Non-Constant Riblet Blade Surface for Variable Airflow Drag Reduction

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Solution Overview

Problem

Existing solutions for reducing drag on turbomachine blades either fail to effectively adapt to varying airflow speeds or complicate the manufacturing process with complex riblet forms.

Innovation Solution

A turbomachine part with a wall divided into three zones: a first zone, a second zone, and a transition zone, where riblets on the first and second zones have constant dimensions, and the transition zone's dimensions evolve to match the second zone's, ensuring easy manufacturing and optimal drag reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If riblets have constant form along the blade, then manufacturing is easy, but drag reduction is not effective due to non-constant flow speed

Engineering Contradiction:

Improvemanufacturing of ribletsVSAvoiddrag of blades

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The riblets are designed with varying dimensions (height, width, spacing) along the blade surface, specifically adapted to local flow conditions. The riblet form changes from the leading edge to the trailing edge to match the non-constant flow speed distribution, with smaller riblets in high-speed regions and larger riblets in low-speed regions, optimizing drag reduction at each location.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The riblet configuration transitions from static constant dimensions to dynamic varying dimensions along the blade. The riblet parameters (height, width, spacing) are designed to evolve continuously or in steps along the flow direction, adapting to the changing flow conditions rather than maintaining a fixed form throughout.

Inventive Principle:

Principle #15Dynamics

2Loss of energy

If riblets have different forms in different zones, then drag reduction is effective, but manufacturing is substantially complicated

Engineering Contradiction:

Improvedrag of bladesVSAvoidmanufacturing of riblets

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The blade surface is divided into multiple zones (first zone, second zone, transition zone) with distinct riblet configurations. Each zone has riblets with specific dimensions optimized for local flow conditions, allowing systematic variation while maintaining manufacturability through modular design and clear zone boundaries.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The riblet parameters (height, width, spacing) are systematically varied across different zones of the blade. The first zone has one set of dimensions, the second zone has another set, and the transition zone provides a gradual or stepped transition between them, enabling adaptation to flow speed variations while maintaining manufacturing feasibility.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If transition zone has evolving riblet form, then drag reduction adapts to flow speed, but manufacturing complexity increases

Engineering Contradiction:

Improveadaptation to flow speedVSAvoidmanufacturing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The transition zone is defined as a distinct segment between the first and second zones, with its own specific riblet configuration. This segmentation allows the transition zone to handle the complexity of form evolution separately, while the first and second zones maintain simpler constant configurations, balancing adaptability with manufacturability.

Inventive Principle:

Principle #1Segmentation

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 reduces drag by adapting riblet form to airflow speed while simplifying the manufacturing process, maintaining a consistent spacing-to-height ratio across zones.

Implementation Method 1

an array of riblets is formed on the first zone, on the second zone, and also on the transition zone... the height, the width, and the spacing of the riblets formed on the first zone being constant on the first zone... the height, the width, and the spacing of the riblets formed on the second zone being constant on the second zone

Methodology Applied

Scientific EffectBoundary layer control: Boundary Layer

Data Source

PatentUS11220326B2Part and method for producing a part having reduced drag by non-constant riblets

Publication Date: 2022.01.11 SAFRAN AIRCRAFT ENGINES SAS

AI summary

Part comprising a wall which comprises a first zone (541), a first zone (541) and the second zone (542), a network of riblets being formed on the first zone (541), the second zone (542) and also on the transition zone (54t) so as to reduce the drag of the part when a flow of air flows along said wall; the height, the width and the spacing of the riblets formed on the transition zone (54t) changing along said transition zone (54t) so as to pass from the height, width and spacing of the riblets formed on the first zone at a first end of the transition zone to the height, width and spacing of the riblets formed on the second zone (542) at a second end of the transition zone (54t), the transition zone (54t) comprising a central portion on which the riblets comprise on one hand the height and the width that are respectively equal to the height and width of the riblets on the first zone (541), and on the other hand a spacing equal to the spacing of the riblets of the second zone (542).