Turbine Casing Arms with Orifices for Flow Control

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Solution Overview

Problem

Existing support casings for axial turbine engines face a trade-off between mechanical strength and minimal disruption to annular flows, as thickened casing arms are necessary for structural support but can disrupt airflow, reducing engine efficiency.

Innovation Solution

A support casing design featuring an outer annular wall, an inner hub, and an annular row of arms with strategically placed orifices that reduce the width of the arms downstream, minimizing flow disruption while maintaining mechanical strength, and potentially being integrally cast for simplicity and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If casing arms are thickened and increased in number to improve mechanical strength, then structural support capability is improved, but flow disruption increases and engine efficiency deteriorates

Engineering Contradiction:

Improvemechanical strength of casing armsVSAvoidengine efficiency

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The casing arms incorporate orifices (openings) that create a porous structure, allowing annular flow to pass through the arms rather than being blocked by solid material. This reduces flow disruption and vortex formation while maintaining structural integrity through the distributed pattern of openings.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The arms exhibit varying thickness and orifice distribution along their length, with the widest section positioned upstream and gradual thinning downstream. Orifices are strategically placed at specific locations to optimize both structural strength in critical areas and flow passage in other areas, creating local variations in properties to satisfy conflicting requirements.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If casing arms are made thinner to reduce flow disruption, then engine efficiency is improved, but mechanical strength deteriorates

Engineering Contradiction:

Improveengine efficiencyVSAvoidmechanical strength of casing arms

Core Design Contradiction:

Loss of energyVSStrength

Solution Approach 1:

By introducing orifices throughout the arm structure, the design achieves sufficient structural strength without requiring the arm to be completely solid. The porous configuration allows the arm to be thinner overall while maintaining load-bearing capacity through the distributed pattern of openings that reduce stress concentration.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The design adds the dimension of flow passage through the arm thickness by incorporating orifices, transforming the arm from a purely two-dimensional structural element to a three-dimensional component that simultaneously provides structural support and flow passage capabilities.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If leading faces with flow extraction scoops are added to casing arms, then flow control is improved, but device complexity and flow disruption increase

Engineering Contradiction:

Improveflow control capabilityVSAvoidcasing arm structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention extracts the flow control function from separate scoops and shutters and integrates it directly into the arm structure itself through the orifices. This eliminates the need for additional movable components while maintaining the ability to influence flow characteristics through the fixed orifice geometry.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The orifices in the casing arms automatically perform flow regulation without requiring external control mechanisms. The flow passes through the orifices based on pressure differential and geometric constraints, providing self-regulating flow control that simplifies the overall system.

Inventive Principle:

Principle #25Self-service

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 design reduces vortex amplification in boundary layers, preserving flow efficiency by minimizing disturbances and allowing for easier maintenance and inspection, while maintaining the mechanical strength of the arms, hub, and wall.

Implementation Method 1

the orifices being configured to allow suction of part of the primary flow, in particular at the level of the annular surfaces

Methodology Applied

Scientific EffectBoundary layer suction: Boundary Layer Suction

Data Source

PatentUS10443416B2Casing with suction arm for axial turbine engine

Publication Date: 2019.10.15 SAFRAN AERO BOOSTERS SA

AI summary

The invention concerns a support casing (24) for a rotor (12) of a turbine engine such as a ducted fan turbojet engine used for propulsion of an aircraft. The casing (24) comprises: an outer annular wall (38) with an inner annular surface (44); an inner hub (40) able to support the rotor (12) of the axial turbine engine and comprising an outer annular surface (42); an annular passage (46) between the annular wall (38) and the inner hub (40); an annular row of arms (48) passing radially through the annular passage (46). Each arm (48) of the casing (24) comprises an orifice (50) arranged in the annular passage (46) radially at the level of one of said annular surfaces (42; 44). Inserts are fitted to the orifices (50) to control the flow passing through.