Movable Vortex Generators on Aircraft Vertical Stabilizers
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Solution Overview
Problem
Aircraft vertical stabilizers face flow separation and stall issues at large angles of attack, particularly during engine failures, where strong rudder deflection is required, leading to reduced aerodynamic effectiveness.
Innovation Solution
A vertical stabilizer design incorporating movable turbulence generation elements that extend only when the rudder angle exceeds a predetermined minimum, typically 25° or 30°, to prevent flow separation and stall, while maintaining a simple construction and low drag under normal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vortex generators are permanently extended to prevent flow separation at large angles of attack, then flow separation is prevented, but drag increases continuously during normal operation
Solution Approach 1:
The vortex generators are designed to be movable between an extended position (for preventing flow separation at large angles of attack) and a retracted position (for minimizing drag during normal operation). This dynamic adjustment allows the system to optimize performance for different flight conditions, resolving the contradiction between reliable flow separation prevention and energy loss through drag.
2Reliability
If vortex generators are added to the fin surface, then flow separation is prevented at large angles of attack, but device complexity increases
Solution Approach 1:
The vortex generators are designed as movable elements that can be extended or retracted based on flight conditions. This dynamic capability, while adding some complexity, allows the system to maintain simplicity during normal operation (retracted) while providing flow separation prevention when needed (extended), thus resolving the contradiction between reliability and device complexity.
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
The solution effectively prevents flow separation and stall at large angles of attack, ensuring reliable aircraft control during critical situations without increasing drag or complexity under normal operation.
Implementation Method 1
Vortex generators, which are also referred to as swirl vanes or turbulence generators, are projections located on surfaces of aircraft components over which flow occurs, which projections are configured and arranged to selectively generate vortices or turbulence in the boundary layer region of the flow and, in this manner, to supply the flow with energy and maintain the flow along the surface.
Implementation Method 2
The turbulence generation element is biased into the retracted position by a biasing element, in particular by an elastic biasing element.
Data Source
AI summary
A vertical stabilizer for an aircraft, including a fin, pivotable rudder, rudder adjustment arrangement, and vortex generator arrangement having on each side of the fin a turbulence generation element, each turbulence generation element disposed in a surface section of the fin and mounted moveably between a first, retracted position, where it is retracted into an interior space of the fin, and a second, extended position, where it projects at least partially outwardly from the fin transversely with respect to the surface section, and a turbulence generation element adjustment arrangement which is coupled to the rudder. The turbulence generation element adjustment arrangement engages the turbulence generation elements to move them. In a range of angular positions of the rudder, the turbulence generation element adjustment arrangement is inoperative for causing a movement of the turbulence generation elements out of the first position.