METHODS FOR OPTIMIZING BOUNDARY LAYER CONTROL (BLC) SYSTEMS AND RELATED SYSTEMS

Abstract

Methods for optimizing Boundary Layer Control (BLC) systems and related systems (e.g. a Laminar Flow Control (LFC) system or systems, a Static Pressure Thrust (SPT) system or systems, a Boundary Layer Ingestion (BLI)/Wake Immersed Propulsion (WIP) system or systems, and/or low-dissipation BLC fluid-movement system or systems) to operate in concert with each other and a bellows air-moving system are disclosed.

Claims

1. An aircraft wing with a system for optimizing boundary layer control, comprising: an enclosing structure having a leading edge, a trailing edge, a first wing portion extending between the leading edge and the trailing edge, and a second wing portion extending between the leading edge and the trailing edge and disposed opposite the first wing portion; an inner cavity defined within the enclosing structure; at least one bellows assembly disposed in the inner cavity and including at least one primary bellows and at least one secondary bellows operating in concert with the primary bellows; wherein the at least one bellows assembly is spaced apart from inner surfaces of the leading edge, the trailing edge, the first wing portion, and the second wing portion so as to define a void between the at least one bellows assembly and the inner surfaces; a first boundary control inlet defined in the first wing portion and in communication with the void; and a second boundary control inlet defined in the second wing portion and in communication with the void.

2. The aircraft wing of claim 1, further comprising at least one further boundary control inlet defined in the first wing portion and in communication with the void.

3. The aircraft wing of claim 1, further comprising a series of boundary control inlets defined in the first wing portion and in communication with the void.

4. The aircraft wing of claim 2, wherein the at least one further boundary control inlet is arranged rearwardly of the first boundary control inlet and aligned, in a lateral direction of the wing, with the first boundary control inlet.

5. The aircraft wing of claim 3, wherein the series of boundary control inlets is arranged rearwardly of the first boundary control inlet and aligned, in a lateral direction of the wing, with the first boundary control inlet; and wherein the boundary control inlets of the series of boundary control inlets are arranged in a front-aft direction of the wing and aligned in the lateral direction of the wing.

6. The aircraft wing of claim 1, further comprising: a blown diffuser disposed proximate the trailing edge and in communication with the void.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Advantages of embodiments of the present invention will be apparent from the following detailed description of the exemplary embodiments thereof, which description should be considered in conjunction with the accompanying drawings in which like numerals indicate like elements, in which:

[0034] FIG. 1 is an exemplary diagram representing a side view look at a body designed to benefit from this bellows-based BLC air moving mechanism.

[0035] FIG. 2 is an exemplary diagram representing a side view look at a body designed to benefit from a bellows-based BLC air moving mechanism.

[0036] FIG. 3 is an exemplary diagram representing a top-down look at a body designed to benefit from a bellows-based BLC architecture.

[0037] FIG. 4 is an exemplary diagram representing a cross-section of a body designed to benefit from increased imperfection tolerance, showing area of favorable pressure gradient.

[0038] FIG. 5 is an exemplary diagram representing a top-down look at a body designed to benefit from Laminar Cascade Propulsion

[0039] FIG. 6 is an exemplary diagram representing a close-up view of the external surface of a body designed to benefit from Laminar Cascade Propulsion.

[0040] FIG. 7 is an exemplary diagram representing an isometric perspective of a legacy Solar powered High Altitude Long Endurance (HALE) aircraft on the left side and the aircraft on the right side is a much larger Solar HALE aircraft which has been designed to exploit Laminar Cascade Propulsion, Static Pressure Thrust, the low-dissipation BLC fluid-movement mechanism disclosed here and related advances.

DETAILED DESCRIPTION

[0041] Aspects of the invention are disclosed in the following description and related drawings directed to specific embodiments of the invention. Alternate embodiments may be devised without departing from the spirit or the scope of the invention. Additionally, well-known elements of exemplary embodiments of the invention will not be described in detail or will be omitted so as not to obscure the relevant details of the invention. Further, to facilitate an understanding of the description, discussion of several terms used herein follows.

