Tapered Micro-Plows for Shock Boundary Layer Control
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Solution Overview
Problem
Conventional methods for reducing shock-induced boundary layer separation in supersonic aircraft inlets, such as active bleeding and micro-vane or micro-ramp vortex generators, are either complex, heavy, or ineffective, leading to performance degradation and foreign object damage hazards.
Innovation Solution
The use of tapered micro-plows, which generate vortex pairs to keep the boundary layer attached to the surface, reducing adverse effects of upwash and shock losses, and are securely fixed due to their large contact area, thereby enhancing resistance to breakage and thermal erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active bleeding is used to reduce shock-induced separation, then separation is reduced, but device complexity and weight increase due to porous surfaces and tubes/plumbing
Solution Approach 1:
The invention extracts the essential function of active bleeding (removing boundary layer fluid) and implements it passively through geometric features (ramps and vanes) that naturally generate vortices to remove low-momentum fluid, eliminating the need for complex porous surfaces and tubing while achieving similar separation control
Solution Approach 2:
The passive vortex generators use the freestream flow itself to generate vortices that perform the boundary layer control function, eliminating the need for external power sources, active control systems, or complex plumbing infrastructure
2Reliability
If micro-vanes are used to modify boundary layer flow, then flow attachment is improved, but foreign object damage hazard increases due to small contact surface and detachment risk
Solution Approach 1:
The invention merges the vortex generation function with the surface geometry itself by integrating ramps and vanes directly into the boundary layer structure, creating a unified feature that cannot detach and eliminates the hazard of loose micro-vanes while maintaining flow control effectiveness
Solution Approach 2:
The ramp and vane geometries use curved and tapered surfaces that generate stronger, more stable vortices compared to flat micro-vanes, improving flow attachment while the integrated design eliminates detachment risks
3Reliability
If micro-ramps are used instead of micro-vanes, then attachment security is improved, but aerodynamic performance deteriorates due to shock wave orientation and vortex lift-off
Solution Approach 1:
The invention applies different geometric features (ramps at certain locations, vanes at others) with specific angles and orientations tailored to local flow conditions, optimizing vortex generation to prevent both attachment issues and adverse shock interactions while avoiding vortex lift-off through proper geometric design
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Tapered micro-plows effectively delay boundary layer separation, reduce shock losses, and minimize foreign object damage hazards by generating vortices that redistribute energy within the boundary layer, maintaining flow attachment and improving aerodynamic performance.
Implementation Method 1
Each tapered micro-plow can generate a vortex pair which minimizes the adverse effects of upwash and shock losses
Implementation Method 2
modify boundary layer flow over a surface by generating pairs of vortices that can keep can the boundary layer flow attached to the surface
Implementation Method 3
The leading edge shocks emanate primarily outward into the boundary layer, rather than up into the supersonic core flow
Data Source
AI summary
A tapered micro-plow, or a series of tapered micro-plows, are submerged in a boundary layer just upstream of a reflection point of an oblique shock. Each micro-plow develops a beneficial pair of vortices which redistribute high energy flow within the boundary layer such that flow separation is prevented or delayed. The beneficial vortex pairs rotate about an axis that is parallel to the flow of fluid, and together rotate such that they induce a velocity on one another which tends to hold them near the surface and delay vortex lift-off.