring-seal member <NUM> to accommodate relative movement between air conditioning pack <NUM> and exterior panel <NUM>. For example, as shown in <FIG>, spring-seal member <NUM> is expandable to accommodate an increase in the size of gap <NUM> as exterior panel <NUM> moves away from air conditioning pack <NUM>. Spring-seal member <NUM> may be fabricated from any material that enables sealing system <NUM> to function as described herein. An example material includes, but is not limited to, a shape memory alloy material. In some examples, spring-seal member <NUM> is biasing device at least partially encapsulated by elastomeric material.

Claim 1:
An aircraft (<NUM>) comprising:
a pack bay (<NUM>) defined on an underside (<NUM>) of the aircraft (<NUM>), comprising an interior (<NUM>);
an air conditioning pack (<NUM>) positioned within interior (<NUM>) configured to discharge heat; and
an exterior panel (<NUM>) in close proximity to the air conditioning pack (<NUM>) comprising an opening (<NUM>) defined therein, and the exterior panel (<NUM>) comprising a first side (<NUM>) facing towards the air conditioning pack (<NUM>), and a second side (<NUM>) defining an exterior aircraft surface (<NUM>), wherein:
the exterior aircraft surface (<NUM>) is configured to be in communication with a free stream airflow (<NUM>) past the aircraft (<NUM>);
at least a portion of the air conditioning pack (<NUM>) is disposed within the opening (<NUM>) to facilitate transferring heat from the air conditioning pack (<NUM>) to the free stream airflow (<NUM>); and
the air conditioning pack (<NUM>) comprises a bottom wall (<NUM>), wherein at least a portion of the bottom wall (<NUM>) extends through the opening (<NUM>) in the exterior panel (<NUM>) for exposing the bottom wall (<NUM>) to the free stream airflow (<NUM>).