Gas Turbine Outlet Guide Vanes with Variable Thickness

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Solution Overview

Problem

Conventional outlet guide vanes in gas turbine engines are primarily designed for aerodynamic considerations, leading to structural weaknesses and the need for additional support vanes to handle axial and torsional loading, which increases complexity and aerodynamic losses.

Innovation Solution

The design of outlet guide vanes with varying thickness to chord ratios, particularly thickening the root and tip, allows for increased structural support and stiffness while minimizing aerodynamic losses by concentrating the thickness increase in regions with more airflow room, enabling the vanes to handle greater torque loading and potentially omitting structural support vanes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If outlet guide vanes are designed with conventional uniform thickness for aerodynamic considerations, then aerodynamic performance is maintained, but structural strength and stiffness are insufficient to handle axial and torsional loading

Engineering Contradiction:
Improvestructural strengthVSAvoidaerodynamic losses
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The patent applies local quality by varying the thickness of outlet guide vanes along their span. The root portion (inner 20-30% span) has increased thickness (0.06-0.08 thickness-to-chord ratio) to handle axial and torsional loading, while the tip portion maintains thinner dimensions (0.03-0.05 thickness-to-chord ratio) to minimize aerodynamic losses. This localized thickness variation optimizes both structural strength where needed and aerodynamic efficiency where critical.

Inventive Principle:
Principle #3Local quality

2Strength

If additional structural support vanes are added to handle loading, then structural strength is improved, but device complexity and aerodynamic losses increase

Engineering Contradiction:
Improvestructural strengthVSAvoidnumber of support vanes
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent makes the outlet guide vanes multi-functional by designing them to simultaneously perform aerodynamic guidance and structural load-bearing functions. The thickened root portion (0.06-0.08 thickness-to-chord ratio) enables the vanes to directly support axial and torsional loading without requiring separate structural support vanes, thereby reducing device complexity while maintaining or improving overall strength.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Stability of the object's composition

If vane thickness is increased to improve structural stiffness, then tangential stiffness is improved, but aerodynamic losses increase

Engineering Contradiction:
Improvetangential stiffnessVSAvoidaerodynamic losses
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent applies local quality by concentrating thickness increases specifically in the root portion (inner 20-30% span) where tangential stiffness is most critical for handling torque loading. The tip portion maintains thinner dimensions (0.03-0.05 thickness-to-chord ratio) to preserve aerodynamic efficiency. This localized approach achieves the required 30-50% increase in tangential stiffness while minimizing aerodynamic penalties.

Inventive Principle:
Principle #3Local quality

4Length of moving object

If the engine is made axially more compact, then engine length is reduced, but structural support requirements increase

Engineering Contradiction:
Improveaxial lengthVSAvoidstructural support
Core Design Contradiction:
Length of moving objectVSStrength

Solution Approach 1:

The patent changes the thickness parameter of the outlet guide vanes, increasing the thickness-to-chord ratio in the root portion to 0.06-0.08 (compared to conventional 0.04-0.06). This parameter change enables the vanes to bear structural loads directly, allowing the engine to achieve axial compactness without compromising structural support capabilities.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3594447B1Gas turbine engine outlet guide vanes
Publication Date: 2021.04.28 ROLLS ROYCE PLC
  • EP3594447B1 patent drawingFigure 1~2
  • EP3594447B1 patent drawingFigure 3~4
  • EP3594447B1 patent drawingFigure 5~6

AI summary

The present disclosure relates to outlet guide vanes in a gas turbine engine, and in particular to such vanes with particular ranges of relative dimensions. Example embodiments include a gas turbine engine (10) comprising a plurality of outlet guide vanes (31) each having a length extending across a bypass duct (22) of the gas turbine engine (10), wherein for each outlet guide vane a minimum thickness to chord ratio is less than 80% of a maximum thickness to chord ratio.