[0042] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. Likewise, the term “embodiments of the invention” does not require that all embodiments of the invention include the discussed feature, advantage or mode of operation.

[0043] FIG. 1 is an exemplary diagram representing a side look at a body designed to benefit from this bellows-based BLC air moving mechanism with bellows mechanism 20, shown expanding. This exemplary embodiment shows outer wing skin surface 10, BLC inlet 50, area of below-ambient pressure 100 (in this case being maintained by bellows mechanism 20, which is contracting elsewhere not shown), bellows mechanism 20, which is shown expanding, and Wake Immersed Propulsion duct 30. This WIP exhaust duct 30, is shown still venting BLC air, also known as the collected & accelerated local wake, overboard out the exhaust duct 30, due to shared plenums & valves of other bellows mechanisms, which are not shown.

[0044] FIG. 2 is an exemplary diagram representing a side view look at a body designed to benefit from an exemplary bellows-based BLC air moving mechanism with bellows mechanism 20, shown contracting. These assemblies can be optimized to operate in concert with each other, so that the combined systematic, sequentially-operating collection of components create and maintain the pressure differential and air flow rate required to achieve the overall goals (e.g., increased areas of laminar flow, areas of Static Pressure Thrust, etc.). This exemplary embodiment shows outer wing skin surface 10, BLC inlet 50, area of below-ambient pressure 100 (in this case being maintained by bellows mechanism 20, which is contracting as shown), bellows mechanism 20, which is shown contracting, and WIP exhaust duct 30. This WIP exhaust duct 30, can vent BLC air, also known as the collected & accelerated local wake, overboard out of the exhaust duct 30, across the trailing edge of the wing due to shared plenums & valves of other bellows mechanisms, which are not shown.

[0045] These assemblies can be optimized to operate in concert with each other, so that the combined systematic, sequentially-operating collection of components create and maintain the pressure differential and air flow rate required to achieve the overall goals (e.g., increased areas of laminar flow, areas of Static Pressure Thrust, etc.).

[0046] FIG. 3 is an exemplary diagram representing a top-down look at a body designed to benefit from an exemplary bellows-based BLC architecture using primary internal bellows assembly 40, and secondary internal bellows assembly 43. This exemplary embodiment shows primary internal bellows assembly 40, and secondary internal bellows assembly 43.

[0047] FIG. 3 shows outer wing skin 10, Primary Bellows Mechanism 40, and Secondary Bellows Mechanism 43. Primary mechanism 40, and Secondary mechanism 43, and the like may be optimized to operate in concert with each other, so that the combined systematic, sequentially-operating collection of components create and maintain the pressure differential and air flow rate required to achieve the overall goals (e.g., increased areas of laminar flow, areas of Static Pressure Thrust, etc.).

[0048] These mechanisms and the like can be optimized to operate in concert with each other, so that the combined systematic, sequentially-operating collection of components create and maintain the pressure differential and air flow rate required to achieve the system design goals (e.g., increased areas of laminar flow, areas of Static Pressure Thrust, etc.).

[0049] In one exemplary embodiment, the BLC apparatus may be switched off or even operated with flow in the opposite direction from normal as a way to manage aircraft energy state. For example, if the aircraft needed to make an emergency descent, turning off the BLC system will greatly increase drag and will increase descent rate accordingly.

[0050] Referring now to FIG. 4, FIG. 4 is an exemplary diagram representing a cross-section of a body designed to benefit from increased imperfection tolerance, showing area of favorable pressure gradient 60. By creating a body that is wider than typical aerodynamic bodies, the local pressure gradient is made more favorable to laminar flow and flow relaminarization. This geometry will allow for surface roughness, waviness, debris contamination and other surface imperfections that would prevent laminar flow across body geometry without such a favorable pressure gradient.

