Stator Vane Pitch Variation for Aircraft Engine FOD Shielding

Solution Overview

Problem

Aircraft engines are susceptible to foreign object damage (FOD) at the leading edges of downstream stator vanes due to varying numbers and clocking of upstream and downstream stator vanes, exposing sensitive sections to impact, leading to performance loss and imbalance.

Innovation Solution

Varying the pitch between downstream stator vanes to shield exposed sections by upstream stator vanes, ensuring major portions of leading edges are circumferentially overlapped, reducing vulnerability to FOD without redesigning the vanes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the number of upstream and downstream stator vanes is made equal with uniform spacing, then the structure is simple and easy to manufacture, but the downstream stator vanes are exposed to foreign objects through the spacing between upstream vanes, leading to foreign object damage

Engineering Contradiction:

Improveresistance to foreign object damageVSAvoidvane pitch distribution complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by creating different pitch distributions in different regions of the downstream stator vane row. Specifically, vanes in the first circumferential region have a different pitch than vanes in the second circumferential region, allowing each region to be optimized for its specific function: the first region for protection against foreign objects and the second region for maintaining aerodynamic performance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces asymmetry by breaking the uniform spacing pattern of downstream stator vanes. The pitch between adjacent downstream vanes varies depending on their circumferential position, creating an asymmetric distribution that strategically shields vulnerable leading edges from foreign object ingress while maintaining overall system functionality

Inventive Principle:

Principle #4Asymmetry

2Reliability

If the pitch between downstream stator vanes is varied to shield leading edges, then protection against foreign object damage is improved, but the manufacturing and assembly complexity increases

Engineering Contradiction:

Improveprotection of leading edgesVSAvoidvane installation complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent segments the downstream stator vane row into distinct circumferential regions with different pitch characteristics. The first circumferential region (spanning approximately 120 degrees) has vanes positioned to maximize shielding, while the second region has vanes positioned for optimal aerodynamic performance. This segmentation allows differentiated optimization without requiring complete redesign of all vanes

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the pitch parameter of downstream stator vanes selectively based on circumferential position. Rather than uniformly changing all vane parameters, the pitch is modified only in specific regions where it provides the most benefit for foreign object protection, while maintaining standard pitch in other regions to simplify manufacturing

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If all downstream stator vanes are made identical with uniform pitch, then manufacturing is simplified, but aerodynamic performance may be compromised due to exposed leading edges requiring protective design modifications

Engineering Contradiction:

Improvevane production simplicityVSAvoidaerodynamic performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by creating different pitch distributions in different regions of the downstream stator vane row. Specifically, vanes in the first circumferential region have a different pitch than vanes in the second circumferential region, allowing each region to be optimized for its specific function: the first region for protection against foreign objects and the second region for maintaining aerodynamic performance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces asymmetry by breaking the uniform spacing pattern of downstream stator vanes. The pitch between adjacent downstream vanes varies depending on their circumferential position, creating an asymmetric distribution that strategically shields vulnerable leading edges from foreign object ingress while maintaining overall system functionality

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentEP4286648B1Aircraft engine with vane row having vanes with differing pitch

Publication Date: 2026.03.25 PRATT & WHITNEY CANADA CORP

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AI summary

An aircraft engine (10), has: an upstream stator (30) having upstream stator vanes (31) circumferentially distributed about a central axis (11); and a downstream stator (40) having downstream stator vanes (41) circumferentially distributed about the central axis (11), the downstream stator (40) located downstream of the upstream stator (30) relative to an airflow flowing within a core gaspath (24) of the aircraft engine (10), a number of the upstream stator vanes (31) being different than a number of the downstream stator vanes (41), major portions of leading edges (41A) of the downstream stator vanes (41) circumferentially overlapped by the upstream stator vanes (31), the downstream stator vanes (41) including: a first pair (44) of circumferentially adjacent vanes of the downstream stator vanes (41) spaced apart by a first pitch (P1), and a second pair (45) of circumferentially adjacent vanes of the downstream stator vanes (41) spaced apart by a second pitch (P2) different than the first pitch (P1).