Wing Ridge Structure for Cross-Flow Instability Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing ridge structures near the leading edge of objects, such as wings, suffer from limited turbulent flow suppression effects due to weakened vortex rows as they travel rearward, and the concave and convex patterns become desynchronized with the cross-flow instability wavefront, leading to interference and potential collapse of the vortex row.
Innovation Solution
A ridge structure with ridge elements aligned at a constant interval and a ridgeline angle set between the boundary layer edge velocity yaw angle and the cross-flow instability angle, extending downstream to maintain a stable vortex row and prevent boundary-layer transition, thereby expanding the laminar flow region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ridgeline angle is set to match the flow line direction (θe), then the smooth shape maintains laminar flow and reduces disturbance, but the vortex row is gradually weakened and attenuated as it travels rearward, limiting the turbulent flow suppression effect to a region immediately behind the SRE
Solution Approach 1:
The patent changes the ridgeline angle parameter from matching the flow line direction (θe) to an intermediate angle between θe and the cross-flow instability angle (θcf). This parameter adjustment allows the ridgeline to maintain synchronization with the cross-flow instability wavefront while still preserving the smooth shape benefit, thereby extending the turbulent flow suppression effect downstream without causing flow separation or vortex collapse.
2Stability of the object's composition
If the ridgeline angle is set to match the cross-flow instability angle (θcf), then the concave and convex pattern synchronizes with the cross-flow instability wavefront, but the pattern becomes desynchronized with the flow line direction, causing interference and potential collapse of the vortex row
Solution Approach 1:
The patent introduces an intermediate ridgeline angle parameter that lies between θe and θcf, optimizing the balance between synchronizing with cross-flow instability and maintaining vortex row stability. This intermediate angle prevents both the flow separation issue (when matching θe) and the vortex collapse issue (when matching θcf), achieving a stable configuration that maintains laminar flow over an extended region.
3Reliability
If disc-like protrusions (DRE) are installed at equal intervals on the leading edge, then stationary cross-flow instability is excited with a specific wavenumber, but the increase of protrusion height causes backwash to become turbulent due to separation, limiting the maximum height and reducing the amplitude of excited instability
Solution Approach 1:
The patent replaces the disc-like protrusions with a sinusoidal ridge structure featuring smooth wave-shaped concave and convex patterns. This curved geometry eliminates flow separation at the crests, allowing the ridgeline height to be increased to two to three times higher than DRE without causing turbulent backwash. The smooth sinusoidal shape maintains laminar flow while effectively exciting stationary cross-flow instability with the desired wavenumber.
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
This configuration effectively suppresses cross-flow instability, causing the boundary-layer transition to recede and reducing frictional resistance on the object surface by maintaining a stable vortex row along the ridgeline angle, thus enhancing the turbulent flow suppression effect.
Implementation Method 1
cross-flow instability amplifies a disturbance, and the boundary layer transitions from a laminar flow state to a turbulent flow state
Implementation Method 2
the boundary layer transitions from a laminar flow state to a turbulent flow state
Implementation Method 3
a strong vortex row was excited behind the SRE
Data Source
AI summary
The ridge structure has ridge elements provided on a top face of a leading edge region directly downstream of a leading edge, which is a laminar flow region of a wing having a swept-back angle relative to a mainstream and provided with a leading edge, and extending in parallel toward downstream of the mainstream. When an angle of a ridgeline connecting vertexes of the ridge elements in an extending direction of the ridge elements relative to x direction is OR, an angle of a flow line of a boundary layer external edge of the mainstream relative to the x direction is θe, and an angle of a wavefront of stationary cross-flow instability, which is a mode in which a stationary disturbance amplifies inside a boundary layer of the surface and appears as a stationary vortex row, relative to the x direction is θcf, θR is between θe and θcf.