[0051] In one exemplary embodiment, an air taxi aircraft can be flown with laminar boundary layers covering its external geometry despite having surface imperfections (caused by bugs, debris, gaps, deformities, defects, etc.) that would prevent laminar flow on bodies without such a favorable pressure gradient.

[0052] Referring now to FIG. 5, FIG. 5 is an exemplary diagram representing a top-down look at a body designed to benefit from Laminar Cascade Propulsion. In this example the body can be an airfoil or fuselage or other body designed for aerodynamic efficiency. The airflow is from left to right and the BLC inlet or inlets 4, are located near an area designed for laminar flow 8. The series, daisy chain or cascade of laminar flow areas 8, can be placed in multiple locations over the body so that the maximum possible surface area of that body can be covered by laminar flow.

[0053] FIG. 6 is an exemplary diagram representing a close-up view of an external surface of a body designed to benefit from Laminar Cascade Propulsion (LCP). In this example the body can be an airfoil, fuselage, or other body designed for aerodynamic efficiency. As with FIG. 5, the airflow is from left to right and the BLC inlet(s) 4, are positioned to aid in the creation and maintenance of laminar flow over the external surface areas engineered for laminar flow 8.

[0054] The length of laminar flow area 8, will be limited by the local Reynolds number, which will relate to the transition of the flow from laminar to turbulent just as it does on non-BLC designs. This fact does not limit the percentage of the body that can be covered by laminar flow, the Reynolds number limit only limits the length of the area engineered to create and maintain laminar flow 8. For example, even an aircraft fuselage or wing chord of absurdly long length can be made to create and maintain laminar flow over a large majority of its external surface area, as long as the designers limit the length of the area engineered to create and maintain laminar flow 8, to respect the limiting local Reynolds number. The series, daisy chain or cascade of BLC inlet(s) 4, and laminar flow area(s) 8, work together to extend the benefits of laminar flow to bodies of functionally unlimited length.

[0055] By installing LCP systems in this way and optimizing the local geometry to benefit from the series, daisy chain or cascade of LFC systems, the entire combination of LFC systems and related external geometry can be optimized for any particular operational goal.

[0056] The number of LFC systems in the cascade will depend on the goals of the designer. For a Solar powered High-Altitude Long Endurance telecommunications aircraft, the goal might be 100% of the airframe covered in Laminar flow maintained by this LFC cascade. Conversely, some airliner designs are unlikely to enjoy Laminar flow over the cockpit windows and other airframe imperfections, so those designs may not be able to have 100% laminar flow. Those designs will need the LFC cascade to be designed for these airframe imperfections, so that the LFC cascade can create Laminar flow in the areas downstream of the imperfections. For example, if the immediate downstream result of a cockpit window is significantly thicker boundary layer, the BLC/LFC system will need to be designed for that specific flow condition, if only in the immediate area of the thicker boundary layer.

[0057] The benefit of greatly increased laminar flow area may be so large that aircraft performance might be high enough that WIP is not needed and the BLC air is not re-accelerated to flying speed like it is in a WIP configuration.

[0058] In yet another exemplary embodiment, the present invention can be used to enable much better propellers. For example, the oversized airfoils used in the larger Solar HALE aircraft on the right in FIG. 7 can be made significantly more efficient by using an exemplary embodiment. The resulting Solar HALE aircraft may have performance superior to that of the legacy design, which is shown on the left side of FIG. 7.

[0059] The foregoing description and accompanying drawings illustrate the principles, preferred embodiments and modes of operation of the invention. However, the invention should not be construed as being limited to the particular embodiments discussed above. Additional variations of the embodiments discussed above will be appreciated by those skilled in the art.

[0060] Therefore, the above-described embodiments should be regarded as illustrative rather than restrictive. Accordingly, it should be appreciated that variations to those embodiments can be made by those skilled in the art without departing from the scope of the invention.