Variable IGV and Strut Configuration for Gas Turbine Wake Control
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Solution Overview
Problem
Conventional strut and inlet guide vane configurations in aircraft gas turbine engines lead to undesirable pressure distortion and reduced rotor efficiency due to thick strut wakes penetrating through the inlet guide vane row, causing forced vibratory stresses on rotor blades.
Innovation Solution
A configuration featuring circumferentially-spaced struts with a plurality of variable inlet guide vanes positioned downstream, where the number of vanes is greater than the struts, and adjustable to redirect strut wakes, minimizing wake impact on rotor blades by aligning struts with vanes and adjusting vane positions for optimal flow redirection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thick struts are used to bear structural loads, then strut strength is improved, but wake penetration through inlet guide vanes increases causing pressure distortion and rotor efficiency loss
Solution Approach 1:
The inlet guide vane row is segmented into multiple vanes (greater number than struts) arranged circumferentially to intercept and redirect strut wakes. Each vane handles a portion of the wake redirection, collectively eliminating the harmful wake penetration while preserving strut structural integrity
Solution Approach 2:
The inlet guide vanes serve as an intermediary element positioned between the struts and rotor blades. They intercept the thick wakes generated by struts and redirect them before the wakes can penetrate to the rotor, thereby protecting rotor efficiency while allowing thick struts to maintain their structural function
2Strength
If struts are positioned to bear structural loads with larger chord lengths, then structural support is improved, but forced vibratory stresses on rotor blades increase
Solution Approach 1:
The inlet guide vanes convert the harmful effect of thick strut wakes into a beneficial flow redirection. By positioning vanes to align with struts and adjusting their angles, the wakes that would otherwise cause vibratory stresses are redirected to follow the vane contours smoothly, eliminating the harmful vibration while preserving the structural benefits of thick struts
3Ease of operation
If inlet guide vanes are positioned downstream of struts to guide air flow, then flow guidance function is improved, but wake penetration and pressure distortion occur
Solution Approach 1:
The inlet guide vanes are made variable with adjustable angles, allowing dynamic optimization of their position and orientation. This enables the vanes to effectively intercept and redirect strut wakes while maintaining proper flow guidance to the rotor, eliminating pressure distortion without sacrificing flow guidance capability
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 reduces strut wake penetration and associated pressure distortion and vibratory stresses, enhancing rotor efficiency and operability margins by effectively redirecting air flow around struts with variable inlet guide vanes.
Implementation Method 1
adjusting a position of a rotation axis of the respective variable inlet guide vanes such that in use a flow direction of air passing around each strut forms a wake which is then substantially redirected by a variable inlet guide vane
Data Source
AI summary
A strut and IGV configuration in a gas turbine engine positioned at an upstream of a rotor includes a plurality of radial struts, for example for bearing engine loads, and a plurality of inlet guide vanes positioned axially spaced apart from the struts. The number of inlet guide vanes is greater than the number of struts. The struts are circumferentially aligned with the inlet guide vanes.